We provide moving charges and magnetism practice exercises, instructions, and a learning material that allows learners to study outside of the classroom. We focus on moving charges and magnetism skills mastery so, below you will get all questions that are also asking in the competition exam beside that classroom.

#### List of moving charges and magnetism Questions

Question No | Questions | Class |
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1 | In figure,the cube is ( 40.0 mathrm{cm} ) on each edge.Four straight segments of wire ( a b, b c, c d ) and ( d a ) form a closed loop that carries a current ( mathrm{I}=5.00 mathrm{A}, ) in the direction shown.A uniform magnetic field of magnitude ( B=0.020 mathrm{T} ) is in the positive y-direction.Determine the magnitude and direction of the magnetic force on each segment |
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2 | Only the current inside the Amperian loop contributes in A. finding magnetic field at any point on the Ampere’s loop B. line integral of magnetic field ( c . ) in both of the above D. in neither of them |
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3 | Magnetic field at a point on the line of current carrying conductor is A. maximum B. infinity c. zero D. finite value |
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4 | A wire is bent in the form of a semicircle of radius ( r ) and carries a current of ( i ) The magnetic induction at the centre of the semicircle is A ( cdot frac{mu_{o} i}{2 r} ) в. ( frac{mu_{o} i}{8 r} ) c. ( frac{mu_{o} i}{4 r} ) D. ( frac{mu_{o} i}{r} ) |
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5 | A tiny bar magnet is kept close to a long current carrying straight wire placed along the z axis. When the center of the magnet is at ( (a, 0.0) ) and it is oriented along the z axis, it experiences A. no net force but a net torque. B. neither net force nor net torque c. both a net force and a net torque. D. a net force but no net torque |
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6 | An electron beam passes through a magnetic field of ( 2 times 10^{-3} W b / m^{2} ) and an electric field of ( 1.0 times 10^{4} V / m ) both acting simultaneously. The path of electron remains undeviating. The speed of electron if the electric field is removed, and the radius of electron path will be respectively. A ( cdot 10 times 10^{6} m / s, 2.43 ) В. ( 2.5 times 10^{6} mathrm{m} / mathrm{s}, 0.43 ) c. ( 5 times 10^{6} mathrm{m} / mathrm{s}, 1.43 ) D. None of these |
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7 | A rectangular coil ( 3 times 3 mathrm{cm} ) consisting of 100 turns caries 0.1 A. If it produces a deflection ( 10^{0}, ) in a field of induction ( 0.1 T, ) the couple per unit twist is A ( cdot 9 times 10^{-2} mathrm{Nm} / ) Degree B. ( 9 times 10^{-5} mathrm{Nm} / ) Degree C. ( 9 times 10^{-2} mathrm{Nm} / mathrm{rad} ) D. ( 0.9 mathrm{Nm} / ) Degree |
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8 | An electron having a charge e moves with a velocity v in X-direction. A magnetic field acts on it in Y-direction. The force on the electron acts in A. positive direction of Y-axis B. negative direction of Y-axis c. positive direction of Z-axis D. negative direction of Z-axis |
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9 | An electron of charge ( e ) and mass ( m ) is moving in a circular loop of radius ( boldsymbol{r} ) with a uniform angular speed ( omega . ) Then which of the following statements are correct? This question has multiple correct options A. The equivalent current flowing in the circular path is proportional to ( r^{2} ) B. The magnetic moment due to circular current loop is independent of ( m ) C. The magnetic moment due to circular loop is equal to ( 2 e / m ) times the angular momentum of the electron D. The angular momentum of the particle is proportional to the areal velocity of electron |
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10 | Assertion A beam of protons is moving towards east in vertically upward magnetic field.Then,this beam will deflect towards south. Reason A constant magnetic force will act on the proton beam. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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11 | 7. A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 V, the resistance (in 2) needed to be connected in series with the coil will be (a) 9995 (b) 99995 (c) 100 (d) 103 (AIEEE 2005) |
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12 | A conducting loop carrying a current is placed in a uniform magnetic field acting perpendicular to the plane of the coil shown in figure. the loop will have a tendency to A. contract B. expand c. move towards positive X-axis D. move towards positive Y-axis |
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13 | The most suitable material to be used as the core of an electromagnet is (soft, hard) iron. |
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14 | The magnetic force between the infinite wire and the square loop is A ( frac{mu_{0} i^{2}}{4 pi}, ) repulsiv B. ( frac{mu_{0} i^{2}}{2 pi}, ) repulsive C ( frac{mu_{0} i^{2}}{4 pi}, ) attractive D. ( frac{mu_{0} i^{2}}{2 pi}, ) attractive |
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15 | A rectangular coil of wire of 500 turns of area ( 10 times 5 c m^{2} ) carries a current of ( 2 A ) in a magnetic field of induction ( 2 times ) ( 10^{-3} T . ) If the plane of the coil is parallel to the field. The torque on the coil is (in ( N m) ) A . 0.1 B. 0.01 c. 0.001 D. |
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16 | Find the distance ( x_{0} ) to the point on the axis at which the value of ( B ) differs by ( eta=1 % ) from that in the middle section of the solenoid. A ( . x_{0} approx R ) в. ( x_{0} approx 7 R ) ( mathbf{c} cdot x_{0} approx 5 R ) D. ( x_{0} approx 3 R ) |
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17 | A conducting bar with mass ( mathrm{m} ) and length L slides over horizontal rails that are connected to a voltage source. The voltage source maintains a constant current I in the rails and bar, and a constant, uniform, vertical magnetic field ( vec{B} ) fills the region between the rails (as shown in fig). Find the magnitude and direction of the net force on the conducting bar. Ignore friction, air resistance and electrical resistance : A. ILB, to the right B. ILB, to the left c. ( 21 L ) B, to the right D. 2ILB, to the left |
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18 | You are required to make an electromagnet from a soft iron bar by using a cell, an insulated coil of copper wire and a switch. Label the poles of the electromagnet. |
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19 | What is a toroid? Mention an expression for magnetic field at a point inside a toroid? |
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20 | The distance between the wires of electric mains is ( 12 mathrm{cm} . ) These wires exprience 4 mgwt per unit length. The value of current flowing in each wire will be if they carry current in same direction A . ( 4.85 mathrm{A} ) B. zero ( mathbf{c} cdot 4.85 times 10^{-2} A ) D. ( 85 times 10^{-4} A ) |
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21 | The value of ( mu ) is ( 4 pi times 10^{-7} H m^{-1} ) A. True B. False |
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22 | The magnetic filed (dB) due to smaller element (dl) at a distance ( (vec{r}) ) from element carrying current i, is ( ^{mathbf{A}} cdot d B=frac{mu_{0} i}{4 pi}left(frac{vec{d} l times vec{r}}{r}right) ) B. ( d B=frac{mu_{0} i}{4 pi} i^{2}left(frac{vec{d} l times vec{r}}{r^{2}}right) ) ( ^{mathbf{c}} d B=frac{mu_{0} i^{3}}{4 pi} ileft(frac{vec{d} l times vec{r}}{2 r^{2}}right) ) ( ^{mathrm{D}} d B=frac{mu_{0}}{4 pi} ileft(frac{vec{d} l times vec{r}}{r^{3}}right) ) |
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23 | ( x ) ( x ) 0 ( w ) |
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24 | Which of the following statement is not correct about two parallel conductors carrying equal currents in the same direction? A. each of the conductors will experience a force B. the two conductors will repel each other C. there are concentric lines of force around each conductor D. each of the conductors will move if not prevented from doing so |
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25 | A solenoid of length ( 0.4 m ) and diameter ( 0.6 m ) consists of a single layer of 1000 turns of fine wire carrying a current of ( mathbf{5} times mathbf{1 0}^{-mathbf{3}} ) A. Calculate the magnetic field on the axis at the middle and at the end of the solenoid: A ( cdot 8.7 times 10^{-6} T, 6.28 times 10^{-6} T ) B . ( 6.28 times 10^{-6} T, 8.7 times 10^{-6} T ) D. ( 8.7 times 10^{-6} T, 8.28 times 10^{-6} T ) |
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26 | A solenoid of length ( 0.4 m ) and having 500 turns of wire carries a current of 3 amp. Calculate the torque required to hold a coil (having radius ( 0.02 mathrm{cm} ) current ( 2 A ) and turns 50 ) in the middle of the solenoid with its axis perpendicular to the axis of the solenoid. ( left(pi^{2}=10right) ) |
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27 | A proton is moving with velocity ( 10^{4} m / s ) parallel to the magentic field of intensity 5 tesla.The force on the proton is A. ( 8 times 10^{-15} N ) B . ( 10^{4} N ) c. ( 1.6 times 10^{-19} N ) D. zero |
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28 | Protons and ( alpha ) -particles of equal momenta enter a uniform magnetic field normally. The radii of their orbits will have the ratio ( A ) B. 2 c. 0.5 ( D ) |
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29 | The direction of the force on a current- carrying wire placed in a magnetic field depends on A. the direction of the current B. the direction of the field c. the direction of the current as well as field D. neither the direction of current nor the direction of field |
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30 | A solenoid of inductance ( 2 mathrm{H} ) carries a current of ( 1 A . ) What is the magnetic energy stored in a solenoid? A . 2 B . 1 J c. 4 J D. 5 J |
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31 | A solenoid of length ( 1.5 mathrm{m} ) and ( 4 mathrm{cm} ) diameter possesses 10 turns per ( mathrm{cm} . ) A current of ( 5 mathrm{A} ) is flowing through it, the magnetic induction at axis inside the solenoid is ( left(mu_{0}=4 pi timesright. ) ( left.10^{-7} w e b e r a m p^{-1} m^{-1}right) ) A ( cdot 4 pi times 10^{-5} ) gauss В . ( 2 pi times 10^{-5} ) gauss c. ( 4 pi times 10^{-5} ) tesla D. ( 2 pi times 10^{-5} ) tesla |
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32 | Draw the magnetic field lines for a current carrying solenoid when a rod made of (i) copper, (ii) aluminium and (iii) iron are inserted within the solenoid as shown. |
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33 | Toroid is A. ring shaped closed solenopid B. rectangular shaped solenoid C. ring shaped open solenoid D. square shaped solenoid |
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34 | A cyclotron is used to accelerate A. Neutron B. Only positively charged particles C . Only negatively charged particles D. Both positively and negatively charged particles |
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35 | Find out the arrow or arrows which give the direction of a force vector. A. Arrow A only B. Arrow B only c. Arrow c only D. Arrows A and D E. Arrows B and E |
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36 | If a charged particle goes unaccelerated in a region containing electric and magnetic fields This question has multiple correct options A. ( vec{E} ) must be perpendicular to ( vec{B} ) B . ( vec{v} ) must be perpendicular to ( vec{E} ) c. ( vec{v} ) must be perpendicular to ( vec{B} ) D. ( E ) must be equal to ( v B ) |
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37 | (a) State Ampere’s circuital law. Use this law to obtain the expression for the magnetic field inside an air cored toroid of average radius r having ‘n’ turns per unit length and carrying a steady current I (b) An observer to the left of a solenoid of N terms each of cross section area ( A ) observes that a steady current lin it flows in the clockwise direction. Depict the magnetic field lines due to the solenoid specifying its polarity and show that it acts as a bar magnet of magnetic momentum ( boldsymbol{m}=boldsymbol{N} boldsymbol{I} boldsymbol{A} ) |
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38 | A closely wound solenoid ( 80 mathrm{cm} ) long has 5 layers of winding of 400 turns each. The diameter of the solenoid is 1.8 ( c m . ) If the current ( 8.0 A ) flows in it the magnitude of magnetic field inside the solenoid near its centre will be ( mathbf{A} cdot 8 pi times 10^{-3} T ) В . ( 6 pi times 10^{-3} T ) c. ( 4 pi times 10^{-3} T ) D. ( 3 pi times 10^{-3} T ) |
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39 | The deflection in a moving coil galvanometer falls from 50 divisions to 10 divisions when a shunt of ( 20 Omega ) is connected with it. The resistance of galvanometer coil is? A . ( 48 Omega ) B . ( 50 Omega ) ( mathbf{c} .52 Omega ) D. ( 30 Omega ) |
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40 | A coil of insulated wire is connected to a battery. If it is taken to a galvanometer, its pointer is deflected, because A. induced current is produced in the galvanometer coil B. the coil acts like a magnet c. the number of turns in the coil of the galvanometer are changed D. none of the above |
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41 | The magnetic field at a distance x on the axis of a circular coil of radius ( mathrm{R} ) is ( frac{1}{8} ) th of that at the centre.The value of ( x ) is A ( cdot frac{R}{sqrt{3}} ) в. ( frac{2 R}{sqrt{3}} ) c. ( R sqrt{3} ) D. ( R sqrt{2} ) |
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42 | A long solenoid of length ( L ) has a mean diameter ( D . ) It has ( n ) layers of winding of ( N ) turns each. If it carries a current ( I ) the magnetic field at its centre will be. A. Proportional to ( D ) B. Inversely proportional to ( D ) c. Independent of ( D ) D. Proportional to L. |
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43 | A steady current flows in a long wire. It is bent into a circular loop of one turn and the magnetic field at the centre of the coil is ( B ). If the same wire is bent into a circular loop of ( n ) turns, the magnetic field at the centre of the coil is: A ( cdot frac{B}{n} ) в. ( n B ) ( c cdot n B^{2} ) D . ( n^{2} B ) |
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44 | According to Ampere’s swimming rule, if a man swims along a direction opposite to the direction of the current, south pole of the needle deflects towards his |
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45 | A rectangular loop carrying a current ( i ) is placed in a uniform magnetic field ( B ). The area enclosed by the loop is ( A ). If there are ( n ) turns in the loop, the torque acting on the loop is given by ( mathbf{A} cdot n i(bar{A} times bar{B}) ) в. ( n i(overline{A . bar{B}}) ) ( frac{i(bar{A} times bar{B})}{n} ) D. ( frac{i(bar{A} . bar{B})}{n} ) |
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46 | If a beam of electrons travels in a straight line in a certain region.Can we say there is no magnetic field? |
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47 | In a moving-coil instrument, the coil is suspended in a radial magnetic field instead of a uniform magnetic field This is done to : A. Increase the sensitivity of the instrument B. increases the accuracy of the instrument c. make the instrument compact and protable D. make its deflection proportinal to current through it |
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48 | A current-carrying wire in a magnetic field is subjected to a magnetic force. If the current in the wire is quadrupled. Find out the change in magnetic force acting on the wire? A. It is quartered B. It is halved c. It is unchanged D. It is doubled E. It is quadrupled |
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49 | In an expt, a beam of electron passes undeviated through mutually perpendicular elec. and mag fields of respective strength ( boldsymbol{E}=mathbf{7 . 2} times ) ( 10^{6} N C^{-1} ) and ( B=2.4 ) T. The velocity of the electron is ( mathbf{A} cdot 17.3 times 10^{7} m s^{-1} ) B . ( 3 times 10^{6} m s^{-1} ) c. ( 2 times 10^{6} m s^{-1} ) D. ( 6 times 10^{6} mathrm{ms}^{-1} ) |
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50 | Two parallel wires carrying current in the same direction attract each other because of A. potential difference between them B. mutual inductance between them c. electric forces between them D. magnetic forces between them |
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51 | A conductor ( A B C D E F, ) shaped as shown, carries a current i. It is placed in the ( x y ) plane with the ends ( A ) and ( E ) on the ( x ) -axis. A uniform magnetic field of magnitude ( B ) exists in the region. The force acting on it will be : This question has multiple correct options A. zero, if ( B ) is in the ( x ) -direction B. ( lambda B i ) in the ( z ) -direction, if ( B ) is in the ( y ) -direction C. ( lambda B i ) in the negative ( y ) -direction, if ( B ) is in the ( z- ) direction D. ( 2 a B i ), if ( B ) is in the ( x ) -direction |
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52 | In toroid magnetic field on axis will be radius ( =0.5 mathrm{cm}, ) current ( =1.5 mathrm{A}, ) turns ( =250, ) permeability ( =700 ) ( mathbf{A} cdot 7.5 ) Tesla B. 10.5 Tesla c. 4.5 Tesla D. 15.5 Tesla |
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53 | Assertion When two long parallel wires, hanging freely are connected in series to a battery, they come closer to each other. Reason Wires carrying current in opposite direction repel each other. A. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion. B. Both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
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54 | Assertion The magnetic force on the closed loop in fig is zero Reason Force (magnetic) on the wire is ( int d F= ) ( int i d vec{l} times vec{B} ) A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
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55 | Two infinitely long current carrying conductors ( X ) and ( Y ) are kept parallel to each other, ( 24 mathrm{cm} ) apart in vacuum They carry currents of ( 5 mathrm{A} ) and ( 7 mathrm{A} ) respectively, in the same direction, as shown in Figure above. Find the position of a neutral point, i.e. a point where resultant magnetic flux density is zero. (Ignore earth’s magnetic field) |
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56 | A wire is lying horizontally in the north south direction and there is a horizontal magnetic field pointing towards the east. Some positive charges in the wire move north and an equal number of negative charges move south. The direction of force on the wire will be : A. East B. Down, into the page. c. Up, out of the page D. west |
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57 | Two long straight wires of length ( l ) lie parallel to one another and carry currents opposite to one another of magnitudes ( i_{1} ) and ( i_{2} ) respectively. The force experienced by each of the straight wires is ( (r ) is the distance of their separation) A . repulsive and equal to ( left(mu_{0} / 2 piright)left(i_{1} i_{2} l / rright) ) B. attractive and equal to ( ( left.mu_{0} / 2 piright)left(i_{1} i_{2} l^{2} / rright) ) c. repulsive and equal to ( left(mu_{0} / 2 piright)left(i_{1} i_{2} l^{2} / rright) ) D. attractive and equal to ( left(mu_{0} / 2 piright)left(i_{1} i_{2} l / rright) ) |
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58 | A conducting circular loop of radius carries a constant current i. It is placed in a uniform mangetic field ( vec{B}_{0} ) such that ( vec{B}_{0} ) is perpendicular to the plane of the loop. The magnetic force acting on the loop is A . ir ( B_{0} ) В . ( 2 pi ) ir ( B_{0} ) c. zero ( mathbf{D} cdot pi ) ir ( B_{0} ) |
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59 | Write Biot-Savart law. Write the path of motion of an electron when it enters in magnetic field at (a) perpendicular (b) an angle ( boldsymbol{theta} ) |
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60 | A magnet of moment ( 4 mathrm{Am}^{2} ) is kept suspended in a magnetic field of induction ( 5 times 10^{-5} T . ) The workdone in rotating it through ( 180^{0} ) is ( mathbf{A} cdot 4 times 10^{-4} J ) В. ( 5 times 10^{-4} J ) c. ( 2 times 10^{-4} J ) D. ( 10^{-4} J ) |
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61 | Electrons move at right angles to a magnetic field of ( 0.03 mathrm{T} ) and enter with a velocity ( 9 times 10^{7} m / s . ) The value of e ( / mathrm{m} ) will be: (Given radius of circular path = ( 1.764 mathrm{cm} ) A ( cdot 1.7 times 10^{11} mathrm{Ckg}^{-1} ) В . ( 2 times 10^{11} mathrm{Ckg}^{-} ) c. ( 2.5 times 10^{11} mathrm{Ckg}^{-1} ) D. none of these |
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62 | The above figure shows a toroidal solenoid whose cross-section is rectangular. Find the magnetic flux (in ( mu W b) ) through this cross-section if the current through the winding equals ( I=1.7 A ) the total number of turns is ( N=1000, ) the ratio of the outside diameter to the inside one is ( eta=1.6 ) and the height is equal to ( h=5.0 mathrm{cm} ) |
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63 | An electric current runs counterclockwise in a rectangular loop around the outside edge of the page which lies flat on your table. A uniform magnetic field is then turned on directed parallel to the page from the top to bottom. The magnetic force on the page will cause: A. the left edge to lift up B. the right edge to lift up c. the top edge to lift up D. the bottom edge to lift up |
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64 | Assertion A charged particle is moving in a circular path under the action of uniform magnetic field as shown in fig. During motion kinetic energy of charged particle is constant. Reason During the motion, magnetic force acting on the particle is perpendicular to instantaneous velocity. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
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65 | A magnetic needle lying parallel to a magnetic field requires W units of work to turn it through ( 60^{0} ). The torque needed to maintain the needle in this position will be: A ( cdot sqrt{3} mathrm{W} ) B. ( W ) c. ( sqrt{3 / 2} mathrm{W} ) D. 2w |
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66 | Two long and parallel straight wires ( A ) and B are carrying currents of 4 A and 7 A in the same direction are separated by a distance of ( 5 mathrm{cm} . ) The force acting on an ( 8 mathrm{cm} ) section of wire ( mathrm{A} ) is: A ( cdot 3 times 10^{-6} N ) B . ( 6 times 10^{-6} N ) c. ( 9 times 10^{-6} N ) D. ( 12 times 10^{-6} N ) |
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67 | A tangent galvanometer has 80 turns of wire. The internal and external diameters of the coil are ( 19 mathrm{cm} ) and ( 21 mathrm{cm} ) respectively. The reduction factor of the galvanometer at a place where ( boldsymbol{H}=mathbf{0 . 3 2} ) oersted will be (1 oersted ( = ) ( mathbf{8 0} boldsymbol{A} / boldsymbol{m}) ) A .0 .0064 B. 0.64 ( c cdot 0.064 ) D. None of these |
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68 | If the magnetic dipole moment of an atom of diamagnetic material, paramagnetic material and ferromagnetic material are denoted by ( mu_{d}, mu_{p} ) and ( mu_{f} ) respectively, then ( mathbf{A} cdot mu_{p}=0 ) and ( mu_{f} neq 0 ) B . ( mu_{d} neq 0 ) and ( mu_{p}=0 ) C ( cdot mu_{d} neq 0 ) and ( mu_{f} neq 0 ) D. ( mu_{d}=0 ) and ( mu_{p} neq 0 ) |
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69 | A particle moving towards south in a vertically downward magnetic field is deflected toward the east.What is the sign of the charge on the particle? |
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70 | Two electrons are entering perpendicularly to the magnetic field. The velocity of one of the electrons is three times greater than the velocity of the other electron. Calculate the ratio of the circular radii of the path followed by the two electrons? A. The faster electron has a radius two times larger than the slower electron B. The faster electron has a radius three times larger than the slower electron C. The faster electron has a radius eight times larger than the slower electron D. The faster electron has a radius sixteen times larger than the slower electron E. The faster electron has a radius sixty-four times larger than the slower electron |
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71 | Two tangent galvanometers, which are identical except in their number of turns, are connected in parallel. The ratio of their resistances of the coils is 1 : 3. If the reflection in the two tangents galvanometers are ( 30^{circ} ) and ( 60^{circ} ) respectively, then the ratio of their number of turns is: A .2: 3 в. 3: 1 c. 1: 2 D. 1: 6 |
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72 | An electric current predominantly produce……………… field around it. A. magnetic B. electric c. gravitational D. all the above |
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73 | Sensitivity of a moving coil galvanometer can be increased by: A. decreasing the number of turn of coil B. increasing the number of turn of coil c. decreasing the area of a coil D. by using a week magnet |
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74 | If a current circular loop is placed in a ( x-y ) plane as shown in adjoining figure and a magnetic field is applied along z-axis, then the loop will A. Contract B. Expand c. Move towards ( -x- ) axis D. Move towards ( +x- ) axis |
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75 | The lateral surface of a long straight solenoid with ( n ) turns per unit length experiences a pressure of ( boldsymbol{p}= ) ( frac{1}{x} mu_{0} n^{2} I^{2} ) when a current ( I ) flows through it. Find ( x ) |
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76 | A long dielectric cylinder of radius ( boldsymbol{R} ) is statically polarized so that at all its points the polarization is equal to ( vec{P}= ) ( alpha vec{r}, ) where ( alpha ) is a positive constant, and ( vec{r} ) is the distance from the axis. The cylinder is set into rotation about |
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77 | The magnetic moment of current ( (boldsymbol{I}) ) carrying circular coil of radius ( (r) ) and number of turns ( (n) ) varies as A ( cdot 1 / r^{2} ) в. ( 1 / r ) ( c ) D ( cdot r^{2} ) |
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78 | A current of i ampere is flowing in an equilateral triangle of side a. The magnetic induction at the centroid will be? A ( cdot frac{mu_{i}}{3 sqrt{3} pi a} ) в. ( frac{3 mu_{i}}{2 pi a} ) ( ^{mathrm{c}} cdot frac{5 sqrt{2} mu_{i}}{3 pi a} ) D. ( frac{9 mu_{i}}{2 pi a_{i}} ) |
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79 | State and explain Ampere’s circuital law. |
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80 | What is the magnetic moment of the atom due to the motion of the electron? | 12 |

81 | A rectangular loop carrying a current ( boldsymbol{i}_{1} ) is situated near a long straight wire carrying a steady current ( i_{2} . ) The wire is parallel to one of the sides of the loop and is in the plane of the loop as shown in the figure. Then the current loop will A. move away from the wire B. move towards the wire c. remain stationary D. rotate about an axis parallel to the wirce |
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82 | A charged particle is shot at an angle ( theta ) to a uniform magnetic field along directed X-axis. Duration its motion along a helical path, whose pitch is equal to the maximum distance from ( x ) axis, the particle will : This question has multiple correct options A. Never move parallel to x-axis B. ( tan theta=2 / p i ) ( mathbf{c} cdot sin theta=1 / p i ) D. ( tan theta=pi ) |
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83 | A long horizontal wire ( boldsymbol{P} ) carries a current ( 50 A ). It is rigidly fixed. Another line wire ( Q ) is placed directly above and parallel to ( P . ) The weight of wire ( Q ) is ( 0.075 N m^{-1} ) and caries a current of ( 25 A . ) Find the position of wire ( Q ) from ( P ) so that wire to remains suspended due to the magnetic repulsion- A. ( 3.33 mathrm{mm} ) B. ( 33.3 mathrm{mm} ) c. 334 mm D. 333 mm |
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84 | A light charged particle is resolving in a circle of radius ‘r’ in electrostatic attraction of a static heavy particle with opposite charge. How does the magnetic field ‘B’ at the centre of the circle due to the moving charge depend on ‘r’? A ( cdot B propto frac{1}{r} ) в. ( B propto frac{1}{r^{2}} ) c. ( _{B} propto frac{1}{r^{frac{3}{2}}} ) D. ( B propto frac{1}{r^{frac{5}{2}}} ) |
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85 | Answer the following Questions: Name and state the rule to determine the direction of a force experienced by a straight conductor carrying placed in a magnetic field which is perpendicular to it. |
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86 | Assertion In meter bridge experiment, a high resistance is always connected in series with a galvanometer. Reason As resistance increases current through the circuit increases. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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87 | A wire of a length 2 m carrying a current of ( 1 mathrm{A} ) is bend to form a circle. The magnetic moment of the coil is ( left(i n A-m^{2}right): ) (a) ( 1 / pi ) (b) ( pi / 2 ) |
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88 | Two thin, long, parallel wires, separated by a distance ‘d’ carry a current of ‘i’ A in the same direction. They will A ( . ) repel each other with a force of ( mu_{0} i^{2} /(2 pi d) ) B. attract each other with a force of ( mu_{0} i^{2} /(2 pi d) ) C . repel each other with a force of ( mu_{0} i^{2} /left(2 pi r d^{2}right) ) D. attract each other with a force of ( mu_{0} i^{2} /left(2 pi d^{2}right) ) |
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89 | Assertion If a charged particle enters from outside at right angles in uniform magnetic field.The maximum time spent in magnetic field may be ( frac{pi m}{B q} ) Reason It can complete only semi-circle in the magnetic field. |
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90 | A uniform conduction wire of length ( 10 g ) and resistance ( R ) is wound up into four turns as a current carrying coil in the shape of equilateral triangle of side ( a . ) If current ( I ) is flowing through the coil then the magnetic moment of the coil is A ( cdot frac{sqrt{3}}{2} a^{2} I ) B. ( frac{a^{2} I}{sqrt{3}} ) c. ( sqrt{3} a^{2} I ) D. ( frac{2 a^{2} I}{sqrt{3}} ) |
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91 | When current flows in a wire, it creates field around it. Fill in the blank: A . gravitational B. magnetic c. repulsive D. attractive |
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92 | Two long conductors, separated by a distance d carry current ( I_{1} ) and ( I_{2} ) in the same direction. They exert a force ( F ) on each other. Now the current in one of them is increased to two times and its direction is reversed. the distance is also increased to 3 d. The new value of the force between them is A ( cdot-frac{2 F}{3} ) B. ( frac{F}{3} ) c. ( -2 F ) D. ( -frac{F}{3} ) |
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93 | For given current distribution, each infinite length wire produces magnetic field ( B ) at origin their resultant magnetic field at origin ( boldsymbol{O} ) is: A . ( 4 B ) В. ( sqrt{2} B ) ( c cdot 2 sqrt{2} B ) D. zero |
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94 | A square of side ( 2.0 mathrm{m} ) is placed in a uniform magnetic field ( mathbf{B}=mathbf{2 . 0} mathbf{T} ) in a direction perpendicular to the plane of the square inwards. Equal current ( mathbf{i}=mathbf{3 . 0 A} ) is flowing in the directions shown in figure. Find the magnitude of the magnetic force on the loop. |
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95 | Assertion If the current in a solenoid is reversed in direction while keeping the same magnitude, the magnetic field energy stored in the solenoid decreases. Reason Magnetic field energy density is proportional to square of current |
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96 | In which of the following situations, the magnetic field can accelerate a charge particle at rest? I. When the magnetic field is uniform with respect to time as well as position 11. When the magnetic field is time varying but uniform w.r.t position III. When the magnetic field is time independent but position dependent. A. I, II and II B. III only c. ॥ only D. None of these |
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97 | What is the strength of the electric field in the velocity selector? A ( cdot 2 times 10^{5} N C^{-1} ) B . ( 2 times 10^{3} N C^{-1} ) c. ( 2 times 10^{6} N C^{-1} ) D. ( 2 times 10^{4} N C^{-1} ) |
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98 | Choose the correct statement. A. Polar molecules have permanent electric dipole moment B. ( C O_{2} ) molecule is a polar molecule ( mathrm{C} cdot mathrm{H}_{2} mathrm{O} ) is a non-polar molecule ” The dipole field at large distances falls of as ( frac{1}{r^{2}} ) E. The dipole moment is a scalar quantity |
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99 | A magnetic field directed along ( Z ) axis varies as ( boldsymbol{B}=boldsymbol{B}_{0} boldsymbol{x} / boldsymbol{a}, ) where ( boldsymbol{B}_{0}= ) 2 tesla and ( a=1 m . ) A conducting square loop of side ( ell=frac{1}{2} m ) is placed with its edges parallel to ( X ) and ( Y ) axes. If the loop is made to move with a constant velocity ( v_{0}=6 m / s ) directed along ( X ) axis, the induced emf (in volts) in the loop is : |
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100 | A straight wire of finite length carrying current I subtends an angle of ( 60^{circ} ) at point ( P ) as shown. The magnetic field at P is: ( ^{mathrm{A}} cdot frac{mu_{0} I}{2 sqrt{3} pi x} ) B. ( frac{mu_{0} I}{2 pi x} ) c. ( frac{sqrt{3} mu_{0} I}{2 pi x} ) D. ( frac{mu_{0} I}{3 sqrt{3} pi x} ) |
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101 | When two infinitely long parallel wires separated by a distance of ( 1 m, ) each carry a current of ( 3 A ), the force in newton/metre length experienced by each will be, ( left(operatorname{given} mu_{0}=4 pi times 10^{-7} mathrm{S.I}right. ) Units). A. ( 2 times 10^{-7} ) B. ( 3 times 10^{-7} ) c ( .6 times 10^{-7} ) D. ( 18 times 10^{-7} ) |
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102 | How will two parallel beams of electron behave while moving in the same direction? A. repel each other B. attract each other c. not interact with each other D. annihilate each other |
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103 | Assertion A charge, whether stationary or in motion produces a magnetic field around it. Reason Moving charges produce only electric field in the surrounding space. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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104 | A negatively charged particle is moving through a magnetic field as pictured below. What is the direction of the force on the particle due to the magnetic field at the instant in the picture? West A. North B. west c. East D. Up E. Down |
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105 | An arrangement with a pair of quarter circular coils of radii ( r ) and ( R ) with a common centre ( C ) and carrying a current I is shown. The permeability of free space is ( mu_{0} . ) The magnetic field at ( mathrm{C} ) is : A ( cdot mu_{0} I(1 / r-1 / R) / 8 ) into the page B. ( mu_{0} I(1 / r-1 / R) / 8 ) out the page C. ( mu_{0}(1 / r+1 / R) / 8 ) into the page D・ ( mu_{0}(1 / r+1 / R) / 8 ) out the page |
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106 | topp Q туре your question ranges, of ( 0-2 V, 0-10 V ) and 0 ( 20 V ). The appropriate circuit to do so is A ( cdot R_{1}=1900 Omega ) ( R_{2}=9900 Omega ) ( R_{3}=19900 Omega ) B . ( R_{1}=2000 Omega ) ( R_{2}=8000 Omega ) ( R_{3}=10000 Omega ) c. ( R_{1}=19900 Omega ) ( R_{2}=9900 Omega ) ( R_{3}=1900 Omega ) D. ( R_{1}=1900 Omega ) ( R_{2}=8000 Omega ) ( R_{3}=10000 Omega ) |
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107 | Assertion Increasing the current sensitivity of a galvanometer necessarily increases the voltage sensitivity. Reason Voltage sensitivity is inversely proportional to current sensitivity. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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108 | A horizontal overhead power line is at a height of ( 5 ~ m ) from the ground and carries a current of ( 100 A ) from east to west. The magnetic field directly below it on the ground is A ( cdot 2.5 times 10^{-6} T ) eastward B . ( 4 times 10^{-6} T ) eastward c. ( 5 times 10^{6} ) southward D. ( 2 times 10^{-6} ) westward |
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109 | The resultant magnetic moment due to two currents carrying concentric coils of radius ( r, ) mutually perpendicular to each other will be A. ( sqrt{2} i ) B. ( sqrt{2} i pi r^{2} ) ( mathbf{c} cdot 2 pi r^{2} ) D. ( sqrt{2} i r^{2} ) |
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110 | Q Type your question- than Segment ( 2, ) but both segments are centered on point ( P ) The segments are connected by straight |
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111 | A current of ( 2 A ) is flowing through a circular coil of radius ( 10 mathrm{cm} ) containing 100 turns. The magnetic flux density at the centre of the coil is ( left(operatorname{in} W b / m^{2}right) ) В. ( 1.26 times 10^{-2} ) c. ( 1.26 times 10^{-4} ) D. ( 1.26 times 10^{-5} ) |
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112 | A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 – divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 volt, the resistence in ohms needed to be connected in series with the coil will be A . 103 B . 10 ( c .9995 ) D. 99995 |
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113 | On connecting a battery to the two corners of a diagonal of a square conductor frame of side ( a ) the magnitude of the magnetic field at the centre will be: A . zero в. ( frac{mu_{0}}{pi a} ) c. ( frac{2 mu_{0}}{pi a} ) D. ( frac{4 mu_{0}}{pi a} ) |
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114 | toppr 5 Q Type your question ( A ) B. ( c ) ( D ) ( E ) |
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115 | Charged particle (charge= ( q ; ) mass ( = ) ( boldsymbol{m} ) ) is rotating in a circle of radius ( boldsymbol{R} ) with uniform speed ( V ), Ratio of its magnetic moment ( (mu) ) to the angular momentum ( (L) ) is ( ^{mathrm{A}} cdot frac{q}{2 m} ) в. ( frac{q}{m} ) c. ( frac{q}{4 m} ) D. ( frac{2 q}{m} ) |
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116 | If a charged particle kept at rest experiences an electromagnetic force This question has multiple correct options A. the electric field must not be zero B. the magnetic field must not be zero c. the electric field may or may not be zero D. the magnetic field may or may not be zero |
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117 | The region between ( boldsymbol{x}=mathbf{0} ) and ( boldsymbol{x}=boldsymbol{L} ) is filled with uniform, steady magnetic field ( B_{0} hat{k} . ) A particle of mass ( m, ) positive charge ( q ) and velocity ( v_{0} hat{i} ) travels along x-axis and enters the region of magnetic field. Neglect gravity throughout the question. The field now extends up to ( x=2.1 L ) If the time spent by the particle in the magnetic field is ( T=frac{pi m}{X times q B_{0}} . ) Find ( X ? ) |
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118 | The following diagram in figure shows a fixed coil of several turns connected to a centre zero galvanometer ( G ) and ( a ) magnet NS which can move in the direction shown in the diagram. How would the observation alter if a more powerful magnet is used? |
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119 | Using Biot-Savart’s law, obtain an expression for magnetic field at a distance ( r ) metre from an infinitely long wire carrying a current of ( i ) ampere. |
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120 | A vertical wire kept in Z-X plane carries a current from ( Q ) to ( P ) (see figure.). The magnetic field due to current will have the direction at the origin 0 along ( A cdot O x ) B. ox ( c cdot ) or D. or |
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121 | Cathode rays are moving between the poles of a magnet. Due to the effect of magnetic field of magnet: A. velocity of rays increase B. velocity of rays decrease c. rays deflected towards south pole D. rays deflected in upward direction and perpendicular to the plane of the paper |
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122 | A particle of charge ( q ) and mass ( m ) starts moving from origin under the action of an electric field ( vec{E}=E_{0} vec{i} ) and magnetic field ( vec{B}=B_{0} vec{k} ). Its velocity at ( (x, 3,0) ) is ( (4 i+3 i), ) the value of ( x ) is: A ( cdot frac{36 E_{o} B_{0}}{q m} ) В. ( frac{25 m}{2 q E_{0}} ) c. ( frac{10 m}{q E_{o}} ) D. ( frac{25 E_{0} B_{0}}{m} ) |
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123 | The angle made by orbital angular momentum of electron with the direction of the orbital magnetic moment is? A ( cdot 120^{circ} ) B. ( 60^{circ} ) ( c cdot 180^{circ} ) D. ( 90^{circ} ) |
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124 | The torque and magnetic potential energy of a magnetic dipole in most stable position in a uniform magnetic field( ( bar{B} ) ) having magnetic moment ( (bar{m}) ) will be. A. – mB, zero B. mB, zero c. zero, mB D. Zero, -mB |
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125 | An otherwise infinite, straight wire has two concentric loops of radii ( a ) and ( b ) carrying equal currents in opposite directions as shown in figure. The magnetic field at the common center is zero for: ( ^{mathrm{A}} cdot frac{a}{b}=frac{pi-1}{pi} ) B. ( frac{a}{b}=frac{pi}{pi+1} ) c. ( frac{a}{b}=frac{pi-1}{pi+1} ) D. ( frac{a}{b}=frac{pi+1}{pi-1} ) |
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126 | The least value of magnetic moment (where ( m ) is the mass of the electron, ( e ) is the charge of electron) is : A ( cdot frac{e h}{m} ) в. ( frac{e h}{4 pi m} ) c. ( frac{2 e h}{pi m} ) D. ( frac{e h}{pi m} ) |
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127 | A current of i amp flows in a loop having circular arc of radius ( r ) subtending an angle ( theta ) as shown in the figure. The magnetic field at the centre of the circle is: A ( cdot frac{mu_{0} i}{4 pi r} ) B. ( left(frac{mu_{0} i}{4 r}right) sin theta ) c. ( left(frac{2 mu_{0} i}{2 r}right) sin theta ) D. ( left(frac{mu_{0} i}{4 pi r}right) sin theta ) |
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128 | The work done in rotating the magnet from the direction of uniform field to the opposite direction to the field is ( W ). The work done in rotating the magnet from the field direction to half the maximum couple position is : A ( .2 ~ W ) B. ( frac{sqrt{3} W}{2} ) c. ( frac{W}{4}(2-sqrt{3}) ) D. ( frac{W}{4}(1-sqrt{3}) ) |
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129 | Potential energy of a bar magnet of magnetic moment ( M ) placed in a magnetic field of induction ( B ) Such that it makes an angle ( theta ) with the direction of ( B ) is ( left(operatorname{take} theta=90^{circ} ) as datum) right. ( mathbf{A} cdot-M B sin theta ) B. ( -M B cos theta ) c. ( M B(1-cos theta) ) D. ( M B(1+cos theta) ) |
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130 | The gyromagnetic ratio of an electron in sodium atom is: A. depending upon the atomic number of the atom B. depending upon the shell number of the atom C. independent of that orbit it is in D. having positive value |
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131 | Define watt. Write down an equation linking watts, volts and amperes. | 12 |

132 | An electron is projected so that it crosses three different regions of space as shown. if ( B_{1}, B_{2} ) and ( B_{3} ) are the magnetic field in the region,then: ( A cdot B_{1} ) is inward B. ( B_{2} ) is outward ( c cdot B_{3} ) is inward D. All of these |
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133 | A current of 1 amp is flowing in the sides of an equilateral triangle of side ( 4.5 times 10^{-2} mathrm{m} . ) Find the magnetic field at the centroid of triangle. |
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134 | State Ampere’s circuital law. Obtain an expression for magnetic induction along the axis of toroid. | 12 |

135 | Match the following and find the correct pairs: List List II (a) Fleming’s (e) Direction of induced current left hand rule (b) Right hand (f) Magnitude and direction of thumb rule ( quad ) magnetic induction (c) Biot-Savart (g) Direction of force due to law ( quad ) magnetic induction (d) Fleming’s (h) Direction of magnetic lines right hand rule due to current ( A cdot a-g, b-e, c-f, d-h ) B. ( a-g, b-h, c-f, d-e ) ( mathbf{C} cdot a-f, b-h, c-g, d-e ) D. a-h, b-g, c-e, d-f |
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136 | A rectangular coil placed in a region having a uniform magnetic field perpendicular to the plane of the coil. An e.m.f. will not be induced in the coil if the: A. magnetic field increases uniformly B. coil is rotated about an axis perpendicular to the plans of the coil and passing through its centre 0 , the coil remaining in the same plane c. coil is routed about the axis ( 0 x ) |
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137 | Q Type your question. ( operatorname{arm} mathrm{PQ}, ) which remains hinged along a horizontal line taken as the y-axis. A uniform magnetic field ( overrightarrow{boldsymbol{B}}=(mathbf{3} hat{mathbf{i}}+ ) ( 4 hat{k}) B_{0} ) exists in the region. The loop is held in the ( x ) -y plane and a current lis passed through it. The loop is now released and is found to stay in the horizontal position in equilibrium. (a) What is the direction of the current n PQ? (b) Find the magnetic force on the arm RS. (c) Find the expression for I in terms of ( B_{0}, ) a b and ( m ) |
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138 | A metal wire of mass ( m ) slides without friction on two rails at distance ( d ) apart. The track is in a vertical uniform field of induction ( vec{B} ). A constant current ( vec{i} ) flows along one rail across the wire and back down the other rail the velocity of the wire as a function of time, assuming it to be at rest initially. A ( cdot frac{B i d}{m} ) в. ( frac{B i d t}{m} ) c. ( frac{m}{text { Bidt }} ) D. None of the above |
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139 | A galvanometer having a coil resistance of ( 60 Omega ) shows full scale deflection when a current of 1.0 amp passes through it. It can be converted into an ammeter to read currents upto 5.0 amp by : A. Putting in parallel a resistance of ( 15 Omega ) B. Putting in parallel a resistance of ( 240 Omega ) c. Putting in series a resistance of ( 15 Omega ) D. Putting in series a resistance of ( 240 Omega ) |
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140 | Which of the following is a source of magnetic field? A. isolated Magnetic pole B. static electric charge c. current loop D. moving light source |
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141 | The earth’s magnetic field at a given point is ( 0.5 times 10^{-5} W b m^{-2} . ) This field is to be annulled by magnetic induction at the centre of a circular conducting loop of radius ( 5.0 mathrm{cm} . ) The current required to be flown in the loop is nearly в. ( 0.4 A ) ( c .4 A ) D. ( 40 A ) |
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142 | A moving coil galvanometer has a coil with 175 turns and area ( 1 mathrm{cm}^{2} ). It uses a torsion band of torsion constant ( 10^{-6} mathrm{N} ) ( mathrm{m} / mathrm{rad} . ) The coil is placed in a magnetic field B parallel to its plane. The coil deflects by ( 1^{circ} ) for a current of ( 1 mathrm{mA} ). The value of ( mathrm{B}(text { in } text { Telsa }) ) is approximately. A ( cdot 10^{-3} ) B . ( 10^{-1} ) ( c cdot 10^{-4} ) D. ( 10^{-2} ) |
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143 | At very close point on the axis of a current carrying circular coil ( ( boldsymbol{x}<<< ) ( R ) ) of radius ( ^{prime} R^{prime}, ) the value of magnetic field decreases by a fraction of ( 5 % ) with respect to centre value. The position of the point from the centre of the coil is :- A ( cdot frac{R}{sqrt{10}} ) в. ( frac{R}{sqrt{30}} ) c. ( frac{R}{sqrt{50}} ) D. ( frac{R}{sqrt{150}} ) |
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144 | The force between two current carrying wires is due to the force. A. magnetic B. electric c. centripetal D. centrifugal |
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145 | Two current carrying loops having ( N_{1} ) turns and ( N_{2} ) turns respectively both carrying a current equal to ( I ) in the same direction, are placed inside a magnetic field ( B ). If the radii of both loops are in the ratio 1: 3 then what will be the ratio of the potential energy of loops in that magnetic field? A ( cdot frac{N_{1}}{N_{2}} ) B. ( frac{2 N_{1}}{N_{2}} ) c. ( frac{N_{1}}{3 N_{2}} ) D. ( frac{N_{1}}{9 N_{2}} ) |
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146 | The magnetic tield at the centre ot a circular coil of radius ( r ) is ( pi ) times that due to a long straight wire at a distance r from it, for equal currents. Figure shows three cases. In all cases the circular path has radius r and straight ones are infinitely long. For same current the ( mathrm{B} ) field at the centre ( mathrm{P} ) in cases 1,2,3 has the ratio: ( ^{mathbf{A}} cdot-left(frac{pi}{4}+frac{1}{2}right):left(frac{pi}{2}right):left(frac{3 pi}{4}-frac{1}{2}right) ) B ( cdotleft(-frac{pi}{2}+1right):left(frac{pi}{2}+1right):left(frac{3 pi}{4}+frac{1}{2}right) ) ( mathbf{C} cdot-frac{pi}{2}: frac{pi}{2}: frac{3 pi}{4} ) D ( cdotleft(-frac{pi}{2}-1right):left(frac{pi}{2}-frac{1}{4}right):left(frac{3 pi}{4}+frac{1}{2}right) ) |
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147 | Force between the two parallel wires carrying currents has been used to define A. ampere B. coulomb c. volt D. watt |
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148 | Two wires each carrying a steady current I are shown in four configurations in Column I. Some of the resulting effects are described in Column II. Match the statements in Column I with the statements in Column II and indicate your answer by darkening appropriate bubbles in the ( 4 mathrm{X} 4 ) matrix given in the ORS. |
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149 | If a long straight wire carries a current of ( 40 mathrm{A} ), then the magnitude of the field B at a point ( 15 mathrm{cm} ) away from the wire is: A ( cdot 5.34 times 10^{5} mathrm{T} ) B. ( 8.34 times 10^{5} mathrm{T} ) c. ( 9.6 times 10^{5} mathrm{T} ) D . 10.2 ( times 10^{5} ) न |
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150 | In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential ( V ) and then made to follow semicircular paths of radius ( R ) using a magnetic field ( B . ) If ( V ) and ( B ) are kept constant, the ratio ( left(frac{operatorname{charg} text { on the ion }}{text { mass of the ion }}right) ) will be proportional to A ( cdot frac{1}{R} ) в. ( frac{1}{R^{2}} ) c. ( R^{2} ) D. ( R ) |
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151 | Two circular coils 1 and 2 are made from the same wire but the radius of 1st coil is twice that of the 2 nd coil. What potential difference in volts should be applied across them so that the magnetic magnetic field at the centres is the same A. 4 times of first coil B. 6 times of first coil c. 2 times of first coil D. 3 times of first coil |
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152 | A hypothetical magnetic field existing in a region is given by ( vec{B}=B_{0} vec{e}_{r}, ) where ( vec{e}_{r} ) denotes the unit vector along the radial direction. A circular loop of radius ( alpha, ) carrying a current ( i, ) is placed with its plane parallel to ( X-Y ) plane and the centre at ( (0,0, d) . ) Find the magnitude of the magnetic force acting on the loop. A ( cdot frac{i 2 pi b_{o} a^{3}}{sqrt{a^{2}+d^{4}}} ) B. ( frac{i 2 d_{o} a^{2}}{sqrt{a^{2}+b^{2}}} ) c. ( frac{pi b_{o} a^{2}}{sqrt{a+d^{2}}} ) D. ( frac{i 2 pi b_{a} a^{2}}{sqrt{a^{2}+d^{2}}} ) |
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153 | A rectangular loop carrying a current ( i ) is situated near a long straight wire such that the wire is parallel to one of the sides of the loop and is in the plane of the loop. If steady current lis established in the wire as shown in fig. the loop will A. rotate about an axis parallel to the wire B. move away from the wire c. move toward the wire D. remain stationary |
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154 | A proton, deutron and an ( alpha ) -particle enter a magnetic field perpendicular to field with same velocity. What is the ratio of the radii of circular paths? A .1: 2: 2 B. 2:1:1 c. 1: 1: 2 D. 1: 2: 1 |
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155 | The figure shows a circuit containing a coil wound over a long and hollow thin tube. Mention two methods to increase the strength of the magnetic field inside the coil. |
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156 | The magnetic moment of a thin round loop with current, if the radius of the loop is equal to ( R=100 m m ) and the magnetic field at its centre is equal to ( B=6.0 mu T, ) is ( 30 times 10^{-x} A-m^{2} ). Find the value of ( x ) |
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157 | A current in the windings on a toroid is 2 A. There are 400 turns and the mean circumferential length is ( 40 mathrm{cm} . ) If the magnetic field inside is ( 1 T ), the relative permeability is : A . 200 B. 2500 ( c cdot 400 ) D. 150 |
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158 | You are sitting in a room in which uniform magnetic field is present in vertically downward direction. When an electron is projected in horizontal direction, it will be moving in circular path with constant speed A. clockwise in vertical plane B. clockwise in horizontal plane c. anticlockwise in vertical plane D. anticlockwise in horizontal plane |
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159 | An ( alpha ) -particle is moving along a circle of radius ( R ) with a constant angular velocity ( omega . ) Point ( A ) lies in the same plane at a distance ( 2 R ) from the center. Point ( A ) records magnetic field produced by the ( alpha ) -particle. If the minimum time interval between successive times at which ( A ) records zero magnetic field is ( t ), the angular speed ( omega, ) in terms of ( t, ) is : A. ( frac{2 pi}{t} ) в. ( frac{2 pi}{3 t} ) c. ( frac{pi}{3 t} ) D. |
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160 | An electric charge in uniform motion produces: A. An electric field only B. A magnetic field only c. Both electric and magnetic fields D. No such field at all |
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161 | (a) Deduce an expression for the frequency of revolution of a charged particle in a magnetic field and show that it is independent of velocity or energy of the particle. (b) Draw a schematic sketch of a cylotron. Explain, giving the essential details of its construction, how it is used to accelerate the charged particles. |
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162 | In a hydrogen atom, the electron moves in an orbit of radius ( 0.5 A^{circ} ) making ( 10^{16} ) revolution per second. The magnetic moment associated with the orbital motion of the electron is ( A m^{2} ) A. ( 1.602 times 10^{-19} ) ? В. ( 1.256 times 10^{-22} ) c. ( 1.67 times 10^{-2} ) D. ( 1.256 times 10^{-23} ) |
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163 | There will be no force experienced if A. two parallel wires carry currents in the same direction B. two parallel wires carry currents in the opposite direction C. a positive charge is projected between the pole pieces of a bar magnet D. a positive charge is projected along the axis of a solenoid carrying current |
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164 | In a moving coil galvanometer, the magnetic pole pieces are made cylindrical and a soft iron core is placed at the centre of the coil,the purpose for doing so is: A. to make the magnetic field strong B. to make the magnetic field strong and radial c. to make the magnetic field uniform D. to make the magnetic field strong and uniform |
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165 | Instrument that used to measure small electric currents ? A. Pipette B. Manometer c. Balance D. Calorimeter E. Galvanometer |
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166 | Which of the following quantities is not affected by a magnetic field? A. Stationary charge B. Moving charge c. change in magnetic flux D. Current flowing in a conductor |
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167 | f current through the conductor Y is reversed in direction, will neutral point lie between ( X ) and ( Y ), to the left of ( X ) or to the right of Y? |
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168 | Two equal electric currents are flowing perpendicular to each other as shown in figure. AB and CD are perpendicular to each other and symmetrically placed with respect to the currents. Where do we expect the resultant magnetic field to be zero? ( A cdot ) on ( A B ) B. on CD ( c ). on both ( A B & ) CD D. on both OD & BO |
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169 | The relation between voltage sensitivity ( sigma_{v} ) and the current sensitivity ( sigma_{i} ) of ( a ) moving coil galvanometer is (Given that ( G ) is the resistance of the galvanometer) A ( cdot sigma_{v}=G sigma_{i} ) в. ( sigma_{v}=frac{sigma_{i}}{G} ) ( mathbf{c} cdot sigma_{v} sigma_{i}=G ) D. ( sigma_{v} sigma_{i}=frac{1}{G} ) |
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170 | Two long thin wires ( A B C ) and ( D E F ) are arranged as shown in figure. They carry equal current ( I ) as shown. The magnitude of the magnetic field at ( O ) is A. zero в. ( mu_{0} I / 4 pi a ) c. ( mu_{0} I / 2 pi a ) D. ( mu_{0} I / 2 sqrt{2} pi a ) |
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171 | An infinitely long straight non-magnetic conducting wire of radius a carries a ( d c ) current I. The magnetic field ( B ), at a distance ( r(r<a) ) from axis of the wire is: A ( cdot frac{mu_{0} I}{2 pi a} ) в. ( frac{mu_{0} I r}{2 pi a^{2}} ) c. ( frac{2 mu_{0} I r}{pi a^{2}} ) D. ( frac{mu_{0} I r^{2}}{2 pi a^{3}} ) |
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172 | How does a solenoid behave like a magnet? Can you determine the north and south poles of a current-carrying solenoid with the help of a bar magnet?? Explain. |
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173 | A proton and an ( alpha ) -particle enter in a uniform magnetic field perpendicular to it with same speed. The ratio of time periods of both particle ( square frac{T_{p}}{T_{alpha}} ) 回 will be ( A cdot 1: 2 ) B. 1:3 c. 2: D. 3: |
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174 | Consider the circular loop having current ( i ) and with central point ( O . ) The magnetic field at the central point ( boldsymbol{O} ) is A ( cdot frac{2 mu_{0} i}{3 pi R} ) acting downward B. ( frac{5 mu_{0} i}{12 R} ) acting downwaro c. ( frac{6 mu_{0} i}{11 R} ) acting downwar D. ( frac{3 mu_{0} i}{7 R} ) acting downwar |
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175 | Write the expression for magnetic potential energy of a magnetic dipole kept in a uniform magnetic field and explain the terms. | 12 |

176 | Is the magnetic dipole moment a vector or a scalar quantity? Write its unit | 12 |

177 | Two galvanometers ( A ) and ( B ) require ( 3 m A ) and ( 6 m A ) respectively, to produce the same deflection of 10 divisions. Then is, A. ( A ) is more sensitive than ( B ) B. ( B ) is more sensitive than ( A ) c. ( A ) and ( B ) are equally sensitive D. Sensitiveness of ( B ) is twice that of ( A ) |
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178 | A uniformly wound solenoidal coil of self-inductance ( 1.8 times 10^{-4} mathrm{H} ) and resistance ( 6 Omega ) is cut into two identical coils. They are now connected in parallel across a 12 volt battery of negligible resistance. Find the current drawn by the circuit in amp. |
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179 | A symmetric star-shaped conducting wire loop is carrying a steady state current I as shown the figure. The distance between the diametrically opposite vertices of the star is ( 4 a . ) The magnitude of the magnetic field at the centre of the loop is |
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180 | Three identical long solenoids ( P, Q, R ) are connected to each other as shown in figure. If the magnetic field at the center of ( boldsymbol{P} ) is ( 2.0 T, ) what would be the field (in ( T ) ) at the center of ( Q ) ? Assume that the field due to any solenoid is confined within the volume of that solenoid only. |
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181 | An electron after being accelerated through a potential difference ( 100 boldsymbol{V} ) enters a uniform magnetic field of ( 0.004 T ) perpendicular to its direction of motion. Calculate the radius of the path described by the electrons. |
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182 | (a) Define one tesla. (b) Derive an expression for force experienced by a current carrying straight conductor placed in a magnetic field. How can we find the direction of force? |
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183 | Assertion Force experienced by moving charge will be maximum if direction of velocity of charge is parallel to applied magnetic field. Reason Force on moving charge is independent of direction of applied magnetic field. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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184 | The value of relative magnetic permeability ( left(mu_{r}right) ) for ferromagnetic materials is A ( cdotleft(mu_{r}=1right) ) В ( cdotleft(mu_{r}>>1right) ) c. ( left(mu_{r}1right) ) |
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185 | A straight horizontal conducting rod of length ( 0.45 mathrm{m} ) and mass ( 60 mathrm{g} ) is suspended by two vertical wires at its ends. A current of ( 5.0 mathrm{A} ) is set up in the rod through the wires. (a) What magnetic field should be set up normal to the conductor in order that the tension in the wires is zero? (b) What will be the total tension in the wires if the direction of current is reversed keeping the magnetic field same as before?(Ignore the mass of the wires.) ( g=9.8 m s^{-2} ) |
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186 | How much length of a very wire is required to obtain a solenoid of length ( I_{0} ) and inductance ( L: ) A ( cdot sqrt{frac{2 pi L l}{mu_{0}}} ) в. ( sqrt{frac{4 pi L l}{mu_{0}^{2}}} ) c. ( sqrt{frac{4 pi L l}{mu_{0}}} ) D. ( sqrt{frac{8 pi L l}{mu_{0}}} ) |
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187 | When an electric current passes through a solenoid, the distance between any two adjacent rings of the solenoid A . decreases B. increases c. does not change D. first increases and then decreases |
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188 | A charged particle moving with constant velocity passes through a region of space without any change in its velocity. If ( mathrm{E} ) and ( mathrm{B} ) represent electric and magnetic fields in that region respectively,what is the ( mathrm{E} ) and ( mathrm{B} ) in this space? A ( . E=0 ) and ( B=0 ) B. ( E=0 ) and ( B neq 0 ) c. ( E neq 0 ) and ( B=0 ) D. ( E neq 0 ) and ( B neq 0 ) |
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189 | Lis a circular ring made of a uniform wire. Current enters and leaves the rind through straight conductors which, if produced, would have passed through the centre ( C ) of the ring. The magnetic field at ( C: ) This question has multiple correct options A. due to the straight conductors is zero B. due to the loop is zero C. due to the loop is proportional to ( theta ) D. due to the loop is proportional to ( (pi-theta) ) |
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190 | Forces ( vec{F} ) experienced by a particle having charge ( q ) and velocity ( vec{v} ) in a magnetic field B is given by ( overrightarrow{boldsymbol{F}}=mathrm{q}(overrightarrow{boldsymbol{v}} times ) ( vec{B} ) ). What is the direction of force acting on electrons (negatively charged particles) falling vertically, at a place where the Earths magnetic field is horizontal pointing towards North? A. East B. west c. vertically up D. Vertically down |
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191 | The force per unit length between two long straight conductors carrying currents 3 A each in the same direction and separated by a distance of ( 2.0 mathrm{cm} ) is A ( cdot 9 times 10^{-7} N / m ) В. ( 9 times 10^{-6} N / m ) c. ( 9 times 10^{-5} N / m ) D. ( 9 times 10^{-4} N / m ) |
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192 | Pick correct statements from among the following: a) Electric field and magnetic field are basically independent b) Electric field and magnetic field are to aspects of the electromagnetic field c) Electric field and magnetic field may be produced by charge at rest d) A moving charge produces both electric and magnetic fields A. a and b are correct B. b and d are correct ( c . ) b, cand d are correct D. a, cand dare correct |
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193 | A wire carrying a current of ( 100 A ) is bent into the form of a circle of radius 5cm. The flux density at the centre of the coil is ( _{-}-_{-}-_{-}-_{-} W b / m^{2} ) begin{tabular}{l} A ( cdot 12.57 times 10^{-5} ) \ hline end{tabular} B . ( 125.7 times 10^{-5} ) c. ( 1.257 times 10^{-5} ) D. ( 1257 times 10^{-5} ) |
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194 | The torque required to hold a small circular coil of 10 turns, are ( 1 m m^{2} ) and carrying a current of ( left[frac{21}{44}right] ) A in the middle of a long solenoid of ( 10^{3} ) turns/m carrying a current of ( 2.5 mathrm{A} ), with its axis perpendicular to the axis of the solenoid is: A ( .1 .5 times 10^{-6} N m ) в. ( 1.5 times 10^{-8} N m ) c. ( 1.5 times 10^{6} mathrm{Nm} ) D. ( 1.5 times 10^{8} mathrm{Nm} ) |
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195 | A posıtively chargea partıcle or cnarge ( q^{prime} ) enters in a uniform magnetic field ‘B directed inward and is deflected a distance ( boldsymbol{y}_{0} ) after traveling a distance shown in the figure. Then the pe use coos FathER30DAY ( A ) UPGRADE NOWI B. ( c ) D. ( E ) |
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196 | Two coils ( A ) and ( B ) are placed parallel to each other at a very small distance apart. The coil ( A ) is connected to an A.C. supply. ( G ) is a very sensitive galvanometer.When the key ( K ) is closed. A. A constant deflection will be observed in the galvanometer for a ( 50 mathrm{Hz} ) supply B. Small variations will be observed in the galvanometer due to applied voltage of ( 50 mathrm{Hz} ) c. oscillations in the galvanometer may be observed when the input a.c. voltage has a frequency of 1 to ( 2 H z ) D. No variations will be observed in the galvanometer even when the input a.c. voltage has a frequency of 1 to ( 2 mathrm{H} ) |
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197 | Magnetic lines of force causes A. The picture on a computer screen B. Radio reception interference C. Aurora Borealis D. V.H.S. films E. All of these |
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198 | Two concentric circular coil of radius ( 20 c m ) and ( 30 c m ) carries current ( 2 A ) and ( 3 A ) respectively in opposite direction then magnetic field at centre will be :- A. ( 4 pi times 10^{-7} ) В. ( 2 pi times 10^{-7} ) c. ( 2 times 10^{-7} ) D. 0 |
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199 | A conducting circular loop of radius carries a constant current I. It is placed in a uniform magnetic field B such that B is perpendicular to the plane of the loop. The magnetic force acting on the loop is ( mathbf{A} cdot ) Вᅵ В. 2 ( pi ) (ВЮА) c. zero D. ( pi ) (ВIR) |
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200 | In hydrogen atom the electron is making ( 6.6 times 10^{15} ) rev/s around the nucleus of radius 0.53 A. The magnetic field produced at the centre of the orbit is nearly A. ( 0.12 W b / m^{2} ) в. ( 1.2 mathrm{Wb} / mathrm{m}^{2} ) c. ( 12 W b / m^{2} ) D. ( 120 W b / m^{2} ) |
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201 | A charged particle accelerated through a potential difference of ( 100 V ) passes through uniform electric and magnetic fields so as to experience no deflection. ( boldsymbol{E}=mathbf{1 5} times mathbf{1 0}^{6} boldsymbol{V} boldsymbol{m}^{-1} ) and ( boldsymbol{B}=mathbf{5} times mathbf{1 0}^{mathbf{3}} boldsymbol{T} ) Then the specific charge ( frac{e}{m} ) is : A ( cdot 4.5 times 10^{4} mathrm{C} / mathrm{kg} ) В . ( 9 times 10^{7} C / k g ) C ( .4 .5 times 10^{3} C / k g ) D. ( 9 times 10^{5} C / k g ) |
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202 | An ( alpha ) -particle describes a circular path of radius ( r ) in a magnetic field ( B ). The radius of the circular path described by the proton of same energy in the same magnetic field is : A ( cdot frac{r}{2} ) B. ( c cdot sqrt{2} r ) D. ( 2 r ) |
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203 | A uniform magnetic field ( vec{B}=(3 hat{i}+ ) ( 4 hat{j}+hat{k}) ) exists in region of space. semicircular wire of radius 1 m carrying current ( 1 A ) having its centre ( operatorname{at}(2,2,0) ) is placed in ( x-y ) plane as shown in figure. The force on semicircular wire will be ( mathbf{A} cdot sqrt{2}(hat{i}+hat{j}+hat{k}) ) B. ( sqrt{2}(hat{i}-hat{j}+hat{k}) ) ( mathbf{c} cdot sqrt{2}(hat{i}+hat{j}-hat{k}) ) D. ( sqrt{2}(-hat{i}+hat{j}+hat{k}) ) |
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204 | Proton which kinetic energy of ( 1 M e V ) moves from south to north. It gets an acceleration of ( 10^{12} m / s^{2} ) by an applied magnetic field (west to east). The value of magnetic field: (Rest mass of proton is ( left.1.6 times 10^{-27} k gright) ) A. ( 0.071 m T ) B. ( 71 m T ) ( c .0 .71 m T ) D. ( 7.1 m T ) |
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205 | The magnetic field inside the coils of a toroid of radius ( R ) and ( N ) turns with a current of ( boldsymbol{I} boldsymbol{A} ) is given by A ( cdot B=frac{mu_{o} N I}{4 pi R} ) в. ( B=frac{mu_{o} N I}{2 pi R} ) C ( . B=mu_{o} N I ) D. None of these |
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206 | Assertion Magnetic field due to current carrying solenoid is independent of its length and cross-sectional area. Reason The magnetic field inside the solenoid is uniform. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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207 | Two identical coils carry equal currents have a common centre and their planes are at right angles to each other. The ratio of the magnitude of the resultant magnetic field at the centre and the field due to one coil is : A . 2: 1 B. 1: 2 ( mathbf{c} cdot sqrt{2}: 1 ) D. ( 1: sqrt{2} ) |
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208 | A charged particle is released from rest in a region of steady and uniform electric and magnetic fields where ( mathrm{E} | mathrm{B} ) The particle will follow. A. circular path B. Elliptical path c. Helical path D. Straight line path |
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209 | An electron beam is moving from left to right of the observer and magnetic field is acting vertically upwards. The direction of force acting on electron is A. towards the observer B. away from the observer c. downwards D. upwards |
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210 | toppr Q Type your question_ this region of space. The correct arrangement for it to escape undeviated is : ( mathbf{A} ) ( B ) ( c ) D. |
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211 | In the given figure, what is the magnetic field at the point ‘0’? A ( cdot frac{mu_{0} I}{4 pi r}+frac{mu_{0} I}{2 pi r} ) ( B cdot frac{mu_{0}}{1 pi} ) C. ( frac{mu_{0} I}{4 r}+frac{mu_{0} I}{4 pi r} ) D. ( frac{mu_{0} I}{4 r}-frac{mu_{0} I}{4 pi r} ) |
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212 | (A) In tangent galvanometer the circular frame is rotated until the plane of the coil is parallel to magnetic meridian (B) In tangent galvanometer current through it is related to deflection of needle as A. A is true, B is false B. A is false, B is true c. A & B are true D. A & B are false |
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213 | A solenoid of ( 0.4 m ) length with 500 turns carries a current of ( 3 A . ) A coil of 10 turns and of radius ( 0.01 m ) carries a current of ( 0.4 A . ) The torque required to hold the coil with its axis at right angles to that of solenoid in the middle point of it is: A ( cdot 6 pi^{2} times 10^{-7} N m ) В. ( 3 pi^{2} times 10^{-7} N m ) ( mathbf{c} cdot 9 pi^{2} times 10^{-7} N m ) D. ( 12 pi^{2} times 10^{-7} N m ) |
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214 | A solenoid ( 60 mathrm{cm} ) long and of radius 4.0 cm has 3 layers of windings of 300 turns each. A ( 2.0 mathrm{cm} ) long wire of mass ( 2.5 mathrm{g} ) lies inside the solenoid (near its centre) normal to its axis; both the wire and the axis of the solenoid are in the horizontal plane. The wire is connected through two leads parallel to the axis of the solenoid to an external battery which supplies a current of ( 6.0 mathrm{A} ) in the wire. What value of current (with appropriate sense of circulation) in the windings of the solenoid can support the weight of the wire? ( g=9.8 m s^{-2} ) |
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215 | A proton, a deuteron and an a-particle are moving with same momentum in a uniform magnetic field. The ratio of magnetic forces acting on them will be A. 1: 1: 2 B. 1: 2: 3 ( c cdot 2: 1: 1 ) D. 1: 1: 1 |
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216 | A proton moving with velocity ( V ) is acted upon by electric field ( boldsymbol{E} ) and magnetic field ( B ). The proton will move undeflected if |
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217 | Two particles having the same momentum enter at right angles into same magnetic field and travel in circular paths of radius ( r_{1} ) and ( r_{2} ). The ratio of their charges is: A ( cdot frac{r_{1}}{r_{2}} ) B. ( left(frac{r_{1}}{r_{2}}right)^{1 / 2} ) ( ^{c} cdotleft(frac{r_{1}}{r_{2}}right)^{2} ) D. ( left(frac{r_{1}}{r_{2}}right)^{-1} ) |
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218 | The current sensitivity of a moving coil galvanometer depends on A. the number of turns in the coil B. moment of inertia of the coil c. current sent through galvanometer D. eddy current in A1 frame |
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219 | A charge particle of charge ( q ) is moving with speed ( v ) in a circle of radius ( R ) as shown in figure. Then the magnetic field at a point on axis of circle at a distance ( x ) from centre is : A ( cdot frac{mu_{0}}{4 pi} frac{q V}{R^{2}} ) в. ( frac{mu_{0}}{4 pi} frac{q V}{left(R^{2}+x^{2}right)} ) c. ( frac{mu_{0}}{4 pi} frac{q V}{x^{2}} ) D. ( frac{mu_{0}}{4 pi} frac{q V R}{left(R^{2}+x^{2}right)^{3 / 2}} ) |
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220 | A proton moving with a constant velocity passes through a region of space with out change in its velocity. If ( mathrm{E} ) and ( mathrm{B} ) represent the electric and magnetic fields respectively, this region may have A. ( E=0, B neq 0 ) B. ( E neq 0, B=0 ) c. ( E ) and ( B ) both parallel ( $ $ ) D. ( E ) and ( B ) inclined at ( 45^{circ} ) angle |
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221 | What is the direction of magnetic field at the centre of a coil carrying current in anticlockwise direction? A. Perpendicular to the axis of coil inwards. B. Perpendicular to the axis of coil outwards c. Along the axis of coil inwards D. Along the axis of coil outwards |
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222 | Two particles of equal charges after being accelerated through the same potential difference enter in a uniform transverse magnetic field and describe circular paths of radii ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2} . ) Then the ratio of their respective masses ( left(M_{1} / M_{2}right) ) is ( mathbf{A} cdot R_{1} / R_{2} ) B. ( left(R_{1} / R_{2}right)^{2} ) c. ( left(R_{2} / R_{1}right) ) as D. ( left(R_{2} / R_{1}right)^{2} ) |
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223 | Field inside a solenoid is A. directly proportional to its length B. directly proportional to current C. inversely proportional to number of turns D. inversely proportional to current |
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224 | A wire loop formed by joining two semi- circular wires of radii ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2} ) carries a current as shown in the adjoining diagram. The magnetic induction at the center ( boldsymbol{O} ) is A ( cdot frac{mu_{0} I}{4 R_{1}} ) B. ( frac{mu_{0} I}{4 R} ) c. ( frac{mu_{0} I}{4}left(frac{1}{R_{1}}-frac{1}{R_{2}}right) ) D. ( frac{mu_{0} I}{4}left(frac{1}{R_{1}}+frac{1}{R_{2}}right) ) |
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225 | The magnetic field due to a circular wire at its center is: A. in the plane of wire B. ( 30^{circ} ) to the plane of wire C. Perpendicular to the plane of wire D. none of the above |
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226 | A particle of charge ( q ) and mass ( m ) moves in a circular path of radius ( r ) in a uniform magnetic field ( B ). The particle is replaced with a particle |
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227 | By inserting an iron core in a coil carrying current,the strength of its magnetic field will: A. Increase B. Decrease c. Remain same D. Become zero |
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228 | A cyclotron is used to accelerate protons to a kinetic energy of 5 MeV. If the strength of magnetic field in the cyclotron is ( 2 T, ) find the radius and the frequency needed for the applied alternating voltage of the cyclotron. (Given: Velocity of proton ( =3 x ) ( left.10^{7} m / sright) ) |
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229 | (a) What are different losses in transformer, suggest steps to minimise the losses in transformer. (b) State principle and explain the working of transformer |
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230 | in the horizontal plane of the circle as shown in the figure. The path consists of eight arcs with alternating radii ( r ) and ( 2 r . ) Each segment of arc subtends equal angle at the common centre ( P . ) The magnetic field produced by current path at point ( boldsymbol{P} ) is A ( cdot frac{3}{8} frac{mu_{0} I}{r} ; ) perpendicular to the plane of the paper and directed inward. B. ( frac{3}{8} frac{mu_{0} mathrm{I}}{mathrm{r}} ; ) perpendicular to the plane of the paper and directed outward. C ( cdot frac{1}{8} frac{mu_{0} I}{r} ; ) perpendicular to the plane of the paper and directed inward. D. ( frac{1}{8} frac{mu_{0} mathrm{I}}{mathrm{r}} ; ) perpendicular to the plane of the paper and directed outward |
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231 | Figure shows a cross-section of a long ribbon of width ( omega ) that is carrying a uniformly distributed total current ( i ) into the page. Calculate the magnitude and direction of the magnetic field ( vec{B} ) at a point ( P ) in the plane of the ribbon at a distance d from its edge. [ begin{array}{ll} P & x times x cdot x times x times x times x \ & d end{array} ] |
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232 | A straight wire carrying a current ( i_{1} ) amp runs along the axis of a circular current ( i_{2} ) amp. Then the force of interaction between the two current carrying conductors is? ( A cdot infty ) B. zero c. ( frac{mu_{0}}{4 pi} frac{2 i_{1} i_{2}}{r} mathrm{N} / mathrm{m} ) D. ( frac{2 i_{1} i_{2}}{r} mathrm{N} / mathrm{m} ) |
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233 | The length of conductor ab carrying current ( I_{2} ) is ( l . ) Find the force acting on it due to a long current carrying conductor having current ( I_{1} ) as shown in Fig. The mid-point of wire ab is distance ( x ) apart from conductor. |
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234 | Error in B is ( mathbf{A} cdot pm 0.9 T ) В. ( pm 0.09 m T ) ( mathbf{c} . pm 0.9 m T ) D. ±0.097 |
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235 | A ( 0.5 m ) long solenoid of ( 10 t u r n s / c m ) has area of cross-section ( 1 mathrm{cm}^{2} ) Calculate the voltage induced across its ends if the current in the solenoid is charged from ( 1 A ) to ( 2 A ) in ( 0.1 s ) |
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236 | An electron enters a magnetic field directed to the right, with a velocity toward the bottom of the screen. What is the direction of force on the electron? A. To the left B. Into the screen c. To the right D. Out of the screen |
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237 | Two identical wires ( A ) and ( B ), each of length ( l ), carry the same current ( l ). Wire ( A ) is bent into a circle of radius ( R ) and wire ( B ) is bent to form a square of side ( a ) If ( B_{A} ) and ( B_{B} ) are the values of magnetic field at the centres of the circle and square respectively, then the ratio ( frac{B_{A}}{B_{B}} ) is: A ( cdot frac{pi^{2}}{16 sqrt{2}} ) в. ( frac{pi^{2}}{16} ) c. ( frac{pi^{2}}{8 sqrt{2}} ) D. ( frac{pi^{2}}{8} ) |
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238 | Assertion Magnetic field interacts with a moving charge and not with a stationary charge. Reason A moving charge produces a magnetic field. |
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239 | An electron and a proton are projected with same velocity perpendicular to a magnetic field. Which particle have greater frequency? |
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240 | The force between two parallel conductors, each of length ( 50 m ) and distant ( 20 mathrm{cm} ) apart, is ( 1 mathrm{N} ). If the current in one conductor is double than that in another one, then their values will respectively be: ( mathbf{A} cdot 100 A ) and ( 200 A ) B. ( 50 A ) and ( 400 A ) c. ( 10 A ) and ( 30 A ) D. ( 5 A ) and ( 25 A ) |
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241 | A rectangular loop PQRS made from a uniform wire has length a, width b and mass m. It is free to rotate about the ( operatorname{arm} mathrm{PQ}, ) which remains hinged along a horizontal line taken as the y-axis. Take the vertically upward direction as the zaxis. A uniform magnetic field ( vec{B}= ) ( (3 hat{i}+4 hat{k}) B_{0} ) exists in the region. The loop is held in the ( x ) -y plane and a current I is passed through it. The loop is now released and is found to stay in the horizontal position in equilibrium. Find the magnetic force on the arm RS. |
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242 | A conductor AB of length ( l ) carrying a current ( i ) is placed perpendicular to a long straight conductor XY carrying a current ( I ) as shown. The force on ( A B ) will be : A ( cdot frac{mu_{0} l i}{2 pi} log 2 ) B ( cdot frac{mu_{0} l i}{2 pi} log 3 ) c. ( frac{3 mu_{0} l i}{2 pi} ) D. ( frac{2 mu_{0} l i}{3 pi} ) |
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243 | An electron of charge ( e ) and mass ( m ) describes a circular path of radius ( r ) when it is projected with a velocity ( v ) perpendicular to a uniform magnetic field, then its frequency is : ( ^{A} cdot frac{1}{2 pi} sqrt{frac{B e}{m}} ) в. ( frac{1}{2 pi} frac{B e}{m} ) c. ( frac{1}{2 pi} frac{m}{B e} ) D. ( frac{1}{2 pi} frac{m e}{2} ) |
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244 | between conductors carrying currents ( I_{1} ) and ( I_{2} ) is varied. Which of the following graphs correctly represents the variation of force ( (boldsymbol{F}) ) between the conductors and distance ( (boldsymbol{d}) ) ? ( A ) в. ( c ) D. none of these |
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245 | A particle with charge ( q ) having momentum ( p ) enters a uniform magnetic field normally. The magnetic filed has magnitude ( B ) and is confined to a region of width ( d, ) where ( d<frac{p}{B q} ) The particle is deflected by an angle ( theta ) in crossing the field. ( A ) [ sin theta=frac{p d}{B q} ] B. [ sin theta=frac{B q}{q d} ] ( c ) [ sin theta=frac{p}{B d q} ] D. [ sin theta=frac{B q d}{p} ] |
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246 | A straight wire lying in a horizontal plane carries a current from magnetic north to magnetic south. What is the direction of force felt by the wire? | 12 |

247 | Deduce an expression for the force on a current carrying conductor placed in a magnetic field. | 12 |

248 | An electron moving at right angle to a uniform magnetic field completes a circular orbit in 1 micro – second. Find the magnetic field. Ans. ( 3.53 times 10^{-5} T ) |
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249 | A vertical circular coil of radius ( 0.1 m ) and having 10 turns carries a steady current. When the plane of the coil is normal to the magnetic meridian, a neutral point is observed at the centre of the coil. If ( boldsymbol{B}_{boldsymbol{H}}=mathbf{0 . 3 1 4} times mathbf{1 0}^{-mathbf{4}} boldsymbol{T} ) the current in the coil is : ( mathbf{A} cdot 0.5 A ) B. 0.25 A ( c cdot 2 A ) D. ( 1 A ) |
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250 | A square loop, carrying a steady current Is placed in a horizontal plane near a long straight conductor carrying a steady current ( I_{1} ) at a distance d from the conductor as shown in figure. The loop will experience: A. a net repulsive force away from the conductor B. a net torque acting upward perpendicular to the horizontal plane C. a net torque acting downward normal to the horizontal plane D. a net attractive force towards the conductor |
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251 | The magnetic induction at a point at a large distance d on the axial line of circular coil of small radius carrying current is ( 120 mu T . ) At a distance 2 d the magnetic induction would be: A. ( 60 mu T ) в. зод ( T ) ( c cdot 15 mu T ) D. 240muT |
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252 | A moving electron enters a uniform magnetic field perpendicularly. Inside the magnetic field, the electron travels along: A. a straight line B. a parabola c. a circle D. a hyperbola |
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253 | A toroid is A. a finite B. an endless C . straight D. either A or B |
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254 | The resistance of a galvanometer is 50 ohm and the maximum current which can be passed through it is ( 0.002 A ) What resistance must be connected to it in order to convert it into an ammeter of range ( 0-0.5 A ? ) A. 0.2 onm B. 0.002 ohm c. 0.02 ohm D. 0.5 ohm |
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255 | The quarks have fractional electronic charge e/3 and 2e/3. Then why is such a fractional electronic charge not reflected on the oil drops? This question has multiple correct options A. Quarks cannot be gained or lost B. Only electrons can be gained or lost c. To lose quark, energy in MeV is required D. single quark is unstable |
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256 | A charged particle is moving in a uniform magnetic field in a circular path. The energy of the particle is doubled. If the initial radius of the circular path was ( R, ) the radius of the new circular path after the energy is doubled will be: A. ( 0.5 R ) в. ( sqrt{2} R ) ( c .2 R ) D. ( frac{R}{sqrt{2}} ) |
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257 | An elevator carrying a charge of ( 0.5 C ) is moving down with a velocity of ( 5 times ) ( 10^{3} m s^{-1} . ) The elevator is ( 4 m ) from the bottom and ( 3 m ) horizontally form ( P ) as shown in figure. What magnetic field (in ( mu T ) ) does it produce at point ( P ? ) |
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258 | A straight current carrying conductor is kept along the axis of circular loop carrying current. The force exerted by the straight conductor on the loop is A. perpendicular to the plane of the loop. B. in the plane of the loop, away from the center. C. on the plane of the loop, towards the center. D. zero. |
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259 | If an oscillation copper disc is placed in a magnetic field, then A. The frequency of oscillations is decreasing continuously. B. The frequency of oscillations is increasing continuously. C. The frequency of oscillations is constant D. None of these. |
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260 | A straight wire of length 0.5 metre and carrying a current of 1.2 ampere is placed in a uniform magnetic field of induction 2 tesla. If the magnetic field is perpendicular to the length of the wire, the force acting on the wire is: A. 2.4 B. 1.2 N c. 3.0 N D. 2.0 N |
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261 | ( boldsymbol{x}=mathbf{0}, boldsymbol{y}=-mathbf{0 . 5 0 0 m}, boldsymbol{z}=mathbf{0} ) | 12 |

262 | A 200 turn closely wound circular coil of radius ( 15 mathrm{cm} ) carries a current of ( 4 mathrm{A} ) The magnetic moment of this coil is: ( mathbf{A} cdot 36.5 A m^{2} ) B . ( 56.5 A m^{2} ) ( mathbf{c} cdot 66.5 A m^{2} ) D. ( 108 A m^{2} ) |
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263 | A hollow tube is carrying an electric current along its length distributed uniformly over its surface. The magnetic field : This question has multiple correct options A. increases linearly from the axis to the surface B. is constant inside the tube c. is zero at the axis D. is zero just outside the tube |
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264 | If a toroid uses bismuth for its core, the field in the core compared to that in empty core will be slightly A. greater B. smaller c. equal D. None of these |
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265 | Find the ratio of the conduction electrons to the total number of atoms in the given conductor. A. Almost 1: 4 B. Almost 1: 2 c. Almost 2: 1 D. Almost 1: 1 |
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266 | A slightly divergent beam of charged particles accelerated by a Potential difference B propagates from a point ( mathbf{A} ) along the axis of solenoid. The beam is brought into focus at a distance I from the point ( A ) at two successive values of magnetic induction ( B_{1} ) and ( B_{2} ). If the specific charge ( mathrm{q} / mathrm{m} ) of the particles is ( frac{boldsymbol{q}}{boldsymbol{m}}=frac{boldsymbol{x} boldsymbol{pi}^{2} boldsymbol{V}}{boldsymbol{l}^{2}left(boldsymbol{B}_{2}-boldsymbol{B}_{1}right)^{2}} cdot ) Find ( boldsymbol{x} ) |
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267 | A charged particle moves in a gravity free space where an electric field of strength ( mathrm{E} ) and a magnetic field of induction B exist. Which of the following statement is/are correct? This question has multiple correct options A. If ( E neq 0 ) and ( B neq 0, ) velocity of the particle may remain constant B. if ( E=0 ), the particle cannot trace a circular path c. if ( E=0 ), kinetic energy of the particle remains constant D. none of these |
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268 | The electrons in the beam of a television tube move horizontally from south to north. The vertical component of the earths magnetic field points down. The electron is deflected towards A . east B. no deflection c. west D. north to south |
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269 | A conducting loop carrying a current ( boldsymbol{I} ) is placed in a uniform magnetic field pointing into the plane of the paper as shown. The loop will have a tendency to: A. contract B. expand c. move towards +ve x-axis D. move towards ve x axis |
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270 | Dimensions of Gyromagnetic ratio are? A ( cdotleft[L^{1} M^{0} T^{1} I^{1}right] ) B . ( left[L^{0} M^{-1} T^{1} Iright] ) C ( cdotleft[L^{1} M^{0} T^{0} I^{-1}right] ) D cdot ( left[L^{-1} M^{0} T^{1} I^{1}right] ) |
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271 | A 2 MeV proton is moving perpendicular to a uniform magnetic field of 2.5 tesla. The force on the proton is В. ( 7.6 times 10^{-11} N ) c. ( 2.5 times 10^{-11} N ) D. ( 7.6 times 10^{-12} N ) |
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272 | An electron and a proton are projected with same velocity perpendicular to a magnetic field.Which particle will describe the smaller circle? |
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273 | A solenoid of ( 1.5 mathrm{m} ) length and ( 4.0 mathrm{cm} ) diameter possesses 100 turns per meter. A current of 5 amperes is flowing through it. The magnetic induction at axis inside the solenoid is: A ( cdot 2 pi times 10^{-4} mathrm{T} ) В . ( 2 pi times 10^{-5} ) Т c. ( 2 pi times 10^{-2} ) gauss D. ( 2 pi times 10^{-5} ) gauss |
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274 | An electron beam is moving between two parallel plates having electric field ( 1.125 times 10^{-6} N / m . ) A magnetic field ( 3 times 10^{-10} T ) is also applied, so that beam of electrons do not deflect. The velocity of the electron is ( A cdot 4225 mathrm{m} / mathrm{s} ) B. 3750 m/s c. ( 2750 mathrm{m} / mathrm{s} ) D. 3200 ( mathrm{m} / mathrm{s} ) |
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275 | A neutral particle is at rest in a uniform magnetic field ( bar{B} ). At ( t=0 ), particle decays into two particles each of mass ( m^{prime} ) and one of them having charge ( ^{prime} q^{prime} ) Both of these move off in separate paths lying in plane perpendicular to ( bar{B} ). At later time, the particles collide. If this time of collision is ( x pi m / q B ) then ( x ) is (neglecting the interaction force). |
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276 | A small current element of length ( d l ) and carrying current is placed at (1,1,0) and is carrying current in ‘ ( +z^{prime} ) direction. If magnetic field at origin be ( vec{B}_{1} ) and at point (2,2,0) be ( vec{B}_{2} ) then A ( cdot vec{B}=vec{B} ) B . ( left|vec{B}_{1}right|=left|2 vec{B}_{2}right| ) c. ( vec{B}_{1}=-vec{B}_{2} ) D . ( vec{B}_{1}=-2 vec{B}_{2} ) |
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277 | The sensitivity of a voltmeter of 1000 ohms is ( 1 mathrm{mV} / ) div When a resistance of ( 99,000 Omega ) is connected in series, its sensitivity becomes: A. 1 Volt / div B. 10 Volt / div c. 1.1 volt / div D. 0.1 volt / div |
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278 | The relation between voltage sensitivity ( left(sigma_{v}right) ) and current sensitivity ( left(sigma_{i}right) ) of ( a ) moving coil galvanometer is (resistance of galvanometer is ( G ) ). A ( cdot frac{sigma_{i}}{G}=sigma_{v} ) в. ( frac{sigma_{v}}{G}=sigma ) c. ( frac{G}{sigma_{v}}=sigma ) D. None of the above |
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279 | Two wires carry currents of ( 100 A ) and ( 200 A ) respectively and they repel each other with a force of ( 0.4 N / m . ) The distance between them will be A . ( 1 m ) B. ( 1 mathrm{cm} ) ( c .50 mathrm{cm} ) D. ( 25 mathrm{cm} ) |
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280 | A metal ring kept (supported by a card board) on the top of a fixed solenoid carry a current I as shown in figure. The centre of the ring coincides with the axis of the solenoid. If the current in the solenoid is switched off, then A. magnetic flux linked with the metal ring increases. B. current induced in the metal ring in clockwise direction c. metal ring will not remain on the cardboard D. both (a) and (b) are correct |
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281 | A current of ( 10 A ) passes through two very long wires held parallel to each other and separated by a distance of 1 ( m ). What is the force per unit length between them? |
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282 | Two circular coils ( X ) and ( Y ) having radii ( mathrm{R} ) and ( mathrm{R} / 2 ) respectively are placed in horizontal plane with their centres coinciding with each other. Coil X has current I flowing through it in the clockwise sense. What must be the current in the coil ( Y ) to make the total magnetic field at the centre of two coils zero? |
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283 | An ammeter has a resistance of ( G ) ohms and range of ( I ) amperes. The value of resistance required in parallel to convert it into an ammeter of range ( boldsymbol{n} boldsymbol{I} ) is A ( . n G ) в. ( (n-1) G ) c. ( G /(n-1) ) D. ( G / n ) |
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284 | Equal currents are passing through two very long and straight parallel wires in the same direction. They will A. repel each other B. attract each other c. lean towards each other D. neither attract nor repel each other |
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285 | There will be no force between two current carrying wires if currents are A. Parallel to each other B. Antiparallel to each other C. Perpendicular to each other D. Nothing can be said |
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286 | A particle initially moving towards south in a vertically downward magnetic field is deflected toward the east. What is the sign of the charge on the particle? |
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287 | A proton and an alpha particle enter into a uniform magnetic field with the same velocity.The period of rotation of the alpha particle will be A. four times that of proton B. two times that of proton c. three times that of proton D. same as that of proton |
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288 | The direction of force on a current carrying conductor placed in a magnetic field can be reversed by reversing the direction of current flowing in the conductor. True/False? |
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289 | Charge ( q ) is uniformly spread on a thin ring of radius ( R ). The ring rotates about its axis with a uniform frequency ( boldsymbol{f} boldsymbol{H} boldsymbol{z} ) The magnitude of magnetic induction at the centre of the ring is A ( cdot frac{mu_{0} q f}{2 R} ) в. ( frac{mu_{0} q}{2 f R} ) c. ( frac{mu_{0} q}{2 pi f R} ) D. ( frac{mu_{0} q f}{2 pi R} ) |
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290 | The S.I. unit of magnetic field intensity is : A. webber B. Tesla c. owersted D. Gauss |
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291 | A toroid of n turns, mean radius R and cross-sectional radius a carries current I. It is placed on a horizontal table taken as ( x-y ) plane. Its magnetic moment ( bar{M} ) is A. is non-zero and points in the z-direction by symmetry B. points along the axis of the toroid ( (bar{M}=M phi) ) c. is zero, otherwise there would be field falling as ( frac{1}{r^{3}} ) at large distances outside the toroid D. is pointing radially outwards |
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292 | A circular loop carrying a current ( I ) is placed in the ( x ) -y plane as shown in figure.An uniform magnetic field ( vec{B} ) is oriented along the positive z-axis.The loop tends to: A. expand B. contract ( c . ) rotate about x-axis D. rotate about y-axis |
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293 | When radiation emitted by a radioactive substance is subjected to a magnetic field, alpha-particles describe a circle in the clockwise direction A. beta and gamma particles will also be deflected in the same direction B. gamma rays will be deflected to describe a circle in the counter clockwise direction but beta particles will not be deflected C . gamma rays will not be deflected and beta rays will move in a circular path in the counter clockwise sense D. beta and gamma rays will describe a circle in the counter clockwise sense |
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294 | Two long parallel wires are at a distance of ( 1 mathrm{m} ). If both of them carry one ampere of current in same direction, then the force of attraction on unit length of the wires will be A ( cdot 2 times 10^{-7} N / m ) B . ( 4 times 10^{-7} N / m ) c. ( 8 times 10^{-7} N / m ) D. ( 10^{-7} N / m ) |
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295 | Write the following steps of an experiment in a sequential order to show that a current carrying conductor sets up a magnetic field around it. (a) Pass the insulted copper wire through the small hole at the centre of the carboard and perpendicular to it. (b) Paste a white paper on a rectangular cardboard and make a small hole at its centre. (c) Connect this wire to a battery, a switch and a variable resistor in series. (d) Clamp this cardboard to a stand in a horizontal position and sprinkle some iron filings over it. (e) Now, when the circuit is closed, the iron filings on the carboard form concentric circles around the wire. A. bdace B. baced c. adbec ( mathbf{D} cdot e d a b c ) |
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296 | Two wires carrying equal current ( I ) are a distance ( a ) apart. If the current through wire one is doubled while the current through the wire two is tripled, what is the ratio of the force that wire two exerts on wire 1 ( F_{1} ) ) to the force that wire one exerts on wire ( 2left(F_{2}right) ? ) A . 4: 09 B. 2:03 ( c cdot 1: 0 ) D. 3:02 E. 9: 04 |
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297 | What is the speed at the top? A ( frac{E}{B} ) в. ( frac{E}{2 text { }} ) c. ( frac{2 E}{B} ) D. ( frac{B}{2 E} ) |
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298 | toppr Q Type your question. cnargea partıcies. wıth a rıela b resia, is found that the filter transmits ( alpha ) – particles each of energy ( 5.3 mathrm{MeV} ). The magnetic field is increased to ( 2.3 mathrm{B} ) Tesla and deuterons are passed into the filter. The energy of each deuteron transmitted by the filter is MeV. A . 28 Mev B. 14Mev c. 7 Mev D. 18Me |
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299 | f the magnetic induction at the center of the rotating sphere is ( vec{B}= ) ( frac{2}{X} mu_{0} omega sigma R(hat{k})left[quad sin ^{3} theta=frac{1}{4}(3 sin thetaright. ) Find ( X ? ) |
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300 | The force of repulsion between two parallel wires is ( f ) when each one of them carries a certain current ( I ). If the current in each is doubled, the force between them would be A ( cdot frac{4}{f} ) B. ( 4 f ) c. ( 2 f ) D. ( f ) |
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301 | A particle with charge ( q ) is projected successively along the ( x ) and ( y ) axes with same speed v. The force on the particle in these situations are ( boldsymbol{q} boldsymbol{v} boldsymbol{B}(-boldsymbol{3} hat{boldsymbol{j}}+boldsymbol{4} hat{boldsymbol{k}}) ) and ( q v B(3 hat{i}) ) respectively. Find the unit vector in direction of ( vec{B} ) |
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302 | A moving coil galvanometer A has 100 turns and resistance ( 10 Omega ). Another galvanometer B has 50 turns and resistance 5Omega. The other quantities are same in both the cases. Then the voltage sensitivity of A. A is greater than that of B. B is greater than that of c. A and B is Same D. cannot be compared |
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303 | The minimum magnetic dipole moment of electron in hydrogen atom is A ( cdot frac{e h}{2 pi m} ) в. ( frac{e h}{4 pi m} ) c. ( frac{e h}{pi m} ) ( D ) |
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304 | A current of ( 4 A ) flows through 5 turn coil of a tangent galvanometer having a diameter of ( 30 mathrm{cm} . ) If the horizontal component of Earth’s magnetic induction is ( 4 times 10^{-5} T ), find the deflection produced in the coil. ( left[text { Given } mu_{0}=4 pi times 10^{-7} H m^{-1}right] ) |
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305 | A device used for measuring small currents due to changing magnetic field is known as: A. galvanometer B. ammeter c. potentiometer D. voltmeter |
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306 | A wire ( 28 mathrm{m} ) long is bent into ( mathrm{N} ) turns of circular coil of diameter ( 14 mathrm{cm} ) forming a solenoid of length ( 60 mathrm{cm} ). Calculate the magnetic field inside it when a current of 5 amp passed through it. ( left(mu_{0}=12.57 times 10^{-7} m^{-1}right) ) A ( cdot 6.67 times 10^{-1} T ) ( T ) в. ( 6.67 times 10^{-4} T ) c. ( 6.67 times 10^{4} T ) D. ( 2.67 times 10^{-4} T ) |
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307 | Ine magnetıc tıeld ( boldsymbol{B} ) at the centre of a circular coil of radius ( r ) is ( pi ) times that due to a long straight wire at a distance ( r ) from it, for equal currents. The following diagram shows three cases. In all cases the circular part has radius ( r ) and straight ones are infinitely long. For the same current the field ( B ) at centre ( P ) in cases 1,2,3 has the ratio: ( ^{mathbf{A}} cdotleft(-frac{pi}{2}right):left(frac{pi}{2}right):left(frac{3 pi}{4}-frac{1}{2}right) ) B ( cdotleft(-frac{pi}{2}+1right):left(frac{pi}{2}+1right):left(frac{3 pi}{4}+frac{1}{2}right) ) ( left(-frac{pi}{2}right):left(frac{pi}{2}right):left(frac{3 pi}{4}right) ) D ( cdotleft(-frac{pi}{2}-1right):left(frac{pi}{2}-frac{1}{4}right):left(frac{3 pi}{4}+frac{1}{2}right) ) |
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308 | The magnetic moment associated with a circular coil of 35 turns and radius 25 ( mathrm{cm}, ) if it carries a current of ( 11 mathrm{A} ) is: A ( .72 .2 A m^{2} ) B . ( 70.5 A m^{2} ) c. ( 74.56 A m 2 ) D. ( 75.56 A m^{2} ) |
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309 | A wire is wound on a long rod of material of relative permeability ( mu_{r}= ) 4000 to make a solenoid. If the current through the wire is ( 5 A ) and number of turns per length is 1000 per meter, then the magnetic field inside the solenoid is: A. ( 25.12 mathrm{mT} ) B. ( 12.56 mathrm{mT} ) c. ( 12.56 T ) D. 25.12 T |
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310 | A neutron, a proton, an electron and an ( alpha ) particle enter perpendicular uniform magnetic field, with the same uniform velocity. The path of electron in the following figure will be: ( A cdot 4 ) B. 3 ( c cdot 2 ) D. |
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311 | projected with a velocity ( v_{0} ) towards a circular region having a uniform magnetic field ( B ) perpendicular and into the plane of paper from point ( boldsymbol{P} ) as shown in the figure. ( boldsymbol{R} ) is the radius and O is the center of the circular region. If the line ( O P ) makes an angle ( theta ) with the direction of ( v_{0} ) then the value of ( v_{0} ) so that particle passes through ( boldsymbol{O} ) is A ( cdot frac{q B R}{m sin theta} ) B. ( frac{q B R}{2 m sin theta} ) c. ( frac{2 q B R}{m sin theta} ) D. ( frac{3 q B R}{2 m sin theta} ) |
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312 | The magnetic field inside a solenoid carrying current. A. is the same at all points B. is zero at all points c. becomes zero at its north pole D. becomes zero at its south pole |
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313 | An observer ( A ) and a charge ( Q ) are fixed in a stationary frame ( F_{1} ). an observer ( mathrm{B} ) is fixed in a frame ( F_{2}, ) which is moving with respect to ( boldsymbol{F}_{1}: ) This question has multiple correct options A. both A and B will observe electric fields B. both A and B will observe magnetic fields C. neither A nor B will observe magnetic fields D. B will observe a magnetic field, but A will not |
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314 | On passing electric current in two long straight conductors in mutually opposite directions, the magnetic force acting between them will be A. attractive B. repulsive c. both attractive and repulsive D. neither attractive nor repulsive |
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315 | An electron, moving along the ( x ) -axis with an initial energy of ( 100 e V ), enters a region of magnetic field ( vec{B}=(1.5 times ) ( left.10^{-3} Tright) hat{k} ) at ( S(text { See figure }) . ) The field extends between ( x=0 ) and ( x=2 c m ) The electron is detected at the point ( Q ) on a screen placed ( 8 mathrm{cm} ) away from the point S. The distance d between P and Q (on the screen) is : (electron’s charge ( =1.6 times 10^{-19} mathrm{C}, ) mass of electron ( left.=9.1 times 10^{-31} k gright) ) A ( .12 .87 mathrm{cm} ) В. ( 1.22 mathrm{cm} ) c. ( 11.65 mathrm{cm} ) D. ( 2.25 mathrm{cm} ) |
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316 | Consider points ( A, B, C, D ) on a horizontal cardboard equidistant from center ( boldsymbol{O} ) as shown in the figure. ( mathbf{A} ) copper wire perpendicular to the cardboard passes through the center ( O ) and carries an electric current flowing upwards. Deflection of magnetic needle will be maximum when it is kept at the point A . ( A ) в. ( B ) ( c . c ) ( D ) |
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317 | A solenoid having an iron core has its terminals connected across an ideal DC source and it is in steady state. If the iron core is removed, the current flowing through the solenoid just after removal of rod. A . increases B. decreases c. remains unchanged D. nothing can be said |
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318 | A charge ( boldsymbol{q}(>mathbf{0}) ) moves towards the centre of a circular loop of radius ( boldsymbol{R} ) along its axis. The magnitude of B along the periphery of the loop is A . zero B. ( frac{mu_{0}}{4 pi} frac{q v R}{sqrt{left(R^{2}+x^{2}right)^{3}}} ) c. ( frac{q v R}{sqrt{R^{2}+x^{2}}} ) D. ( frac{mu_{0}}{4 pi} frac{q v R}{sqrt{R^{2}+x^{2}}} ) |
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319 | The number of electrons to be put on a spherical conductor of radius ( 0.1 m ) to produce an electric field of ( 0.036 N / C ) just above its surface is A ( cdot 2.7 times 10^{5} ) В. ( 2.6 times 10^{5} ) c. ( 2.5 times 10^{5} ) D. ( 2.4 times 10^{5} ) |
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320 | When a charged particle is projected perpendicular to a magnetic field: A. Its path is circular in a plane perpendicular to the plane of magnetic field B. The speed and kinetic energy of the particle remains constant C. The velocity and momentum of the particle changes only in direction D. The time period of revolution, angular and frequency of revolution is independent of velocity of the particle and radius of circular path |
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321 | A current carrying conductor experiences a force when placed in a magnetic field. Type 1 for true and 0 for false |
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322 | A moving coil ammeter requires a potential difference of ( 0.4 V ) across it for full scale deflection. It has fixed shunt resistance of 0.01 ohm with a coil circuit resistance of ( boldsymbol{R}=mathbf{1} boldsymbol{k} ) ohm. The value of shunt required to give full scale deflection when the total current is ( 10 A ) is equal to A. 0.02 ohm B. 0.04 ohm c. 0.05 ohm D. 0.06 ohm |
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323 | In the given figure, what is the magnetic field induction at point 0 A ( cdot frac{mu_{0} l}{4 pi r} ) в. ( frac{mu_{0} l}{4 r}+frac{mu_{0} l}{2 pi r} ) c. ( frac{mu_{o} l}{4 r}+frac{mu_{0} l}{4 pi r} ) D. ( frac{mu_{0} l}{4 r}-frac{mu_{0} l}{4 pi r} ) |
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324 | Which of the following particle would follow the path as shown in the above figure? A. Proton B. Electron C . Neutron D. x-ray E. Photon of red ligth |
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325 | A current i is flowing in a conductor as shown in the figure. The magnetic induction at point 0 will be : A . zero B. ( mu_{0} i / r ) ( c cdot 2 mu_{0} i / r ) ( mathbf{D} cdot mu_{0} i / 4 r ) |
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326 | A non-relativistic proton beam passes without deviation through a region of space where there are uniform transverse mutually perpendicular electric and magnetic fields with ( boldsymbol{E}= ) ( 120 k V m^{-1} ) and ( B=50 m T . ) Then the beam strikes a grounded target. Find the force imparted by the beam on the target if the beam current is equal to ( boldsymbol{i}=mathbf{0 . 8} boldsymbol{m} boldsymbol{A} ) Mass of protons ( =1.67 times 10^{-27} k g ) |
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327 | Assertion A current carrying conductor experiences a force in a magnetic field. Reason The net charge on a current carrying conductor is zero. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
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328 | Pitch of the helical path described by the particle is : A. ( frac{2 pi m v_{0}}{B_{0} q} ) В. ( frac{sqrt{3} pi m v_{0}}{2 B_{0} q} ) c. ( frac{pi m v_{0}}{B_{0} q} ) D. ( frac{2 sqrt{3} pi m v_{0}}{B_{0} q} ) |
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329 | A proton moving with a constant velocity passes through a region of space without any change in its velocity. If E and B represent the electric and magnetic fields respectively, this region of space may not have A. ( E=0, B=0 ) B. ( E=0, B neq 0 ) c. ( E neq 0, B=0 ) D. ( E neq 0, B neq 0 ) |
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330 | If the work done in turning a magnet of magnetic moment ( M ) by an angle of ( 90^{circ} ) from the magnetic meridian is n times the corresponding work done to turn it through an angle of ( 60^{circ} ), then the value of ( n ) is A . 1 B. 2 ( c cdot frac{1}{2} ) D. |
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331 | A long horizontally fixed wire carries a current of 100 ampere. Directly above and parallel to it is a fine wire that carries a current of 20 ampere and weights 0.04 newton per meter. The distance between the two wires for which the upper wire is just supported by magnetic repulsion is: ( mathbf{A} cdot 10^{-2} m m ) B. ( 10^{-2} mathrm{cm} ) ( mathrm{c} cdot 10^{-2} mathrm{m} ) D. ( 10^{-2} k m ) |
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332 | A particle of charge ( q ) and mass ( m ) moves in a circular orbit of radius r with angular speed ( omega . ) The ratio of the magnitude of its magnetic moment to that of its angular momentum depends on A. ( omega ) and ( q ) B. ( omega, q ) and ( m ) c. ( q ) and ( m ) D. ( omega ) and ( m ) |
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333 | State two ways by which the magnetic field of a solenoid can be made stronger | 12 |

334 | Assertion: Diamagnetism is universal, it is present in all materials.
Reason: Field due to induced magnetic |
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335 | A square loop ( A B C D, ) carrying a current ( boldsymbol{I}_{1}, ) is placed near and coplanar with a long straight conductor ( boldsymbol{X} boldsymbol{Y} ) carrying a current ( I_{1} ), as shown in figure. The net force on the loop will be A ( cdot frac{mu_{0} I_{1} I_{2}}{2 pi} ) B. ( frac{mu_{0} I_{1} I_{2} L}{2 pi} ) c. ( frac{2 mu_{0} I_{1} I_{2} L}{2 pi} ) D. ( frac{2 mu_{0} I_{1} I_{2}}{3 pi} ) |
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336 | The coercivity of a small magnet where the ferromagnet gets demagnetised is ( 3 times 10^{3} A m^{-1} . ) The current required to be passed in a solenoid of length ( 10 mathrm{cm} ) and number of turns ( 100, ) so that the magnet gets demagnetised when inside the solenoid, is: A . ( 6 A ) в. 30 тА ( c .60 m A ) D. ( 3 A ) |
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337 | Find the magnetic field intensity due to a thin wire carrying current ( I ) in the figure : A ( cdot frac{mu_{0} i}{2 pi R}(pi-a+tan a) ) в. ( frac{mu_{0} i}{2 pi R}(pi-a) ) c. ( frac{mu_{0} i}{2 pi R}(pi+a) ) D. ( frac{mu_{0}}{2 pi R}(pi+a-text { tana }) ) |
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338 | The magnetic force per unit length on a wire carrying a current of ( 10 mathrm{A} ) and making an angle of ( 45^{0} ) with the direction of a uniform magnetic field of ( 0.20 mathrm{T} ) is A ( cdot 2 sqrt{2} N m^{-1} ) B. ( frac{2}{sqrt{2}} N m^{-1} ) ( ^{c} cdot frac{sqrt{2}}{2} N m^{-1} ) D. ( 4 sqrt{2} N m^{-1} ) |
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339 | Find the magnetic induction ( B ) on the axis as a function of ( x ) A ( cdot B=frac{1}{2} mu_{0} n Ileft(1-frac{x}{sqrt{x^{2}+R^{2}}}right) ) в. ( quad B=frac{1}{2} mu_{0} n Ileft(2-frac{x}{sqrt{x^{2}+R^{2}}}right) ) c. ( _{B}=frac{1}{2} mu_{0} n Ileft(R-frac{x}{sqrt{x^{2}+R^{2}}}right) ) D. ( B=frac{1}{2} mu_{0} n Ileft(X-frac{x}{sqrt{x^{2}+R^{2}}}right) ) |
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340 | Which is the magnitude of force on a current I carrying conductor of length ( l ) placed in a magnetic field B ? A ( . B I l^{2} ) в. Вl/ c. ( B l I ) D. ( B I^{2} ) |
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341 | A device used for detecting small currents due to changing magnetic field is known as: A. Galvanometer B. Ammeter c. Voltmeter D. Potentiometer |
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342 | An electron enters a chamber in which a uniform magnetic field is present as shown. Ignore gravity. During its motion inside the chamber field A. The force on the electron remains constant B. The kinetic energy of the electron remains constantt c. The momentum of the electron remains constant D. The speed of the electron increases at a uniform rate |
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343 | An electric field of ( 1500 V / m ) and ( a ) magnetic field of ( 0.04 W b / m^{2} ) act on a moving electron. The minimum uniform speed along a straight line the electron could have is. A ( cdot 1.6 times 10^{15} mathrm{m} / mathrm{s} ) в. ( 6 times 10^{-16} mathrm{m} / mathrm{s} ) C ( .3 .75 times 10^{4} mathrm{m} / mathrm{s} ) D. ( 3.75 times 10^{2} mathrm{m} / mathrm{s} ) |
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344 | A long solenoid has magnetic field strength of ( 3.14 times 10^{-2} mathrm{T} ) inside it when a current of ( 5 A ) passes through it The number of turns in 1 m of the solenoid is A. 1000 B. 3000 c. 5000 D. 10000 |
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345 | A magnetic dipole in a constant magnetic field has A. Minimum potential energy when the torque is maximum. B. Zero potential energy when the torque is minimum. C. Zero potential energy when the torque is maximum. D. Maximum potential energy when the torque is maximum. |
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346 | A circular coil expands radially in a region of magnetic field and no electromotive force is produced in the coil. This is because A. the magnetic field is constant B. the magnetic field is in the same plane as the circular coil and it may or may not vary c. the magnetic field has a perpendicular (to the plane of the coil) component whose magnitude is decreasing suitably ( D . ) both ( (b) ) and ( (c) ) |
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347 | If a charged particle goes unaccelerated in a region containing electric and magnetic fields, then This question has multiple correct options A. ( vec{E} ) must be perpendicular to ( vec{B} ) B . ( vec{v} ) must be perpendicular to ( vec{E} ) C. ( vec{v} ) must be perpendicular to ( vec{B} ) D. E must be equal to vB |
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348 | An ideal solenoid of cross-sectional ( operatorname{area} 10^{-4} m^{2} ) has 500 turns per metre. At the centre of this solenoid, another coil of 100 turns is wrapped closely around it, if the current in the coil charges from 0 to ( 2 A ) in 3.14 ms, the emf developed in the second coil is: ( mathbf{A} cdot 1 m V ) B. ( 2 m V ) ( mathbf{c} .3 m V ) D. ( 4 mathrm{mV} ) |
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349 | A particle of charge q is moving with velocity v in the presence of crossed electric field E and magnetic field B as shown. Write the condition under which the particle will continue moving along x-axis. How would the trajectory of the particle be affected if the electric field is suddenly switched off? |
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350 | A proton moving with a constant speed passes through a region of space without any change in its speed. If ( boldsymbol{E} ) and ( B ) represent the electric and magnetic fields respectively, this region of space may have a) ( boldsymbol{B} neq mathbf{0}, boldsymbol{E}=mathbf{0} ) b) ( boldsymbol{B}=mathbf{0}, boldsymbol{E} neq mathbf{0} ) c) ( B=0, E=0 ) d) ( boldsymbol{B} neq mathbf{0}, boldsymbol{E} neq mathbf{0} ) ( A cdot a, b, c ) are true B. b, c, dare true ( c cdot a, b, d ) are true D. a, c, d are true |
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351 | topp ( Q ) Type your question as ‘positive’ when the wires repel each ther and ‘negative’ when the wires attract each other, the graph showing the dependence of ‘F’, on the product ( I_{1} I_{2}, ) would be ( c ) ( D ) |
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352 | The force exerted on a current-carrying wire placed in a magnetic field is zero when the angle between the wire and the direction of magnetic field is. A ( .180^{circ} ) B. ( 90^{circ} ) ( c cdot 60^{circ} ) D. ( 15^{circ} ) |
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353 | Give the principle of moving coil galvanometer? What is the advantage of radial magnetic field in the galvanometer? | 12 |

354 | A galvanometer of resistance ( 50 Omega ) is connected to a battery of ( 8 V ) along with a resistance of ( 3950 Omega ) in series. A full scale deflection of 30 div is obtained in the galvanometer. In division, the resistance in series should be A. 1950 в. 7900 c. 2000 D. 7950 |
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355 | The rigid conducting thin wire frame carries an electric current ( I ) and this frame is inside a uniform magnetic field ( vec{B} ) as shown in fig. Then A. the net magnetic force on the frame is zero but the torque is not zero B. the net magnetic force on the frame and the torque due to magnetic field are both zero c. the net magnetic force on the frame is not zero and the torque is also not zero D. none of these |
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356 | A uniform conducting wire ( A B C ) lying in ( X Y ) plane has a mass of ( 10 g . A ) current of ( 2 A ) flows through it. The wire is kept in a uniform magnetic field ( B=2 T ) which acceleration of the wire is A. Zero B ( cdot 12 m / s^{2} ) and along postive ( Y ) -axis C. ( 12 times 10^{-3} mathrm{m} / mathrm{s}^{2} ) along postive ( Y ) -axis D. ( 12 m / s^{2} ) and along postive ( X ) -axis |
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357 | The magnetic field at the centre of circular loop in the circuit carrying current ( I ) shown in the figure is : A ( cdot frac{mu_{0}}{4 pi} frac{2 I}{r}(1+pi) ) в. ( frac{mu_{0}}{4 pi} frac{2 I}{r}(pi-1) ) c. ( frac{mu_{0}}{4 pi} frac{2 I}{r} ) D. ( frac{mu_{0}}{4 pi} frac{I}{r}(pi+1 ) |
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358 | An electron is shot in a steady electric and magnetic field such that its velocity is ( V ). Electric field ( E ) and magnetic field ( boldsymbol{B} ) are mutually perpendicular. The magnitude of ( boldsymbol{E} ) is 1 volt ( / mathrm{cm} ) and that of ( boldsymbol{B} ) is 2 tesla. Now it happens that the Lorentz (Magnetic) force cancels with the electrostatic force on the electron, then the velocity of the electron is: A. ( 50 mathrm{ms}^{-1} ) B. ( 2 mathrm{cms}^{-1} ) c. ( 0.5 mathrm{cms}^{-1} ) D. ( 200 m s^{-1} ) |
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359 | What is a solenoid? Draw a sketch to show the magnetic field pattern produced by a current carrying solenoid |
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360 | Two circular coils ( P ) and ( Q ) are made from similar wire but radius of ( Q ) is twice that of ( P ). Relation between the values of potential difference across them so that the magnetic induction at their centers may be the same is : ( mathbf{A} cdot V_{Q}=2 V_{P} ) B. ( V_{Q}=3 V_{P} ) ( mathbf{c} cdot V_{Q}=4 V_{P} ) D. ( v_{Q}=frac{1}{4} V_{P} ) |
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361 | Two long parallel wires are a distance 2 a apart, as shown. Point P is in the plane of the wires and a distance a from wire X. When there is a current lin wire ( X ) and no current in wire ( Y ), the magnitude of the magnetic field at ( P ) is ( B_{0} . ) When there are equal currents lin the same direction in both wires, the magnitude of the magnetic field at P is? A. ( frac{2 B_{0}}{3} ) в. ( B_{0} ) c. ( frac{10 B_{0}}{9} ) D. ( frac{4 B}{3} ) |
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362 | Best method to increase the sensitivity of the moving coil galvanometer is to decrease A. radius of the coil B. number of turns of the coil c. external magnetic field D. couple per unit twist |
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363 | The figure shows the cross-section of two long coaxial tubes carrying equal currents ( I ) in opposite directions. If ( B_{1} ) and ( B_{2} ) are magnetic fields at point and ( 2, ) as shown in figure then ( mathbf{A} cdot B_{1} neq 0 ; B_{2}=0 ) B . ( B_{1}=0 ; B_{2}=0 ) c. ( B_{1} neq 0 ; B_{2} neq 0 ) D. ( B_{1}=0 ; B_{2} neq 0 ) |
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364 | toppr Q Type your question the conductor, is correctly represented by the figure: ( A ) B. ( c ) ( D ) |
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365 | A long solenoid has magnetic field strength of ( 3.14 times 10^{-2} mathrm{T} ) inside it when a current of ( 5 A ) passes through ¡t. The number of turns in 1 m length of the solenoid is A. 1000 в. 3000 ( c .5000 ) D. 10000 |
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366 | Two particles of different masses ( m_{1} ) and ( m_{2}, ) different charges ( Q_{1} ) and ( Q_{2} ) are accelerated through the same potential difference and then enter a uniform magnetic field in a direction perpendicular to the field. If they trace circular paths of same radius, then the ratio of their masses ( left(m_{1} / m_{2}right) ) must be A ( cdot Q_{2} / Q_{1} ) в. ( Q_{1} / Q_{2} ) c. ( left(Q_{1} / Q_{2}right)^{1 / 2} ) the D. ( left(Q_{2} / Q_{1}right)^{1 / 2} ) |
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367 | The deflection in galvanometer falls to ( left[frac{1}{4}right]^{t h} ) when it is shunted by ( 3 Omega ). If additional shunt of ( 2 Omega ) is connected to earlier shunt, the deflection in galvanometer falls to A ( cdot frac{1}{2} ) B. ( frac{1^{r d}}{3} ) c. ( frac{1}{4}^{t h} ) D. ( frac{1}{8.5} ) |
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368 | A proton of charge ( e ) moving at speed ( v_{0} ) is placed midway between two parallel wires ( a ) distance a apart, each carrying current ( I ) in the same direction. The force on the proton is: A . 0 в. ( quad e v_{0} frac{I_{0}}{2 pi a} ) ( ^{mathrm{c}} cdot operatorname{ev}_{0} frac{I_{0}}{2 pi(2 a)} ) D. ( _{e v_{0}} frac{I_{0}}{2 pi frac{a}{2}} ) E. Unable to be determined |
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369 | An electron enters with a velocity ( v ) to the right in a magnetic field ( B ), also to the right. What direction is the force ( boldsymbol{F} ) on the electron? A. An upward force B. A downward force c. A force to the left D. No force if felt |
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370 | A charged particle moving at right angles to a uniform magnetic field: A. Gains energy B. Loses energy c. Neither gains nor loses energy D. Either gains or loses energy |
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371 | A current-carrying ring is placed in a magnetic field. The direction of the field is perpendicular to the plane of the ring This question has multiple correct options A. there is no net force on the ring B. the ring will tend to expand c. the ring will tend to contract D. either (b) or (c) depending on the directions of the current in the ring and the magnetic field |
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372 | Deflection in the galvanometer is A. Towards right B. Left c. No defection D. None of these |
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373 | A bar magnet of magnetic moment ( 2 A m^{2} ) is free to rotate about a vertical axis passing through its center. The magnet is released from rest from east west position. Then the KE of the magnet as it takes N-S position is ( left(B_{H}=25 mu Tright) ) A. ( 25 mu J ) в. ( 50 mu J ) c. ( 100 mu J ) D. ( 12.5 mu J ) |
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374 | Write the correct option by observing the figures. A. Magnetic field in ( A ) stronger. B. Magnetic field in ( B ) stronger. C. Magnetic field in ( A ) and ( B ) are same D. Magnetic field in ( A ) and ( B ) are weaker. |
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375 | A bar magnet of magnetic moment 3.0 ( A-m^{2} ) is free to rotate about a vertical axis passing through its centre. The magnet is released from rest from east west position. Then the kinetic energy of the magnet as it takes North- South position is : (horizontal component of earths magnetic field is ( 25 mu mathrm{T}) ) B. 75 ( mu ) J c. ( 100 mu ) J D. 12.5 ( mu ) ) |
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376 | The coils made of the same material in two moving coil galvanometers have their areas in the ratio of 2: 3 and the number of turns in the ratio of 4: 5 These two coils carry the same current and are situated in the same field. The deflections produced by these two coils will be in the ratio of: ( mathbf{A} cdot 8: 15 ) B. 15: 8 c. 8: 1 D. 1: 4 |
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377 | A loop carrying a current ( i ), lying in the plane of the paper, is in the field of a long straight wire with current ( boldsymbol{i}_{0} ) (inward) as shown in figure. If the torque acting on the loop is given by ( tau=frac{mu_{0} i i_{0}}{x pi r}[sin theta](b-a) . ) Find ( x ) |
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378 | Magnetic field inside a long solenoid carrying current is: A. same at all points (uniform) B. different at poles and at the centre c. zero D. different at all points |
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379 | The pattern of the magnetic field around a conductor due to an electric current flowing through it depends on A. amount of current flowing through the conductor B. amount of voltage supplied to the conductor c. size of conductor D. shape of the conductor |
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380 | Two long and parallel straight wires ( A ) and B carrying currents of ( 8.0 mathrm{A} ) and 5.0 A in the same direction are separated by a distance of ( 4.0 mathrm{cm} . ) Estimate the force on a ( 10 mathrm{cm} ) section of wire ( mathrm{A} ) | 12 |

381 | A proton is projected with a speed of ( 3 times 10^{6} m / s ) horizontally from east to west. A uniform magnetic field B of strength ( 2 times 10^{-3} T ) exists in the vertically upward direction the magnitude of magnetic force on proton is ( boldsymbol{F} times mathbf{1 0}^{-16} boldsymbol{N} ). What is the value of ( boldsymbol{F} ) ? |
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382 | The intensity of magnetic induction at the center of a circular coil carrying a current is ( B ). If the number of turns and radius are doubled, the intensity of magnetic induction at the center with the same current will be A ( .2 B ) в. ( 4 B ) ( c . B ) D. ( 0.5 B ) |
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383 | A charged particle with velocity ( 2 times ) ( 10^{3} m / s ) passes undeflected through electric and magnetic field. Magnetic field is 1.5 tesla. The electric field intensity would be A ( cdot 2 times 10^{3} N / C ) в. ( 1.5 times 10^{3} N / C ) c. ( 3 times 10^{3} N / C ) ( mathbf{D} cdot 4 / 3 times 10^{-3} N / C ) |
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384 | charge particles are pictured in the same magnetic field which points into the screen (represented by blue ( X^{prime} ) s) The particles are moving at the same speeds but in different directions, as indicated by the red arrows. How do the particles rank, in terms of the force they experience due to their movements in the magnetic field, greatest first? A. 1,2,3 B. 1 and 2 tie, 3 c. 3,1 and 2 tie D. 3,2,1 E. All tie |
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385 | A tightly-wound long solenoid has n turns per unit length,radius r and carries a current ( i . ) A particle having charge ( q ) and mass ( m ) is projected from a point on the axis in the direction perpendicular to the axis.The maximum speed for which particle does not strike the solenoid will be A ( cdot frac{mu_{o} q r n i}{2 m} ) B. ( frac{mu_{o} q r n i}{m} ) c. ( frac{2 mu_{o} q r n i}{3 m} ) D. None of these |
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386 | Assertion When radius of a circular loop carrying current is doubled, its magnetic moment becomes four times. Reason Magnetic moment depends on the area of the loop. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
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387 | The magnetic field ( overline{boldsymbol{d} boldsymbol{B}} ) due to a small current element dl at a distance ( vec{r} ) and carrying current ‘i’ is A ( left.cdot frac{mu_{0}}{d B}=frac{frac{d bar{d}}{4 pi} i}{r}right) ) В ( cdot frac{ }{d B}=frac{mu_{0}}{4 pi} i^{2}left(frac{overline{d l} times bar{r}}{r^{2}}right) ) ( ^{mathbf{C}} cdot frac{mu_{0}}{d B}=frac{frac{mu}{4 pi} i^{2}}{r} ) D ( cdot frac{mu_{0}}{d B} ileft(frac{overline{d l} times bar{r}}{r^{3}}right) ) |
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388 | Which of the following is the correct decreasing order of the strengths of four fundamental forces of nature? A. Electromagnetic force >weak nuclear force>gravitational force>strong nuclear force. B. Strong nuclear force>weak nuclear force>electromagnetic force>gravitational force c. Gravitational force>electromagnetic force>strong nuclear force>weak nuclear force D. strong nuclear force>electromagnetic force>weak nuclear force>gravitational force |
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389 | Can a current carrying straight electric wires attract the nearby iron objects towards them? |
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390 | The diagram below represents five different same-length identical wires(red) carrying the same amount of current in the same magnetic field (blue) with current directions and magnetic field directions indicated by arrows. Which wire(s) experience(s) the most force due to the magnetic field? |
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391 | The operating magnetic field for accelerating protons in a cyclotron oscillator having frequency of 12 MHz is ( left(q=1.6 times 10^{-19} mathrm{C}, m_{p}=1.67 times 10^{-27}right. ) kg and ( left.1 mathrm{MeV}=1.6 times 10^{-13} mathrm{J}right) ) A . 0.69 न B . 0.79 न c. 0.59 न D. 0.49 ( T ) |
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392 | An electron moves with a constant speed v along a circle of radius r. The magnetic moment will be (e is the electron charge) A . evr B. ( frac{e v r}{2} ) ( mathbf{c} cdot pi r^{2} e v ) D. ( 2 pi r e v ) |
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393 | Two long parallel conductors carry currents of ( 12 mathrm{A} ) and ( 8 mathrm{A} ) respectively in the same direction. If the wires are 10 cm apart, find where the third parallel wire also carrying a current must be placed so that the force experienced by it shall be zero. Answer in the form of ( x times 10^{-2} m . ) Find ( x ) |
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394 | Two charges of same magnitude move in two circles of radii ( boldsymbol{R}_{1}=boldsymbol{R} ) and ( R_{2}=2 R ) in a region of constant uniform magnetic field ( B_{0} ) The work ( W_{1} ) and ( W_{2} ) done by the |
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395 | A square loop of uniform conducting wire is as shown in figure.A current ( boldsymbol{I} ) (in ampere) enters the loop from one end and exits the loop from opposite end as shown in figure. The length of one side of square loop is ( l ) |
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396 | A moving coil galvanometer has 48 turns and area of coil is ( 4 times 10^{-2} m^{2} . ) If the magnetic field is ( 0.2 T, ) then to increase the current sensitivity by ( 25 % ) without changing area (A) and field (B) the number of turns should become: A . 24 B. 36 ( c cdot 60 ) ( D cdot 54 ) |
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397 | A ( H e^{2+} ) ion travels at right angles to a magnetic field of ( 0.80 mathrm{T} ) with a velocity of ( 10^{5} m / s . ) If ( mathrm{M} ) is the magnitude of the magnetic force on the ion, find ( x ) such that ( boldsymbol{x}=boldsymbol{M} times mathbf{1 0}^{mathbf{1 6}} ) |
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398 | If a conducting rod of length ( 4 l ) is rotated about at point ( boldsymbol{O} ) in a uniform magnetic field ( B ) directed into the paper and ( D E=l, E A=3 l ), then which of the folowing is true? [ begin{array}{rrrrrrrrrr} times & times & times & times & times & times & times & times & times & times & times \ times & times & times & times & times & times & times & times & times & times & times \ times & times & times & times & times & times & times & times & times & times & times \ times & times & times & times & times & times & times & times & times & times & times \ times & times & times & times & multicolumn{1}{c} {omega_{M}} & times & times & times & times & times \ multicolumn{1}{c} {times} & times & times & times E_{times} & & times & times & times & times & times \ times & times & times & times & times & times & times & times & times & times & times \ times & times & times & times & times & times & times & times & times & times & times \ times & times & times & times & times & times & times & times & times & times & times end{array} ] A. [ V_{A}-V_{E}=frac{9}{2} B omega l^{2} ] B. [ V_{E}-V_{A}=frac{9}{2} B omega l^{2} ] ( mathbf{c} ) [ V_{D}-V_{E}=frac{B omega l^{2}}{2} ] D. ( V_{A}-V_{E}=4 B omega l^{2} ) |
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399 | A beam of cathode rays is subjected to crossed electric (E) and magnetic fields (B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by : ( ^{mathbf{A}} cdot frac{B^{2}}{2 v E^{2}} ) B. ( frac{2 v B^{2}}{E^{2}} ) c. ( frac{2 v E^{2}}{B^{2}} ) D. ( frac{E^{2}}{2 v B^{2}} ) |
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400 | A coil in the shape of an equilateral triangles of side I is suspended between the pole pieces of a permanent magnet such that ( mathrm{B} ) is in plane of the coil. If due to a current i in the triangle, a torque ( tau ) acts on it, the side I of the triangle is : ( ^{mathrm{A}} cdot frac{2}{sqrt{3}}left(frac{tau}{B i}right)^{1 / 2} ) в. ( frac{2}{3}left(frac{tau}{B i}right) ) ( ^{c} cdotleft(frac{tau}{sqrt{3} B i}right)^{1 / 2} ) D. ( frac{1}{sqrt{3}} frac{tau}{B i} ) |
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401 | Find the magnitude and direction of the force vector applied to the loop if the vector ( vec{p}_{m} ) coincides in direction with the magnetic field produced by the current ( I ) at the point where the loop is located A ( cdot vec{F}=-frac{mu_{0} I p_{m}}{pi r^{2}} vec{e}_{r} ; vec{F} uparrow downarrow vec{r} ) B・ ( vec{F}=-frac{mu_{0} I p_{m}}{2 pi r^{2}} overrightarrow{e_{r}} ; vec{F} uparrow downarrow vec{r} ) C・ ( vec{F}=-frac{mu_{0} I p_{m}}{3 pi r^{2}} overrightarrow{e_{r}} ; vec{F} uparrow downarrow vec{r} ) D・ ( vec{F}=-frac{mu_{0} I p_{m}}{4 pi r^{2}} overrightarrow{e_{r}} ; vec{F} uparrow downarrow vec{r} ) |
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402 | A solenoid has a core of a material with relative permeability ( 400 . ) The windings of the solenoid are insulated from the core and carry a current of ( 2 A ).f the number of turns is 1000 per meter, calculate (a) ( boldsymbol{H} ) (b) ( B ) and ( (c) ) the magnetising current ( boldsymbol{I}_{m} ) |
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403 | In a cyclotron, If a deuteron can gain an energy of ( 40 mathrm{MeV} ), then a proton can an energy of: A. 40 Mev B. 80 Mev c. 20 Mev D. 160 Mev |
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404 | Magnetic filed at point ( ^{prime} boldsymbol{P}^{prime} ) due to both infinite long current carrying wires is :- ( ^{A} cdot frac{mu_{0}}{2 pi} ) в. ( frac{5 mu_{0}}{6 pi} ) ( c cdot frac{5 mu_{0}}{6 pi} mathrm{c} ) ‘ ( frac{mu_{0}}{2 pi} ) с |
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405 | ( x=0.500 mathrm{m}, y=0.500 mathrm{m}, mathrm{z}=0 ) | 12 |

406 | When the face of a coil towards an observer seems to carry current in direction, north polarity is induced on that face. A. electromagnet B. right angles c. permanent D. anticlockwise |
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407 | A moving coil galvanometer has a coil of area ( A ) and number of turns ( N . A ) magnetic field B is applied on it. The torque acting on it is given by ( boldsymbol{tau}=boldsymbol{k} boldsymbol{i} ) where i is current through the coil. If moment of inertia of the coil is I about the axis of rotation. If the value of k in terms of galvanometer parameters ( (mathrm{N}, mathrm{B}, mathrm{A}) ) is given by ( k=x times N B A ). Find ( x ) |
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408 | A bar magnet, held horizontally, is set into angular oscillations in the earth’s magnetic field. Its time periods are ( T_{1} ) and ( T_{2} ) at two places where the angles of dip are ( theta_{1} ) and ( theta_{2} ) respectively. The ratio of the resultant magnetic fields at these two places will be: This question has multiple correct options A. ( T_{1} sin theta_{1}: T_{2} sin theta_{2} ) B. ( T_{mathrm{i}} cos theta_{1}: T_{2} cos theta_{2} ) c. ( T_{2}^{2} sin theta_{2}: T_{1}^{2} sin theta_{1} ) D. ( T_{2}^{2} cos theta_{2}: T_{1}^{2} cos theta_{1} ) |
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409 | The magnetic field lines inside the solenoid are in the form of A. parallel straight lines. B. circular lines. c. anticlockwise lines. D. all |
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410 | The graph gives the magnitude ( B(t) ) of ( a ) uniform magnetic field that exist throughtout a conducting loop. perpendicular to the plane of the graph according to the magnitude of the emf induced in the loop greatest first A. ( b>(d=epsilon)(d=epsilon)>(a=c) ) c. ( b<d<epsilon<epsilon(a=c)>(d=epsilon) ) |
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411 | In the statement of Fleming’s left hand rule, what do the direction of centre finger represents A. motion B. magnetic field c. current D. none |
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412 | A circular coil of 300 turns and diameter ( 14 mathrm{cm} ) carries a current of 15 A. The magnitude of magnetic moment associated with the loop is? A . 51.7 J ( T^{-1} ) B . 69.2 J ( T^{-1} ) c. 38.6 J ( T^{-1} ) D. 19.5 J ( T^{-1} ) |
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413 | The force of repulsion between two parallel wires is ( boldsymbol{F} ) when each one of them carries a certain current I. If the current in each is doubled, the force between them would be ( A cdot 8 F ) в. ( 4 F ) ( c cdot 2 F ) D. ( F ) |
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414 | A rod of length ( l ) carrying current ( i ) is kept in uniform magnetic field of magnitude ( B ) is shown in figure. Then the force on rod due to magnetic field is: A. zero B. ilBsintheta ( mathbf{c} cdot i l B cos theta ) D. ( i l B ) |
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415 | A wire is bent in the form of a circular arc with a straight portion ( boldsymbol{A B} ) Magnetic induction at ( O ) when current |
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416 | A coil of moving coil galvanometer twists through ( 90^{circ} ) when a current of one microampere is passed through it.lf the area of the coil is ( 10^{-4} m^{2} ) and it has 100 turns, calculate the magnetic field of the magnet of the galvanometer.Given ( k=10^{-8} N- ) ( boldsymbol{m} / ) degree |
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417 | Q Type your question- respectively as shown in figure. Assuming that these are placed in the same plane, the magnetic fields will be zero at the centre of the loop when the separation H is ( A cdot frac{1_{e}}{I_{I} pi} ) В ( cdot frac{I_{c} R}{I_{e}} ) ( c cdot frac{pi 1}{I F} ) D. ( frac{1_{e}}{I_{R}} ) |
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418 | 18. In the above question, if the coil is in the magnetic field of 1.2 T, the field being in the plane of coil, then the torque acting on it is (a) 1.42 Nm (b) 2.84 Nm (c) zero Nm (d) 0.71 Nm |
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419 | What effect did you ignore in your calculation A. effect of gravity B. effect of magnetic force c. effect of electric force D. ( K E ) of the particle |
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420 | An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has magnitude ( ^{mathrm{A}} cdot frac{mu_{o} n^{2} e}{r} ) в. ( frac{mu_{o} n e}{2 r} ) c. ( frac{mu_{o} n e}{2 pi r} ) D. zero |
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421 | A solenoid of 10 henry inductance and 2 ohm resistance, is connected to a 10 volt battery. In how much the magnetic energy will be increases to ( 1 / 4 ) th of the maximum value? A ( .3 .5 mathrm{sec} ) B. 2.5 sec ( c .5 .5 mathrm{sec} ) D. 7.5 sec |
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422 | The length of side of a square loop is 4m. This loop is placed in a uniform magnetic field of 2.5 t. Outside the loop, the magnetic field is zero and it is coming out side from magnetic field perpendicularly with velocity ( 2 mathrm{m} / mathrm{s} ). Find the value of induced emf in loop after one second. |
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423 | gauss is equal to ( mathbf{A} cdot 10^{4} T ) B ( cdot 10^{-4} T ) ( mathbf{c} cdot 10^{3} T ) D. none of these |
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424 | An electron having energy ( 10 e V ) is circulating in a path of radius ( 0.1 m ) having a magnetic field of ( 10^{-4} ) T. The speed of the electron will be : A ( .2 .0 timesleft(10^{6}right) m s^{-1} ) B . ( 4.8 timesleft(10^{6}right) m s^{-1} ) c. ( 2.0 timesleft(10^{12}right) m s^{-1} ) D. ( 4.8 timesleft(10^{12}right) m s^{-1} ) |
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425 | A wire carrying a current of 5 A is placed perpendicular to a magnetic induction of ( 2 mathrm{T} ). The force on each centimeter of the wire is : A . ( 0.1 mathrm{N} ) B. 10 N ( c cdot 100 N ) D. 1N |
12 |

426 | The formation of a dipole is due to two equal and dissimilar point charges placed at a A. short distance B. Iong distance c. above each other D. None of these |
12 |

427 | A charged particle enters into a uniform magnetic field with velocity vector at an angle of ( 45^{circ} ) with the magnetic field. The pitch of the helical path followed by the particle is ( p . ) The radius of the helix will be A ( cdot frac{p}{sqrt{2} pi} ) B. ( sqrt{2 p} ) c. ( frac{p}{2 pi} ) D. ( frac{sqrt{2 p}}{pi} ) |
12 |

428 | Three very long straight current carrying conductors are placed parallel to each other as shown in the figure. The conductors ( 1 & 3 ) are fixed where as conductor 2 is free to move. If the conductor 2 is pulled towards right through a very small distance ( x, ) find the net force acting on it and angular frequency of the resulting oscillation. |
12 |

429 | Which of the three components of acceleration have non-zero values? A . ( x ) and ( y ) B. ( y ) and ( z ) c. ( z ) and ( x ) D. ( x, y ) and ( z ) |
12 |

430 | A conducting rod ( P Q ) of length ( 5 mathrm{m} ) oriented as shown in figure is moving with velocity (2 ( mathrm{m} / mathrm{s} ) ) in rotation in a uniform magnetic field ( (3 hat{j}+4 hat{k}) ) Tesla. The emf induced in the rod is A. 32 volts B. 40 volts c. 50 volts D. none |
12 |

431 | A current ( I_{1} ) carrying wire ( A B ) is placed near another long wire CD carrying current ( I_{2} ). If wire ( A B ) is free to moves, it will have: A. rotational motion only B. translational motion only c. rotational as well as translational motion D. neither rotational nor translational motion |
12 |

432 | Assertion To protect any instrument from external magnetic field, it is put inside an iron body. Reason Iron is a magnetic substance. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
12 |

433 | Figure shows an Amperian path ( A B C D A ). Part ( A B C ) is in verical plane PSTU while part ( C D A ) is in horizontal plane ( P Q R S ). Direction of circulation along the path is shown by an arrow near point ( B ) and ( D ) ( oint vec{B} cdot d vec{l} ) for this path according to Ampere’s law will be: ( mathbf{A} cdotleft(I_{1}-I_{2}+I_{3}right) mu_{0} ) B・ ( left(-I_{1}+I_{2}right) mu_{0} ) ( mathrm{c} cdot I_{3} mu_{0} ) ( mathbf{D} cdotleft(I_{1}+I_{2}right) mu_{0} ) |
12 |

434 | The Biot Savart’s Law in vector form is ( ^{mathrm{A}} cdot_{overline{delta B}}=frac{mu_{0}}{4 pi} frac{d l(vec{l} times vec{r})}{r^{3}} ) B・ ( _{overline{delta B}}=frac{mu_{0}}{4 pi} frac{I(bar{d} l times vec{r})}{r^{3}} ) ( ^{mathbf{C}} cdot frac{mu_{0}}{delta B}=frac{I(vec{r} times overrightarrow{d l})}{4 pi} frac{r^{3}}{ } ) D ( cdot frac{ }{delta B}=frac{mu_{0}}{4 pi} frac{I(vec{d} l times vec{r})}{r^{2}} ) |
12 |

435 | An electron does not suffer any deflections while passing through a region. This makes sure that there is no magnetic field in that region. Is the given statement true or false? |
12 |

436 | A vertical wire carries a current in upward direction. An electron beam sent horizontally towards the wire will be deflected (gravity free space): A. towards right B. towards left c. upwards D. downwards |
12 |

437 | The magnetic moment ( (mu) ) of a revolving electron around the nucleus varies with principal quantum number ( n ) as : A. ( mu propto 1 / n ) В ( cdot mu propto 1 / n^{2} ) c. ( mu propto n ) D. ( mu propto n^{2} ) |
12 |

438 | The magnetic field inside a long straight solenoid carrying current: A . Is zero B. Decreases as we move towards its end c. Increases as we move towards its end D. Is same at all points |
12 |

439 | An electron revolving in an orbit of radius ( 0.5 dot{A} ) in a hydrogen atom executes ( 10^{16} ) revolutions per second. The magnetic moment of electron due to its orbital motion will be A. ( 1.256 times 10^{-23} mathrm{Am}^{2} ) B. ( 653 times 10^{-26} mathrm{Am}^{2} ) c. ( 10^{-3} ) Am ( ^{2} ) D. ( 256 times 10^{-26} mathrm{Am}^{2} ) |
12 |

440 | An electron and a proton each travel with equal speeds around circular orbits in the same uniform magnetic field as indicated (not to scale) in fig. The field is into the page on the diagram. The electron travels …. around the ( ldots . ) circle and the proton travels… around the ( ldots . ) circle A. clockwise, smaller, counterclockwise, larger B. counterclockwise, larger, counterclockwise, smaller c. clockwise, larger, counterclockwise, smaller D. counterclockwise, larger, clockwise, smaller |
12 |

441 | A proton, a deutron and an ( alpha ) -particle with same kinetic energy enter perpendicularly in a uniform magnetic field, then the ratio of radii of their circular paths is B . ( sqrt{2}: 1: 1 ) c. ( 1: sqrt{2}: 1 ) D. ( 1: 2: sqrt{2} ) |
12 |

442 | Obtain the expression for the deflecting torque acting on the current carrying rectangular coil of a galvanometer in a uniform magnetic field. Why is a radial magnetic field employed in the moving coil galvanometer? | 12 |

443 | Write Ampere’s circuital law. Obtain an expression for magnetic field on the axis of current carrying very long solenoid. Draw necessary diagram. | 12 |

444 | An electron in a circular orbit of radius ( 0.5 A^{o} ) makes ( 7 times 10^{15} ) revolutions in each second. This electron orbit is equivalent to a magnetic shell of moment ( (text { in } A m) ) A. ( 88 times 10^{-25} ) B . ( 8.89 times 10^{-25} ) c. ( 44 times 10^{-25} ) D. 4.4 ( times 10^{-25} ) |
12 |

445 | For a given distance from a current element, the magnetic induction is maximum at an angle measured with respect to axis of the current. The angle is : A ( cdot frac{3 pi}{4} ) B. ( frac{pi}{4} ) c. ( frac{pi}{2} ) D. ( 2 pi ) |
12 |

446 | An ( alpha ) particle is moving along a circle of radius ( R ) with a constant angular velocity ( omega . ) Point ( A ) lies in the same plane at a distance ( 2 R ) from the centre. Point ( A ) records magnetic field produced by ( alpha ) particle. If the minimum time interval between two successive times at which ( A ) records zero magnetic field is ( ^{prime} t^{prime}, ) the angular speed ( omega, ) in terms of ( t ) is A ( cdot frac{2 pi}{t} ) в. ( frac{2 pi}{3 t} ) c. ( frac{pi}{3 t} ) D. ( frac{pi}{t} ) |
12 |

447 | A charged particle of mass ( m ) and charge ( q ) is accelerated through a potential difference of ( V ) volt. It enters a region of uniform magnetic field which is directed perpendicular to the direction of motion of the particle. The particle will move on a circular path of radius given by A ( cdot frac{V m}{q B^{2}} ) B. ( frac{2 V m}{q B^{2}} ) c. ( sqrt{frac{2 V m}{q}} cdotleft(frac{1}{B}right) ) D. ( sqrt{frac{V m}{q}} cdotleft(frac{1}{B}right) ) |
12 |

448 | Assertion A rectangular current loop is in an arbitrary orientation in an external uniform magnetic field. No work is required to rotate the loop about an axis perpendicular to its plane. Reason All positions represent the same level of energy. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
12 |

449 | Choose the correct statements: This question has multiple correct options A. For a closed surface, the surface integration ( oint vec{B} cdot overrightarrow{d s} ) is always zero, where ( vec{B} ) is magnetic field B. A current carrying circular loop is in a uniform external magnetic field and is free to rotate about its diametrical axis will be in stable equilibrium when flux of total magnetic field (external field + field due to the loop itself) is maximum. C . Spectral energy distributed graph of a black body is shown in figure. If temperature (in ( mathrm{K} ) ) of the black body is doubled and surface area is halved, the area under the graph will be eight times. D. In keplers third law, ( frac{T^{2}}{R^{3}} ) depends on the mass of the Sun, around which a planet is revolving. |
12 |

450 | A short bar magnet of magnetic moment ( 0.4 J T^{-1} ) is place in a uniform magnetic field of 0.16 T. The magnet is stable equilibrium when the potential energy is ( mathbf{A} cdot-0.064 J ) B. zero c. ( -0.082 J ) D. 0.064 |
12 |

451 | A particle of mass ( M ) and charge ( Q ) moving with velocity ( vec{v} ) describe a circular path of radius ( R ) when subjected to a uniform transverse magnetic field of induction ( boldsymbol{B} ). The work done by the field when the particle completes one full circle is: ( ^{mathbf{A}} cdotleft(frac{M v^{2}}{R}right)^{2 pi R} ) B. zero с. ( B Q 2 pi R ) D. ( B Q v 2 pi R ) |
12 |

452 | State the rule to determine the direction of current induced in a coil due to its rotation in a magnetic field. |
12 |

453 | A closely wound solenoid of 800 turns and area of cross-section ( 2.5 times 10^{-4} m^{2} ) carries a current of ( 3.0 A ). Explain the sense in which the solenoid acts line a bar magnet. What is its associated magnetic moment? ( mathbf{A} cdot 6 J / T ) в. ( 0.9 J / T ) c. ( 9 J / T ) D. ( 0.6 J / T ) |
12 |

454 | A straight conductor carries a current. Assume that all free electrons in the conductor move with the same drift velocity ( v . A ) and ( B ) are two observers on a straight line ( X Y ) parallel to the conductor. A is stationary. B moves along XY with a velocity ( v ) in the direction of the free electrons: A. A and B observe the same magnetic field B. A observes a magnetic field, B does not C. A and B observe magnetic fields of the same magnitude but opposite directions D. A and B do not observe any electric field |
12 |

455 | Two parallel wires carrying currents in the same direction attract each other because of A. potential difference between them B. mutual inductance between them c. electric forces between them D. magnetic forces between them |
12 |

456 | Whend ( approx a ) but wires are not touching the loop, it is found that the net magnetic field on the axis of the loop is zero at a height ( h ) above the loop. In that case : A. Current in wire 1 and wire 2 is in the direction PQ and RS, respectively such ( h approx a ) B. Current in wire 1 and wire 2 is in the direction PQ and SR, respectively and ( h approx a ) c. current in wire 1 and wire 2 is in the direction PQ and SR, respectively and ( h approx 1.2 a ) D. Current in wire 1 and wire 2 is in the direction PQ and RS, respectively and ( h approx 1.2 a ) |
12 |

457 | The radius of the curved part of the wire is ( R, ) the linear parts are assumed to be very long. Find the magnetic induction of the field at the point ( O ) if a currentcarrying wire has the shape shown in figure above. A ( cdot B=frac{3 mu_{0}}{4} frac{i}{R} ) В. ( B=frac{mu_{0}}{2} frac{i}{R} ) c. ( _{B}=frac{2 mu_{0}}{3} frac{i}{R} ) D. ( B=frac{mu_{0}}{4} frac{i}{R} ) |
12 |

458 | If ( mathrm{E} ) and ( mathrm{B} ) denote electronic and magnetic field respectively, which of the following is dimensionless? A ( cdot sqrt{mu_{0} varepsilon_{0}} frac{E}{B} ) в. ( quad mu_{0} varepsilon_{0} frac{E}{B} ) ( ^{mathbf{c}} cdot_{mu_{0} varepsilon_{0}}left(frac{B}{E}right)^{2} ) D. ( frac{E}{varepsilon_{0}} frac{mu_{0}}{B} ) |
12 |

459 | Two long parallel wires are at a distance of 1 metre. Both of them carry one ampere of current. the force of attraction per unit length between the two wires is A ( cdot 2 times 10^{-7} mathrm{Nm}^{-1} ) В. ( 2 times 10^{-8} N m^{-1} ) c. ( 5 times 10^{-8} mathrm{Nm}^{-1} ) D. ( 10^{-7} N m^{-1} ) |
12 |

460 | Derive the formula for the force acting between two parallel current carrying conductors. |
12 |

461 | An electron having charge ( 1.6 times 10^{-19} mathrm{C} ) and mass ( 9 times 10^{-31} mathrm{kg} ) is moving with ( 4 times 10^{6} mathrm{m} / mathrm{s} ) speed in a magnetic field of ( 2 times 10^{-1} ) tesla in a circular orbit. The force acting on an electron and the radius of circular orbit will be: A ( cdot 1.28 times 10^{-14} N, 1.1 times 10^{-3} m ) B . ( 1.28 times 10^{15} N, 1.2 times 10^{-12} m ) C . ( 1.28 times 10^{-13} N, 1.2 times 10^{-4} mathrm{m} ) D. none of these |
12 |

462 | Assertion A stationary charged particle in a magnetic field does not experience a force. Reason The force acting on a charged particle does not depend on velocity of the particle A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
12 |

463 | Two particles ( X ) and ( Y ) having equal charges, after being accelerated through the same potential difference, enter a region of uniform magnetic field and describe circular paths or radii ( boldsymbol{R}_{1} ) and ( R_{2} ) respectively. The ratio of mass of ( X ) to that of ( Y ) is equal to: ( ^{mathbf{A}} cdotleft(frac{R_{1}}{R_{2}}right)^{2} ) B. ( left(frac{R_{1}}{R_{2}}right) ) ( ^{mathbf{C}} cdotleft(frac{R_{1}}{R_{2}}right)^{1 / 2} ) D. ( frac{R_{2}}{R_{1}} ) |
12 |

464 | A horizontal overhead power line carries a current of ( 90 mathrm{A} ) in east to west direction. Magnitude of magnetic field due to the current ( 1.5 mathrm{m} ) below the line is A . 1.27 в. ( 1.2 times 10^{-10} T ) c. ( 0 T ) D. ( 1.2 times 10^{-5} T ) |
12 |

465 | Assertion Cyclotron does not accelerate electron. Reason Mass of the electrons is very small. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |

466 | An electron of charge ( e ) moves in a circular orbit of radius ( r ) around a nucleus the magnetic field due to orbit motion of the electron at the site of the nucleus is ( B ). The angular velocity ( omega ) of the electron is: A ( cdot omega=frac{mu_{0} e B}{4 pi r} ) B. ( omega=frac{mu_{0} e B}{pi r} ) c. ( _{omega=frac{4 pi r B}{mu_{0} e}} ) D. ( omega=frac{2 pi r B}{mu_{0} e} ) |
12 |

467 | State the principle of moving coil galvanometer? | 12 |

468 | State Fleming’s left hand rule. | 12 |

469 | A ( 0.5 m ) long straight wire in which a current of ( 3.2 A ) is flowing is kept at right angle to a uniform magnetic field of ( 2.0 T . ) The force acting on the wire will be: A ( .2 N ) в. 2.4 и ( c .3 .2 N ) D. 3N |
12 |

470 | By inserting a soft iron piece into a solenoid, strength of the magnetic field A. increases B. decreases c. first increases then decreases D. remains unchanged |
12 |

471 | Ampere’s circuital law holds good for: A. conduction current only B. displacement current only C. both conduction current and displacement current D. none of these |
12 |

472 | A current carrying conducting square frame of side I carrying current lis placed in a uniform transverse magnetic field ( vec{B} ) as shown in the figure. Choose the incorrect statement. A. Magnitude of force on the frame is ( 4 I B l ) B. Magnitude of torque on the frame ( I l^{2} B ) C. Torque on the frame is zero D. Both (1) and (2) |
12 |

473 | A horizontal wire ( 0.1 mathrm{m} ) long carries a current of 5 A. Find the magnitude of the magnetic field, which can support the weight of the wire. Assume wire to be of ( operatorname{mass} 3 times 10^{-3} k g m^{-1}: ) A ( .5 .88 times 10^{-2} T ) B . ( 4.88 times 10^{-3} T ) ( mathbf{c} .5 .88 times 10^{-3} T ) D. ( 5.88 times 10^{-4} T ) |
12 |

474 | The magnetic force on a moving charge in a magnetic field acts A. Only at right angles to the direction of motion of the particle. B. Only at right angles to magnetic field. C. At right angles to the field and the direction of motion of the particle. D. Parallel to the field as well as the direction of motion of the particle. |
12 |

475 | A galvanometer of resistance ( 50 Omega ) is connected to a battery of ( 3 V ) along with a resistance of ( 2950 Omega ) in series shown, full-scale deflection of 30 divisions. The additional series resistance required to reduce the deflection to 20 divisions is A . ( 4440 Omega ) B. 1500Omega c. ( 7400 Omega ) D. ( 2950 Omega ) |
12 |

476 | If current in the coil decreases, then strength of the magnetic field A. decreases B. increases c. sometimes decreases and sometimes increases D. remains unchanged |
12 |

477 | A current carrying loop is placed in a uniform magnetic field in four different orientations as shown in figure. Arrange them in the decreasing order of potential energy ( widehat{Q} ) 2 3 A. 4,2,3,1 В. 1,4,2,3 ( mathbf{c} cdot 4,3,2,1 ) D. 1,2,3,4 |
12 |

478 | ( L ) is circular loop carrying a current. ( boldsymbol{P} ) is a point on its axis ( O X . d l ) is an element of length on the loop at a point ( A ) on it. The magnetic field at ( P: ) This question has multiple correct options A. due to ( L ) is directed along ( O X ) B. due to dl is directed along ( O X ) c. due to dl is perpendicular to ( O X ) D. due to dl is perpendicular to ( A P ) |
12 |

479 | Factors which govern the force experienced by a current carrying conductor placed in a uniform magnetic field depends on A. strength of the magnetic field in which conductor is placedd B. strength of current flowing through the conductor. c. length of conductor. D. all |
12 |

480 | An ideal solenoid having 5000 turns ( / m ) has an aluminium core and carries a current of ( 5 A . ) If ( chi_{A l}=2.3 times 10^{-5}, ) then the magnetic field developed at center will be A. ( 0.031 T ) ( T ) в. ( 0.048 T ) c. 0.0277 D. ( 0.050 T ) |
12 |

481 | It two parallel wires carry current in opposite directions A. The wires attract each other B. The wires repel each other C. The wires experience neither attraction nor repulsion D. The forces of attraction or repulsion do not depend on current direction |
12 |

482 | A moving coil galvanometer A has 200 turns and resistance ( 100 . ) Another meter ( mathrm{B} ) has 100 turns and resistance ( 40 . ) All the other quantities are same in both the cases. The current sensistivity of A. B is double as that of A B. A is 2.5 times of B c. A is 5 times of B D. B is 5 times of A |
12 |

483 | In Thomsons method, electric field of intensity ( boldsymbol{E}, ) magnetic field of induction ( B ) and velocity ( V ) of the electrons were in mutually perpendicular directions. The condition for velocity is A. ( V=E / B ) в. ( V=B / E ) c. ( V=B E ) D. ( V=sqrt{B / E} ) |
12 |

484 | If two protons are moving with speed ( boldsymbol{v}=mathbf{4 . 5} times mathbf{1 0}^{mathbf{5}} mathbf{m} / mathrm{s} ) parallel to each other then find the ratio of electrostatic and magnetic force between them? ( mathbf{A} cdot 4.4 times 10^{5} ) В. ( 2.2 times 10^{5} ) c. ( 3.3 times 10^{5} ) D. ( 1.1 times 10^{5} ) |
12 |

485 | The magnetic field at the center of a long circular coil carrying current will be: A. parabolic lines B. circular lines c. parallel straight lines D. perpendicular straight lines |
12 |

486 | In the figure shown a circular current carrying conductor lies in yz plane and its centre is at point O.If ( B_{A} ) and ( B_{B} ) are the A ( . B_{A}=B_{B} ) В. ( B_{A}>B_{B} ) c. ( B_{A}<B_{B} ) D. None of these |
12 |

487 | A current I flows in a infinitely long wire with cross section in the form of a semicircular ring of radius R. The magnitude of the magnetic induction at its axis is A ( cdot frac{mu_{0} I}{pi^{2} R} ) в. ( frac{mu_{0} mathrm{I}}{2 pi^{2} mathrm{R}} ) c. ( frac{mu_{0} mathrm{I}}{2 pi mathrm{R}} ) D. ( frac{mu_{0} I}{4 pi mathrm{R}} ) |
12 |

488 | toppr ( t ) Q Type your question magnetic force acting on each wire? ( A ) B. ( c ) D. E. There is no net force acting on either wire |
12 |

489 | A charged particle entering a magnetic field from outside in a direction perpendicular to the field A. can never complete one rotation inside the field B. may or may not complete one rotation in the field depending on its angle of entry into the field c. will always complete exactly half of a rotation before leaving the field D. may follow a helical path depending on its angle of entry into the field |
12 |

490 | What is a solenoid? Draw the pattern of magnetic field lines of (i) A current carrying solenoid and (ii)A bar magnet. List two distinguishing features between the two fields. |
12 |

491 | A current of ( 10^{-7} ) ampere produces 50 division deflection in a galvanometer. Then its figure of merit will be A ( cdot 10^{-4} ) amp ( / d i v ) B . ( 10^{-8} ) amp / div ( mathbf{c} cdot 10^{-10} mathrm{amp} / mathrm{div} ) D. ( 2 times 10^{-9} ) amp/div |
12 |

492 | A current of ( 1 mathrm{A} ) is flowing along positive x-axis through a straight wire of length ( 0.5 mathrm{m} ) placed in a region of a magnetic field given by ( vec{B}=(2 hat{i}+4 hat{j}) ) T. The magnitude and the direction of the force experienced by the wire respectively are: A ( cdot sqrt{18} N, ) along positive z-axis B. ( sqrt{20} N ), along positive ( x ) -axis c. ( 2 N, ) along positive z-axis D. ( 4 N ), along positive y-axis |
12 |

493 | State Biot-Savart law. | 12 |

494 | The total momentum of electrons in a straight wire of length ( l=1000 m ) carrying a current ( mathrm{I}=mathbf{7} mathbf{0} boldsymbol{A}, ) will be (in ( N-s) ) A . ( 0.40 times 10^{-6} ) B. ( 0.20 times 10^{-6} ) c. ( 0.80 times 10^{-6} ) D. ( 0.16 times 10^{-6} ) |
12 |

495 | When a magnet M is pushed in and out of a circular coil ( C ) connected to a very sensitive galvanometer ( G ) as shown in the figure with frequency f then which of the following holds true? A. constant deflection will be observed in the galvanometer. B. visible small variation will be observed in the galvanometer if ( f ) is about 50 Hz c. oscillation in the deflection will be seen clearly when ( f=1 ) or ( 2 mathrm{Hz} ) D. no variation in the deflection will be seen even when ( f=1 ) or 2 Hz. |
12 |

496 | A particle of charge ( q ) and mass ( m ) is moving through a region of space where crossed magnetic and electric fields produce a zero net force on the charge. At a later time, the Electric field is reduced by a factor of two. What effect will this have on the motion of the particle? Select all that apply. A. The particle will continue to move in a circle of the same radius. B. The particle will eventually move in a circle of twice the radius C. The particle will eventually move in a circle of half the radius D. The particle will eventually follow a curved-noncircular path E. The particle will follow a straight line path. |
12 |

497 | If a charged particle goes unaccelerated in a region containing electric and magnetic fields: A . ( vec{E} ) must be parallel to ( vec{B} ) B. ( bar{V} ) must be perpendicular to Electric field c. ( vec{V} ) must be parallel to ( vec{B} ) D. ( E ) must be equal to ( v B ) |
12 |

498 | An insulating rod of length ( l ) carries a charge ( q ) distributed uniformly on it. The rod is pivoted at its mid-point and is rotated at a frequency ( f ) about a fixed axis perpendicular to the rod and passing through the pivot. The magnetic moment of the rod system is A ( cdot frac{1}{12} pi q f l^{2} ) В . ( pi q f l^{2} ) c. ( frac{1}{6} pi q f l^{2} ) D. ( frac{1}{3} pi q f l^{2} ) |
12 |

499 | What is a solenoid? | 12 |

500 | (i) Why does a current carrying, freely suspended solenoid rest along a particular direction? (ii) State the direction in which it rests. |
12 |

501 | Energy associated with an electric field is analogous to whereas the energy associated with the magnetic field is analogous to A. kinetic energy, potential energy B. potential energy, potential energy c. potential energy, kinetic energy D. kinetic energy, kinetic energy |
12 |

502 | In a circular coil (1) of radius ( boldsymbol{R} ), current ( I ) is flowing and in another coil (2) of radius ( 2 R ) a current ( 2 I ) is flowing, then the ratio of the magnetic fields produced by the two coils is A . 1: B. 2: c. 1: 2 D. 3: |
12 |

503 | A current of ( 0.6 A ) produces a deflection of 30 in the tangent galvanometer. Calculate the value of current will produce a deflection of 60 A. ( 1.2 mathrm{A} ) в. 1.8 А c. 2.4 А D. 3.0 A |
12 |

504 | A very high magnetic field is applied to a stationary charge. Then, the charge experiences A. A force in a direction of magnetic field B. A force perpendicular to the magnetic field c. A force in an arbitrary direction D. No force |
12 |

505 | A cylindrical conducting rod is kept with its axis along positive z-axis, where a uniform magnetic field exists parallel to z-axis. The current induced in the cylinder is A. zero B. clockwise as seen from +z-axis c. anti-clockwise as seen from +z-axis D. opposite to the direction of magnetic field |
12 |

506 | Two parallel wires ( 2 mathrm{m} ) apart carry currents of 2 A and 5 A respectively in the same direction, the force per unit length acting between these two wires is: A ( cdot 2 times 10^{-6} mathrm{N} mathrm{m}^{-1} ) В. 3 ( times 10^{-6} mathrm{N} mathrm{m}^{-1} ) c. ( 1 times 10^{-6} mathrm{N} mathrm{m}^{-1} ) D. ( 4 times 10^{-6} mathrm{N} mathrm{m}^{-1} ) |
12 |

507 | A helium nucleus (charge ( +2 e ) ) completes one round of a circle of radius ( 0.8 m ) in 2 sec. Find the magnetic field at the centre of the circle. |
12 |

508 | STATEMENT-1: A Solenoid tend to contract (along its length) when a current is passed through it. STATEMENT-2: If current in two coaxial circular rings of equal radii is in same sense( as seen by an observer on axis away from both the rings), the rings attract each other. Further the given current carrying rings attract each other because parallel current attracts. A. Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement- B. Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement- c. Statement-1 is True, Statement-2 is False D. Statement-1 is False, Statement-2 is True |
12 |

509 | Complete the given statement, the strength of an electromagnet can be: A. increased by adding a ferromagnetic core B. decreased by adding turns of wire to the coil C. increased by reducing the current through the wire D. increased by adding an aluminum core E. decreased by adding more layers of wire to the coil |
12 |

510 | A straight wire of length ( 50 mathrm{cm} ) carrying a current of ( 2.5 A ) is suspended in mid- air by a uniform magnetic field of ( 0.5 T ) (as shown in figure). The mass of the wire is ( left(boldsymbol{g}=mathbf{1 0 m} / boldsymbol{s}^{2}right) ) ( mathbf{A} cdot 100 g m ) В. ( 125 g m ) ( mathbf{c} cdot 62.5 g m ) D. ( 250 g m ) |
12 |

511 | A toroid wound with 100 turns/m of wire carries a current of ( 3 A ). The core of toroid is made of iron having relative magnetic permeability of ( mu_{r}=5000 ) under given conditions. The magnetic field inside the iron is ( left(text { Take } mu_{o}=4 pi times 10^{-7} T m A^{-1}right) ) A ( .0 .15 T ) в. ( 1.5 times 10^{-2} T ) c. ( 0.47 T ) D. ( 1.88 T ) |
12 |

512 | Consider six wires into or out of the page, all with the same current. Rank the line integral of the magnetic field(from most positive to most negative) taken counterclock wise around each loop shown as positive in accordance with right hand screw rule. ( mathbf{A} cdot B>C>D>A ) В . ( B>C=D>A ) c. ( B>A>C=D ) D. ( C>B=D>A ) |
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513 | A galvanometer coil ( 5 mathrm{cm} times 2 mathrm{cm} ) with 200 turns is suspended vertically in a field of ( 5 times 10^{-2} ) T.The suspension fibre needs a torque of ( 0.125 times 10^{-7} N-m ) to twist it through one radian. If ( i ) is the strength of the current required to be maintained in the coil when we require a deflection of ( 6^{circ} ) then find ( x ) such that ( boldsymbol{x}=boldsymbol{i} times mathbf{1 0}^{8} ) |
12 |

514 | The direction of magnetic lines of forces close to a straight conductor carrying current will be – A. A long the length of the conductor B. Radially outward c. circular in a plane perpendicular to the conductor D. Helical |
12 |

515 | Maximum iron filings stick to the middle of a bar magnet when it is brought near them. A. True B. False |
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516 | The magnetic field at ( O ) due to current in the wire segment BC of the infinite wire forming a loop as shown in figure is ( ^{A} cdot frac{mu_{0} I}{4 pi d}left(cos phi_{1}+cos phi_{2}right) ) в. ( frac{mu_{0}}{4 pi} ) c. ( frac{mu_{0} I}{4 pi d}left(sin phi_{1}+sin phi_{2}right) ) D. ( frac{mu_{0}}{4 pi} ) |
12 |

517 | A galvanometer, with a scale divided into 100 equal divisions, has a current sensitivity of 10 div per ( mathrm{m} mathrm{A} ) and voltage sensitivity 2 div per ( mathbf{m V} ). To read ( 5 A ) full scale deflection A. Shunt resistance should be ( 1 Omega ) B. Shunt resistance should be ( 0.1 Omega ) c. shunt resistance should be ( 0.01 Omega ) D. Shunt resistance should be ( 0.001 Omega ) |
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518 | Find the magnetic field due to conducting wire at point ( O, ) at centre of semicircle of radius ( r ) and carrying a current ( i ) as shown in the figure. ( ^{A} cdot frac{mu_{0}}{4 r} ) в. ( frac{mu_{0} i}{4 r}(1+2 pi) ) c. ( frac{mu_{0} i}{4 r}(pi-2) ) D. ( frac{mu_{0} i}{4 pi r}(pi+2) ) |
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519 | A moving coil galvanometer has resistance ( 50 Omega ) and it indicates full deflection at ( 4 m A ) current. A voltmeter is made using this galvanometer and a 5k. ( Omega ) resistance. The maximum voltage that can be measured using this voltmeter, will be close to: A . ( 10 V ) B. 20V c. ( 40 V ) D. ( 15 V ) |
12 |

520 | If a copper rod carries a direct current, the magnetic field associated with the current will be: A. only inside the rodd B. only outside the rod c. both inside and outside the rod D. neither inside nor outside the rod |
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521 | A proton moves with a speed of ( 5.0 times ) ( 10^{6} mathrm{m} / mathrm{s} ) along the ( mathrm{x} ) -axis. It enters a region where there is a magnetic field of magnitude ( 2.0 . ) Tesla directed at an angle of ( 30^{circ} ) to the ( x ) -axis and lying in the xy-plane. The magnitude of the magnetic force on the proton is? A. ( 0.8 times 10^{-13} mathrm{N} ) В. ( 1.6 times 10^{-13} mathrm{N} ) c. ( 8.0 times 10^{-13} mathrm{N} ) D. ( 8.01 times 10^{-13} mathrm{N} ) E ( .16 times 10^{-13} mathrm{N} ) |
12 |

522 | If a charged particle projected in a gravity-free room deflects, then A. there must be an electric field B. there must be a magnetic field c. both fields cannot be zero D. none of these |
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523 | Assertion The bar magnet falling vertically along the axis of the horizontal coil will be having acceleration less than ( g ) Reason Clockwise current induced in the coil. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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524 | Conisder a block of conducting material of resistivity ( rho ) shown in fig., Current enters at ( A ) and leaves at ( D ) For current entering at ( A, ) the electric |
12 |

525 | A magnetic moment of an electron orbiting in a circular orbit of radius ( r ) with a speed ( v ) is equal to: A ( cdot frac{e v r}{2} ) в. ( e v r ) c. ( frac{e r}{2 v} ) D. none of these |
12 |

526 | Figure shows an equilateral triangle ( A B C ) of side ( l ) carrying currents as shown, and placed in a uniform magnetic field ( B ) perpendicular to the plane of triangle. The magnitude of magnetic force on the triangle is A . il B. 3il ( c .2 i l ) D. zer |
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527 | A conductor ( A B ) carries a current ( i ) in a magnetic field ( vec{B} . ) If ( overrightarrow{A B}=vec{r} ) and the force on the conductor is ( vec{F} ). Then This question has multiple correct options A ( cdot vec{F} ) does not depend on the shape of ( A B ) В ( cdot vec{F}=i(vec{r} times vec{B}) ) c. ( vec{F}=i(vec{B} times vec{r}) ) D ( cdot|vec{F}|=i(vec{r} cdot vec{B}) ) |
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528 | A straight wire of 0.3 m carrying a current of ( 2 mathrm{A} ) in the downward direction is placed in a magnetic field of ( 0.1 mathrm{T} ) as shown in the figure. Find out the magnitude of the force on the wire? A . ( 0.06 N ) B. 2.0 N c. ( 6.7 mathrm{N} ) D. 0.15N E. 0.015N |
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529 | A current carrying wire and a rectangular loop are placed as shown in figure then A. The wire will be repelled by the rectangular loop B. The wire will attracted by the rectangular loop c. There will not be any change in position of wire D. Loop will rotate |
12 |

530 | A charged oil drop weighing ( 1.6 times ) ( 10^{-15} N ) is found to remain suspended in a uniform electric field of intensity ( 2 times 10^{3} N C^{-1} . ) Find the charge on the drop. |
12 |

531 | State and explain Biot-Savart Law. | 12 |

532 | Current of 10 ampere and 2 ampere are passed through two parallel wires A and B, respectively in opposite directions. If the wire ( A ) is infinitely long and the length of the wire ( mathrm{B} ) is ( 2 mathrm{m} ), the force on the conductor ( B ) which is situated at 10 ( mathrm{cm} ) distance from A will be ( mathbf{A} cdot 8 times 10^{-5} N ) B ( cdot 4 times 10^{-5} N ) c. ( 8 pi times 10^{-7} N ) D. ( 4 pi times 10^{-7} N ) |
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533 | Two concentric circular coils ( X ) and ( Y ) of radii ( 16 mathrm{cm} ) and ( 10 mathrm{cm}, ) respectively, lie in the same vertical plane containing the north to south direction. Coil X has 20 turns and carries a current of ( 16 mathrm{A} ) coil ( Y ) has 25 turns and carries a current of 18 A. The sense of the current in ( X ) is anticlockwise, and clockwise in ( Y ), for an observer looking at the coils facing west. Give the magnitude and direction of the net magnetic field due to the coils at their centre |
12 |

534 | The electric and magnetic field differ in that : A. the electric lines of force are closed curves, while magnetic field lines are not B. the magnetic field lines are closed, while electric lines are not C. the electric lines can give direction of electric field, while magnetic lines cannot D. the magnetic lines can give direction of magnetic field, while electric lines cannot |
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535 | The force of repulsion between two parallel wires is ( f ) when each one of them carries a certain current I. If the current in each is doubled, the force between them would be A. ( 4 / f ) B. ( 4 f ) ( c cdot 2 f ) D. ( f ) |
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536 | n fig, there is a uniform conducting structure in which each small square has side ( a ). The structure is kept in a uniform magnetic field ( B ). Then the magnetic force on the structure will be: ( A cdot 2 sqrt{2} i B a ) B. ( sqrt{2} i ) Ва ( a ) ( c .2 i B a ) D. ( i B a ) |
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537 | An electric charge in uniform motion produces: A. an electric field only B. a magnetic field only c. both electric and magnetic fields D. no such field at all |
12 |

538 | If in a circular coil A of radius R, current is flowing and in another coil B of radius ( 2 mathrm{R} ) a current 2 I is flowing, then the ratio of the magnetic fields ( B_{A} ) and ( mathrm{B}_{B}, ) produced by them will be A B. 2 ( c cdot 1 / 2 ) D. 4 |
12 |

539 | The following diagram in figure shows a fixed coil of several turns connected to a centre zero galvanometer ( G ) and ( a ) magnet NS which can move in the direction shown in the diagram. Describe the observation in the galvanometer if the magnet is moved rapidly towards the coil. |
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540 | An electron ( left(operatorname{mass}=9.1 times 10^{-31}right. ) charge ( left.=-1.6 times 10^{-19} mathrm{C}right) ) experiences no deflection if subjected to an electric field of ( 3.2 times 10^{5} V / m ) and a magnetic field of ( 2.0 times 10^{-3} mathrm{Wb} / mathrm{m}^{2} . ) Both the fields are normal to the path of electron and to each other. Ifthe electric field is removed, then the electron will revolve in an orbit of radius: A . ( 45 mathrm{m} ) в. 4.5 т c. ( 0.45 m ) D. ( 0.045 mathrm{m} ) |
12 |

541 | A current loop consists of two identical semicircular parts each of radius ( mathrm{R} ), one lying in the ( x ) -y plane and the other in ( x-z ) plane. If the current in the loop is i., the resultant magnetic field due to the two semicircular parts at their common centre is A ( cdot frac{mu_{0} i}{sqrt{2} R} ) В. ( frac{mu_{0} i}{2 sqrt{2} R} ) c. ( frac{mu_{0} i}{2 R} ) D. ( frac{mu_{0} i}{4 R} ) |
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542 | Assertion A stationary charged particle in a magnetic field does not experience a force. Reason The force acting on a charged particle does not depend on velocity of the particle A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |

543 | In a coaxial, straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero: A. outside the cable B. inside the inner conductor c. inside the outer conductor D. in between the two conductors |
12 |

544 | A magnetic needle placed near a wire carrying alternating current does not show any deflection. | 12 |

545 | Currents ( I_{1} ) and ( I_{2} ) flow in the wires shown in figure. The field is zero at distance ( x ) to the right of ( O . ) Then ( x=left(frac{I_{1}}{I_{2}}right) a ) 3. ( x=left(frac{I_{2}}{I_{1}}right) a ) ( x_{x}=left(frac{I_{1}-I_{2}}{I_{1}+I_{2}}right) a ) ( x=left(frac{I_{1}+I_{2}}{I_{1}-I_{2}}right) a ) |
12 |

546 | Assertion: Magnetic force between two short magnets, when they are co-axial follows inverse square law of distance. Reason : The magnetic forces between two poles do not follow inverse square law of distance A. If both assertion and reason are true and reason is the correct explanation of assertion. B. If both assertion and reason are true and reason is not the correct explanation of assertion. c. If assertion is true but reason is false D. If both assertion and reason are false |
12 |

547 | Two concentric coils of 10 turns each are placed in the same plane. Their radii are ( 20 mathrm{cm} ) and ( 40 mathrm{cm} ) and carry ( 0.2 mathrm{A} ) and 0.3 A current respectively in opposite directions. The magnetic induction (in tesla) at the centre is : A ( cdot frac{3}{4} mu_{0} ) в. ( frac{5}{4} mu_{0} ) c. ( frac{7}{4} mu_{0} ) D. ( frac{9}{4} mu_{0} ) |
12 |

548 | If long hollow copper pipe carries a direct current, the magnetic field associated with the current will be: A. only inside the pipe B. only outside the pipe c. neither inside nor outside the pipe D. both inside and outside the pipe |
12 |

549 | Under what condition the force acting on charge particle moving in the magnetic field minimum? A. If it is either moving parallel to the magnetic field intensity. B. If it is either moving antiparallel to the magnetic field intensity. C. Charge particle moves perpendicular to the velocity vector. D. Both A and B |
12 |

550 | A coil carrying current ( l ) has radius and number of units ( n ). It is rewound so that radius of new coil is ( frac{r}{4} ) and it carries current ( l . ) The ratio of magnetic moment of new coil to that of original coil is A . B. ( frac{1}{2} ) ( c cdot frac{1}{4} ) D. 8 |
12 |

551 | A beam of protons enters a uniform magnetic field of ( 0.3 T ) with a velocity of ( 4 times 10^{5} mathrm{m} / mathrm{s} ) in a direction making an angle of ( 60^{circ} ) with the direction of magnetic field. The path of motion of the particle will be : A . circular B. straight line c. parabolic D. helical |
12 |

552 | A toroid has a core(non-ferromagnetic) of inner radius ( 25 mathrm{cm} ) and outer radius ( 26 mathrm{cm}, ) around which 3500 turns of a wire are wound. If the current in the wire is ( 11 A ), the magnetic field inside the core of the toroid is? |
12 |

553 | A proton and an ( alpha- ) particle (with their masses in the ratio of 1: 4 and charges in the ratio of 1: 2 ) are accelerated from rest through a potential difference V. If a uniform magnetic field (B) is set up perpendicular to their velocities, the ratio of the radii ( r_{p}: r_{alpha} ) of the circular path described by them will be : A. ( 1: sqrt{2} ) Th ( : sqrt{2} cdot sqrt{2} ) B. 1: 2 ( c cdot 1: 3 ) D. ( 1: sqrt{3} ) |
12 |

554 | An electron beam projected along positive ( x ) -axis deflects along the positive y-axis.lf this deflection is caused by a magnetic field,what is the direction of the field? | 12 |

555 | 9. In a region, steady and uniform electric and magnetic fields are present. These fields are parallel to each other. A charged particle is released from rest in this region. The path of the particle will be (a) an ellipse (b) a circle (c) a helix (d) a straight line (AIEEE 2006) |
12 |

556 | A current passing through a circle coil of two turns produces a magnetic field ( B ) as its centre. The coil is then rewound so as to have four turns and the same current is passed through it. The magnetic field at its centre now is A ( .2 B ) B. ( B / 2 ) ( c cdot B / 4 ) D. ( 4 B ) |
12 |

557 | A charge ‘q’ moves in a region where electric field and magnetic field both exist, then force on it is : – ( mathbf{A} cdot q(vec{V} times vec{B}) ) B ( cdot q vec{E}+q(vec{V} times vec{B}) ) ( mathbf{c} cdot q vec{E}+q(vec{B} times vec{V}) ) ( mathbf{D} cdot q vec{B}+q(vec{E} times vec{V}) ) |
12 |

558 | What we call the conductivity of a magnetic substance for the lines of force with respect to air? A. Magnetic induction B. Magnetic permeability c. Magnetic flux density D. Intensity of magnetization |
12 |

559 | A force vector is acting on a unit length of a thin wire, carrying a current ( boldsymbol{I}= ) ( 80 A, ) at a point ( O . ) Find the magnitude and direction of the force vector, if the wire is bent as shown in figure above, the distance between the long parallel segments of the wire being equal to ( l= ) ( mathbf{2 0} boldsymbol{c m} ) A. ( 1.3 N ) B. ( 0.26 N ) c. ( 2.6 N ) D. ( 0.013 N ) |
12 |

560 | A square frame of side carries i produces a field ( B ) at its centre. The same current is passed through a circular coil having the same perimeter as the square. The field at the centre of circular coil is ( mathrm{B} ) ‘. Find the ratio of ( left(mathrm{B}^{prime} / mathrm{B}right) ). A. ( frac{pi^{2}}{3 sqrt{2}} ) В. ( frac{pi^{2}}{5 sqrt{2}} ) c. ( frac{pi^{2}}{7 sqrt{2}} ) D. ( frac{pi^{2}}{8 sqrt{2}} ) |
12 |

561 | A power line lies along the east-west direction and carries a current of 10 ampere. The force per metre due to the earth’s magnetic field of ( 10^{-4} ) tesla is: ( mathbf{A} cdot 10^{-5} mathbf{N} ) B. ( 10^{-4} ) N ( mathbf{c} cdot 10^{-3} mathbf{N} ) D. ( 10^{-2} ) N |
12 |

562 | Two streams of electrons are moving parallel to each other in the same direction. They A. attract each other B. repel each other c. cancel the electric field of each other D. cancel the magnetic field of each other |
12 |

563 | The direction of the force on a current carrying conductor held perpendicular to an uniform magnetic field is given by: A. Fleming’s right hand rule B. Ampere’s swimming rule c. Maxwell’s right hand cork screw rule D. Fleming’s left hand rule |
12 |

564 | A galvanometer coil has a resistance of ( 50 Omega ) and the meter shows full scale deflection for a current of ( 5 m A ). This galvanometer is converted into voltmeter of range ( 0-20 V ) by connecting A. ( 3950 Omega ) in series with galvanometer B. ( 4050 Omega ) in series with galvanometer c. ( 3950 Omega ) in parallel with galvanometer D. ( 4050 Omega ) in parallel with galvanometer |
12 |

565 | The magnetic flux through the cross- section of the toroidal solenoid is A ( cdot frac{mu_{0} N i h}{2 pi} ) В. ( frac{mu_{0} N i h(b-a)}{2 pi r} ) c. ( frac{mu_{0} N i h}{2 pi} log _{e} frac{b}{a} ) D. ( frac{mu_{0} N^{2} i h}{2 pi} log _{e} frac{a}{b} ) |
12 |

566 | A point charge is moving in a circle with constant speed. Consider the magnetic field produced by the charge at a fixed point ( boldsymbol{P} ) (not at the center of circle) on the axis of the circle. A. it is constant in magnitude only B. it is constant in direction only c. it is constant both in direction and magnitude both D. it is constant neither in magnitude nor in direction both |
12 |

567 | At what distance from a long straight wire carrying a current of ( 12 A ) will the magnetic field be equal to ( 3 times ) ( mathbf{1 0}^{-mathbf{5}} boldsymbol{W b} / boldsymbol{m}^{2} ? ) A. ( 8 times 10^{-2} mathrm{m} ) В. ( 12 times 10^{-2} mathrm{m} ) c. ( 18 times 10^{-2} mathrm{m} ) D. ( 24 times 10^{-2} mathrm{m} ) |
12 |

568 | The ratio of magnetic field at centre of circular loop to the magnetic field at the centre of square loop, which are made by a constant length current carrying wire : A ( cdot frac{pi^{2}}{16} ) в. ( frac{pi^{2}}{8 sqrt{2}} ) c. ( frac{pi^{2}}{4 sqrt{2}} ) D. ( frac{pi^{2}}{2 sqrt{2}} ) |
12 |

569 | Sensitivity of a moving coil galvanometer can be increased by Fill in the blank. A. decreasing number of turns in rectangular coil B. decreasing magnetic induction of magnetic field C. increasing area of rectangular coil D. increasing twist constant of phosphor bronze fiber |
12 |

570 | A proton moves in the positive ( z- ) direction after being accelerated from rest through a potential difference ( V ) The proton then passes through a region with a uniform electric field ( E ) in the positive x-direction and a uniform magnetic field ( B ) in the positive ( y- ) direction, but the proton’s trajectory is not affected. If the experiment were repeated using a potential difference of ( 2 V, ) the proton would then be A. deflected in positive ( x ) -direction B. deflected in negative ( x ) -direction c. deflected in positive ( y ) -direction D. deflected in negative ( y ) -direction |
12 |

571 | A coil of radius ( mathrm{R} ) carries a current I. Another concentric coil of radius ( boldsymbol{r}(boldsymbol{r}<<boldsymbol{R}) ) caries current ( frac{boldsymbol{I}}{2} . ) Initially planes of the two coils are mutually perpendicular and both the coils are free to rotate about common diameter. They are released from rest from this position. The masses of the coils are ( mathbf{M} ) and m respectively ( (boldsymbol{m}>K_{1} ) |
12 |

572 | Prakash peddles a stationary bicycle, the pedals of which are attached to a 100 turn coil of area ( 0.1 m^{2} . ) The coil rotates at half a revolution per second and it is placed in a uniform magnetic field of ( 0.01 T ) perpendicular to the axis of rotation of the coil. Determine the maximum voltage generated in the coil. |
12 |

573 | Two charges of same magnitude move in two circlesof radii ( boldsymbol{R}_{1}=boldsymbol{R} ) and ( boldsymbol{R}_{2}= ) ( 2 R ) in a region of constant uniform magnetic field ( B_{0} . ) The work ( W_{1}, ) and ( W_{2} ) done by the magnetic field in the Two cases, respectively are such that: A ( . W_{1}=W_{2}=0 ) В. ( W_{1}>W_{2} ) c. ( W_{1}=W_{2} neq 0 ) D. ( W_{1}<W_{2} ) |
12 |

574 | A particle of charge ( q ) and mass ( m ) is moving at a speed ( v ) enters a uniform magnetic field of strength ( B ) as shown below. How much work is done by the magnetic field on the charge as the field accelerates the charge into a circle of radius ( r ? ) ( r ) 9 ( A ) B. ( mathbf{c} cdot q v B r ) D. ( m v^{2} ) E. Cannot be determined |
12 |

575 | If there is a circular coil having n turns, the field produced is A. ( 1 / n ) times as that produced by single turn. B. ( n ) times as large as that produced by a single turn. C. ( 2 / n ) times as large as that produced by a single turn. D. all |
12 |

576 | A uniform magnetic field ( vec{B}=B_{0} hat{j} ) exists in a space. A particle of mass ( m ) and charge q is projected towards negative ( x ) -axis with speed ( v ) from the a point ( (d, 0,0) . ) The maximum value v for which the particle does not hit ( y ) -z plane is? ( mathbf{A} cdot frac{2 B q}{d m} ) B. ( frac{B q d}{m} ) ( mathbf{c} cdot frac{B q}{2 d m} ) D. ( frac{B q d}{2 m} ) |
12 |

577 | A uniform magnetic field of 1.5 T exists in a cylindrical region of radius ( 10.0 mathrm{cm} ) its direction parallel to the axis along east to west. A wire carrying current of ( 7.0 mathrm{A} ) in the north to south direction passes through this region. What is the magnitude and direction of the force on the wire if,(a) the wire intersects the axis,(b) the wire is turned from N-S to northeast-northwest direction,(c) the wire in the N-S direction is lowered from the axis by a distance of ( 6.0 mathrm{cm} ) ? |
12 |

578 | A large solenoid of windings of 400 turns per meter carries a current ( 5 mathrm{A} ) The magnetic field at the centre of the solenoid is about: A . ( 1.2 mathrm{mT} ) B. zero c. ( 5.0 mathrm{mT} ) D. 2.5 mT |
12 |

579 | A galvanometer of resistance ( 50 Omega ) giving full scale deflection for a current of 10 milliampere is to be changed into a voltmeter of range ( 100 mathrm{V} ) A resistance of ( _{-1}-ldots_{text {has to be }} ) |
12 |

580 | Magnetic field strength at the centre of regular pentagon made of a conducting wire of uniform cross section area as shown in figure is : (i amount of current enters at A and leaves at E) ( mathbf{A} cdot frac{5 mu_{0} i}{4 pi a}left[2 sin frac{72^{0}}{2}right] ) ( B . quad 0 ) C ( cdot frac{3 mu_{0} i}{4 pi}left[2 sin frac{72^{0}}{2}right] ) D. ( frac{mu_{0} i}{4 pi a}left[2 sin frac{72^{0}}{2}right] ) |
12 |

581 | The equation of line on which magnetic field is zero due to system of two perpendicular infinitely long current carrying straight wires, is A. ( x=y ) B. ( x=2 y ) c. ( x=3 y ) D. ( 3 x=y ) |
12 |

582 | A copper wire of diameter ( 1.6 m m ) carries a current ( i . ) The maximum magnetic field due to this wire is ( 5 x ) ( 10^{-3} T . ) The value of ( i ) is A ( .40 A ) в. ( 5 A ) ( c cdot 20 A ) D. 2A |
12 |

583 | Two conducting coils are placed coaxially now a cell is connected in one coil then they will :- A. Attract to each other B. Repel to each other ( c . ) Both (1)( &(2) ) D. They will not experience any force |
12 |

584 | A wire along ( x- ) axis carries a current ( 3.5 A . ) Find the force on a ( 1 mathrm{m} ) section of the wire exerted by ( vec{B}=(0.74 hat{j}- ) ( mathbf{0} . mathbf{3 6} hat{boldsymbol{k}}) boldsymbol{T} .(text { in } mathbf{N}): ) A. ( 2.59 hat{k}+1.263 ) 3 в. ( 1.26 hat{k}-2.59 hat{jmath} ) c. ( -2.59 hat{k}-1.26 hat{j} ) D . ( -1.26 hat{k}+2.59 hat{j} ) |
12 |

585 | A beam of protons with a velocity ( 4 times ) ( 10^{5} m s^{-1} ) enters a uniform magnetic field of ( 0.3 mathrm{T} ) at an angle of ( 60^{circ} ) to the magnetic field. Find the pitch of the helix (which is the distance travelled by a proton in the beam parallel to the magnetic field during one period of the rotation). Mass of the proton ( =1.67 times ) ( mathbf{1 0}^{-2 mathbf{7}} mathbf{k g} ) ( A cdot 2.3 mathrm{cm} ) B. 5.35 ( mathrm{cm} ) ( c cdot 4.35 mathrm{cm} ) D. 6.35 ( mathrm{cm} ) |
12 |

586 | A circular coil of 16 turns and radius 10 ( mathrm{cm} ) carrying a current of ( 0.75 mathrm{A} ) rests with its plane normal to an external field of magnitude ( 5.0 times 10^{-2} ) T. The coil is free to turn about an axis in its plane perpendicular to the filed direction. When the coil is turned slightly and released, it oscillates about its stable equilibrium with a frequency of ( 2.0 / s ) What is the moment of inertia of the coil about its axis of rotation? A ( .1 .2 times 10^{4} g-c m^{2} ) B. ( 3 times 10^{4} k g-m^{2} ) c. ( 0.3 times 10^{4} k g-m^{2} ) D. ( 1.2 times 10^{4} k g-m^{2} ) |
12 |

587 | The shunt required to send ( 10 % ) of the main current through a moving coil galvanometer of resistance ( 99 Omega ) is ( mathbf{A} cdot 99 Omega ) в. ( 9.9 Omega ) c. ( 9 Omega ) D. ( 10 Omega ) E . ( 11 Omega ) |
12 |

588 | For a positively charged particle moving in a ( x ) -y plane initially along the ( x ) -axis, there is a sudden change in its path due to the presence of electric and/or magnetic fields beyond P. The curved path is shown in the ( x ) -y plane and is found to be non-circular.Which one of the following combinations is possible? A ( cdot vec{E}=0, vec{B}=b hat{i}+c hat{k} ) в. ( vec{E}=a hat{i}, vec{B}=c hat{k}+a hat{i} ) c. ( vec{E}=0, vec{B}=c hat{j}+b hat{k} ) D. ( vec{E}=a hat{i}, vec{B}=c hat{k}+b hat{j} ) |
12 |

589 | Magnetic field due to a toroid inside its turns is given by ( ( n ) is thenumber of turns per unit length of the toroid and ( boldsymbol{I} ) is the current in the loop) ( mathbf{A} cdot B=mu_{o} n I ) В. ( B=epsilon_{o} n I ) ( mathbf{c} cdot B=frac{mu_{o}}{4 pi} n I ) D. None of these |
12 |

590 | A circular current carrying coil has a radius ( R ). The distance from the centre of the coil on the axis where the magnetic induction will be ( left(frac{1}{8}right)^{t h} ) of its value at the centre of the coil is A ( cdot frac{R}{sqrt{3}} ) в. ( R sqrt{3} ) с. ( 2 R sqrt{3} ) । D. ( left(frac{2}{sqrt{3}}right)^{R} ) |
12 |

591 | If the current in a wire is directed east wards and it is kept in a magnetic field directed northwards, the direction of force on the wire is: A. due west B. due south c. vertically upwards D. vertically downwards |
12 |

592 | Calculate force per unit length acting on the wire B due to the current flowing in the wire ( A ) |
12 |

593 | Two thin, long,parallel wires,seperated by a distance ‘d’ carry a current of ‘i’A in the same direction.They will: A. Attract each other B. Repel,each other c. Depend upon the material of wire D. Can’t say |
12 |

594 | A conducting circular loop made of a thin wire, has area ( 3.5 times 10^{-3} m^{2} ) and resistance ( 10 Omega ). It is placed perpendicular to a time dependent magnetic field ( B(t)=(0.4 T) sin (50 pi t) ) The field is uniform in space. Then the net charge flowing through the loop during ( t=0 s ) and ( t=10 m s ) is close to: A. ( 0.14 m C ) В. ( 0.21 mathrm{mC} ) ( c cdot 6 m C ) D. ( 7 m C ) |
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595 | How can you verify that a current carrying wire produces a magnetic field with the help of an experiment? | 12 |

596 | A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of the magnetic field is ( A cdot B / 2 ) B. B ( c cdot 2 B ) D. 4 B |
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597 | A proton is projected horizontally eastward in a uniform magnetic field, which is horizontal and southward in direction. The proton will be deflected A. upwarddardpwardd B. downward c. northward D. southward |
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598 | A current I flows in the anticlockwise direction through a square loop of side a lying in the xoy plane with its center at the origin. The magnetic induction at the center of the square loop is A ( cdot frac{2 sqrt{2} mu_{0} I}{pi a} hat{e}_{x} ) B. ( frac{2 sqrt{2} mu_{0} I}{pi a} hat{e}_{z} ) ( ^{mathrm{c}} cdot frac{2 sqrt{2} mu_{0} I}{pi a^{2}} hat{e}_{z} ) D. ( frac{2 sqrt{2} mu_{0} I}{pi a^{2}} hat{e}_{x} ) |
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599 | Which of the following changes would cause the pointer to deflect through a larger angle? A. Move the magnet faster B. Move the magnet away from the solenoid c. Unwind some of the turns of the solenoid D. Keep the magnet stationary |
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600 | A wire in the form of a circular loop of one turn carrying a current produces a magnetic field ( B ) at the centre. If the same wire is looped into a coil of two turns and carries the same current, the new value of magnetic induction at the centre is: ( A .3 B ) в. ( 5 B ) ( c .4 B ) D. 2 ( B ) |
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601 | Complete the following sentence A current carrying solenoid behaves like ( a ) A. bar magnet B. resistance c. inductance D. none of these |
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602 | toppr ) Q Type your question the rigure. the alstance ( boldsymbol{a} ) Is ( mathbf{U} . mathbf{I} boldsymbol{Z} mathbf{U} boldsymbol{m} ) When the two charges are at the locations as shown in the figure, what are the magnitude and direction of the net magnetic field they produce at point ( boldsymbol{P ?} ) (Take ( boldsymbol{v}=mathbf{4 . 5 0} times mathbf{1 0}^{mathbf{6}} mathbf{m} boldsymbol{s}^{-1} ) and ( boldsymbol{v}^{prime}= ) ( left.9.00 times 10^{6} m s^{-1}right) ) A ( .4 .38 times 10^{-4} T, ) into the page B. ( 4.38 times 10^{-4} T ), out of the page ( c: quad 10^{-4} T, ) into the page D. ( 2.9 times 10^{-9} T, ) out of the page |
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603 | A uniform electric field and uniform magnetic field are acting along the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along the direction of fields, then the electron A. will turn towards right of direction of motion B. speed will decrease c. speed will increase D. will turn towards left direction of motion |
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604 | A current of one ampere is passed through a straight wire of length 2 metre. The magnetic field at a point in air at a distance of ( 3 mathrm{m} ) from one end of the wire but lying on the axis of the wire will be: A ( cdot mu_{0} / 2 pi ) B . ( mu_{0} / 4 pi ) c. ( mu_{0} / 8 pi ) D. zero |
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605 | In the following diagram an arrow shows the motion of the coil towards the bar magnet. (i) State in which direction the current flows: ( A ) to ( B ) or ( B ) to ( A ) ? (ii) Name the law used to come to the conclusion. |
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606 | When a current carrying coil is placed in a uniform magnetic field of induction ( B, ) then a torque ( tau ) acts on it. If ( I ) is the current, ( n ) is the number of turns and ( A ) is the face area of the coil and the normal to the coil makes an angle ( theta ) with ( boldsymbol{B}, ) Then A ( cdot tau=B I n A ) B. ( tau=B ) In ( A sin theta ) ( mathbf{c} cdot tau=B operatorname{In} A cos theta ) ( mathbf{D} cdot tau=B I n A tan theta ) |
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607 | Consider two thin identical conducting wires covered with very thin insulating material. One of the wires is bent into a loop and produces magnetic field ( B_{1} ) at its centre when a current ( I ) passes through it. The second wire is bent into a coil with free identical loops adjacent to each other and produces magnetic field ( B_{2} ) at the centre of loops with current ( I / 3 ) passing through it. The ratio ( boldsymbol{B}_{1}: boldsymbol{B}_{2} ) A. 1: 1 B. 1: 3 c. 1: 9 D. 9: 1 |
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608 | A long copper wire is wound in the form of a coil of radius ( r . ) A current of ( 2 A ) is passed through this coil and the magnetic induction at the centre of this coil is noted. The same wire is now folded end to end and coil of the same radius ( r ) is prepared and the same current is passed through it. The magnetic induction at the centre A. Will be doubled B. Will be halved c. will remain same D. Will drop to zero |
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609 | Which of the following material is used in making the core of a moving coil galvanometer? A. copper B. Nickel c. Iron D. Both (a) and (b) |
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610 | Explain Fleming’s left hand rule with the help of labelled diagram. | 12 |

611 | The self-inductance of an air core solenoid of 100 turns is 1 m ( H ). The self- inductance of another Solenoid of 50 turns (with the same length and crosssectional area) with a core having relative permeability 500 is A . ( 125 mathrm{mH} ) B. 24 mH c. ( 60 mathrm{mH} ) D. 30 mH E. ( 45 mathrm{mH} ) |
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612 | The diagram below shows a positively charged particle moving toward the right and about to enter a magnetic field whose direction is shown by the blue arrows. What is the direction of the force on the positively charged particle (from our point of view) at the instant it enters the magnetic field? A . right B. left c. up D. toward us E. away from us |
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613 | A deuteron of kinetic energy 50 keV is describing a circular orbit of radius 0.5 metre in a plane perpendicular to the magnetic field ( B ). The kinetic energy of the proton that describes a circular orbit of radius 0.5 metre in the same plane with the same ( B ) is A . ( 25 ~ k e V ) В. ( 50 mathrm{keV} ) c. ( 200 mathrm{keV} ) D. ( 100 mathrm{keV} ) |
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614 | When does a moving charged particle not experience any force while moving through a uniform magnetic field? |
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615 | A circular current carrying coil has a radius ( R ). The distance from the centre of the coil on the axis where the magnetic induction will be ( frac{1}{8} ) to its value at the centre of the coil, is : A ( cdot frac{R}{sqrt{3}} ) в. ( R sqrt{3} ) c. ( 2 sqrt{3} R ) D. ( frac{2}{sqrt{3}} R ) |
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616 | If expressions for the magnetic field at a point due to a current element, in C.G.S.system is given by ( overrightarrow{d B}=frac{mu_{0}}{4 pi} frac{i(d overrightarrow{d times vec{r}})}{a * r^{3}} ) Find a. |
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617 | The path of a charged particle moving in a magnetic field can be a : This question has multiple correct options A. Straight line B. Circle c. Parabola D. Helix |
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618 | Assertion The magnetic field at the ends of a very long current carrying solenoid is half of that at the centre. Reason If the solenoid is sufficiently long, the field within it is uniform. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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619 | Which one of the following are used to express the intensity of magnetic field in vacuum? A . oersted B. tesla c. gauss D. none of these |
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620 | (a) Explain giving reasons, the basic difference in converting a galvanometer into (i) a voltmeter and (ii) an ammeter (b) Two long straight parallel conductors carrying steady currents ( I_{1} ) and ( I_{2} ) are separated by a distance ( ^{prime} d^{prime} ) Explain briefly, with the help of a suitable diagram, how the magnetic field due to one conductor acts on the other. Hence deduce the expression for the force acting between the two conductors. Mention the nature of this force. |
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621 | Two long thin charged rods with charge density ( lambda ) each are placed parallel to each other at a distance d apart. The force per unit length exerted on one rod by the other will bewhere ( left(boldsymbol{K}=frac{mathbf{1}}{mathbf{4} boldsymbol{pi} varepsilon_{0}}right) ) A ( cdot frac{K 2 lambda}{d} ) в. ( frac{K 2 lambda^{2}}{d} ) c. ( frac{K 2 lambda}{d^{2}} ) D. ( frac{K 2 lambda^{2}}{d^{2}} ) |
12 |

622 | A current-carrying conductor when placed in a magnetic field always experiences a force. Is the given statement true or false? | 12 |

623 | A rectangular loop carrying current lis located near an infinite long straight conductor carrying current l as shown in the figure. The loop, A. remain stationary B. is attracted towards the wire C. is repelled away from the wire D. will rotate about an axis parallel to the wire |
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624 | A beam of protons is moving horizontally towards you. As it approaches you, it passes through a magnetic field which is directed upwards. As you see it, the magnetic field will deflect the beam to the: A. Right B. Left c. Top D. Bottom |
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625 | In a crossed field, the magnetic field induction is ( 2.0 T ) and electric field intensity is ( 20 times 10^{3} V / m . ) At which velocity the electron will travel in a straight line without the effect of electric and magnetic fields? A ( cdot frac{20}{16} times 10^{3} mathrm{ms}^{-1} ) B. ( 10 times 10^{3} mathrm{ms}^{-1} ) c. ( 20 times 10^{3} mathrm{ms}^{-1} ) D. ( 40 times 10^{3} mathrm{ms}^{-} ) |
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626 | In cyclotron the gyro radius is: A. proportional to momentum B. proportional to energy C. inversely proportional to momentum D. inversely proportional to energy |
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627 | Two parallel beams of positrons moving in the same direction will A. Repel each other B. Will not interact with each other c. Attract each other D. Be deflected normal to the plane containing the two beams |
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628 | (a) Write Fleming’s left-hand rule for the direction of force on a current carrying conductor placed in a magnetic field. (b) Draw a diagram to show lines of magnetic field inside and around a current carrying solenoid. (c) Write the names of four devices where current carrying conductor is used along with magnetic fields |
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629 | If a charged particle is projected perpendicular to a uniform magnetic field, then a) it revolves in circular path b) its K.E. remains constant c) its momentum remains constant d) its path is spiral A. only a, bare correct B. only a, c are correctt c. only b, dare correct D. only a, dare correctt |
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630 | A proton goes undeflected in a crossed electric and magnetic field (the fields are perpendicular to each other) at a speed of ( 10^{5} mathrm{m} / mathrm{s} ). The velocity is perpendicular to both the fields. When the electric field is switched off, the proton moves along a circle of radius 2 ( mathrm{cm} . ) Find the magnitude of the electric and the magnetic fields. Take the mass of the proton ( =1.6 times 10^{-27} mathrm{kg} ) |
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631 | A charge particle of charge ( q, ) mass ( m ) is projected with a velocity ( vec{v}=v hat{i} ). The electric field ( overrightarrow{boldsymbol{E}}=boldsymbol{E} hat{boldsymbol{k}} ) and magnetic field ( vec{B}=B hat{j} ) is applied. The acceleration of the particle is then A ( frac{q v B}{m} ) в. ( frac{q E}{m} ) c. ( frac{q(E+v B) hat{k}}{m} ) ( D ) |
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632 | Establish the formula for intensity of magnetic field at the centre of a current carrying circular coil. | 12 |

633 | A current loop consists of two identical semicircular parts each of radius ( mathrm{R} ), one lying in the ( x ) -y plane and the other in ( x-z ) plane. If the current in the loop is i. The resultant magnetic field due to the two semicircular parts at their common centre is A ( cdot frac{mu_{0} i}{2 sqrt{2} R} ) B. ( frac{mu_{0} i}{2 R} ) c. ( frac{mu_{0} i}{4 R} ) D. ( frac{mu_{0} i}{sqrt{2} R} ) |
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634 | A current ( I=5.0 A ) flows along a thin wire shaped as shown in figure above. The radius of a curved part of the wire is equal to ( R=120 m m ), the angle ( 2 varphi=90^{circ} . ) Find the magnetic induction of the field at the point ( O ) in ( mu T . ) If the answer is ( X ) then enter ( frac{X}{7} ) |
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635 | ( mathbf{1} ) ( boldsymbol{m} ) long wire is folded in the form of a circular coil and 100 m ( A ) electric current is flowing in it, then magnetic field at a point ( 1 ~ m ) away from its centre on its axis : ( ^{text {A }} cdot frac{10^{-5}}{4 pi} T ) в. ( frac{10^{-8}}{2 pi} T ) ( ^{text {c. }} cdot frac{10^{-5}}{2 pi} T ) D. ( frac{10^{-8}}{4 pi} T ) |
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636 | Write the dimensions of ( boldsymbol{E} / boldsymbol{B} ). Here ( , boldsymbol{E} ) is the electric field and ( B ) is the magnetic field. |
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637 | What do you mean by a solenoid? | 12 |

638 | A beam of electrons moving with a uniform speed of ( 4 times 10^{7} m s^{-1} ) is projected normal to the uniform magnetic field where ( boldsymbol{B}=mathbf{1 0}^{-3} boldsymbol{W} boldsymbol{b} / boldsymbol{m}^{2} ) What is path of the beam in magnetic field? |
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639 | A moving charge will produce A. no field B. a magnetic field. c. a small electric field. D. None of these |
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640 | A uniform electric field and a uniform magnetic field are produced, and are pointed in the same direction. An electron is projected with its velocity pointed in the same direction A. The electron will turn to its left B. The electron velocity will decrease in magnitude c. The electron will turn to its right D. The electron velocity will increase in magnitude |
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641 | A circular coil connected to a cell of e.m.f ( boldsymbol{E} ) produced a magnetic field. The coil is unwound, stretched to double its length, rewound into a coil of ( frac{1}{3} ) of the original radius and connected to a cell of e.m.f ( boldsymbol{E}_{1} ) to produce the same field at the centre. Then ( boldsymbol{E}_{mathbf{1}} ) is : ( mathbf{A} cdot frac{E}{2} ) B. ( frac{2 E}{3} ) c. ( frac{9 E}{4} ) D. ( frac{E}{6} ) |
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642 | A very long straight wire carries a current I. At the instant when a charge ( +Q ) at point ( P ) has velocity ( vec{V}, ) as shown, the force on the charge is A. Along ox B. Opposite to oy c. Along oy D. Opposite to ox |
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643 | A charged particle moves in a gravityfree space without change in velocity. Which of the following is/are possible? This question has multiple correct options A. ( E=0, B=0 ) 0 B. ( E=0, B neq 0 ) c. ( E neq 0, B=0 ) D. ( E neq 0, B neq 0 ) |
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644 | The correct expression for Ampere’s law is : A ( . int B . d l=Sigma i ) в. ( int B . d l=frac{1}{sum i} ) c. ( int B . d l=mu_{0} sum i ) ‘ – ( int B . d l=frac{sum i}{mu_{0}} ) |
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645 | Find the magnitude of force acting on the conductor carrying current ( boldsymbol{I} ) as shown in the diagram. The magnitude of magnetic field is ( B ) and direction is into the plane of paper: ( mathbf{A} cdot I(2 L+mu R) B ) ( mathbf{B} cdot I(2 L+R) B ) ( mathbf{c} cdot I(2 L+2 R) B ) D. none of these |
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646 | The length of conductor ab carrying current ( I_{2} ) is ( l . ) The force acting on it due to a long current carrying conductor as shown in figure. The midpoint of wire ab is distance ( x ) apart from long wire. The magnitude of the force on the wire is: A ( cdot frac{mu_{0} I}{2 pi} log _{e} frac{x+l / 2}{x-l / 2} ) В. ( frac{mu_{0} I}{2 pi x} ) c. ( frac{mu_{0} I}{2 pi} log _{e} frac{x-l / 2}{x+l / 2} ) D. ( _{mu_{0} text { Ilog }_{e}} frac{x-l / 2}{x+l / 2} ) |
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647 | The magnetic field at center ( O ) of the ( operatorname{arcin} ) figure is A ( cdot frac{mu_{0} I}{4 pi times r}[sqrt{2}+pi] ) ( ^{mathbf{B}} cdot frac{mu I}{2 pi r}left[frac{pi}{4}+(sqrt{2}-1)right] ) C ( frac{mu_{0}}{4 pi} times frac{I}{r}[(sqrt{2}-pi)] ) ( ^{mathrm{D}} cdot frac{mu_{0}}{4 pi} times frac{I}{r}left[left(sqrt{2}+frac{pi}{4}right)right] ) |
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648 | An electron is moving towards east in a magnetic field acting vertically downwards. So the electron is deflected towards: A. South B. North c. East D. west |
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649 | The figure showing Fleming’s left hand rule is given. Which figure or thumb shows the direction of flow of electric current? A. First finger B. Second finger c. Thumb D. Small finger |
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650 | Identify the wrong statement. A. Current loop is equivalent to a magnetic dipole B. Magnetic dipole moment of a planar loop of area ( A ) carrying current ( l ) is ( l^{2} A ) C. Particles like proton, electron carry an intrinsic magnetic moment D. The current loop (magnetic moment ( m ) ) placed in a uniform magnetic field, ( B ) experiences a torque ( tau= ) ( m times B ) E. Ampere’s circuit law is not independent of Biot Savart’s law |
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651 | In the given loop the magnetic field at the centre 0 is : A ( cdot frac{mu_{0} I}{4}left(frac{r_{1}+r_{2}}{r_{1} r_{2}}right) ) out of the page B. ( frac{mu_{0} I}{4}left(frac{r_{1}+r_{2}}{r_{1} r_{2}}right) ) into the page c. ( frac{mu_{0} I}{4}left(frac{r_{1}-r_{2}}{r_{1} r_{2}}right) ) out of the page D. ( frac{mu_{0} I}{4}left(frac{r_{1}-r_{2}}{r_{1} r_{2}}right) ) into the page |
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652 | Name any one instrument which works on the principle of tangent law in magnetism |
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653 | Two protons are moving with same velocity in magnetic field of same magnitude, then : A. magnetic force on protons may be zero B. magnetic force on both must be same to each other c. magnetic force on both may or may not be same to each other D. both ( (a) ) and ( (c) ) are correct |
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654 | A square loop ( A B C D ) carrying a current ( i, ) is placed near and coplanar with a long straight conductor ( boldsymbol{X} boldsymbol{Y} ) carrying a current ( I, ) the net force on the loop will be: A ( cdot frac{2 mu_{0} I i}{3 pi} ) B. ( frac{mu_{0} I i}{2 pi} ) c. ( frac{2 mu_{0} text { Ii } L}{3 pi} ) D. ( frac{mu_{0} I i L}{2 pi} ) |
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655 | Derive an expression for the magnetic induction at a point on the axis of a current carrying circular coil using Biot-Savart law. | 12 |

656 | An ( alpha ) -particle and proton are accelerated from rest through same potential difference and both enter into a uniform perpendicular magnetic field. Find the ratio of their radii of curvature. A. ( sqrt{7}: 1 ) B. ( sqrt{5}: 1 ) c. ( sqrt{2}: 1 ) D. ( sqrt{3}: 1 ) |
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657 | A straight conductor carries a current. Assume that all free electrons in the conductor move with the same drift velocity v. A and B are two observers on a straight line XY parallel to the conductor. A is stationary. B moves along XY with a velocity v in the direction of the free electrons. A. A and B observe the same magnetic field B. A observes a magnetic field, B does not c. A and B observe magnetic fields of the same magnitude but opposite directions D. A and B do not observe any electric field |
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658 | Electric field and magnetic field in a region of space is given by ( vec{E}=E_{o} hat{j} ) and ( vec{B}=B_{o} hat{j} cdot A ) particle of specific charge ( alpha ) is released from origin with velocity ( vec{v}=v_{o} hat{i} ).Then path of particle. Note- ( boldsymbol{E}_{boldsymbol{o}}, boldsymbol{B}_{boldsymbol{o}} ) and ( boldsymbol{v}_{boldsymbol{o}} ) are constant values ( A ). is a circle B. is a helix with uniform pitch c. is a helix with non-uniform pitch D. is cycloid |
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659 | You are sitting in a room in which a strong magnetic field is directed from your left towards right. A beam of electrons is directed from front towards you. What would be the direction of magnetic force on this beam? A. downwards B. upwards. c. towards right D. towards left |
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660 | Three long, straight and parallel wires are arranged as shown in figure. The force experienced by ( 10 mathrm{cm} ) length of wire ( boldsymbol{Q} ) is A ( .1 .4 times 10^{-4} N ) toward the right B. ( 1.4 times 10^{-4} N ) toward the left c. ( 2.6 times 10^{-4} N ) toward the right D. ( 2.6 times 10^{-4} N ) toward the left |
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661 | An electron enters a uniform magnetic field with a path perpendicular to the field lines and moves in a circular path of radius ( boldsymbol{R} ) A positron (same mass of an electron |
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662 | Fill in the blanks: A current carrying solenoid when freely suspended, it always rests in direction. A. north-south B. vertical c. east-west D. a direction inclined to north-south |
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663 | A long solenoid with 40 turns per ( mathrm{cm} ) carries a current of ( 1 A . ) The magnetic energy stored per unit volume is ( boldsymbol{J} / boldsymbol{m}^{3} ) A . ( 3.2 pi ) B. ( 32 pi ) c. ( 1.6 pi ) D. ( 6.4 pi ) |
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664 | An iron rod is placed parallel to the magnetic field of intensity ( 2000 mathrm{A} / mathrm{m} ) The magnetic flux through the rod is ( 6 times 10^{-4} W b ) and its cross-sectional area is ( 3 mathrm{cm}^{2} ). The magnetic permeability of the rod in ( frac{W b}{A-m} ) is: A ( cdot 10^{-1} ) B. ( 10^{-2} ) ( mathbf{c} cdot 10^{-3} ) D. ( 10^{-4} ) |
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665 | The most suitable material to be used as the core of an electromagnet is A. Iron B. steel c. copper D. Aluminium |
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666 | A positive charge is at rest in a uniform magnetic field directed to the right. What force does the positive charge feel, due to the magnetic field? A. An upward force B. A downward force c. A force to the left D. No force is felt. |
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667 | A permanent magnet moving coil gives full scale deflection at ( 40 mathrm{mV} ) potential difference and 8 mA current. What will be the required series resistance when it is used as voltmeter of range ( 0200 mathrm{V} ? ) A . 19556 ohm B. 20163 ohm ( c cdot 23884 ) ohm D. 24995 ohm |
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668 | Maximum current that can pass through galvanometer is ( 0.002 A ) and resistance of galvonameter is ( boldsymbol{R}_{boldsymbol{g}}= ) ( 50 Omega ) find out shunt resistance to convert in into ammeter of range ( 0.5 A ) A . ( 0.5 Omega ) B. ( 0.2 Omega ) ( c .0 .7 Omega ) D. ( 0.9 Omega ) |
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669 | A thin rod is bent in the shape of a small circle of radius r. If the charge per unit length of the rod is ( sigma, ) and if the circle is rotated about its axis at a rate of rotations per second, the magnetic induction at a point on the axis at a large distance y from the centre is? A ( cdot mu_{0} pi r^{3} n frac{sigma}{y^{3}} ) В ( cdot 2 mu_{0} pi r^{3} n frac{sigma}{y^{3}} ) c. ( left(frac{mu_{0}}{4 pi}right) r^{3} n frac{sigma}{y^{3}} ) D ( cdotleft(frac{mu_{0}}{2 pi}right)^{r^{3}} n frac{sigma}{y^{3}} ) |
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670 | A permanent magnet has the shape of a sufficiently thin disc magnetized along its axis. The radius of the disc is ( boldsymbol{R}= ) 1.0 ( c m . ) Evaluate the magnitude of a molecular current ( I^{prime} ) flowing along the rim of the disc if the magnetic induction at the point on the axis of the disc, lying at a distance ( boldsymbol{x}=mathbf{1 0} boldsymbol{c m} ) from its centre, is equal to ( B=30 mu T ) |
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671 | The field ( B ) at the centre of a circular coil of radius ( r ) is ( pi ) times that due to a long straight wire at a distance ( r ) from it for equal currents. The figure shows three cases. In all cases the circular part has radius ( r ) and straight ones are infinitely long. For same current, the field ( B ) at the centre ( P ) in cases 1,2,3 has the ratio: ( ^{mathbf{A}} cdotleft(-frac{pi}{2}right): frac{pi}{2}:left(frac{3 pi}{4}-frac{1}{2}right) ) B ( cdotleft(-frac{pi}{2}+1right):left(frac{pi}{2}+1right):left(frac{3 pi}{4}-frac{1}{2}right) ) ( mathbf{C} cdot-frac{pi}{2}: frac{pi}{2}: frac{3 pi}{4} ) D ( cdotleft(-frac{pi}{2}-1right):left(frac{pi}{4}+frac{1}{4}right):left(frac{3 pi}{4}+frac{1}{2}right) ) |
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672 | the ( x y ) -plane along the lines ( x=pm R ) The wire located at ( x=+R ) carries a constant current ( I_{1} ) and the wire located at ( x=-R ) carries a constant current ( boldsymbol{I}_{2} ) A circular loop of radius ( boldsymbol{R} ) is suspended with its centre at ( (0,0, sqrt{3} R) ) and in a plane parallel to the ( boldsymbol{x} boldsymbol{y} ) -plane. This loop carries a constant current ( I ) in the clockwise direction as seen from above the loop. The current in the wire is taken to be positive if it is in the ( +hat{boldsymbol{j}} ) direction. Which of the following statements regarding the magnetic field ( vec{B} ) is (are) true? This question has multiple correct options A ( cdot ) If ( I_{1}=I_{2} ), then ( vec{B} ) cannot be equal to zero at the origin (0,0,0) B. If ( I_{1}>0 ) and ( I_{2}<0 ), then ( vec{B} ) can be equal to zero at the origin (0,0,0) C ( cdot ) If ( I_{1}0, ) then ( vec{B} ) can be equal to zero at the origin (0,0,0) D. If ( I_{1}=I_{2} ), then the ( z ) -component of the magnetic field at the centre of the loop is ( left(-frac{mu_{0} I}{2 R}right) ) |
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673 | If a magnet is dropped along the axial line of a horizontally held copper ring, then the acceleration of the magnet while it passing through the ring will A. Less than that due to gravity B. Equal to that due to gravity c. More than that due to gravity D. Depend on the size of the ring and magnet |
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674 | Meena draws magnetic field lines of field close to the axis of a current carrying circular loop. As she moves away from the centre of the circular loop she observes that the lines keep on diverging. How will you explain her observation: |
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675 | In moving coil galvanometer, strong horses shoe magnet of concave shaped pole pieces is used to? A. Increase space for rotation of coil B. Reduce weight of galvanometer c. Protect magnetic field which is parallel to plane of coil at any position D. Make magnetic induction weak at the cnetre |
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676 | A particle of charge ( q ) and mass ( m ) moves in a circular orbit of radius ( r ) with angular speed ( omega . ) The ratio of the magnitude of its magnetic moment to that of its angular momentum depends on A. ( omega ) and ( q ) B. ( omega, q ) and ( m ) c. ( q ) and ( m ) D. ( omega ) and ( m ) |
12 |

677 | The AC voltage across a resistance can be measured using a A. moving magnet galvanometer B. moving coil galvanometer c. hot wire voltmeter D. potentiometer |
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678 | Some equipotential surfaces of the magnetic scalar potential are shown in figure. Magnetic field at a point in the region is: A ( cdot 10^{-4} mathrm{T} ) B . ( 0.5 times 10^{-4} mathrm{T} ) c. ( 2 times 10^{-4} mathrm{T} ) D. None of these |
12 |

679 | A wire of length ( 44 mathrm{cm} ) is bent into a circle and a current of ( 9.8 A ) is passed through it. The intensity of magnetic induction at the centre of the circle is ( mathbf{A} cdot 8.8 times 10^{-6} T ) B . ( 8.8 times 10^{-5} T ) c. ( 8.4 times 10^{-6} T ) D. ( 61.5 times 10^{-5} T ) |
12 |

680 | Ampere rule is used to determine: A. direction of current B. direction of magnetic field c. direction of motion of the conductor D. magnitude of current |
12 |

681 | (AUDOD 00) (U) 10 8. A magnetic needle is kept in a non-uniform magnetic field. It experiences (a) a force but not torque (b) a force and a torque (c) neither a force, nor a torque (d) a torque but not force (AIEEE 2005) |
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682 | A proton moving with a velocity V is acted upon by electric field E and magnetic field B. The proton will move undeflected if A. E is perpendicular to B B. E is parallel to V and perpendicular to B C. E is parallel to B and both are perpendicular to D. E, V and B are mutually perpendicular and ( V=E / B ) |
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683 | If magnetic flux through area ( 20 m^{2} ) at point ( P ) in magnetic field is 50 Weber then magnetic induction at point ( boldsymbol{P} ) is : A . ( 5 T ) в. ( 200 T ) c. ( 1000 T ) D. ( 2.5 T ) |
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684 | toppr Q Type your question with same speed. P is a point on a line joining the beams, at a distance ( x ) from any one beam. The magnetic field at P is B. If ( mathrm{B} ) is plotted against ( mathrm{x} ), which of the following best represents the resulting curve ? ( A ) B. ( c ) ( D ) |
12 |

685 | An electron accelerated by a potential difference ( V=1.0 k V ) moves in a uniform magnetic field at an angle ( boldsymbol{alpha}= ) ( 30^{circ} ) to the vector ( B ) whose modulus is ( B=29 ) mT.Find the pitch of the helical trajectory of the electron. ( A cdot 1 m ) B. ( 1 mathrm{cm} ) ( c cdot 2 m ) D. ( 2 mathrm{cm} ) |
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686 | A uniform field of ( 30 mathrm{mT} ) exists in the ( +x ) direction. A particle of charge +ve and ( operatorname{mass} 1.67 times 10^{-27} mathrm{kg} ) is projected through the field in the ( +Y ) direction with a speed of ( 4.8 times 10^{6} m / s ) (a) Find the force on the charged particle in magnitude and direction (b) Find the force if the particle were negatively charged. (c) Describe the nature of path followed by the particle in both the cases. |
12 |

687 | A bar magnet has coercivity ( 4 times ) ( 10^{3} A m^{-1} . ) It is desired to demagnetize it by inserting it inside a solenoid ( 12 mathrm{cm} ) long and has 60 turns. The current that should be sent through the solenoid is: ( A cdot 8 A ) в. ( 10 A ) ( c .12 A ) D. ( 14 A ) |
12 |

688 | In an experiment to determine e/m using Thomson’s method, electrons from the cathode accelerate through a potential difference of ( 1.5 mathrm{kV} ). The beam coming out of the anode enters crossed electric and magnetic field of strengths ( 2 times 10^{4} V / m ) and ( 8.6 times 10^{-4} T ) respectively, The value of e/m.of electron will be A ( cdot 1.6 times 10^{11} mathrm{C} / mathrm{kg} ) B . ( 1.7 times 10^{11} mathrm{C} / mathrm{kg} ) C ( .1 .8 times 10^{11} mathrm{C} / mathrm{kg} ) D. ( 1.9 times 10^{11} mathrm{C} / mathrm{kg} ) |
12 |

689 | A proton moves at a speed ( boldsymbol{v}=mathbf{2} times ) ( 10^{6} m / s ) in a region of constant magnetic field of magnitude ( boldsymbol{B}= ) ( 0.05 T . ) The direction of the proton when it enters this field is ( theta=30^{circ} ) to the field. When you look along the direction of the magnetic field, the path is a circle projected on a plane perpendicular to the magnetic field. How far will the protons move along the direction of ( boldsymbol{B} ) when 2 projected circles have been completed? |
12 |

690 | There wires are situated at the same distance. A current of ( 1 A, 2 A, 3 A ) flows through these wires in the same direction. What is ratio ( boldsymbol{F}_{1} / boldsymbol{F}_{2} ) where ( boldsymbol{F}_{1} ) is force on 1 and ( F_{2} ) on ( 2 ? ) A . ( 7 / 8 ) B. c. ( 9 / 8 ) D. none of the above |
12 |

691 | toppr OGII Q Type your question_ What is an centered on point ( P ) The segments are connected by straight wires as shown, and an unseen source of EMF creates a constant counterclockwise current in the wire. What is the direction of the magnetic field created at point ( P ) due to each wire segment? A. Both segments 1 and 2 create magnetic field that is into the page at point ( P ) B. Both segments 1 and 2 create magnetic field that is out of the page at point ( P ) c. Segment 1 creates magnetic field that is out of the page; Segment 2 creates magnetic field that is into the page at point P. D. Segment 1 creates magnetic field that is into the page: Segment 2 creates magnetic field that is out of the page at point P. |
12 |

692 | An electron and a proton travel with equal speeds and in the same direction, at ( 90^{circ} ) to a uniform magnetic field. They experience forces which are initially A. in opposite direction and differ by a factor of about 1840 B. in the same direction and differ by a factor of about 1840 c. equal in magnitude but in opposite directions D. identical |
12 |

693 | A wire ( A B ) is carrying a steady current 12 A and is lying on the table. Another wire CD carrying 5 A is held directly above ( A B ) at a height of ( 1 mathrm{mm} ). Find the mass per unit length of the wire CD so that it remains suspended at its position when left free. Give the directions of the current flowing in ( mathrm{CD} ) with respect to that in ( A B[text { Take the value of } g= ) ( left.10 m s^{-2}right] ) |
12 |

694 | A stream of electrons and protons are directed towards a narrow slit in a screen (see figure). The intervening region has a uniform electric field ( boldsymbol{E} ) (vertically downwards) and a uniform magnetic field ( B ) (out of the plane of the figure) as shown. Then: This question has multiple correct options A ( cdot ) electron and protons with speed ( frac{|E|}{|B|} ) will pass through the slitt B. protons with speed ( frac{|E|}{|B|} ) will pass through the slit. electrons of the same speed will not c. neither electrons nor protons will go through the slitt irrespective of their speed D. electrons will always be deflected upwards irrespective of their speed |
12 |

695 | A charged particle (charge q) is moving in a circle of radius ( R ) with uniform speed A ( cdot frac{q v R}{2} ) B ( cdot q v R^{2} ) c. ( frac{q v R^{2}}{2} ) D. ( q v R ) |
12 |

696 | Two parallel beams of positron moving in the same direction will : A. not interact with each other B. repel each other c. attract each other D. be deflected normal to the plane containing the two beams |
12 |

697 | In a circuit for finding the resistance of a galvanometer by half deflection method, a ( 6 V ) battery and a high resistance of ( 11 k Omega ) are used. The figure of merit of the galvanometer ( 60 mu A / ) division. In the absence of shunt resistance, the galvanometer produces a deflection of ( theta=9 ) divisions when current flows in the circuit. The value of the shunt resistance that can cause the deflection of ( boldsymbol{theta} / 2, ) is closest to A . ( 55 Omega ) B. ( 110 Omega ) c. ( 220 Omega ) D. ( 550 Omega ) |
12 |

698 | The magnetic moment vectors ( mu_{s} ) and ( mu_{l} ) associated with the intrinsic spin angular momentum ( S ) and orbital angular momentum ( l, ) respectively, of an electron are predicted by quantum theory (and verified experimentally to a high accuracy) to be given by: ( boldsymbol{mu}_{s}=-(e / boldsymbol{m}) boldsymbol{S} ) ( boldsymbol{mu}_{l}=-(e / 2 m) l ) Which of these relations is in accordance with the result expected classically? Outline the derivation of the classical result. |
12 |

699 | The force of repulsion between two parallel wires is ( f ) when each one of them carries a certain current I. If the current in each is doubled, the force between them would be A ( cdot 4 / f ) B. ( 4 f ) ( c cdot 2 f ) ( D ) |
12 |

700 | The figure shows a point ( P ) on the axis of a circular loop carrying current I.The correct direction of magnetic field vector at ( P ) due to ( overrightarrow{d l} ) is represented by ( A ) B. 2 ( c cdot 3 ) ( D ) |
12 |

701 | A closely wound solenoid ( 80 mathrm{cm} ) long has 5 layers of windings of 400 turns each. The diameter of the solenoid is 1.8 ( mathrm{cm} . ) If the current carried is ( 8.0 mathrm{A} ) estimate the magnitude of B inside the solenoid near its centre. |
12 |

702 | A system consists of two parallel planes carrying currents producing a uniform magnetic field of induction ( boldsymbol{B} ) between the planes. Outside this space there is no magnetic field. If the magnetic force acting per unit area of each plane is ( F_{1}=frac{B^{2}}{x mu_{0}} . ) Find ( x ) |
12 |

703 | A long straight wire of circular crosssection is made of a non-magnetic material. The wire is of radius a.The wire carries a current ( I ) which is uniformly distributed over its cross- section. The energy stored per unit length in the magnetic field contained within the wire is ( mathbf{A} cdot u=frac{mu_{0} I^{2}}{8 pi} ) B. ( U=frac{mu_{0} I^{2}}{16 pi} ) ( ^{mathbf{C}} cdot U=frac{mu_{0} I^{2}}{4 pi} ) D. ( U=frac{mu_{0} I^{2}}{2 pi} ) |
12 |

704 | Currents of ( 10 A, 2 A ) are passed through two parallel wires ( A ) and ( B ) respectively in opposite directions. If the wire A is infinitely long and the length of the wire B is ( 2 m, ) the force on the conductor ( B ) which is situated at ( 10 mathrm{cm} ) distance from A will be ( mathbf{A} cdot 8 times 10^{-5} N ) B . ( 5 times 10^{-5} N ) c. ( 8 pi times 10^{-7} N ) D. ( 4 pi times 10^{-7} N ) |
12 |

705 | Pick correct statement(s): This question has multiple correct options A. Newton’s ( 3^{r d} ) law is applicable for all frames of reference and all systems B. Presence of a conductor near another conductor increases capacitance of system c. Magnetic moment of a toroid is zero D. In a perfectly inelastic collision two colliding objects will always stick together after collision |
12 |

706 | A charged particle (charge q) is moving in a circle of radius ( R ) with uniform speed v. The associated magnetic moment ( mu ) is given by A ( cdot q v R ) в. ( _{q v} frac{R}{2} ) ( mathbf{c} cdot q v R^{2} ) D. ( _{q v} frac{R^{2}}{2} ) |
12 |

707 | A coil carrying a heavy current and having large number of turns is mounted in a N-S vertical plane. A current flows in the clockwise direction. A small magnetic needle at its centre will have its north pole in A. east-north direction B. west-north direction c. east-south direction D. west-south direction |
12 |

708 | Magnetic field which keeps the particles in circular path must A. remain a constant everywhere B. increase gradually with a rate proportional to kinetic energy of the particle C. increase gradually with a rate proportional to speed of the particle D. none of these |
12 |

709 | ( mathbf{A}-mathbf{4} . mathbf{8 0} mu mathbf{C} ) charge is moving at a constant velocity of ( 6.80 times 10^{5} m / s ) in the ( +x ) direction relative to a reference frame.At the instant when the point charge is at the origin,what is the magnetic field vector it produces at the following points ( x=0, y=0.500 mathrm{m}, z=0 ? ) |
12 |

710 | Figure shows a small loop carrying current ( I . ) The curved portion is an arc of a circle of radius ( R ) and the straight portion is a chord to the same circle subtending at an angle ( theta . ) The magnetic induction at center ( O ) is : A . zero B. always inward irrespective of the value of ( theta ) c. inward as long as ( theta ) is less than ( pi ) D. always outward irrespective of the value of ( theta ) |
12 |

711 | If the magnetizing field on a ferromagnetic material is increased, its permeability. A . Decreased B. Increased c. Is unaffected D. May be increased or decreased |
12 |

712 | A current of ( 1 A ) flowing along positive ( x ) axis through a straight wire of length ( 0.5 m ) placed in a region of a magnetic field given by ( vec{B}=(2 hat{i}+4 hat{j}) ) T. The magnitude and direction of the force experienced by the wire respectively are: A. ( sqrt{18} N, ) along positive ( z ) axis B. ( sqrt{20} N ), along positive ( x ) axis c. ( 2 N ) along positive z axis D. ( 4 N ) along positive Y axis |
12 |

713 | A closed curve encircles several conductors.The line integral ( int overrightarrow{boldsymbol{B}} cdot boldsymbol{d} overrightarrow{boldsymbol{l}} ) around this curve is ( 3.83 times 10^{-7} T-m ) If you were to integrate around the curve in the opposite direction, what could be the value of the line integral? |
12 |

714 | A beam of cathode rays is subjected to crossed.Electric (E) and Magnetic fields (B). The fields are adjusted such that the beam is not deflected.The specific charge of the cathode rays is given by – (where ( V ) is the potential difference between cathode and anode) A ( cdot frac{B^{2}}{2 V E^{2}} ) B. ( frac{2 V B^{2}}{E^{2}} ) ( ^{mathbf{C}} cdot frac{2 V E^{2}}{B^{2}} ) D. ( frac{E^{2}}{2 V B^{2}} ) |
12 |

715 | A particle carrying a charge equal to 100 times the charge on an electron is rotating one rotation per second in a circular path of radius ( 0.8 mathrm{m} ). The value of the magnetic field produced at the centre will be: ( left(mu_{0}=text { permeability for vacuum }right) ) ( ^{A} cdot frac{10^{-7}}{mu_{0}} ) B . ( 10^{-17} mu_{0} ) ( mathbf{c} cdot 10^{-6} mu_{0} ) D. ( 10^{-7} mu_{0} ) |
12 |

716 | A rectangular loop of sides ( 10 mathrm{cm} ) and 5 cm carrying a current I and 12 A is placed in different orientations as shown in the figures above. If there is a uniform magnetic field of ( 0.3 mathrm{T} ) in the positive z direction, in which orientations the loop would be in (i) stable equilibrium and (ii) unstable equilibrium? ( A cdot(A) ) and (B), respectively B. (A) and (C), respectively ( c cdot(B) ) and (D), respectively D. (B) and (C), respectively |
12 |

717 | A portion of a conductive wire is bent in the form of a semicircle of radius r as shown below in figure. At the centre of semicircle, the magnetic induction will be: A. zero B. inifinite C ( cdot frac{mu_{0}}{4 pi} cdot frac{pi i}{2 r} ) tesla D. ( frac{mu_{0}}{4 pi} cdot frac{pi i}{r} ) tesla |
12 |

718 | Two long, thin, parallel conductors, separated by a distance d carry currents ( i_{1} ) and ( i_{2} . ) The force acting on unit length of any one conductor is ( mathrm{F} ) : This question has multiple correct options A . F is attractive, if ( i_{1} ) and ( i_{2} ) flow in the same directions B. F is attractive, if ( i_{1} ) and ( i_{2} ) flow in the opposite directions c. F is the same for both conductors D. F is the different for the two conductors |
12 |

719 | If a galvanometer has full scale deflection current ( I_{G} ) and resistance ( G ) A shunt resistance ( R_{A} ) is used to convert it into an ammeter of range ( boldsymbol{I}_{mathbf{0}} ) and a resistance ( R_{V} ) is connected in series to convert it into a voltmeter of range ( V_{0} ) such that ( V_{0}=I_{0} G ) then ( R_{A} R_{V} ) and ( frac{R_{A}}{R_{V}} ) respectively are ( ^{mathbf{A}} cdot G^{2} ) and ( frac{I_{G}^{2}}{left(I_{0}-I_{G}right)^{2}} ) в. ( G^{2} ) and ( frac{I_{0}^{2}}{left(I_{0}-I_{G}right)^{2}} ) ( ^{mathrm{c}} cdot G^{2} ) and ( frac{I_{G}}{left(I_{0}-I_{G}right)^{2}} ) D. ( G^{2} ) and ( frac{I_{G}^{2}}{left(I_{0}+I_{G}right)^{2}} ) |
12 |

720 | A circular coil of radius ( 25 mathrm{cm} ), carries a current of ( 50 A ). If it has 35 turns, the flux density at the centre of the coil is ( W b / m^{2} ) A ( cdot pi times 10^{-3} ) В. ( 1.4 pi times 10^{-3} ) c. ( 14 pi times 10^{-3} ) D ( .2 pi times 10^{-3} ) |
12 |

721 | In an electric motor, wires carrying a current of ( 5 A ) are placed at right angles to a magnetic field of induction 0.8 T. If each wire has length of ( 20 mathrm{cm} ), then the force acting on each wire is : A ( .0 .2 N ) в. 0.4 N ( c cdot 0.6 N ) D. ( 0.8 N ) |
12 |

722 | No net force acts on a rectangular coil carrying a steady current when suspended freely in a uniform magnetic field. A. True B. False |
12 |

723 | Q Type your question through the side, along the diameter of a cross section of the coil. From out point of view, we are looking straight through the coil. We can see from the diagram that from out perspective, the coil carries a clockwise conventional current, and the straight wire carries a conventional current to the right. From our perspective, what is the direction of the force on the segment of straight wire in the coil, due to the magnetic field produced by the coil? A. Away from us B. Toward us ( c cdot u p ) D. Down E . Right |
12 |

724 | A circular coil of wire is connected to a battery of negligible internal resistance and has magnetic induction ( B ) at its centre. If the coil is unwound and rewound to have double the number of turns, and is connected to the same battery, then the magnetic induction at the center is : ( mathbf{A} cdot 2 B ) в. ( 4 B ) ( c . B ) D. ( 0.5 B ) |
12 |

725 | The oscillator frequency of a cyclotron is 10 MHz what should be the operating magnetic field accelerating proton? A . 0.156 न B. 0.256 T c. 0.356 न D. 0.656 T |
12 |

726 | A circular loop of area ( 1 mathrm{cm}^{2}, ) carrying a current of ( 10 mathrm{A}, ) is placed in a magnetic field of ( 0.1 mathrm{T} ) perpendicular to the plane of the loop. The torque on the loop due to the magnetic field is? A. zero B. ( 10^{-4} mathrm{N}-mathrm{m} ) ( c cdot 10^{-2} N-m ) D. 1N-m |
12 |

727 | A vertical straight conductor carries a current vertically upwards. A point P lies to the east of it at a small distance and another point ( Q ) lies to the west at the same distance the magnetic field at ( mathrm{P} ) is : A. greater than at ( Q ) B. same as at ( Q ) c. less than at ( Q ) D. greater or less than at Q depending upon the strength of current |
12 |

728 | A coil of radius ( pi ) meters, 100 turns carries a current of ( 3 A ). The magnetic induction at a point on its axis at a distance equal to ( sqrt{3} ) times its radius from its centre is : A. ( 7.2 times 10^{-6} mathrm{Wbm}^{-2} ) в. ( 7.4 times 10^{-6} mathrm{Wbm}^{-2} ) c. ( 7.5 times 10^{-6} mathrm{Wbm}^{-2} ) D. ( 7.83 times 10^{-6} mathrm{Wbm}^{-2} ) |
12 |

729 | The resistance of a galvanometer is ( 50 Omega ) and the current required to give full-scale deflection is ( 100 mu A ). In order to convert it into an ammeter, reading upto ( 10 A, ) it is necessary to put resistance of: ( mathbf{A} cdot 5 times 10^{-3} Omega ) in parallel B. ( 5 times 10^{-4} Omega ) in parallel ( mathrm{c} cdot 10^{5} Omega ) in series D. ( 99950 Omega ) in series |
12 |

730 | To send ( 10 % ) of the main current through a moving coil galvanometer of resistance 99 the shunt required is- A . 1 B. 9 ( c cdot 100 ) ( D cdot 19 ) |
12 |

731 | The magnetic field intensity due to a solenoid at end point ( boldsymbol{P} ) is : A. ( mu_{0} n I ) в. ( frac{mu_{0} n I}{2} ) c. ( frac{mu_{0} n I}{2}(cos theta-cos phi) ) D. ( frac{mu_{0} n I}{2}(sin theta-sin phi) ) |
12 |

732 | A solenoid with 600 turns per metre and a radius of ( 2 mathrm{cm}, ) carries a time varying current ( i(t)=left(6+4 t^{2}right) ) A. The electric field at a distance ( 4 mathrm{cm} ) from the axis of the solenoid at ( t=2 s ) will be ( (operatorname{in} mu vee mathrm{m} ) -1 to the nearest integer 4.48 3.60 ( c .68 ) 38 |
12 |

733 | A proton takes ( 10^{-12} ) seconds to complete one revolution in uniform magnetic field. The time taken in another orbit of double the radius in the same field is B . ( 2 times 10^{-12} ) seconds c. ( 4 times 10^{-12} ) seconds D. ( 10^{-12} ) seconds |
12 |

734 | What is a solenoid? Compare the magnetic field produced by a solenoid with the magnetic field of a bar magnet. Draw neat figures and name various components. |
12 |

735 | If the magnetic moment of the coil is ( 36 times 10^{-X} A m^{2} . ) Find ( X ? ) | 12 |

736 | Two identical circular wires ( P ) and ( Q ) each of radius ( boldsymbol{R} ) and carrying current ( I^{prime} ) are kept in perpendicular planes such that they have a common centre as shown in the figure. Find the magnitude and direction of the net magnetic field at the common centre of the two coils. |
12 |

737 | Two long straight parallel conductors carry steady current ( boldsymbol{I}_{1} ) and ( boldsymbol{I}_{2} ) separated by a distance d. If the currents are flowing in the same direction, show how the magnetic field set up in one produces an attractive force on the other. Obtain the expression for this force. Hence define one ampere |
12 |

738 | There will be no force between two wires carrying currents if currents are A. parallel to each other B. antiparallel to each other C. perpendicular to each other D. none of these. |
12 |

739 | What should be the magnitude and direction of electric field? A ( cdot 7 N c^{-1}, ) Vertically up ( perp ) to velocity B. ( 7 N c^{-1} ), horizontally and ( perp ) to velocity C . ( 14 N c^{-1} ), horizontally parallel to velocity D. none of these |
12 |

740 | In the given diagram, a line of force of a particular force field is shown. Out of the following options, it can never represent This question has multiple correct options |
12 |

741 | The magnetic field of an electromagnetic wave is given by ( : vec{B}= ) ( mathbf{1 . 6} times mathbf{1 0}^{-mathbf{6}} cos left(mathbf{2} times mathbf{1 0}^{mathbf{7}} boldsymbol{z}+mathbf{6} timesright. ) ( left.10^{15} tright)(2 hat{i}+hat{j}) frac{W b}{m^{2}} ) The associated electric field will be :- A ( cdot vec{E}=4.8 times 10^{2} cos left(2 times 10^{7} z+6 times 10^{15} tright)(hat{i}-2 hat{j}) frac{V}{m} ) B ( cdot vec{E}=4.8 times 10^{2} cos left(2 times 10^{7} z-6 times 10^{15} tright)(2 hat{i}+hat{j}) frac{V}{m} ) C・ ( vec{E}=4.8 times 10^{2} cos left(2 times 10^{7} z-6 times 10^{15} tright)(-2 hat{j}+hat{i}) frac{V}{m} ) D・ ( vec{E}=4.8 times 10^{2} cos left(2 times 10^{7} z+6 times 10^{15} tright)(-hat{i}+2 hat{j}) frac{V}{m} ) |
12 |

742 | A circular current carrying coil has a radius r. Find the distance from the centre of coil, on its axis, where the magnetic induction will be ( 1 / 8 ) th of its value at the centre of coil. |
12 |

743 | Magnetic moment of the spinning electron is in the direction of its spin angular momentum. B. Spin Velocity c. spin angular velocity D. angular acceleration |
12 |

744 | A pair of long, straight current-carrying wires and four marked points are shown in above figure. Find out the points at which net magnetic field is zero? A. Point 1 only B. Points 1 and 2 only c. Point 2 only D. Points 3 and 4 only E. Point 3 only |
12 |

745 | Define magnetization. Write its Sl unit and dimensions. | 12 |

746 | A closed iron ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet is: A. equal to g B. less thang c. more than g D. depends on the diameter of the ring and length of magnet |
12 |

747 | A toroid having average diameter ( 2.5 mathrm{m} ) number A turns ( 400, ) current ( =2 A ) and magnetic field has 10 T what will be induced magnetic field (in amp/m). A ( cdot frac{10^{5}}{4 pi} ) в. ( frac{10^{8}}{4 pi} ) c. ( frac{10^{8}}{2 pi} ) D. ( frac{10^{2}}{2 pi} ) |
12 |

748 | A current of i ampere is flowing through each ofthe bent wires as shown the magnitude and direction of magnetic field at 0 is A ( cdot frac{mu_{0} mathrm{i}}{4}left(frac{1}{mathrm{R}}+frac{2}{mathrm{R}^{prime}}right) ) В. ( frac{mu_{0} mathrm{i}}{4}left(frac{1}{mathrm{R}}+frac{3}{mathrm{R}^{prime}}right) ) c. ( frac{mu_{0} text { i }}{8}left(frac{1}{R}+frac{3}{2 R} primeright) ) D. ( frac{mu_{0} mathrm{i}}{8}left(frac{1}{mathrm{R}}+frac{3}{mathrm{R}^{prime}}right) ) |
12 |

749 | A particle of mass ( 2 times 10^{-5} k g ) moves horizontally between two horizontal plates of a charged parallel plate capacitor between which there is an electric field of ( 200 N C^{-1} ) acting upward. A magnetic induction of ( 2.0 T ) is applied at right angles to the electric field in a direction normal to both ( vec{B} ) and ( vec{v} ). If ( g ) is ( 9.8 m s^{-2} ) and the charge on the particle is ( 10^{-6} C, ) then find the velocity of charge particle so that it continues to move horizontally ( mathbf{A} cdot 2 m s^{-1} ) B. 20 ( m s^{-1} ) c. ( 0.2 m s^{-1} ) D. ( 100 mathrm{ms}^{-1} ) |
12 |

750 | A current I flows in a circular arc of radius R, which subtends an angle ( frac{pi}{6} ) radian at the center. The magnetic induction B at the center is ( A cdot frac{I_{l d}}{4 R_{D}} ) B. ( frac{I_{mu}}{2_{R}} ) c. ( frac{I mu_{0}}{24 R_{0}} ) D. ( frac{I mu_{0}}{12 R_{R}} ) |
12 |

751 | Two identical current carrying coaxial loops, carry current I in opposite sense. A simple amperian loop passes through both of them once. Calling the loop as ( C ) then which statement is correct? This question has multiple correct options ( mathbf{A} cdot oint bar{H} cdot overline{d l}=mp 2 mu_{0} I ) B. the value of ( oint bar{H} . bar{d} l ) is independent of sense of ( C ). C. there may be a point on C where B and ( d l ) are parallel. D. none of these |
12 |

752 | A charged particle begins to move from the origin in a region which has a uniform magnetic field in the ( x- ) direction and a uniform electric field in the ( y- ) direction. Its speed is ( v ) when it reaches the point ( (x, y, z) . ) Then, ( v ) will depend A. only on ( x ) B. only on ( y ) c. on both ( x ) and ( y ), but not ( z ) D. on ( x, y ) and ( z ) |
12 |

753 | A long solenoid of radius ( 2 mathrm{cm} ) has 100 turns/cm and carries a current of ( 5 A ). A coil of radius ( 1 mathrm{cm} ) having 100 turns and a total resistance of ( 20 Omega ) placed inside the solenoid co-axially. The coil is connected to galvanometer. If current in the solenoid is reversed in direction. Fine the charge flow through the galvanometer. A ( cdot 2 times 10^{-4} mathrm{C} ) B. ( 1 times 10^{-4} mathrm{C} ) c. ( 4 times 10^{-4} mathrm{c} ) D. ( 8 times 10^{-4} mathrm{C} ) |
12 |

754 | A particle of charge ( q ) and mass ( m ) is moving through a region of space at right angles to an electric field and a magnetic field, where the crossed magnetic and electric fields produce a zero net force on the charge. If the speed of the charge is doubled, which of the following changes will again produce a zero net force on the charge? This question has multiple correct options A ( cdot ) Reducing the Electric field to ( frac{1}{2} E ) B. Increasing the Electric field to ( 2 E ) c. Reducing the Magnetic field to ( frac{1}{2} B ) D. Increasing the Magnetic field to ( 2 B ) E. Doubling both the Magnetic and Electric Fields |
12 |

755 | A particle of charge ( 16 times 10^{-18} C ) moving with velocity ( 10 m / s ) along the X-axis enters a region where a magnetic field of induction ( B ) is along the ( Y ) -axis, and an electric field of magnitude ( 10 V m^{-1} ) is along the negative Z-axis. If the charged particle continues moving along the X-axis, the magnitude of ( B ) is : A ( cdot 1 W b / m^{2} ) B . ( 10^{5} mathrm{Wb} / mathrm{m}^{2} ) ( mathbf{c} cdot 10^{6} W b / m^{2} ) D. ( 10^{-3} W b / m^{2} ) |
12 |

756 | (i) Define ampere in terms of force between two current carrying conductors. (ii) What is an ideal transformer? |
12 |

757 | to detect small alternating currents. Which of the diagrams shows how a diode could be connected in order to make conversion? ( A ) B. ( c ) D. |
12 |

758 | A particle with a specific charge ( mathrm{S} ) is fired with a speed ( V ) towards a wall at a distance d, perpendicular to the wall. The minimum magnetic field that must exist in this region for the particle to not hit the wall is : A ( cdot frac{V}{s d} ) в. ( frac{2 V}{s d} ) c. ( frac{V}{2 s d} ) D. ( frac{V}{4 s d} ) |
12 |

759 | A charged particle moves through a magnetic field in a direction perpendicular to it. Then the A. Speed of the particle remains unchanged B. Direction of the particle remains unchanged c. Acceleration remains unchanged D. Velocity remains unchanged |
12 |

760 | (a) What is shunt? (b) State Ampere’s circuital law. Using the law, obtain an expression for the magnetic field well aside the solenoid of finite length. |
12 |

761 | The magnetic field around a currentcarrying coil lasts. A. For three hours B. As long as current flows thorugh it c. Till its half-life period D. Field is permanent |
12 |

762 | A proton of charge ( e ) and mass ( m_{p} ) moves in a circular path of radius ( r ) in a uniform magnetic field ( boldsymbol{B} ) The momentum of the proton can be described by the expression: ( mathbf{A} cdot e B r ) B. ( 2 e B r ) ( c cdot e B r^{2} ) D. ( e B r m_{p} ) E ( cdot 2 e B r m_{p} ) |
12 |

763 | The magnetic induction at the centre 0 of the arc due to current in portion ( boldsymbol{A B} ) will be A. zero в. ( frac{mu_{0} i}{r} ) c. ( frac{mu_{0} i}{2 r} ) D. ( frac{mu_{0}}{4 r_{0}} ) |
12 |

764 | Two parallel wires carrying currents ( boldsymbol{I}_{1} ) and ( I_{2} ) in opposite directions and separated by a distance ( d ) experience a A . Replusive force ( mu_{0} I_{1} I_{2} / 2 pi d ) B. Attractive force ( mu_{0} I_{1} I_{2} / 2 pi d ) C. Repulsive force ( mu_{0} I_{1} I_{2} / 2 pi d^{2} ) D. Attractive force ( mu_{0} I_{1} I_{2} / 2 pi d^{2} ) |
12 |

765 | A long straight wire carries a current 10 amp. An electron travels with a velocity ( mathbf{5 . 0} times mathbf{1 0}^{mathbf{6}} mathrm{m} / mathrm{sec} ) parallel to the wire 0.1 ( mathrm{m} ) away from it and in a direction opposite to the current. What force does the magnetic field of current exert on the electron? В. ( 0.8 times 10^{-16} N ) c. ( 1.6 times 10^{-17} N ) D. ( 1.6 times 10^{-16} N ) |
12 |

766 | In a long straight conductor carrying current, if the current is tripled and the distance of the point from the conductor is doubled, then the ratio of new magnetic induction to old magnetic induction is A .3: 2 B . 2: 3 ( c cdot 4: 9 ) 9: 4 |
12 |

767 | A circular coil of 20 turns and ( 10 mathrm{cm} ) radius is placed in a uniform magnetic field of ( 0.10 T ) normal to the plane of the coil. If the current in the coil is ( 5 A ) cross-sectional area is ( 10^{-5} m^{2} ) and coil is made up of copper wire having free electron density about ( 10^{29} m^{-3}, ) then the average force on each electron in the coil due to magnetic field is. ( mathbf{A} cdot 2.5 times 10^{25} N ) B . ( 5 times 10^{25} N ) C ( .4 times 10^{25} N ) D. ( 3 times 10^{25} N ) |
12 |

768 | Two parallel wires ( P ) and ( Q ) carry electric currents of ( 10 A ) and ( 2 A ) respectively in mutually opposite directions. The distance between the wires is ( 10 mathrm{cm} ). If the wire ( P ) is of infinite length and wire ( mathrm{Q} ) is ( 2 m ) long, then the force acting ( mathrm{Q} ) will be ( mathbf{A} cdot 4 times 10^{-5} N ) B. ( 8 times 10^{-5} N ) c. ( 6 times 10^{-5} N ) D. ( 14 times 10^{-5} N ) |
12 |

769 | A triangular loop of side ( l ) carries a current ( i . ) It is placed in a magnetic field B such that the plane of the loop is in the direction of ( B ). The torque on the loop is: A . ( i )Вᅵ В ( cdot i^{2} N l ) ( ^{mathrm{c}} cdot frac{sqrt{3}}{4} B i l^{2} ) D. infinity |
12 |

770 | A proton is travelling along the ( x ) direction with velocity ( 5 times 10^{6} m s^{-1} ) The magnitude of force experienced by the proton in a magnetic field ( B= ) ( (0.2 hat{i}+0.4 hat{k}) ) tesla is A. ( 3.2 times 10^{-13} N ) N В. ( 5.3 times 10^{-13} N ) c. ( 3.2 times 10^{13} N ) D. ( 6.3 times 10^{-13} ) 3 E ( .3 .5 times 10^{-12} N ) |
12 |

771 | Two long current carrying thin wires, both with current ( I ), are held by insulating threads of length ( L ) and are in equilibrium as shown in the figure, with threads making an angle ‘ ( boldsymbol{theta}^{prime} ) with the vertical. If wires have mass ( lambda ) per unit length then the value of ( I ) is ( :(g= ) gravitational acceleration) A ( cdot 2 sqrt{frac{pi g L}{mu_{0}} tan theta} ) B. ( 2 sin theta sqrt{frac{pi lambda g L}{mu_{0} cos theta}} ) c. ( sin theta sqrt{frac{pi lambda g L}{mu_{0} cos theta}} ) D. ( sqrt{frac{pi lambda g L}{mu_{0}}} tan theta ) |
12 |

772 | (a) An em wave is travelling in a medium with a velocity ( vec{v}=v hat{i} ). Draw a sketch showing the propagation of the em wave, indicating the direction of the oscillating electric and magnetic fields. (b) How are the magnitudes of the electric and magnetic fields related to the velocity of the em wave? |
12 |

773 | A charged particle having charge ( 10^{-6} C ) and mass of ( 10^{-10} k g ) is fired from the middle of the plate making an angle ( 30^{circ} ) with plane of the plate. Length of the plate is ( 0.17 mathrm{m} ) and it is sperated by 0.1 m.Electric field ( E=10^{-3} N / C ) is present between the plates.Just outside the plates magnetic field is present. Find the velocity of projection of charged particle and magnitude of the magnetic field perpendicular to the plane of the figure,if it has to graze the plate at ( C ) and ( A ) parallel to the surface of the plate .(Neglect gravity) |
12 |

774 | Assertion A cyclotron cannot accelerate neutrons. Reason Neutrons are neutral. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
12 |

775 | Find the magnitude and direction of the force vector applied to the loop if the vector ( vec{p}_{m} ) is parallel to the straight conductor. A ( cdot vec{F}=20 ) В . ( vec{F}=10 ) c. ( vec{F}=0 ) D. ( vec{F}=50 ) |
12 |

776 | The ratio of the diameters of wires of circular and straight parts is ( ^{A} cdot frac{1}{sqrt{2}} ) B. ( frac{2 sqrt{3}}{pi} ) ( c cdot frac{3 sqrt{3}}{2 pi} ) ( D cdot sqrt{2} ) |
12 |

777 | A very long straight wire carries a current ( I . ) At the instant when a charge ( +Q ) at point ( P ) has velocity ( vec{v}, ) as shown in figure, the force on charge is A. along OY B. opposite to OY c. along ox D. opposite to OX |
12 |

778 | A wire of length ( l ) carries a current ( i ) along x-axis. A magnetic field exits given by ( boldsymbol{B}=boldsymbol{B}_{0}(hat{boldsymbol{i}}+hat{boldsymbol{j}}+hat{boldsymbol{k}}) boldsymbol{T} ). The magnitude of the magnetic force acting on the wire is A ( . i l B_{0} ) в. ( sqrt{3} B_{0} ) il c. ( 2 i l B_{0} ) D. ( sqrt{2} B_{0} ) il |
12 |

779 | A current I ampere flows along an infinitely long straight thin walled hollow metallic cylinder of radius ( r . ) The magnetic field at any point inside the cylinder at a distance ( x ) from the axis of the cylinders is: A ( cdot frac{mu_{0} I}{4 pi r} ) В. ( frac{mu_{0} I}{2 pi r} ) c. ( frac{mu_{0} I}{2 pi x} ) D. zero |
12 |

780 | singly ionized helium(x), ionized deuteron(y), alpha(z) particles are projected into a uniform magnetic field ( mathbf{3} times mathbf{1 0}^{-4} ) Tesla with velocities ( 10^{5} boldsymbol{m} boldsymbol{s}^{-1} ) ( 0.4 times 10^{4} m s^{-1} ) and ( 2 times 10^{3} m s^{-1} ) respectively. The correct relation between the ratio of the angular momentum to the magnetic moment of the particles is : A. ( x>y=z ) в. ( x<y<z ) c. ( x<zx>y ) |
12 |

781 | Three long straight parallel wires ( X, Y, Z ) carry currents as shown; the resultant force on ( Y ) is A. Towards ( X ) B. Towards ( Z ) C. Perpendicular to the plane of the figure D. Zero |
12 |

782 | A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity then A. its velocity will increase B. its velocity will decrease c. it will turn towards left of its motion D. it will turn towards right of its motion |
12 |

783 | Protons move rectilinearly in the region of space where there are uniform mutually perpendicular electric and magnetic fields ( mathrm{E} ) and B.The trajectory of protons lies in the plane ( x z ) as shown in the figure and forms an angle ( theta ) with X-axis.Find the pitch of the helical trajectory along which the protons will move after the electric field is switched off. |
12 |

784 | A demagnetize a small ferromagnet, a current of ( 2 A ) is required to be passed in a solenoid of length ( 20 mathrm{cm} ) and number of turns 100. The coercivity of the magnet is: B. ( 1000 A m^{-1} ) c. ( 1250 A m^{-1} ) D. ( 3750 A m^{-1} ) |
12 |

785 | Figure shows a bar magnet and a long straight wire ( mathrm{W} ), carrying current into the plane of paper.Point ( P ) is the point of intersection of axis of magnet and the line of shortest distance between magnet and the wire. If ( P ) is the midpoint of the magnet, then which of the following statements is correct? A. magnet experiences a torque in clockwise direction B. magnet experiences a torque in anticlockwise direction C. magnet experiences a force, normal to the line of shortest distance D. magnet experiences a force along the line of shortest distance |
12 |

786 | An equilateral triangular loop is kept near to a current carrying long wire as shown in figure. Under the action of magnetic force alone, the loop A. must move along positive or negative X-axis B. must move in XY plane and not along X- of Y- axis c. does not move D. moves but which way we cannot predict |
12 |

787 | A long solenoid has 200 turns per cm and carries a current I. The magnetic field at its centre is ( 6.28 times ) ( 10^{-2} W b / m^{2} . ) Another long solenoid has 100 turns per ( mathrm{cm} ) and it carries a current i/3. The value of the magnetic field at its centre is A ( cdot 1.05 times 10^{-2} mathrm{Wb} / mathrm{m}^{2} ) B . ( 1.05 times 10^{-5} mathrm{Wb} / mathrm{m}^{2} ) c. ( 1.05 times 10^{-3} mathrm{Wb} / mathrm{m}^{2} ) D. ( 1.05 times 10^{-4} mathrm{Wb} / mathrm{m}^{2} ) |
12 |

788 | A positively charged particle, having charge ( q, ) is accelerated by a potential difference V. This particle moving along the ( x ) -axis enters a region where an electric field ( mathrm{E} ) exists. The direction of the electric field is along positive y-axis. The electric field exists in the region bounded by the line ( x=0 ) and ( x=a ) Beyond the line ( x=a ) (i.e., in the region ( x>a ) ), there exists a magnetic field of strength B, directed along the positive y-axis. Find the pitch of the helix formed after the particle enters the region ( x geq ) a. (Mass of the particle is ( m ) ) |
12 |

789 | A charged particle moving in a magnetic field experiences a resultant force ? A. In the direction opposite to the field B. In the direction of field c. In the direction perpendicular to both the field and its velocity D. None of the above |
12 |

790 | A conductor (shown in the figure) carrying constant current I is kept in the ( x ) -y plane in a uniform magnetic field ( vec{B} ). If ( F ) is the magnitude of the total magnetic force acting on the conductor, then the correct statement(s) is (are) This question has multiple correct options ( mathbf{A} cdot ) if ( vec{B} ) is along ( hat{z}, F propto(L+R) ) B. if ( vec{B} ) is along ( widehat{x}, F=0 ) C. if ( vec{B} ) is along ( hat{y}, F propto(L+R) ) D. if ( vec{B} ) is along ( hat{z}, F=0 ) |
12 |

791 | A closed curve encircles several conductors.The line integral ( int overrightarrow{boldsymbol{B}} cdot boldsymbol{d} overrightarrow{boldsymbol{l}} ) around this curve is ( 3.83 times 10^{-7} T-m ) What is the net current in the conductors? A . ( 0.1 A ) в. ( 0.2 A ) ( c .0 .3 A ) D. ( 0.4 A ) |
12 |

792 | An infinite number of electric charges each equal to 2 nano coulombs in magnitude are placed along ( x ) -axis at ( x=1 mathrm{cm}, x=3, quad x=9 mathrm{cm}, x=27 mathrm{cm} ) and so on. In these setup if the consecutive charges have oppsoite ( operatorname{sign}, ) then the electric potential at ( x=0 ) will be? |
12 |

793 | A neutron, a proton, an electron and an ( boldsymbol{alpha}- ) particle enter a region of uniform magnetic field with the same velocities. The magnetic field is perpendicular and directed into the plane of the paper. The tracks of the particles are labelled in the figure. The electron follows the track Q Magnetic field ( A . D ) B. ( B ) ( c cdot C ) ( mathbf{D} cdot A ) |
12 |

794 | A current of ( 10 mathrm{A} ) is flowing in a wire of length 1.5 m. When it is placed in a uniform magnetic field of 2 Tesla then a force of ( 15 mathrm{N} ) acts on it. The angle between the magnetic field and the direction of current flow will be : A ( .30^{circ} ) B . ( 45^{circ} ) ( c cdot 60^{circ} ) D. ( 90^{circ} ) |
12 |

795 | In a moving coil galvanometer a radial magnetic field is applied with concave magnetic poles, to have A) uniform magnetic field B) the plane of the coil parallel to field Choose the correct option among the following A. both A and B are true B. both A and B false c. A is true, B is false D. A is false, B is true |
12 |

796 | What current density is required to provide a pressure difference of 1 atm between any two points if ( B=2.2 T ) and ( l=35 m m ) A ( .1 .4 times 10^{3} mathrm{Am}^{-2} ) в. ( 7.2 times 10^{6} ) Ат ( ^{-} ) c. ( 1.3 times 10^{5} mathrm{Am}^{-2} ) D. ( 1.3 times 10^{6} mathrm{Am}^{-2} ) |
12 |

797 | A circular coil of closely wound N turns and radius r carries a current I. If the expressions of The magnetic field at its centre is ( frac{mu_{0} N i}{x R} . ) Find ( x ) |
12 |

798 | In the statement of Fleming’s left hand rule, force acting on the conductor is is represented by A. thumb B. fore finger c. middle finger D. none |
12 |

799 | Two long thin parallel conductors of the shape shown in figure above carry direct currents ( I_{1} ) and ( I_{2} ). The separation between the conductors is ( a ), the width of the right-hand conductor is equal to ( b ) With both conductors lying in one plane, the magnetic interaction force between them reduced to a unit of their length is given as ( F_{1}=frac{mu_{0} I_{1} I_{2}}{x pi b} ln frac{a+b}{a} ) Find ( boldsymbol{x} ) |
12 |

800 | Three wires are carrying same constant current ( i ) indifferent directions. Four loops enclosing the wires in different manners are shown in figure. The direction of ( d vec{l} ) is shown in figure. |
12 |

801 | A rectangular coil of a moving coil galvanometer contains 100 turns, each having area ( 15 c m^{2} . ) It is suspended in the radial magnetic field ( 0.03 mathrm{T} ). The twist constant of suspension fibre is ( 15 times 10^{-10} mathrm{N}-mathrm{m} / ) degree. Calculate the sensitivity of the moving coil galvanometer. |
12 |

802 | A proton, a deutron and an ( alpha ) particle accelerated through the same potential difference enter a region of uniform magnetic field, moving at right angles to ( B ). What is the ratio of their radii.? A .2: 1: 1 B. ( 1: sqrt{2}: sqrt{2} ) c. 1: 2: 1 D. 1: 1: 2 |
12 |

803 | An alpha-particle (charge 2e) moves along a circular path of radius ( 1 A ) with a uniform speed of ( 2 times 10^{6} m s^{-1} ) Calculate the magnetic field produced at the centre of the circular path |
12 |

804 | A positively charged particle (proton) is projected towards east.The magnetic field is towards south.The particle will be deflected towards A. North B. Down c. up D. west |
12 |

805 | If an electron is moving with velocity ( bar{v} ) produces a magnetic field ( bar{B} ), then A. the direction of field ( bar{B} ) will be same as the direction of velocity ( bar{v} ) B. the direction of field ( bar{B} ) will be opposite as the direction of velocity ( bar{v} ) C. the direction of field ( bar{B} ) will be perpendicular as the direction of velocity ( bar{v} ) D. the direction of field ( bar{B} ) does not depend upon the direction of velocity ( bar{v} ) |
12 |

806 | A conducting gas is in the form of a long cylinder. Current flows through the gas along the length of the cylinder. The current is distributed uniformly across the cross-section of the gas. Disregard thermal and electrostatic forces among the gas molecules. Due to the magnetic fields set up inside the gas and the forces which they exert on the moving ions, the gas will tend to A. expand B. contract c. expand and contract alternately D. none of the above |
12 |

807 | A positive charge ‘q’ of mass ‘m’ is moving along the +x axis. We wish to apply a uniform magnetic field ( B ) for time ( Delta t, ) so that the charge reverses its direction, crossing the y axis at a distance ( d ). Then: A ( cdot B=frac{m v}{q d} ) and ( Delta t=frac{pi d}{v} ) B. ( B=frac{m v}{2 q d} ) and ( Delta t=frac{pi d}{2 v} ) c. ( _{B}=frac{2 m v}{q d} ) and ( Delta t=frac{pi d}{2 v} ) D. ( B=frac{2 m v}{q d} ) and ( Delta t=frac{pi d}{v} ) |
12 |

808 | Assertion A charged particle moves along positive y-axis with constant velocity in uniform electric and magnetic fields.If magnetic field is acting along positive ( x ) -axis,then electric field should act along positive z-axis. Reason To keep the charged particle undeviated the relation ( vec{E}=vec{B} times vec{v} ) must hold good. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |

809 | A straight steel wire of length ( l ) has magnetic moment ( m ). If the wire is bent in the form of a semicircle, the new value of the magnetic dipole moment is A . ( m ) в. ( frac{m}{2} ) ( c cdot frac{m}{pi} ) D. ( frac{2 m}{pi} ) |
12 |

810 | Derive an expression for magnetic field strength at any point on the axis of a circular current carrying loop using Biot-Savart’s law. | 12 |

811 | Electrons at rest are accelerated by a potential of ( V ) volt. These electrons enter the region of space having a uniform, perpendicular magnetic induction field B. The radius of the path of the electrons inside the magnetic field is? A ( cdot sqrt{(m e V) / B e} ) B. ( sqrt{(2 m e V) / B e} ) ( mathbf{c} cdot sqrt{(m e V) / 2 B e} ) D. None of these |
12 |

812 | A galvanometer of resistance ( 50 Omega ) is connected to a battery of ( 3 V ) along with a resistance of ( 2950 Omega ) in series. A full- scale deflection of 30 divisions is obtained in the galvanometer. In order to reduce this deflection to 20 divisions, the resistance in series should be equal to A . ( 5050 Omega ) B. ( 5550 Omega ) c. ( 6050 Omega ) D. ( 4450 Omega ) |
12 |

813 | The value of magnetic field due to a small element of current carrying conductor at a distance r and lying on the plane perpendicular to the element of conductor is A. zero B. Maximum c. Inversely proportional to the current D. None of the above |
12 |

814 | In cyclotron the resonance condition is: A. the frequency of revolution of charged particle is equal to the frequency of A.C. voltage sources B. the frequency of revolution of charged particle is equal to the frequency of applied magnetic field C. the frequency of revolution of charged particle is equal to the frequency of rotation of earth D. the frequency of revolution of charged particle, frequency of A.C. source and frequency of magnetic field are equal |
12 |

815 | Two free parallel wires carrying currents in the opposite directions A. attract each other B. repel each other C. do not affect each other D. get rotated to be perpendicular to each other |
12 |

816 | A person who is moving parallel to the charge and at the same velocity as the charge will measure. A. A magnetic field and an electric field due to the moving charge. B. A magnetic field, but not an electric field due to the moving charge. C. An electric field, but not a magnetic field due to the moving charge. D. Neither an electric field nor a magnetic field due to the moving charge. E. A decrease in the amount of charge. |
12 |

817 | Assertion A wire bent into an irregular shape with the points ( P ) and ( Q ) fixed. If a current passed through the wire, then the area enclosed by the irregular portion of the wire increases. Reason Opposite currents carrying wires repel each other. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |

818 | A certain current on passing through a galvanometer produces a deflection of 100 divisions. When a shunt of one ohm is connected, the deflection reduces to 1 division. The galvanometer resistance is A. ( 100 Omega ) B. ( 99 Omega ) ( c .10 Omega ) D. ( 9.9 Omega ) |
12 |

819 | A circular loop of radius ( 1 mathrm{m} ) is kept in a magnetic field of strength 2 T directed perpendicular to the plane of loop. Resistance of the loop wire is ( 2 mathrm{m} . mathrm{A} ) conductor of length ( 2 mathrm{m} ) is sliding with a speed ( 1 mathrm{m} / mathrm{s} ) as shown in the figure. Find the instantaneous force acting on the rod [Assume that the rod has negligible resistance] ( A cdot 8 N ) B. 16 N ( c .24 mathrm{N} ) D. 32 |
12 |

820 | Two concentric coils of radius ( r ) are kept mutually perpendicular to each other. If current flowing through both the coils is ( I, ) then the resultant magnetic moment due to the two coils will be A . ( sqrt{2} I pi r^{2} ) В. ( sqrt{2} I r^{2} ) c. ( sqrt{2} I r ) D. ( 2 pi r^{2} ) |
12 |

821 | If a conducting rod ( A B ) placed in a uniform magnetic field pointing in positive z-direction (as shown in figure), moves parallel to y-axis, then end ( A ) of the rod will be A. Neutral B. Positively charged c. Negatively charged D. None of these |
12 |

822 | A helium nucleus makes a full rotation in a circle of radius ( 0.8 m ) in 2 sec. The value of the magnetic field induction ( boldsymbol{B} ) in tesla at the centre of circle will be A ( cdot 2 times 10^{-19} mu_{0} ) B . ( 10^{-19} / mu_{0} ) ( mathbf{c} cdot 10^{-19} varphi_{0} ) D. ( 2 times 10^{-20} / mu_{0} ) |
12 |

823 | In a current-carrying solenoid, the magnetic field direction is given by the right hand rule such that the A. Encircling fingers indicate the direction of electric current B. Encircling fingers indicate the direction of magnetic field C. Extended right thumb will point in the direction of the axial magnetic field D. Both (2) and (3) |
12 |

824 | Distance between two very long parallel wires is ( 0.2 m . ) Electric currents of ( 4 A ) in one wire and ( 6 A ) in the other wire are passing in the same direction. Find the position of a point on the perpendicular line joinig the two wires at which the magnetic field intensity is zero. |
12 |

825 | A solenoid is A . an electromagnet B. a temporary magnet C. a permanent magnet D. Both 1 and 2 |
12 |

826 | A loop of magnetic moment ( overrightarrow{boldsymbol{M}} ) is placed in the orientation of unstable equilibrium position in uniform magnetic field ( vec{B} ). The external work done in rotating it through an angle ( theta ) is A. ( -M B(1-cos theta) ) B. ( -M B(cos theta) ) ( mathbf{c} cdot M B cos theta ) D. ( M B(1-cos theta) ) |
12 |

827 | If a current carrying wire carries 10 A current then the magnetic field is X. Now the current in the wire increases to 100 A, them magnetic field in the wire becomes ( A cdot>x ) B. D. all December 27, 2019 Yashassvi Padigala ( B ) Share Save |
12 |

828 | If ( mu_{r} ) be the relative permeability and ( varepsilon_{r} ) be the relative dielectric constant of a medium, its refractive index is: ( ^{A} cdot frac{1}{sqrt{mu_{r} epsilon_{r}}} ) в. ( frac{1}{mu_{t} epsilon_{r}} ) c. ( sqrt{mu_{r} epsilon_{r}} ) D. ( mu_{r} epsilon_{r} ) |
12 |

829 | Derive the expression for magnetic field at a point on the axis of a circular current carrying loop. |
12 |

830 | State condition when magnitude of force on a current carrying conductor placed in a magnetic field is zero. A. When current in conductor is in the direction of magnetic field. B. When current in conductor is perpendicular to the direction of magnetic field. c. Always zero D. None of these |
12 |

831 | A moving coil galvanometer has a coil of area ( A ) and number of turns ( N . A ) magnetic field ( mathrm{B} ) is applied on it. The torque acting on it is given by ( boldsymbol{tau}=boldsymbol{k} boldsymbol{i} ) where i is current through the coil. If moment of inertia of the coil is I about the axis of rotation. A charge ( Q ) is passed almost instantaneously through coil If the maximum angular deflection in it ( mathbf{s} boldsymbol{theta}=boldsymbol{Q} sqrt{frac{boldsymbol{pi} boldsymbol{N} boldsymbol{A} boldsymbol{B}}{boldsymbol{x} boldsymbol{I} boldsymbol{i}_{0}}} . ) Find ( mathbf{x} ) |
12 |

832 | n the following diagram, which particle has highest ( e / m ) value? ( A ) B. ( c ) ( D ) |
12 |

833 | Determine the force acting between two parallel current carrying conductor wires. Write theoretical definition of ampere on this basis. |
12 |

834 | Which among the following is not an electronic component used in constructing a toroid? A. copper wires B. laminated iron c. ferrite core D. aluminium powder |
12 |

835 | Figure below shows two infinitely long and thin current carrying conductors ( boldsymbol{X} ) and ( Y ) kept in vacuum, parallel to each other, at a distance ( ^{prime} a ) How much force per unit length acts on |
12 |

836 | A proton with kinetic energy ( 8 e V ) is moving in a uniform magnetic field. The kinetic energy of a deuteron moving in the same path in the same magnetic field will be: A ( .2 e V ) B. ( 4 e V ) ( c .6 e V ) D. ( 8 e V ) |
12 |

837 | A wire is lying parallel to a square coil. Same current is flowing in same direction in both of them. The magnetic induction at any point P inside the coil will be : A . zero B. more than that produced by only coil c. less than that produced by only coil D. equal to that produced by only coil |
12 |

838 | The magnetic field at the origin due to a current element ( i . vec{d} l ) placed at a position ( vec{r} ) is This question has multiple correct options A ( frac{mu_{0} i}{4 pi} frac{overrightarrow{d l} times vec{r}}{r^{3}} ) В. ( frac{mu_{0} i}{4 pi} frac{vec{r} times vec{d} l}{r^{3}} ) ( ^{mathrm{C}}-frac{mu_{0} i}{4 pi} frac{vec{r} times vec{d} l}{r^{3}} ) D. ( -frac{mu_{0} i}{4 pi} frac{vec{d} l times vec{r}}{r^{3}} ) |
12 |

839 | The force between two parallel conductors, each of length ( 50 mathrm{cm} ) and distant ( 20 mathrm{cm} ) apart is ( 100 mathrm{N} ). If the current in one conductor is double that in another one then the values will respectively be(Given ( left.mu_{0}=4 pi times 10^{-7}right) ) B. ( 50 A ) and ( 100 A ) c. ( 10 A ) and ( 20 A ) D. ( 5 A ) and ( 10 A ) |
12 |

840 | Two current carrying wires are a distance ( a ) apart and experience a Force ( F ) between them. The wires are moved a distance ( 2 a ) apart. Which of the following is a possible value for the new force between the wires? A ( cdot frac{1}{4} F ) в. ( frac{1}{2} ) ( c . F ) D. ( 2 F ) E . ( 4 F ) |
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841 | Assertion Current in wire-1 is in the direction as shown in figure.The bottom wire is fixed.To keep the upper wire stationary current in it should be in opposite direction. Reason Under the above condition,equilibrium of upper wire is stable. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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842 | Figure shows a square loop of side ( 1 m ) and resistance 1Omega. The magnetic field on left side of line PQ has a magnitude ( B=1.0 T . ) The work done in pulling the loop out of the field uniformly in ( 1 s ) is 4. 1 В. ( 10 J ) begin{tabular}{l} ( .0 .1 .] ) \ hline end{tabular} 0.100 |
12 |

843 | An electron is projected at an angle ( theta ) with a uniform magnetic field. If the pitch of the helical path is equal to its radius, then the angle of projection is ( mathbf{A} cdot tan ^{-1} pi ) В ( cdot tan ^{-1} 2 pi ) ( mathbf{c} cdot cot ^{-1} pi ) D. ( cot ^{-1} 2 pi ) |
12 |

844 | The magnetic field at the centre of a circular loop of area ( A ) is ( B ). The magnetic moment of the loop is A ( cdot frac{B A^{2}}{mu_{0} pi} ) B. ( frac{B A sqrt{A}}{mu} ) ( ^{mathrm{c}} cdot frac{B A sqrt{A}}{mu_{0} pi} ) D. ( frac{2 B A sqrt{A}}{mu_{0} sqrt{pi}} ) |
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845 | A laser lamp is of ( 9 m W ) diameter ( = ) ( 2 m m . ) Then what is the amplitude of magnetic field associated with it? A ( .49 mu T ) B. ( 98 mu T ) c. ( 9.8 mu T ) D. ( 4.9 mu T ) |
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846 | What is the trajectory of the charged particle if the initial velocity of the particle is perpendicular to the direction of the magnetic field? |
12 |

847 | A short bar magnet placed with its axis at ( 30^{0} ) with a uniform external magnetic field of ( 0.35 T ) experiences a torque of magnitude equal to ( 4.5 times 10^{-2} mathrm{N} ) m. The magnitude of magnetic moment of the given magnet is A ( cdot 26 J T^{-1} ) B . ( 2.6 J T^{-1} ) c. ( 0.26 J T^{-1} ) D. ( 0.026 J T^{-1} ) |
12 |

848 | In a moving coil galvanometer, the deflection of the coil ( theta ) is related to the electric current ( i ) by the relation A. ( i propto tan theta ) В ( . i propto theta ) ( mathbf{c} cdot i propto theta^{2} ) ( D cdot i propto sqrt{theta} ) |
12 |

849 | If the value of ( theta ) increases then the magnetic moment value A. Increases B. Decreases c. Remains same D. Cannot be said |
12 |

850 | law gives the quantitative relationship between current and magnetic field due to the current carrying conductor. |
12 |

851 | Which line shows the path of gamma radiation in a magnetic field? ( A ) B. ( c ) 0.0 ( E ) |
12 |

852 | Mark the incorrect option. A. Ampere’s law states that flux ( B ) through any closed surface is ( mu_{0} ) times the current passing through the area bounded by closed sourface B. Gauss’s law for magnetic field in magnetostatics serves the same purpose as Gauss’s law for electric for electric field in electrostatics C. Gauss’s law for magnetic field states that the flux of ( B ) through any closed surface is always zero, whether or not there are currents within the surface D. All the above |
12 |

853 | A uniform electric field and a uniform magnetic field are produced pointing in the same direction. An electron is projected with its velocity pointed in the same direction.Then: A. the electron will turn to its right B. the electron will turn to its left c. the electron velocity will increase in magnitude D. the electron velocity will decrease in magnitude |
12 |

854 | Two circular coils are made of two identical wires of the same length. If the number of turns of the two coils are 4 and ( 2, ) then the ratio of magnetic inductions at the centres will be: ( A cdot 4: 1 ) B. 2: ( c cdot 1: 2 ) D. 1: |
12 |

855 | Figure shows three cases: in all cases the circular part has radius ( r ) and straight ones are infinitely long. For the same current the ratio of field ( B ) at center ( P ) in the three cases ( B_{1}: B_{2}: B_{3} ) is : ( ^{mathrm{A}} cdotleft(-frac{pi}{2}right):left(frac{pi}{2}right):left(frac{3 pi}{4}-frac{1}{2}right) ) ( ^{mathrm{B}} cdotleft(-frac{pi}{2}+1right):left(frac{pi}{2}+1right):left(frac{3 pi}{4}+frac{1}{2}right) ) ( ^{c} cdotleft(-frac{pi}{2}right):left(frac{pi}{2}right):left(frac{3 pi}{4}right) ) ( left(-frac{pi}{2}-1right):left(frac{pi}{2}-frac{1}{4}right):left(frac{3 pi}{4}+frac{1}{2}right) ) |
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856 | A galvanometer gives full scale deflection of 1 volt when acting like a voltmeter when connected in series with ( 2 k Omega ) resistance. The same galvanometer gives ( 500 mathrm{mA} ). Full scale deflection when acting like a ammeter when connected with shunt resistance of value ( 0.2 Omega ) in parallel. Find out the resistance of galvanometer |
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857 | State whether the given statement is True or False.
The magnetic lines of force are always parallel to a straight conductor carrying an electric current. |
12 |

858 | When a solenoid is activated, the force that moves the plunger is A. an electromagnetic field B. a permanent magnetic field c. varying voltage D. a steady current |
12 |

859 | The sensitiveness of a moving coil galvanometer can be increased by decreasing A. the number of turns in the coil B. the area of coil c. the magnetic field D. the couple per unit twist of the suspension |
12 |

860 | Three long straight wires ( A, B ) and ( C ) are carrying currents as shown in figure. Then the resultant force on B is directed A. perpendicular to the plane of the paper and outward B. perpendicular to the plane of the paper and inward c. towards ( A ) D. towards |
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861 | A conductor of length 2 m carrying current ( 2 mathrm{A} ) is held parallel to an infinitely long conductor carrying current of ( 12 mathrm{A} ) at a distance of ( 100 mathrm{mm} ) the force j on a small conductor is: A ( cdot 8.6 times 10^{-5} N ) B. ( 6.6 times 10^{-5} N ) c. ( 7.6 times 10^{-5} N ) D. 9.6 ( times 10^{-5} N ) |
12 |

862 | In Thomsons method, a beam of electrons accelerated through a p.d. of ( 285 V, ) passes undeflected through perpendicular electric and magnetic fields of intensities ( 10^{5} V / m ) and ( 10^{-2} W b / m^{2} ) respectively. Then the value of e/m of electron is: A ( cdot 1.75 times 10^{11} C / k g ) В. ( 1.66 times 10^{11} C / k g ) c. ( 1.84 times 10^{11} C / k g ) D. ( 1.89 times 10^{11} C / k g ) |
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863 | The magnetic field of a solenoid can be increased by A. adding more loops per metre B. increasing the current c. putting an iron core inside the coil to make an electromagnet D. All of the above |
12 |

864 | A long straight wire is carrying current in ( +z ) direction. The ( x ) -y pkane contains a closed circular loop carrying current ( I_{2} ) and not encircling the straight wire. The force on the loop will be. B . ( mu_{0} I_{1} I_{2} / 4 pi ) c. zero D. Depends on the distance of the circle of the loop from the wire |
12 |

865 | A current carrying loop is placed in a uniform magnetic field in four different orientations I, II, III and IV as shown in figure. Arrange them in decreasing order of potential energy. ( A cdot|>|||>||>mid V ) B. |> || > ||| > IV c. ।>IV> || > || |
12 |

866 | Immediately below the current carrying wire a stream of electrons are projected parallel to the wire as shown. They will be A. accelerated to the right B. retarded D. deflected downwardd |
12 |

867 | The sensitivity of moving coil galvanometer can be increased by increasing A. Number of turns of the coil B. Magnetic field c. Area of the coil D. Couple per unit twist of suspension |
12 |

868 | A potential difference of ( 600 mathrm{V} ) is applied across the plates of a parallel plate capacitor placed in a magnetic field. The separation between the plates is ( 3 mathrm{mm} . ) An electron projected vertically upward, parallel to the plates, with a velocity of ( 2 times 10^{6} m s^{-1} ) moves undeflected between the plates. Find the magnitude and direction of the magnetic field in the region between the capacitor plates. Find the magnitude and direction of the magnetic field in the region between the capacitor plates. Given the Charge of the electron ( =-1.6 times 10^{-19} C ) |
12 |

869 | An arbitrary shaped closed coil is made of a wire of length L and a current ampere is flowing in it. If the plane of the coil is perpendicular to magnitude field ( vec{B}, ) the force on the coil is? A. zero B . IBL c. 2 IBL D. ( frac{1}{2}^{18 L} ) |
12 |

870 | An electron doesn’t suffer any deflection while passing through a region of uniform magnetic field What is the direction of magnetic field? |
12 |

871 | A uniform magnetic field B is set up along the positive ( x ) -axis. A particle of charge ‘q’ and mass ‘m’ moving with a velocity v enters the field at the origin in ( X-Y ) plane such that it has velocity components both along and perpendicular to the magnetic field B. Trace, giving reason, the trajectory followed by the particle. Find out the expression for the distance moved by the particle along the magnetic field in one rotation |
12 |

872 | Express ( 90 mathrm{cm} ) as a percent of ( 4.5 mathrm{m} ) | 12 |

873 | In an experiment electrons are accelerated,from rest, by applying a voltage of ( 500 V . ) Calculate the radius of the path if a magnetic field ( 100 m T ) is then applied.[Charge of the electron = ( 1.6 times 10^{-19} C ) Mass of the electron ( = ) ( 9.1 times 10^{-31} k g ) A. ( 7.5 times 10^{-4} m ) В. ( 7.5 times 10^{-3} m ) ( c .7 .5 m ) D. ( 7.5 times 10^{-2} mathrm{m} ) |
12 |

874 | Two wires carrying current in opposite directions are placed a distance ( a ) apart Which of the following will cause the greatest increase in the magnitude of the force between the wires? A. Doubling the current in one wire. B. Doubling the current in both wires. c. Doubling the distance between the wires to ( 2 a ) D. Decreasing the distance between the wires to E. Running the currents in the same direction |
12 |

875 | Answer the following questions: (i) Obtain the expression for the cyclotron frequency. (ii) A deuteron and a proton are accelerated by the cyclotron. Can both be accelerated with the same oscillator frequency? Given reason to justify your answer |
12 |

876 | A non-planar closed loop of arbitrary shape carrying a current ( I ) is placed in uniform magnetic field.The force acting on the loop A. is zero only for one orientation of loop in magnetic field B. is zero for two symmetrically located positions of loop in magnetic field c. is zero for all orientations D. is never zero |
12 |

877 | Which of the following observations are true for Hans Oersteds experiment? a. When current passes through the wire the compass needle comes to restt in a direction along the Earths magnetic field. b. When placed just above the wire, North Pole of the compass needle deflects towards the east when current is passes from A to B. c. When placed just below the wire, North Pole of the compass needle deflects towards the east when current is passes from B to A i.e. on reversing the direction of current ( A cdot ) a and ( c ) B. a and b ( c . ) b and ( c ) D. All of the above |
12 |

878 | A 2 MeV proton is moving perpendicular to uniform magnetic field of 2.5 T. The magnetic force on the proton. A ( cdot 8 times 10^{-12} mathrm{N} ) B . ( 4 times 10^{-12} mathrm{N} ) c. ( 16 times 10^{-12} mathrm{N} ) D. ( 2 times 10^{-12} mathrm{N} ) |
12 |

879 | toppr Q Type your question insulted from each other. The entire loop lies in the plane (of the paper). A uniform magnetic filed ( vec{B} ) point into the plane of the paper. At ( t=0 ), the loop starts rotating about the common diameter as axis with a constant angular velocity ( omega ) in the magnetic field. Which of the following option is/are correct? A. The rate of change of the flux is maximum when the plane of the loops is perpendicular to plane of the paper B. The net emf induced due to both the loops is proportional to cos ( omega t ) C. The emf induced in the loop is proportional to the sun of the areas of the two loops. D. non of the above. |
12 |

880 | A toroid has a core (non -ferromagnetic) of inner radius ( 25 mathrm{cm} ) and outer radius ( 26 mathrm{cm}, ) around which 3500 turns of a wire are wound. If the current in the wire is ( 11 A, ) what is the magnetic field (a) outside the toroid, (b) inside the core of the toroid, and (c) in the empty space surrounded by the toroid. |
12 |

881 | In an orbit of radius ( 0.4 A^{0} ) an electron revolves with a frequency of ( 6.25 times 10^{15} ) Hz. The magnetic induction field at its centre is (in Tesla): A . ( 4 pi ) в. ( 2 pi ) ( c cdot 4 ) ( D cdot 2 ) |
12 |

882 | Relation between magnetic moment and angular velocity is ( A . M propto omega ) B. ( M propto omega^{2} ) c. ( M propto sqrt{omega} ) D. None of these |
12 |

883 | A charge ‘q’ moves in a region where electric field and magnetic field both exist, then force on it is : – ( mathbf{A} cdot q(vec{V} times vec{B}) ) B ( cdot q vec{E}+q(vec{V} times vec{B}) ) ( mathbf{c} cdot q vec{E}+q(vec{B} times vec{V}) ) ( mathbf{D} cdot q vec{B}+q(vec{E} times vec{V}) ) |
12 |

884 | A loosely wound helix made of stiff wire is mounted vertically with the lower end just touching a dish of mercury when a current from the battery is started in the coil through the mercury A. the wire oscillates B. the wire continues making contact c. the wire breaks contact just when the current is passed D. the mercury will expand by heating due to passage of current |
12 |

885 | A current is passed through a straight wire. The magnetic field established around it has its lines of forces: A . circular B. parabolic c. elliptical D. no fixed shape |
12 |

886 | The force on a charged particle moving through a magnetic field is maximum when A. Moving with the field B. Moving against the field C. Moving at a ( 45^{circ} ) angle to the field D. Moving at a ( 90^{circ} ) angle to the field E. The particle will not be affected |
12 |

887 | A circular coil of 100 turns has an effective radius of ( 0.05 m ) and carries a current of ( 0.1 A ). How much work is required to turn it in an external magnetic field of ( 1.5 W b / m^{2} ) through ( 180^{circ} ) about its axis perpendicular to the magnetic field? The plane of the coil is initially perpendicular to the magnetic field : A . 0.456 .5 в. ( 2.65 J ) c. ( 0.2355 J ) D. 3.95J |
12 |

888 | (a) Write using Biot – Savart Law, the expression for magnetic field ( vec{B} ) due to an element ( overrightarrow{d l} ) carrying current ( I ) at a distance ( vec{r} ) from it in a vector form. Hence derive the expression for the magnetic field due to a current carrying loop of radius ( R ) at a point ( P ) distant ( x ) from its centre along the axis of the loop. (b) Explain how Biot – Savart law enables one to express the Ampere’s circuital law in the integral form, viz., [ overrightarrow{boldsymbol{B}} cdot overrightarrow{boldsymbol{d}} boldsymbol{l}=boldsymbol{mu}_{boldsymbol{o}} boldsymbol{I} ] where ( I ) is the total current passing through the surface. |
12 |

889 | A bar magnet is hung by a thin cotton thread in a uniform horizontal magnetic field and is in equilibrium state. the energy required to rotate it by ( 60^{circ} ) is ( W ) Now the torque required to keep the magnet in this new position is. A. ( frac{2 W}{sqrt{3}} ) B. ( frac{W}{sqrt{3}} ) c. ( sqrt{3} W ) D. ( frac{sqrt{3}}{2} W ) |
12 |

890 | Find the circulation of the vector ( vec{B} ) around the square path ( Gamma ) with side ( l ) located as shown in the figure above. ( mathbf{A} cdot oint vec{B} d r=2(1-mu) B l sin theta ) в. ( oint vec{B} d r=(1+mu) B l sin theta ) c. ( oint vec{B} d r=2(1-+mu) B l sin theta ) D. ( oint vec{B} d r=(1-mu) B l sin theta ) |
12 |

891 | How toroid is different from solenoid. | 12 |

892 | Ratio of the currents ( I_{1} ) and ( I_{2} ) flowing through the circular and straight parts is A ( cdot frac{sqrt{3}}{2 pi} ) B. ( frac{2 sqrt{3}}{5} ) ( c cdot frac{3 sqrt{3}}{2 pi} ) D. ( frac{3 sqrt{3}}{2 sqrt{2} pi} ) |
12 |

893 | A current carrying loop of radius ( 2 mathrm{cm} ) has ( 4 A ) current flowing in an anti- clockwise direction. The plane of the loop makes an angle of ( theta ) with the direction of the magnetic field which is in an upward direction. the value of the magnetic field is 0.7 Tesla.if potential energy of loop in magnetic field is ( approx ) ( 0.01 J, ) then value of ( theta ) is: A ( cdot 45^{circ} ) B . ( 60^{circ} ) ( c .30^{circ} ) D. None of these |
12 |

894 | Following is square shape loop, whose one arm ( B C ) produces magnetic field ( B ) at the center of coil. The resultant magnetic field due to all the arms will be: ( A cdot 4 B ) в. ( B / 2 ) ( c . B ) D. ( 2 B ) |
12 |

895 | Find the resultant magnetic moment when ( boldsymbol{theta}=mathbf{2 4 0}^{circ} ) ( mathbf{A} cdot M / 4 pi ) в. ( 2 M / pi ) c. ( 3 M / pi ) D. ( 3 sqrt{3} M / 4 pi ) |
12 |

896 | In the above question, the tension in the two wires, if the direction of the current is reversed, keeping the magnetic field the same is A . 1.0 в. 2.0N c. 3.0 D. 4.0N |
12 |

897 | In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential V and then made to describe semicircular paths of radius R using a magnetic field B. If ( mathrm{V} ) and ( mathrm{B} ) are kept constant, the ratio ( ( left.frac{text { Charge on the ion }}{text { Mass of the ion }}right) ) wil be proportional to A ( -frac{1}{R} ) в. ( frac{1}{R^{2}} ) ( c cdot R^{2} ) D. |
12 |

898 | ( 0.8 mathrm{J} ) work is done in rotating a magnet by ( 60^{circ}, ) placed parallel to a uniform magnetic field. How much work is done in rotating it ( 30^{circ} ) further? A ( cdot 0.8 times 10^{7} ) erg B. ( 0.8 e r g ) ( c .8 J ) D. 0.45 |
12 |

899 | A long wire is bent into the shape PQRST as shown in the following Figure with ( Q R S ) being a semicircle with centre ( O ) and radius ( r ) metre. ( A ) current of ( I ) ampere flows through it in the direction ( boldsymbol{P} rightarrow boldsymbol{Q} rightarrow boldsymbol{R} rightarrow boldsymbol{S} rightarrow boldsymbol{T} ) Then, the magnetic induction at the point ( O ) of the figure in vacuum is ( ^{mathbf{A}} cdot_{mu_{0} i}left[frac{1}{2 pi r}+frac{1}{4 r}right] ) В ( cdot mu_{0} ileft[frac{1}{2 pi r}-frac{1}{4 r}right] ) c. ( frac{mu_{0} i}{4 r} ) D. ( frac{mu_{0} i}{pi r} ) |
12 |

900 | If ( epsilon_{0} ) and ( mu_{0} ) are, respectively, the electric permittivity and magnetic permeability of free space, ( epsilon ) and ( mu ) are the corresponding quantities in a medium, the index of refraction of the medium in terms of the above parameters is A ( cdot sqrt{frac{mu epsilon}{mu_{0} epsilon_{0}}} ) в. ( sqrt{frac{epsilon}{mu_{0} epsilon_{0}}} ) c. ( sqrt{frac{2}{mu_{0} epsilon_{0}}} ) D. ( sqrt{frac{1}{mu_{0} epsilon_{0}}} ) |
12 |

901 | A wire bent as shown in Figure carries a current ( I ). Find the magnetic field at ( P: ) A ( frac{mu_{0}}{4} ) в. ( frac{3 mu_{0}}{2 R} ) c. ( frac{7 mu_{0} I}{8 R} ) D. ( frac{mu_{0}}{8_{D}} ) |
12 |

902 | A wire carrying current ( i ) has the configuration shown in the figure. Two semi-infinite straight sections, each tangent to the same circle, are connected by a circular arc, of angle ( boldsymbol{theta} ) along the circumference of the circle, with all sections lying in the same plane. What must ( theta ) (in rad) be in order for ( B ) to be zero at the center of the circle? |
12 |

903 | A galvanometer is shunted by ( frac{1}{r} ) of its resistance. Find the fraction of total current passing through the galvanometer. |
12 |

904 | For an ideal toroid, in which turns are closely spaced, the external magnetic field is A. Very high B. Infinity c. zero D. one |
12 |

905 | The figure above shows which magnetic instrument? A. solenoid B. power transformer c. toroid D. None of these |
12 |

906 | A circular coil a carrying current produces a magnetic field ( B_{0} ) at its centre. This coil is made itself to 10 turns and the same current is set up in it. The magnetic field ( B ) at its centre would be A. ( B=B_{0} ) В. ( B=10 B_{0} ) c. ( B=50 B_{0} ) D. ( B=100 B_{0} ) |
12 |

907 | A strong magnetic field is applied on a stationary electron. Then the electron: A. moves in the direction of the field B. remains stationary c. starts spinning D. moves opposite to the direction of the field |
12 |

908 | A rectangular loop carrying a current is situated near a long straight wire such that the wire is parallel to the one of the sides of the loop and is in the plane of the loop. If a steady current lis established in wire as shown in the figure, the loop will A. Rotate about an axis parallel to the wire B. Move away from the wire or towards right c. Move towards the wire D. Remain stationary |
12 |

909 | When will the couple acting on the coil be (i) maximum (ii) minimum? A. (i) When plane of coil is normal to the magnetic field, (ii) When plane of coil is normal to the magnetic field B. (i) When plane of coil is parallel to the magnetic field (ii) When plane of coil is parallel to the magnetic field. C. (i) When plane of coil is parallel to the magnetic field, (ii) When plane of coil is normal to the magnetic field D. None of the above |
12 |

910 | The diagram above shows a positively charged particle moving toward the right and about to enter a magnetic field whose direction is shown by the blue arrows. What is the direction of the force on the positively charged particle (from our point of view at the instant it enters the magnetic field? A. Right B. Left c. up D. Toward us E. Away from us |
12 |

911 | A particle of charge ( boldsymbol{q}=mathbf{1 6} times mathbf{1 0}^{-18} mathbf{C} ) moving with ( 10 m s^{-1} ) along ( x- ) axis enter a magnetic field of induction ( boldsymbol{B} ) along the ( y- ) axis and an electric field ( 10^{4} mathrm{Vm}^{-1} ) along negative ( z- ) direction. If the particle continues to move along ( x- ) axis then the strength of magnetic field is ( mathbf{A} cdot 10^{5} mathrm{Wbm}^{-2} ) B. ( 10^{16} mathrm{wbm}^{-2} ) c. ( 10^{-3} mathrm{wbm}^{-2} ) D. ( 10^{3} mathrm{wbm}^{-2} ) |
12 |

912 | Find the magnetic moment vector of the loop A ( cdot(0.1 hat{i}+0.05 hat{j}-0.05 hat{k}) A m^{2} ) B . ( (0.1 hat{i}+0.05 hat{j}+0.05 hat{k}) A m^{2} ) C ( cdot(0.1 hat{i}-0.05 hat{j}+0.05 hat{k}) A m^{2} ) D. ( (0.1 hat{i}-0.05 hat{j}-0.05 hat{k}) A m^{2} ) |
12 |

913 | The magnetic field at the center of the circular loop as shown in figure, when a single wire is bent to form a circular loop and also extends to form straight sections, is : ( ^{text {A }} cdot frac{mu_{0} I}{2 R} odot ) ( ^{text {В }} cdot frac{mu_{0} I}{2 R}left(1+frac{1}{pi sqrt{2}}right) odot ) c. ( frac{mu_{0} I}{2 R}left(1-frac{1}{pi sqrt{2}}right) otimes ) ( stackrel{mathrm{D}}{frac{mu_{0}}{R}}left(1-frac{1}{pi sqrt{2}}right) otimes ) |
12 |

914 | toppr Q Type your question. point of time direction of magnetic field is reversed then which of the following path is/are possible for the charged particle. Here ( boldsymbol{v}_{0} ) and ( boldsymbol{B}_{0} ) are positive constants. ( A ) в. ( c ) D. None of the abç |
12 |

915 | A spring of spring constant ( boldsymbol{K} ) is fixed at one end has a small block of mass ( m ) and charge ( q ) is attached at the other end. The block rests over a smooth horizontal surface. A uniform and constant magnetic field ( B ) exists normal to the plane of the paper as shown in the figure. An electric field ( overrightarrow{boldsymbol{E}}=boldsymbol{E}_{0} hat{boldsymbol{i}}left(boldsymbol{E}_{0} text { is a positive constant }right) ) is switched on at ( t=0 ) sec. The block moves on the horizontal surface without ever lifting off the surface. Where is the normal reaction acting on the block maximum? |
12 |

916 | Derive the formula ( frac{boldsymbol{F}}{boldsymbol{l}}=frac{boldsymbol{mu}_{o}}{mathbf{2} boldsymbol{pi}} cdot frac{boldsymbol{i}_{1} boldsymbol{i}_{2}}{boldsymbol{r}} ) as the force per unit length between two parallel wires each of length I meter, carrying currents ( i_{1} ) and ( i_{2} ) amperes and separated by a distance r meters. Define ampere with the help of this formula. |
12 |

917 | An electron moves at right angle to a magnetic field of ( 1.5 times 10^{-2} T ) with a speed of ( 6 times 10^{7} m / s . ) If the specific charge on the electron is ( 1.7 times ) ( 10^{11} C / k g, ) the radius of the circular path will be A . ( 2.9 mathrm{cm} ) B. 3.9 ( mathrm{cm} ) c. ( 2.35 mathrm{cm} ) D. ( 2 mathrm{cm} ) |
12 |

918 | ( vec{B}=-(0.31 T) hat{i} ) what will be the angle between ( hat{text { iand }} ) B. (length of wire is 0.01m) A . в. ( (0.01085 N) hat{k} ) c. ( (-0.01085 N) hat{k} ) D. ( (0.01085 N) hat{i} ) |
12 |

919 | What reading would you expect of a square-wave current, switching rapidly between ( +0.5 A ) and ( -0.5 A, ) when passed through an ac ammeter? ( mathbf{A} cdot mathbf{0} ) B. ( 0.5 A ) c. 0.25 D. ( 1.0 A ) |
12 |

920 | A long straight wire is carrying current ( l_{1}=frac{2}{5} A ) along ( +z ) direction. The ( x-y ) plane contains a closed circular loop carrying and not encircling the straight wire, then the force (in newton) on the loop will be ? (radius of the circular loop ( left.boldsymbol{R}=frac{3}{4} boldsymbol{m}right) ) A . 0 B. 2 ( c cdot-1 ) D. |
12 |

921 | Electric current is passed through a straight conductor passing through the center of a piece of cardboard.Some iron fillings are sprinkled on the cardboard and tapped.The iron fillings around the conductor A. Settle as parallel lines B. Settle as circles c. settle at one point D. Do not acquire any regular pattern |
12 |

922 | Unit of magnetic induction ( B ) is : A ( frac{N}{A m} ) в. ( frac{N A}{m} ) c. ( frac{N m}{A} ) D. ( frac{N}{A} ) |
12 |

923 | A range of galavanometer is ‘ ( V ) ‘, when ( 50 Omega ) resistance is connected in series. Its range gets doubled when ( 500 Omega ) resistance is connected in series. Galvanometer resistance is ( mathbf{A} cdot 100 Omega ) в. 200Omega c. ( 300 Omega ) D. ( 400 Omega ) |
12 |

924 | The magnetic field due to a current carrying circular loop of radius ( 3 mathrm{cm} ) at a point on the axis at a distance of ( 4 mathrm{cm} ) from the centre is ( 54 mu ) T. What will be its value at the centre of the loop? A. 125 и ( T ) в. ( 150 mu T ) c. ( 250 mu T ) D. ( 75 mu T ) |
12 |

925 | The segment ( A B ) of wire carrying current ( I_{1} ) is placed perpendicular to a long straight wire carrying current ( boldsymbol{I}_{2} ) as shown in figure.The magnitude of force experienced by the straight wire ( A B ) is A ( cdot frac{mu_{o} I_{1} I_{2}}{2 pi} 1 n 3 ) В. ( frac{mu_{o} I_{1} I_{2}}{2 pi} 1 n 2 ) c. ( frac{2 mu_{o} I_{1} I_{2}}{2 pi} ) D. ( frac{mu_{o} I_{1} I_{2}}{2 pi} ) |
12 |

926 | Compare Biot-Savart law with Coulomb’s law for electrostatic field. | 12 |

927 | Seema’s uncle was advised by his doctor to have an MRI (Magnetic Resonance Imaging) scan of his brain. Her uncle felt it to be expensive and wanted to postpone it. When Seema learnt about this, she took the help of her family and also approached the doctor, who also offered a substantial discount. She then convinced her uncle to undergo the test to enable the doctor to know the condition of his brain. The information thus obtained greatly helped the doctor to treat him properly. Based on the above paragraph, answer the question. Assuming that MRI test was performed using a magnetic field of ( 0.1 mathrm{T} ), find the minimum and maximum values of the force that the magnetic field could exert on a proton moving with a speed of ( mathbf{1 0}^{4} mathbf{m} / mathbf{s} ) Given charge of proton ( =1.6 times 10^{-19} mathrm{C} ) |
12 |

928 | There are two wires ( a b ) and ( c d ) in a vertical plane as shown in figure.Direction of current in wire ( a b ) is rightwards.Choose the correct options This question has multiple correct options A. If wire ( a b ) is fixed then wie ( c d ) can be kept in equilibrium by the current in ( c d ) in leftward direction B. Equilibrium of wie ( c d ) will be stable equilibrium C. If wire ( c d ) is fixed,then wire ( a b ) can be kept in equilibrium by flowing current in ( c d ) in rightward direction D. Equilibrium of wire ( a b ) will be stable equilibrium |
12 |

929 | A moving coil galvanometer has a coil of area ( A ) and number of turns ( N . A ) magnetic field B is applied on it. The torque acting on it is given by ( boldsymbol{tau}=boldsymbol{k} boldsymbol{i} ) where i is current through the coil. If moment of inertia of the coil is I about the axis of rotation. If the value of torsional constant if current ( i_{0} ) produces angular deflection of ( pi / 2 ) rad is ( C=frac{x N B A i_{0}}{pi} . ) Find ( x ) |
12 |

930 | The correct Biot-Savart law in vector form is? ( ^{mathbf{A}} cdot d vec{B}=frac{mu_{0}}{4 pi} frac{I(d vec{l} times vec{r})}{r^{2}} ) в. ( d vec{B}=frac{mu_{0}}{4 pi} frac{I(d vec{l} times vec{r})}{r^{3}} ) ( ^{mathrm{c}} cdot d vec{B}=frac{mu_{0}}{4 pi} frac{I d bar{l}}{r^{2}} ) D ( cdot d vec{B}=frac{mu_{0}}{4 pi} cdot frac{I d vec{l}}{r^{3}} ) |
12 |

931 | A long straight wire of radius R carries current ( i . ) The magnetic field inside the wire at distance ( r ) from its centre is expresses as: ( mathbf{A} cdotleft(frac{mu_{0} i}{pi R^{2}}right) cdot r ) в. ( left(frac{2 mu_{0} i}{pi R^{2}}right) cdot pi ) ( ^{text {c. }}left(frac{mu_{0} i}{2 pi R^{2}}right) cdot r ) D. ( left(frac{mu_{0} i}{2 pi R}right) cdot ) |
12 |

932 | A small coil of N turns has an area A and a current i flows through it. The magnetic dipole moment of the coil will be ( A cdot ) i ( N A ) B . ( i^{2} mathrm{NA} ) ( c cdot i N^{2} A ) D. iN/A |
12 |

933 | A uniform electric field ‘E’ is directed towards positive X-axis. If at ( X=0, ) the electric potential is zero, then the potential at ( boldsymbol{X}=+boldsymbol{X}_{0}, ) would be A ( cdot frac{E}{X_{0}} ) в. ( frac{-E}{X_{0}} ) c. ( -E X_{0} ) D. ( E X_{0} ) |
12 |

934 | The force experienced by a current carrying conductor placed in a magnetic field is largest when magnetic feild,current and length of conducter is more Type 1 for true and 0 for false |
12 |

935 | When a steel core is placed in a solenoid, it acts like an electromagnet. A. True B. False |
12 |

936 | A moving-coil galvanometer has its coil of 24 turns and ( 12 Omega ) resistance. By how much the number of turns should be increased so that the current sensitivity of the galvanometer increases by ( 25 % ? ) If, in doing so, the resistance of the coil increases to ( 20 Omega ), what will be the effect on the voltage-sensitivity of the galvanometer? |
12 |

937 | Assertion The magnetic field at the ends of a very long current carrying solenoid is half of that at the center. Reason If the solenoid is sufficiently long, the field within it is uniform. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
12 |

938 | A circular coil of 100 turns has an effective radius of ( 0.05 mathrm{m} ) and carries a current of 0.1 A. How much work is required to turn it in an external magnetic field of ( 1.5 W b m^{-2} ) through ( 180^{circ} ) about an axis perpendicular to the magnetic field? |
12 |

939 | Two parallel wires in free space are ( 10 mathrm{cm} ) apart and each carries a current of ( 10 A ) in the same direction. The force exerted by one wire on other per metre of length of the wire is A ( cdot 2 times 10^{-6} N ) B . ( 2 times 10^{-4} N ) c. ( 2 times 10^{-3} N ) D ( cdot 2 times 10^{-2} N ) |
12 |

940 | Phosphor-Bronze wire is used for suspension in a moving coil galvanometer because it has. A. High conductivity B. High resistivity c. Large couple per unit twist D. Small couple per unit twise |
12 |

941 | State the rule to determine the direction of a Magnetic field produced around a straight conductor carrying current |
12 |

942 | Which rule determines the direction of force experienced by a current Carrying straight conductor placed in a magnetic field which is perpendicular to it. A. Maxwell right hand grip rule B. Fleming’s left hand rule C. Fleming’s right hand rulel D. None |
12 |

943 | When a permanent magnet is moved towards a coil, current is induced in the coil by faraday’s law. What is the source of energy associated with the current produced? |
12 |

944 | Explain with neat diagram the principle, construction and working of a cyclotron. | 12 |

945 | A moving charge can produce a magnetic field. How does a current loop behaves like a magnetic dipole? | 12 |

946 | A small ball of volume ( V ) made of paramagnetic with susceptibility ( chi ) was slowly displaced along the axis of a current-carrying coil from the point where the magnetic induction equals ( B ) out to the region where the magnetic field is practically absent. What amount of work was performed during this process? |
12 |

947 | Write Ampere circuital law in mathematical form. Derive an expression of magnetic field at the axis of a current carrying long solenoid. Draw necessary diagram. |
12 |

948 | (a)Draw a schematic sketch of a cyclotron. Explain clearly the role of crossed electric and magnetic field in accelerating the charge. Hence derive the expression for the kinetic energy acquired by the particles. (b) An ( alpha ) – particle and a photon are released from the centre of the cyclotron and made to accelerate: (i) Can both be accelerated at the same cyclotron frequency? Give reason to justify your answer (ii) When they are accelerated in turn, which of the two will have higher velocity at the exit slit. |
12 |

949 | A positively charged particle of ( 2.0 C ) moves upward into an area where both a magnetic field of the magnitude ( 4.0 times 10^{-4} T ) and an electric field of the magnitude ( 0.1 N / C ) are acting. Find out the velocity at which particle must move if it is not deflected when it enters this area? A ( cdot 4.0 times 10^{-3} mathrm{m} / mathrm{s} ) B. ( 125 mathrm{m} / mathrm{s} ) c. ( 250 m / s ) D. ( 500 m / s ) E. The particle will be deflected to the left regardless of ts velocity |
12 |

950 | A proton is moving with velocity ( 10^{4} m / s ) parallel to the magnetic field of intensity 5 tesla.The force on the proton is A. ( 8 times 10^{15} N ) B . ( 10^{4} N ) c. ( 1.6 times 10^{-19} N ) D. zero |
12 |

951 | Figure shows a conducting loop ( A B C D A ) placed in a uniform magnetic field (strength ( B ) ) perpendicular to its plane. The part ( A B C ) is the (three- fourth) portion of the square of side Iength ( l ). The part ( A D C ) is a circular arc of radius ( R ). The points ( A ) and ( C ) are connected to a battery which supplies a current ( I ) to the circuit. The magnetic force on the loop due to the field ( B ) is : A . zero В. ( B I l ) c. ( 2 B I R ) D. [ frac{B I l R}{I+R} ] |
12 |

952 | Under what condition is the force acting on a charge moving through a uniform magnetic field minimum? |
12 |

953 | A specimen of iron of permeability ( 8 times ) ( 10^{-3} ) Weber/A m is placed in a magnetic field of strength ( 160 mathrm{A} / mathrm{m} ) Magnetic induction in this iron is: ( mathbf{A} cdot 0.8 W b / m^{2} ) B. ( 5 times 10^{5} mathrm{Wb} / mathrm{m}^{2} ) c. ( 1.28 W b / m^{2} ) D . ( 20 times W b / m^{2} ) |
12 |

954 | A galvanometer in a circuit: A. measures current B. measures voltage C. measures emf D. indicates flow of current |
12 |

955 | f a current lis flowing in a loop of radius r as shown in adjoining figure, then the magnetic field induction at the centre 0 will be A. zero в. ( frac{mu_{0} I theta}{4 pi r} ) c. ( frac{mu_{0} I sin theta}{4 pi r} ) D. ( frac{2 mu_{0} I sin theta}{4 pi r^{2}} ) |
12 |

956 | Cathode rays gain kinetic energy when accelerated by an electric field. If they are subjected to a uniform magnetic field, then their A. energy increases B. momentum increases c. energy and momentum decrease D. energy and momentum remain unaffected |
12 |

957 | The leakage flux of a toroid is less because A. It is asymmetrical B. It has an open-loop core c. It is symmetrical. D. It has a straight core |
12 |

958 | Write the formula of Biot-Sevart law in vector form. Obtain an expression of magnetic field on the axis of a current carrying circular loop. Draw necessary diagram. |
12 |

959 | A moving coil galvanometer A has 100 turns and resistance ( 10 Omega ). Another galvanometer B has 50 turns and 5 ( Omega ) The other quantities are same in both the cases. Then the voltage sensitivity of : A. A is greater than that of B. B is greater than that of c. ( A ) and ( B ) is same D. Cannot be compared |
12 |

960 | The intensity of magnetic induction field at the centre of a single turn circular coil of radius ( 5 mathrm{cm} ) carrying of 0.9 A current is: A . ( 36 pi times 10^{-7} mathrm{T} ) В . ( 9 pi times 10^{-7} T ) ( mathbf{c} cdot 36 pi times 10^{-6} T ) D. ( 9 pi times 10^{-6} T ) |
12 |

961 | A long wire carries a steady current. IT is bent into a circle of one turn and the magnetic field at the centre of the coil is ( B ). It is then bent into a circular loop of ( n ) turns. The magnetic field at the centre of the coil will be: ( mathbf{A} cdot n B ) B . ( n^{2} B ) ( c cdot 2 n B ) D. ( 2 n^{2} B ) |
12 |

962 | What is the main reason for using a solenoid instead of a straight wire to produce magnetic field? |
12 |

963 | The coil in a MCG has an area of ( 4 mathrm{cm}^{2} ) and 500 turns. The intensity of magnetic induction is 2T. When a current of ( 10^{-4} ) A is passed through it, the deflection is ( 20^{0} ). The couple per unit twist is (N-m) A. ( 3 times 10^{-6} ) B. ( 2 times 10^{-6} ) ( mathbf{c} cdot 4 times 10^{-6} ) D. ( 5 times 10^{-6} ) |
12 |

964 | The magnetic induction at 0 due to a current in conductor shaped as shown in figure is: A ( cdot frac{mu_{0} i}{4 pi}left[frac{3 pi}{2 a}+frac{sqrt{2}}{b}right] ) В ( cdot frac{mu_{0} i}{4 pi}left[frac{3 pi}{4 a}-frac{sqrt{2}}{b}right] ) ( ^{text {c. }} cdot frac{mu_{0} i}{2 pi}left[frac{3 pi}{4 a}-frac{1}{sqrt{2} b}right] ) D. ( frac{mu_{0}}{2 pi}left[frac{1}{a}+frac{1}{b}right. ) |
12 |

965 | On connecting a shunt of ( 12 Omega, ) the deflection of galvanometer reduces from 50 to 20 divisions. Calculate resistance of galvanometer. |
12 |

966 | The magnetic field generated along the axis of a solenoid is proportional to: A. its length B. square of current flowing in it c. number of turns per unit length in it D. reciprocal of its radius |
12 |

967 | Calculate magnetic flux density of the magnetic field at the centre of a circular coil of 50 tunrs, having radius of ( 0.5 mathrm{m} ) and carrying a current of ( 5 mathrm{A} ) |
12 |

968 | What is the name given to a cylindrical coil whose diameter is less in comparison to its length? |
12 |

969 | A voltmeter has a resistance of ( G ) ohms and range ( V ) volts. The value of resistance required in series to convert it into voltmeter of range ( n V ) is A ( . n G ) в. ( G / n ) c. ( G /(n-1) ) D. ( (n-1) G ) |
12 |

970 | toppr ( t ) Q Type your question of the forces exerted on the wires? ( A ) в. ( c ) D. |
12 |

971 | Two long straight wires are set parallel to each other at separation ( r ) and each carries a current ( i ) in the same direction. The strength of the magnetic field at any point midway between the two wires is A ( cdot frac{mu_{0} i}{pi r} ) в. ( frac{2 mu_{0}}{pi r} ) c. ( frac{mu_{0} i}{2 pi r} ) D. zero |
12 |

972 | A solenoid is ( 2.0 mathrm{m} ) long and ( 3.0 mathrm{cm} ) in diameter. It has 5 layers of winding of 1000 turns each and carries a current of 5.0 A. What is the magnetic field at its centre? A ( cdot 1.5 times 10^{-3} T ) в. ( 1.5 times 10^{-2} T ) c. ( 1.5 times 10^{-4} T ) D. ( 2.5 times 10^{-2} T ) |
12 |

973 | A metallic rod ( C D ) rests on a thick metallic wire ( P Q R S ) with arms ( P Q ) and ( R S ) parallel to each other, at a distance ( l=40 mathrm{cm}, ) as shown in following figure. A uniform magnetic field ( B=0.1 T ) acts perpendicular to the plane of this paper, pointing inwards (i.e., aways from the reader). The rod is now made to slide towards right, with a constant velocity of ( boldsymbol{v}=mathbf{5 . 0} boldsymbol{m} boldsymbol{s}^{-1} ) How much emf is induced between the two ends of the rod ( C D ? ) |
12 |

974 | A current i, indicated by the crosses in figure, is established in a strip of copper of height ( h ) and width ( w . A ) uniform field of magnetic induction B is applied at right angle to the strip. Calculate voltage V necessary between |
12 |

975 | A positively charged particle of charge 1 C and mass 40 g, is revolving along a circle of radius ( 40 mathrm{cm} ) with velocity ( 5 mathrm{m} / mathrm{s} ) in a uniform magnetic field with centre at origin 0 in ( x ) -y plane ( . A t t=0 ) the particle was at ( (0,0.4 mathrm{m}, 0) ) and velocity was directed along positive ( x ) direction.Another particle having charge ( 1 mathrm{C} ) and mass ( 10 mathrm{g} ) moving uniformly parallel to z-direction with velocity ( frac{40}{pi} m / s ) collides with revolving particle at ( t=0 ) and gets stuck with it. Neglecting gravitational force and coulombian force,calculate ( x, y ) and ( z ) coordinates of the combined particle at ( t=frac{pi}{40} sec ) |
12 |

976 | A long wire bent as shown in figure carries current ( I . ) If the radius of the semicircular portion is ( a ), the magnetic field at center ( C ) is: A ( cdot frac{mu_{0} I}{4} ) B. ( frac{mu_{0} I}{4 pi a} sqrt{pi^{2}+4} ) c. ( frac{mu_{0} I}{4 a}+frac{mu_{0} I}{4 pi a} ) D. ( frac{mu_{0} I}{4 pi a} sqrt{pi^{2}-4} ) |
12 |

977 | An infinitely long straight conductor is bent into shape as shown in figure. It carries a current I A. and the radius of circular loop is r metre. Then the magnetic induction at the centre of the circular loop is: ( A ) B. ( frac{mu_{0}}{pi r_{0}} ) c. ( frac{mu_{0} i}{2 pi r}(pi+1) ) D ( cdot frac{mu_{0} i}{2 pi r}(pi-1) ) |
12 |

978 | If a shunt of ( frac{1}{10} t h ) of the coil resistance is applied to a moving coil galvanometer, its sensitivity becomes A. 10 fold в. ( frac{1}{10} ) fold c. 11 fold D. ( frac{1}{11} ) fold |
12 |

979 | The sensitivity of a galvanometer will increase if A. radius of coil is increased B. number of turns in coil is decreased c. radius of coil is decreased D. a strong field is used |
12 |

980 | A particle of mass ( mathrm{M} ) and charge ( mathrm{Q} ) moving with velocity ( vec{v} ) describe a circular path of radius R when subjected to a uniform transverse magnetic field of induction B. The work done by the field when the particle completes one full circle is ( ^{mathbf{A}} cdotleft(frac{M v^{2}}{R}right)^{2 pi R} ) в. zero с. ( B Q 2 pi R ) D. ( B Q v 2 pi R ) |
12 |

981 | In an atom, electrons revolve around the nucleus. This gives rise to A. only electric field B. only magnetic field c. both electric and magnetic fields D. none of the above |
12 |

982 | In a cyclotron, magnetic field of ( 1.4 W b / m^{2} ) is used. To accelerate protons, how rapidly should the electric field between the Dees he reversed? ( left(boldsymbol{pi}=mathbf{3 . 1 4 2}, boldsymbol{M} boldsymbol{p}=mathbf{1 . 6 7} times mathbf{1 0}^{-mathbf{2 7}} mathbf{k g}, boldsymbol{e}=right. ) ( left.mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} mathbf{C}right) ) |
12 |

983 | toppr ( Q ) electrostatic field is maintained in a direction normal to the common axis of the coils. A narrow beam of (single species) charged particles al accelerated through ( 15 k V ) enters this region in a direction perpendicular to both the axis of the coils and the electrostatic field. If the beam remains undeflected when the electrostatic field is ( 9.0 times 10^{-5} V m^{-1}, ) make a simple guess as to what the beam contains. Why is the answer not unique? Consider two parallel co-axial circular coils of equal radius ( R ), and number of turns ( N, ) carrying equal currents in the same direction, and separated by a distance ( R ) Show that the field on the |
12 |

984 | A charged particle moves in a circular path in a uniform magnetic field.If the speed is reduced then its time period will A. increase B. decrease c. remain same D. None of these |
12 |

985 | A circular loop of radius R carrying a current lis placed in a uniform magnetic field B perpendicular to the loop. The force on the loop is: A ( .2 pi R I B ) В. ( 2 pi R I^{2} B^{3} ) ( mathbf{c} cdot pi R^{2} I B ) D. zero |
12 |

986 | A galvanometer of resistance, ( G ) is shunted by a resistance ( S ) ohm. To keep the main current in the circuit unchanged, the resistance to be put in series with the galvanometer is A ( cdot frac{S^{2}}{(S+G)} ) B. ( frac{S G}{(S+G)} ) c. ( frac{G^{2}}{(S+G)} ) D. ( frac{G}{(S+G)} ) |
12 |

987 | A wire of length L metre carrying current ampere is bent in the form of a circle. What is the magnitude of magnetic dipole moment? A ( cdot I L^{2} / 4 pi ) B . ( I^{2} L^{2} / 4 pi ) c. ( I^{2} L / 8 pi ) D. ( I L^{2} / 8 pi ) |
12 |

988 | Two current carrying loops of same area but of different materials have same current flowing in them in anticlockwise direction. if a magnetic field is applied in upward direction then potential energy of loop 1 and loop 2 will always be: A. Different B. Equal c. can be different or equal depend upon material D. Can’t say |
12 |

989 | Find ampere force acting on the frame | 12 |

990 | An arc of a circle of radius ( R ) subtends an angle ( frac{pi}{2} ) at the centre. It carries a current ( i . ) The magnetic field at the centre will : A ( cdot frac{mu_{0} i}{2 R} ) в. ( frac{mu_{0} i}{8 R} ) c. ( frac{mu_{0} i}{4 R} ) D. ( frac{mu_{0} i}{5 R} ) |
12 |

991 | A ( 2 mathrm{m} ) long conductor, carries a current of ( 50 mathrm{A} ) at a magnetic field of ( 10^{-1} ) T. The force on the conductor is: A . 10 N B. 100 N ( c cdot 1000 N ) D. ( 10,000 mathrm{N} ) |
12 |

992 | A solenoid of length ( 0.4 mathrm{m}, ) having 500 turns and 3 A current flows through it. A coil of radius ( 0.01 mathrm{m} ) and have 10 turns and carries current of 0.4 A has to placed such that its axis is perpendicular to the axis of solenoid then torque on coil will be A ( cdot 5.92 times 10^{-7} N cdot m ) В. ( 5.92 times 10^{-5} mathrm{N} . mathrm{m} ) c. ( 5.92 times 10^{-4} N . m ) D. ( 5.92 times 10^{-3} N . m ) |
12 |

993 | The charge is moving along the direction of magnetic field. Then force acting on it is A. Maximum B. qvB c. zero D. Bil |
12 |

994 | A circular coil of magnetic moment ( 0.355 J T^{-1} ) rests with its plane normal to an external field of magnitude ( 5.0 times ) ( 10^{-2} mathrm{T} . ) The coil is free to turn about an axis in its plane perpendicular to the field direction. When the coil is turned slightly and released, it oscillates about its stable equilibrium with a frequency of ( 2 mathrm{Hz} ). The moment of inertia of the coil about its axis of rotation is? A ( cdot 1.13 times 10^{-1} mathrm{kg} mathrm{m}^{2} ) B . ( 1.13 times 10^{-2} ) kg ( m^{2} ) C ( cdot 1.13 times 10^{-3} mathrm{kg} mathrm{m}^{2} ) D. ( 1.13 times 10^{-4} mathrm{kg} mathrm{m}^{2} ) |
12 |

995 | The sensitivity of a moving coil galvanometer increases with the decrease in A. number of turns B. area of coil c. magnetic field D. couple per unit twist |
12 |

996 | ( boldsymbol{x}=mathbf{0 . 5 0 0 m}, boldsymbol{y}=mathbf{0}, boldsymbol{z}=mathbf{0} ) | 12 |

997 | I ne rectangular wıre trame, shown In the figure has a width d, mass ( m ) resistance ( R ) and a large length. ( A ) uniform magnetic field B exists to the left of the frame. A constant force ( F ) starts pushing the frame into the magnetic field at ( t=0 ) (a)Find the acceleration of the frame when its speed has increased to (b how that after some time the frame will move with a constant velocity till the whole frame enters into the magnetic field. Find the velocity ( v_{0} ) (c) Show that the velocity at time t is given byv ( =boldsymbol{v}_{0}left(mathbf{1}-boldsymbol{e}^{frac{-F t}{m v_{0}}}right) ) [ begin{array}{ll} x & x \ x & x \ x & x \ x & x \ x & x end{array} ] |
12 |

998 | Three ions ( H^{+}, H e^{+} ) and ( O^{+2} ) having same kinetic energy pass through a region in which there is a unit magnetic field perpendicular to their velocity, then A ( cdot H^{+} ) will be least deflected B. ( H e^{+} ) and ( O^{+2} ) will be deflected equally c. ( O^{+2} ) will be deflected most D. All will be deflected equally |
12 |

999 | 1) ( I, ) is placed in a horizontal plane near a long straight conductor carrying steady current ( I_{1} ) at a distance ( d ) from the conductor as shown in figure. The loop will experience A. A net repulsive force away from the conductor B. A net torque acting upward perpendicular to the horizontal plane c. A net torque acting downward normal to the horizontal plane D. A net attractive force towards the conductor |
12 |

1000 | A moving coil galvanometer is based on the A. heating effect of current B. magnetic effect of current c. chemical effect of current D. peltier effect of current |
12 |

1001 | A charged particle ( A ) of charge ( q=2 C ) has velocity ( boldsymbol{v}=mathbf{1 0 0} boldsymbol{m} / boldsymbol{s} . ) When it passes through point ( A ) and has velocity in the direction shown, the strength of magnetic field at point ( B ) due to this moving charge is ( (r=2 m) ) A ( .2 .5 mu T ) B. ( 5.0 mu T ) c. ( 2.0 mu T ) D. none of these |
12 |

1002 | Assertion A galvanometer can be used as a voltmeter to measure the voltage across a given section of the circuit. Reason For this it must be connected in parallel with that section of the circuit. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |

1003 | A copper wire of diameter ( 1.6 m m ) carries a current of ( 20 A ). Find the maximum magnitude of the magnetic field ( vec{B} ) due to this current. |
12 |

1004 | If an electron and a proton having same momenta enter perpendicular to a magnetic field, then : A. curved path of electron and proton will be same (ignoring the sense of revolution) B. They will move undeflected c. curved path of electron is more curved than that of the proton D. Path of proton is more curved |
12 |

1005 | A long solenoid has 200 turns per ( mathrm{cm} ) and carries a current ( i . ) The magnetic field at its centre is ( 6.28 times ) ( 10^{-2} W b / m^{2} ) Another long solenoid has 100 turns per cm and it carries a current ( i / 3 . ) The value of the magnetic field at its centre is : A ( cdot 1.05 times 10^{-4} W b / m^{2} ) B . ( 1.05 times 10^{-2} mathrm{Wb} / mathrm{m}^{2} ) c. ( 1.05 times 10^{-5} mathrm{Wb} / mathrm{m}^{2} ) D. ( 1.05 times 10^{-3} mathrm{Wb} / mathrm{m}^{2} ) |
12 |

1006 | Two current-carrying parallel conductors are shown in the figure. The magnitude and nature of force acting between them per unit length will be : A ( cdot 8 times 10^{-8} N / m, ) attractive B. ( 3.2 times 10^{-5} N / m ), repulsive c. ( 3.2 times 10^{-5} N / m ), attractive D. ( 8 times 10^{-8} N / m ), repulsive |
12 |

1007 | The wires which connect the battery of an automobile to its starting motor carry a current of 300 A (for a short time). What is the force per unit length between the wires if they are ( 70 mathrm{cm} ) long and ( 1.5 mathrm{cm} ) apart? Is the force attractive or repulsive? |
12 |

1008 | Nu Which pictured, moving northeast through a magnetic field that points straight up. What is the direction of the force on the negatively charged particle at the moment it is pictured? North west ( – ) East South A. Northeast B. Southeast c. Southwest D. Northwest E. Up |
12 |

1009 | Evaluate the magnitude and direction of magnetic field at point ( boldsymbol{O} ) A ( cdot frac{3 mu_{0} i}{8 a}, ) с в. ( frac{mu_{0} i}{2 sqrt{2} b}, ) с с. ( frac{3 mu_{0} i}{8 a}+frac{mu_{0} i}{2 sqrt{2} b}, ) с D. ( frac{3 mu_{0} i}{8 a}+frac{mu_{0} i}{2 sqrt{2} b}, otimes ) |
12 |

1010 | Assertion A proton and an alpha particle having the same kinetic energy are moving in circular paths in a uniform magnetic field. The radii of their circular paths will be equal Reason Any two charged particles having equal kinetic energies and entering a region of uniform magnetic field ( vec{B} ) in a direction perpendicular to ( vec{B}, ) will describe circular trajectories of equal radii. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |

1011 | If the current sensitivity of a galvanometer is doubled, then its voltage sensitivity will be A. doubled B. halvedd c. unchanged D. four times |
12 |

1012 | A positively charged croquet ball rolls at ( 4.0 m / s ) northward through a ( 2.00 T ) magnetic field which points westward. If the charge on the croquet ball is ( 1.0 C ) how much force acts on the croquet ball due to the magnetic field and in what direction? A. Amount of Force ( -2.00 N ), Direction of Force – up B. Amount of Force ( -8.00 N ), Direction of Force – south C. Amount of Force ( -8.00 N ), Direction of Force – down D. Amount of Force ( -0.500 N ), Direction of Force – up E. Amount of Force ( -8.00 N ), Direction of Force – up |
12 |

1013 | The wire shown in figure carries a current of ( 40 A . ) If ( r=3.14 c m ) the magnetic field at point p will be : A ( .1 .6 times 10^{-3} T ) В. ( 3.2 times 10^{-3} T ) c. ( 6 times 10^{-4} T ) D . ( 4.8 times 10^{-3} T ) |
12 |

1014 | A cyclotron’s oscillator frequency is 10 MHz and the operating magnetic field is ( 0.66 mathrm{T} . ) If the radius of its dees is ( 60 mathrm{cm} ) then the kinetic energy of the proton beam produced by the accelerator is? ( mathbf{A} cdot 9 mathrm{MeV} ) B. 10 Mev c. 7 Mev D. 11 Mev |
12 |

1015 | Why don’t two magnetic lines of force intersect with each other? | 12 |

1016 | A particle having mass ( m ) and charge ( q ) is released from the origin in a region in which electric field and magnetic fields are given by ( vec{B}=-B_{0} hat{j} ) and ( vec{E}=E_{0} hat{k} ) Find the speed of the particle as a function of its ( z- ) coordinate. A ( cdot sqrt{frac{q E z}{m}} ) B. ( sqrt{frac{2(q v B+q E) z}{m}} ) D. ( sqrt{frac{2 q E z}{m}} ) |
12 |

1017 | The area of the coil in a moving coil galvanometer is ( 80 mathrm{cm}^{2} ) and it has 200 turns. The magnetic induction of the radial field is ( 0.2 mathrm{T} ) and the couple per unit twist of the suspension wire is ( 2 x ) ( 10^{-6} N m ) per degree. If the deflection is 4, the current passing through it is ( A cdot 0.25 mathrm{m} mathrm{A} ) в. 2.5 ( mathrm{m} ) А c. ( 0.025 mathrm{mA} ) D. 250 mA |
12 |

1018 | Figure shows a square current-carrying loop ( A B C D ) of side ( 2 m ) and current ( boldsymbol{I}=frac{1}{2} boldsymbol{A} . ) The magnetic moment ( overrightarrow{boldsymbol{M}} ) of the loop is: A ( cdot(hat{i}-sqrt{3} hat{k}) A-m^{2} ) ( mathbf{B} cdot(hat{j}-hat{k}) A-m^{2} ) c. ( (sqrt{3} hat{i}-hat{k}) A-m^{2} ) D. ( (hat{i}-hat{k}) A-m^{2} ) |
12 |

1019 | A solenoid ( 1.5 mathrm{m} ) long and ( 4.0 mathrm{cm} ) in diameter possesses 10 turns/cm. current of 5 A is flowing through it. Then the magnetic induction (i) inside and (ii) at one end on the axis of solenoid are respectively A ( cdot 2 pi times 10^{-3} T, pi times 10^{-3} T ) В . ( 3 pi times 10^{3} T, 1.5 pi times 10^{3} T ) c. ( 0.5 pi times 10^{3} 10^{3} T, 4 pi times 10^{3} T ) D. ( 4 pi times 10^{3} T, 2 pi times 10^{3} ) |
12 |

1020 | The magnitude of force experienced by the arc ( M N ) is A. zero B. ( frac{mu_{0} V I_{0}}{pi R b} ) C ( frac{mu_{0} V I_{0}}{2 pi R b} ) D. none of these |
12 |

1021 | The magnetic moment ( (mu) ) of a revolvng electron around the nucleus varies with principle quantum number n as ( mathbf{A} cdot mu propto n ) в. ( mu propto 1 / n ) c. ( mu propto n^{2} ) D. ( mu propto 1 / n^{2} ) |
12 |

1022 | Two infinite long wires, each carrying current ( I, ) are lying along ( x ) -axis and ( y ) axis, respectively. ( A ) charged particle, having a charge ( q ) and mass ( m ), is projected with a velocity ( u ) along the straight line ( O P . ) The path of the particle is (neglect gravity) a: A. straight line B. circle c. helix D. cycloid |
12 |

1023 | A small circular loop of conducting wire has radius ( a ) and carries current ( I ). It is placed in a uniform magnetic field ( boldsymbol{B} ) perpendicular to its plane such that when rotated slightly about its diameter and replaced, it starts performing simple harmonic motion of time period ( T . ) If the mass of the loop is ( m ) then: ( ^{mathbf{A}} cdot_{T}=sqrt{frac{2 m}{I B}} ) в. ( T=sqrt{frac{pi m}{I B}} ) ( ^{mathrm{c}} cdot T=sqrt{frac{2 pi m}{I B}} ) D ( cdot T=sqrt{frac{pi m}{2 I B}} ) |
12 |

1024 | The magnetic field at the center of the coil of radius ( r ) and carrying a current ( I ) as shown in the figure is : (the wires crossing at ( P ) are insulated from each other) A ( cdot frac{mu_{0}}{4 pi} frac{2 I}{r}(1+pi) ) в. ( frac{mu_{0}}{4 pi} frac{2 I}{r}(pi-1) ) c. ( frac{mu_{0}}{4 pi} frac{2 I}{r}left(pi^{2}+1right) ) D. ( frac{mu_{0}}{4 pi} frac{2 pi I}{r} ) |
12 |

1025 | Current ( i ) is flowing in a coil of area ( A & ) number of turns ( N, ) then magnetic moment of the coil is ( M ) is equal to A. ( N i A ) в. ( frac{N i}{A} ) c. ( frac{N i}{sqrt{A}} ) D. ( N^{2} A i ) |
12 |

1026 | A conductor carries a constant current along the closed path abcdefgha nvolving 8 of the 12 edges each of ength I.Find the magnetic dipole moment of the closed path. The answer is ( M=x I l^{2} hat{j} ) then ( x ) is |
12 |

1027 | Two proton beams are moving in the parallel direction. Which of the following statements are correct. This question has multiple correct options A. Force between the proton beams will be attractive B. Magnetic force between proton beams will be attractive C. Repulsive force will be greater than attractive forces D. Magnetic and electrostatic forces will cancel each other |
12 |

1028 | A circular coil of wire carries a current. ( P Q ) is a part of a very long wire carrying a current and passing close to the circular coil. If the direction of currents are those as shown in the Figure, what is the direction of force acting on ( P Q ? ) A. Parallel to ( P Q ), towards ( P ) B. Parallel to ( P Q ), towards ( Q ) C. At right angles to ( P Q ), towards right D. At right angles to ( P Q ), towards left |
12 |

1029 | A ( 2.00 m ) length of wire carrying ( 3.00 A ) of conventional current southward through a ( 5.00 T ) magnetic field directed straight up experience how much force due the field and in what direction? A. Amount of Force ( -7.5 N ), Direction of Force – west B. Amount of Force ( -30.0 N ), Direction of Force – west c. Amount of Force ( -7.5 N ), Direction of Force – east D. Amount of Force ( -30.0 mathrm{N} ), Direction of Force – east E. Amount of Force ( -3.33 mathrm{N} ), Direction of Force – north |
12 |

1030 | A long current carrying conductor of length ( l ) is placed in a uniform magnetic field strength ( B ). If current in conductor is ( i A, ) write down the formula of force exerted on current carrying conductor. What will be the maximum force? Write its direction. |
12 |

1031 | An electric field ( boldsymbol{E} ) and a magnetic field ( B ) act over the same region in which an electron enters along the ( x ) -axis. The combination of ( E ) and ( B ) which permits the electron to go undeflected is: A. ( E ) along ( Y ) -axis and ( B ) along ( Y ) -axis B. ( E ) along ( Y ) -axis and ( B ) along ( Z ) -axis c. ( E ) along ( X ) -axis and ( B ) along ( Z ) -axis D. ( E ) along ( Y ) -axis and ( B ) along ( X ) -axis |
12 |

1032 | Magnetic field is not associated with A. a change in uniform motion B. an accelerated charge. c. a deaccelerated charge D. a stationary charge. |
12 |

1033 | A light beam travelling in the ( x ) direction is described by the electric field ( boldsymbol{E}_{boldsymbol{y}}=mathbf{3 0 0 v} / boldsymbol{m} sin left(boldsymbol{t}-frac{boldsymbol{x}}{c}right) cdot mathbf{A} mathbf{n} ) electron is constrained to move along the y-direction with a speed of ( 2.0 times ) ( 10^{7} m / s . ) Find the maximum magnetic force on the electron. ( mathbf{A} cdot 2 times 10^{-18} ) B . ( 2.5 times 10^{-18} ) C ( .3 times 10^{-18} ) D. ( 3.2 times 10^{-18} ) |
12 |

1034 | The net magnetic flux through any closed surface, kept in a magnetic field is A . zero в. ( frac{mu_{0}}{4 pi} ) c. ( 4 pi mu_{0} ) D. ( frac{4 mu_{0}}{pi} ) |
12 |

1035 | What kind of energy change takes place when a magnet is moved towards a coil having a galvanometer at its ends? A. Mechanical energy changes to the magnetic energy. B. Magnetic energy changes to the electrical energy c. Mechanical energy changes to the electrical energy. D. None of the above |
12 |

1036 | Two large parallel sheets having linear current densities ( J ) and ( -J_{0} ) as shown in figure, then magnetic field in region ( b ) is:- ( mathbf{b} ) begin{tabular}{|l|l|l|l|l|l|} hline & ( mathrm{X} ) & ( mathrm{X} ) & ( mathrm{X} ) & ( mathrm{X} ) & ( mathrm{X} ) & ( -mathrm{J} ) \ hline end{tabular} A . zero в. ( frac{mu_{0} J}{2} ) c. ( mu_{0} ). D. None of these |
12 |

1037 | A long straight wire of radius R carries a steady current ( I_{o}, ) uniformly distributed throughout the cross-section of the wire. The magnetic field at a radial distance r from the centre of the wire, in the region ( r>R ), is? A ( cdot frac{mu_{o} I_{o}}{2 pi r} ) В ( cdot frac{mu_{o} I_{o}}{2 pi R} ) ( ^{mathbf{C}} cdot frac{mu_{o} I_{o} R^{2}}{2 pi r} ) D. ( frac{mu_{o} I_{o} r^{2}}{2 pi R} ) E ( cdot frac{mu_{o} I_{o} r^{2}}{2 pi R^{2}} ) |
12 |

1038 | The number of turns per unit length of a long solenoid is ( 10 . ) If its average radius is ( 5 mathrm{cm} ) and it carries a current of ( 10 mathrm{A} ) then the ratio of flux densities obtained at the centre and at one endpoint will be A .1: 2 B . 2: 1 c. 1: 1 D. 1: 4 |
12 |

1039 | Two flat circular coils are made of two identical wires each of length ( 20 mathrm{cm} ) one coil has 4 turns while the second has ( 2 . ) If the same current flows through the two, then find ratio of the field at their centre |
12 |

1040 | A loop carrying current ( I ) lies in the ( x ) ( boldsymbol{y} ) plane as shown in figure. The unit vector ( hat{k} ) is coming out of the plane of the paper. The magnetic moment of the current loop is ( mathbf{A} cdot a^{2} I hat{k} ) B cdot ( left(frac{pi}{2}+1right) a^{2} I hat{k} ) c. ( -left(frac{pi}{2}+1right) a^{2} I hat{k} ) D. ( (2 pi+1) a^{2} I hat{k} ) |
12 |

1041 | Find the magnetic moment of the spiral with a given current. A ( cdot p=25 m A cdot m^{2} ) B . ( p=15 mathrm{mA} cdot mathrm{m}^{2} ) C ( cdot p=30 mathrm{mA} cdot mathrm{m}^{2} ) D. ( p=50 mathrm{mA} cdot mathrm{m}^{2} ) |
12 |

1042 | The radius of the curved part of the wire is ( R=100 m m, ) the linear parts of the wire are very long. Find the magnetic induction at the point ( O ) if the wire carrying a current ( I=8.0 A ) has the shape shown in the figure. в. ( 0.60 mu T ) ( c .0 mu T ) D. ( 0.70 mu T ) |
12 |

1043 | An ( alpha ) particle and a proton travel with same velocity in a magnetic field perpendicular to the direction of their velocities. Find the ratio of the radii of their circular paths. A .4: B. 1: c. 2: D. 1: |
12 |

1044 | If a charged particle projected in a gravity-free room deflects This question has multiple correct options A. there must be an electric field B. there must be a magnetic field c. both fields cannot be zero D. both fields can be non-zero |
12 |

1045 | Two thin long wires carry currents ( boldsymbol{I}_{mathbf{1}} ) and ( I_{2} ) along ( x ) -and ( y ) -axes respectively as shown in figure. Consider the points only in ( x ) -y plane. This question has multiple correct options A. Magnetic field is zero at least at one point in each quadrant B. Magnetic field can be zero somewhere in the first quadrant c. Magnetic field can be zero somewhere in the second quadrant D. Magnetic field is non-zero in second quadrant |
12 |

1046 | A very long straight conducting wire, lying along the z-axis, carries a current of ( 2 A . ) The integral ( oint vec{B} . d vec{l} ) is computed along the straight line ( P Q ), where ( P ) has the coordinates ( (2 c m, 0,0) ) and ( Q ) has the coordintes ( (2 c m, 2 c m, 0) . ) The integral has the magnitude (in Sl units) ( ^{A} cdot frac{pi}{2} times 10^{-7} ) В . ( 8 pi times 10^{-7} ) D. ( pi times 10^{-7} ) |
12 |

1047 | A circular coil carrying a current I has radius R and number of turns N. If all the three, i.e., the current I, radius R and number of turns ( mathrm{N} ) are doubled, then magnetic field at its centre becomes. A. Double B. Half c. Four times D. One fourth |
12 |

1048 | A solenoid with a soft iron core is called ( mathbf{a} ) A. Electromagnet B. Magnettet c. conducts D. Insulator |
12 |

1049 | Assertion An electric field is preferred in comparison to magnetic field for detecting the electron beam in a television picture tube Reason Electric field requires low voltage. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |

1050 | The speed at any point is A ( cdot sqrt{frac{3 q E y}{m}} ) B. ( sqrt{frac{q E y}{m}} ) c. ( sqrt{frac{q E y}{2 m}} ) D. ( sqrt{frac{2 q E y}{m}} ) |
12 |

1051 | Assertion Cyclotron is a device which is used to accelerate the positive ions. Reason Cyclotron frequency depends upon the velocity A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
12 |

1052 | State biot-savart law in vector from along with expression. |
12 |

1053 | A long straight conductor, carrying a current ( i, ) is bent to form an almost complete circular loop of radius ( r ) as shown. The magnetic field at the centre of the loop: A ( cdot ) has magnitude ( frac{mu_{0} i}{r}left(1-frac{1}{pi}right) ) B. has magnitude ( frac{mu_{0} i}{r}left(1+frac{1}{pi}right) ) c. has magnitude ( frac{mu_{0} i}{2 r}left(1-frac{1}{pi}right) ) D. has magnitude ( frac{mu_{0} i}{2 r}left(1+frac{1}{pi}right) ) |
12 |

1054 | When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. A. True B. False c. Ambiguous D. Data insufficient |
12 |

1055 | In the adjoining diagram, a currentcarrying loop pqrs placed with its sides parallel to a long current-carrying wire. The currents ( i_{1} ) and ( i_{2} ) in the wire and loop are ( 20 mathrm{A} ) and 16 A respectively. If ( a= ) ( 15 mathrm{cm}, mathrm{b}=6 mathrm{cm}, ) and ( mathrm{d}=4 mathrm{cm}, ) what will be the force on current ( i_{2} ) in the loop is clockwise instead of anticlockwise? |
12 |

1056 | Two identical galvanometers are joined by connecting wires. One of them is placed on the table and the other is held in the hand. One in the hand is shaken violently so that it shows a deflection of 10 division. The reading in the other galvanometer (on the table) is A . zero B. 10 division c. 5 division D. insufficient data to reply |
12 |

1057 | Which one of the following is NOT correct? A. Dimensional formula of thermal conductivity (K) is ( M^{1} L^{1} T^{-3} K^{-1} ) B. Dimensional formula of potential (V) is ( M^{1} L^{2} T^{-3} A^{-1} ) C. Dimensional formula of permeability of free space ( left(mu_{0}right) ) is ( M^{1} L^{1} T^{-2} A^{-2} ) D. Dimensional formula of RC is ( M^{0} L^{0} T^{-1} ) |
12 |

1058 | A mono energetic electron beam with the speed of ( 5.2 times 10^{6} m s^{-1} ) enters into the magnetic field of induction ( 3 x ) ( 10^{-4} T, ) directed normal to the beam. Then the radius of the circle traced by the beam: ( left(operatorname{given} e / m=1.76 times 10^{11} C K g^{-1}right) ) B. ( 0.98 m ) ( c .0 .089 m ) D. ( 9.8 m ) |
12 |

1059 | A coil of area ( A ), turns ( N ) and carrying current ( i ) is placed with its face parallel to the lines of magnetic induction ( B ) The work done in rotating the coil through an angle of ( 180^{0} ) is ( mathbf{A} cdot i N A B ) в. 2 iNA ( B ) c. ( frac{i N A B}{2} ) D. Zero |
12 |

1060 | Magnetic field in a region is given by ( vec{B}=B_{o} x hat{k} . ) Two loops each of side a is placed in this magnetic region in the ( x ) y plane with one of its sides on x-axis. If ( F_{1} ) is the force on loop 1 and ( F_{2} ) be the force on loop 2 then: A ( . F_{1}=F_{2}=0 ) B. ( F_{1}>left{F_{3},{2} $ $right. ) ( mathbf{c} cdot F_{2}>F_{1} ) D. ( F_{1}=F_{2} neq 0 ) |
12 |

1061 | A steady current ( I ) flows along an infinitely long hollow cylindrical conductor of radius ( mathbf{R} . ) This cylinder is placed coaxially inside an infinite solenoid of radius ( 2 mathrm{R} ). The solenoid has n turns per unit length and carries a steady current ( I . ) Consider a point ( mathbf{P} ) at a distance r from the common axis. The correct statement ( (s) ) is (are): This question has multiple correct options A. in the region ( 0<mathrm{r}<mathrm{R} ), the magnetic field is non-zero B. in the region ( R<r<2 R ), the magnetic field is along the common axis c. in the region ( mathrm{R}<mathrm{r}2 R ), the magnetic field is non-zero |
12 |

1062 | Find Ampere force acting on the frame. A. ( F=4.0 mu N ) в. ( F=0.80 mu N ) c. ( F=0.40 mu N ) D. ( F=8.0 mu N ) |
12 |

1063 | An electron is moving vertically downwards at any place. The direction of magnetic force acting on it due to horizontal component of earth’s magnetic field will be A. towards east B. towards west c. towards north D. towards south |
12 |

1064 | If the orientation of the current loop in a magnetic field is changed then potential energy of loop is also changed.Enter 1 if True and 0 if False. | 12 |

1065 | The parts of two concentric circular arcs joined by two radial lines and carries current ( i . ) The arcs subtend an angle ( theta ) at the center of the circle. The magnetic field at the centre 0 , is A ( cdot frac{mu_{0} i(b-a) theta}{4 pi a b} ) В. ( frac{mu_{0} i(b-a)}{pi-theta} ) c. ( frac{mu_{0} i(b-a) theta}{pi a b} ) D. ( frac{mu_{0} i(a-b)}{2 pi a b} ) |
12 |

1066 | Deduce the relation for the magnetic induction at a point along the axis of a circular coil carrying current. |
12 |

1067 | By which factor the magnetic field produced by a wire at distance ( 2 mathrm{cm} ) from the wire than at ( 4 mathrm{cm} ) from the wire is stronger if wire length is ( 2 mathrm{m} ) and carries a 10 -amp current : A .2 B. ( 2 sqrt{2} ) ( c cdot 4 ) D. ( 4 sqrt{2} ) ( E ) |
12 |

1068 | An infintely long straight wire carrying current of ( 10 mathrm{A} ) is passing through the centre of the above circuit vertically with the direction of the current being into the plane of the circuit.What is the force acting on the wire at the centre due to the current in the circuit?What is the force acting on the arc ( A C ) and the straight segment CD due to the current at the centre? |
12 |

1069 | In a moving cell galvanometer, we use a radial magnetic field so that the galvanometer scale is A. logarithmic B. exponential c. linear D. none of the above |
12 |

1070 | Three moving coil galvanometer ( boldsymbol{A}, boldsymbol{B} ) and ( C ) are made of coils of three different material having torsional constant ( 1.8 times 10^{-8}, 2.8 times 10^{-8} ) and ( 3.8 times 10^{-8} ) respectively. If the three galvanometers are identical in all other respect, then in which of the above cases, current sensitivity is maximum? A. ( A ) в. ( C ) ( c . B ) D. same in each case |
12 |

1071 | Non-relativistic protons move reactilinearly in the region of space where there are uniform mutually perpendicular electric and magnetic fields with E and B. The trajectory of the protons lie in the plane ( X ) -Y as shown in fig. and forms an angle ( phi phi ) with ( X ) -axis. If the pitch of the helical trajectory along which the protons will move after the electric field is switched off is Pitch ( =frac{boldsymbol{x} boldsymbol{pi} boldsymbol{m} boldsymbol{E}}{boldsymbol{q} boldsymbol{B}^{2}} boldsymbol{t a n} boldsymbol{phi} ). Find ( boldsymbol{x} ) |
12 |

1072 | Two long, thin, parallel conductors separated by a distance carry currents ( i_{1} ) and ( i_{2} . ) The force per unit length on one of them is F. Then This question has multiple correct options ( mathbf{A} cdot F proptoleft(i_{1} i_{2}right) ) B . ( F proptoleft(i_{1} i_{2}right)^{2} ) ( mathbf{c} cdot F propto frac{1}{d^{2}} ) ( D cdot F propto frac{1}{d} ) |
12 |

1073 | A current carrying ring is placed in a magnetic field. The direction of the field is perpendicular to the plane of the ring. Which of the following correct for this? This question has multiple correct options A. There is no net force on the ring B. The ring will tend to expand c. The ring will tend to contract (b) or D. Either (c) depending on the directions of the current in the ring and the magnetic field |
12 |

1074 | ( boldsymbol{x}=mathbf{0}, boldsymbol{y}=mathbf{0}, boldsymbol{z}=+mathbf{0 . 5 0 0 m} ) | 12 |

1075 | The relation between magnetic field and current is given by Biot-Savart law. Illustrate Biot-Savart law with necessary figure. |
12 |

1076 | How does doubling number of turns in a toroidal coil affect the value of magnetic flux density? A. Four times B. Eight times c. Half D. Double |
12 |

1077 | Two long thin conductors ( 10 mathrm{cm} ) apart carry currents in the ratio 1: 2 in the same direction. The magnetic field midway between them is ( 2 times 10^{-3} ) Tesla. The force on 1 metre length of any conductor will be : ( mathbf{A} cdot 2 pi times 10^{-3} ) Newton B. ( 2 times 10^{-3} ) Newton c. ( pi ) Newton D. 1 Newton |
12 |

1078 | If the galvanometer shows no deflection then the value of ( mathrm{R} ) for the circuit shown in the figure is ( length ( A B=100 mathrm{cm} ) ) A. 30 ohms B. 60 ohms ( c .10 ) ohms D. 120 ohms |
12 |

1079 | Assertion The magnetic field produced by a current carrying solenoid Is independent of its length and cross- sectional area. Reason The magnetic field inside the solenoid is uniform. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |

1080 | Assertion When current is represented by a straight line, the magnetic field will be circular. Reason According to Fleming’s left hand rule, direction of force is parallel to the magnetic field A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
12 |

1081 | A wire bent as shown in Fig is oriented along yz plane. Find the magnetic field at ( P ) and ( P_{1} ) A ( cdot frac{mu_{0} I}{4 a}, frac{mu_{0} I}{2 pi x_{x}} ) B. ( frac{mu I}{4 a}, frac{mu I}{2 pileft(x^{2}+a^{2}right)} ) C. ( frac{mu_{0} I}{4 a}, frac{mu_{0} I}{2 pi aleft(x^{2}+a^{2}right)} ) D. none of thes |
12 |

1082 | If a positively charged particle is moving as shown in the figure, then it will get deflected due to magnetic field towards: A . ( +x ) direction B. +y direction c. – x direction D. tz direction |
12 |

1083 | Fleming’s left hand rule tells us about direction of magnetic force due to current in magnetic field, but what is its magnitude? |
12 |

1084 | The nature of the magnetic field in a moving coil galvanometer is Radial magnetic field. State True or False. | 12 |

1085 | A toroid with mean radius ( r_{0} ) and diameter ( 2 a ) has ( N ) turns carrying current I. What is the magnetic field B inside the toroid? A ( cdot frac{mu_{0} N I}{2 pi r_{0}} ) В. ( frac{mu_{0} N I}{2 pileft(r_{0}+aright)} ) c. ( frac{mu_{0} N I}{pileft(r_{0}+aright)} ) D. zero |
12 |

1086 | Two parallel wires each of length ( 5 m ) are placed at a distance of ( 10 mathrm{cm} ) apart in air. They carry equal currents along the same direction and experience a mutually attractive force of ( 3.6 times ) ( 10^{-4} N . ) Find the current through the conductors. |
12 |

1087 | The galvanometer deflection, when key ( K_{1} ) is closed but ( K_{2} ) is open, equals ( theta_{0} ) (see figure). On closing ( K_{2} ) also and adjusting ( R_{2} ) to5 ( Omega, ) the deflection in galvanometer becomes ( frac{theta_{0}}{5} ). The resistance of the galvanometer is, then, given by [Neglect the internal resistance of battery ( ] ) A . ( 12 Omega ) B . ( 25 Omega ) ( c .5 Omega ) D. ( 22 Omega ) |
12 |

1088 | Derive an expression for the force per unit length acting on the two straight parallel current carrying conductors. In which condition will this force be attractive and repulsive? Define the standard unit of current |
12 |

1089 | A closely wound, circular coil with radius ( 2.40 mathrm{cm} ) has 800 turns. The distance ( x ) from the centre of the coil, along the axis, at which the magnetic field is half of its value at the centre, is ( 184 times 10^{-x} m . ) Find the value of ( x ) |
12 |

1090 | The strength of an electromagnet can be increased by. A. increasing the current in the coil B. decreasing the current in the coil c. decreasing the number of turns in the coil D. increasing the length of air gap between its poles |
12 |

1091 | An elastic circular wire of length ( ell ) carries a current ( I_{0} . ) It is placed in a uniform magnetic field ( vec{B} ) (out of paper) such that its plane is perpendicular to the direction of ( vec{B} ). The wire will experience: A. No force B. A stretching force c. A compressive force D. A touque |
12 |

1092 | Assertion No net force acts on a rectangular coil carrying a steady current when suspended freely in a uniform magnetic field. Reason Force on coil in magnetic field is always non-zero. A. If both Assertion and Reason are correct and Reason is the correct explanation of Assertion. B. If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion. C. If Assertion is correct but Reason is incorrect. D. If Assertion is incorrect but Reason is correct. |
12 |

1093 | ( underbrace{ } ) | 12 |

1094 | A rectangular loop carrying a current is situated near a long straight wire such that the wire is parallel to the one of the sides of the loop and is in the plane of the loop. If a steady current lis established in wire as shown in figure, the loop will: A. rotate about an axis parallel to the wire B. move away from the wire or towards right c. move towards the wire D. remain stationary |
12 |

1095 | Two identical circular loops PP. | 12 |

1096 | ( A 25 mathrm{cm} ) long solenoid has radius ( 2 mathrm{cm} ) and 500 total number of turns. It carries a current of 15 A. If it is equivalent to magnet of the same size and magnetization ( vec{M} ) Magnetic moment vloume), then ( overrightarrow{|M|} ) is. B. 30000Am” c. ( 30000 pi A m^{-1} ) D. ( 3 pi A m^{-1} ) |
12 |

1097 | If the force per unit length on wire ( boldsymbol{B} ) is given by ( 2.88 times 10^{-x} N m^{-1} . ) Find ( x ) |
12 |

1098 | The self-inductance of an air core solenoid of 100 turns is 1 m ( H ). The self- inductance of another Solenoid of 50 turns (with the same length and crosssectional area) with a core having relative permeability 500 is A . ( 125 mathrm{mH} ) B. 24 mH c. ( 60 mathrm{mH} ) D. 30 mH E. ( 45 mathrm{mH} ) |
12 |

1099 | The electric current in a circular coil of two turns produced a magnetic induction of ( 0.2 T ) at its centre. The coil is unwound and is rewound into a circular coil of four turns. The magnetic induction at the centre of the coil now is, in ( T: ) (if same current flows in the coil) A . 0.2 B. 0.4 ( c .0 .6 ) D. 0.8 |
12 |

1100 | A positively charged disk is rotated clockwise as shown in the figure. The direction of the magnetic field at point ( A ) in the plane of the disk is ( A cdot otimes ) into the page B. ( rightarrow ) towards right ( mathbf{c} . leftarrow ) towards left D. odot out of the page |
12 |

1101 | If ( 6 mathrm{mm} ) is the distance moved by the thimble on the main scale for 6 rotations then pitch of the screw is : ( mathbf{A} cdot 1 mathrm{mm} ) B. ( 1 mathrm{cm} ) ( c .0 .1 mathrm{mm} ) D. 0.01 cm |
12 |

1102 | The magnetic lines of force inside a current carrying solenoid are: A. along the axis and parallel to each other B. perpendicular to the axis and parallel to each other c. circular and do not intersect each other D. circular and intersect each other |
12 |

1103 | A beam of cathode rays moves from left to right in a plane of the paper and it enters into a uniform magnetic field acting perpendicular to the plane of the paper and inwards. Now, the cathode rays are deflected: A. Downwards B. Upwards c. In a direction perpendicular to the plane of the paper and inwards D. In a direction perpendicular to the plane of the paper and outwards |
12 |

1104 | The coil of the moving coil galvanometer is wound over an aluminium frame A. because aluminium is a good conductor B. because aluminium is very light. c. because aluminium is comparatively cheaper D. to provide electro-magnetic damping. |
12 |

1105 | A wire carrying a current of ( 5 A ) is placed perpendicular to a magnetic induction of ( 2 T . ) The force on each centimeter of the wire is A. ( 0.1 N ) в. ( 10 N ) c. ( 100 N ) D. ( 1 N ) |
12 |

1106 | How will crowding the wires of a solenoid, more closely together, will affect the strength of the field inside it? A. Field strength increases B. Field strength decreases c. Can’t be said D. Field strength will remain unchanged |
12 |

1107 | A solenoid of length ( 1.0 m, ) radius ( 1 mathrm{cm} ) and total turns 1000 wound on it, carries a current of 5 A. Calculate the magnitude of the axial magnetic field inside the solenoid. If an element was to move with a speed of ( 104 m / s ) along the axis of this current carrying solenoid, what would be the force experienced by this electron? |
12 |

1108 | Obtain an expression for the self- inductance of a long solenoid. |
12 |

1109 | Electrons at rest are accelerated by a potential of ( boldsymbol{V} ) volt. These electrons enter the region of space having a uniform, perpendicular magnetic induction field ( B ). The radius of the path of the electrons inside the magnetic field is: A ( .1 / B sqrt{m V / e} ) B. ( frac{sqrt{2 m V / e}}{B} ) c. ( m V / q B ) D. ( 1 / B sqrt{V / e} ) |
12 |

1110 | A uniform electric field and a uniform magnetic field acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity, then A. It will turn towards left of direction of motion B. It will turn towards right to direction of motion c. Its velocity will increase D. Its velocity will decrease |
12 |

1111 | Draw a labelled diagram showing the magnetic field lines of a loop carrying current. Mark the direction of current and the direction of magnetic field by arrows in your diagram. |
12 |

1112 | Two particles ( X ) and ( Y ) having equal charges, after being accelerated through the same potential difference, enter a region of uniform magnetic field and describe circular paths of radii ( boldsymbol{R}_{1} ) and ( R_{2}, ) respectively. The ratio of masses of ( X ) and ( Y ) is ( ^{mathbf{A}} cdotleft(frac{R_{1}}{R_{2}}right)^{1 / 2} ) B. ( left(frac{R_{2}}{R_{1}}right) ) ( ^{mathbf{c}} cdotleft(frac{R_{1}}{R_{2}}right)^{2} ) D. ( left(frac{R_{1}}{R_{2}}right) ) |
12 |

1113 | toppr LOGIN JolN Now Q Type your question Which table gives the correct directions for the magnetic field at the two positions around the wire? wire field on right side of (6) wire head on with conventional current flow out of page ( A ) begin{tabular}{|l|l|} hline & Direction of Field \ hline Right of the Wire & toward right side of page \ Below the Wire & toward bottom of page \ hline end{tabular} B. begin{tabular}{|l|c|} hline & Direction of Field \ hline Right of the Wire & toward left of page \ Below the Wire & toward top of page \ hline end{tabular} ( mathbf{c} ) begin{tabular}{|l|l|} hline & Direction of Field \ hline Right of the Wire & toward top of page \ Below the Wire & toward right side of page \ hline end{tabular} D. begin{tabular}{|l|l|} hline & Direction of Field \ hline Right of the Wire & toward bottom of page \ Below the Wire & toward left side of page \ hline end{tabular} ( E ) begin{tabular}{|l|l|} hline & Direction of Field \ hline Right of the Wire & toward lower left portion of page \ Below the Wire & toward upper right portion of page \ hline end{tabular} |
12 |

1114 | Draw the magnetic field lines of the field produced by a current carrying circular loop. Explain with reason whether the field will be stronger at a point at the center of loop or near the circumference of loop. |
12 |

1115 | A long horizontal rigidly supported wire carries a current ( i_{a}=96 A . ) Directly above it and parallel to it at a distance, another wire of ( 0.144 N ) weight per metre is carrying a current ( i_{b}=24 A, ) in a direction same as the lower wire. If the weight of the second wire is balanced by the force due to magnetic repulsion, then its distance (in mm) from the lower wire is: A . 9.6 B. 4.8 c. 3.2 D. 1.6 |
12 |

1116 | In which case would the particle move in a straight line along the negative direction of y-axis (i.e., move along – ( hat{y} ) )? A. ( (I I I)(i i)(P) ) B . ( (I I)(i i i)(Q) ) c. ( (I V)(i i)(S) ) D. ( (I I I)(i i)(R) ) |
12 |

1117 | ( A, B ) and ( C ) are parallel conductors of equal lengths carrying currents ( boldsymbol{I}, boldsymbol{I} ) and ( 2 I ) respectively. Distance between ( A ) and ( B ) is ( x . ) Distance between ( B ) and ( C ) is also ( x . F_{1} ) is the force exerted by ( B ) on ( A . F_{2} ) is the force exerted by ( C ) on ( A ) Choose the correct answer. ( mathbf{A} cdot F_{1}=2 F_{2} ) B . ( F_{2}=2 F_{1} ) ( mathbf{c} cdot F_{1}=F_{2} ) D. ( F_{1}=-F_{2} ) |
12 |

1118 | toppr Q Type your question_ constant speed. The field deflects the particle, a distance h above the original line of flight as shown in the Figure. The particle leaves the field region with momentum, if ( h<<d, ) of about : ( frac{q B d^{2}}{2 h}, ) making an angle ( frac{2 h}{d} ) with initial direction B. ( frac{q B h^{2}}{2 d}, ) making an angle ( frac{2 h}{d} ) with initial direction ( frac{q B d}{2}, ) making an angle ( frac{2 d}{h} ) with initial direction ( frac{q B h}{2}, ) making an angle ( frac{2 d}{h} ) with initial direction |
12 |

1119 | An electron passes undeflected through perpendicular electric and magnetic fields of intensity ( 3.4 times ) ( mathbf{1 0}^{mathbf{3}} boldsymbol{V} / boldsymbol{m} ) and ( mathbf{2} times mathbf{1 0}^{-mathbf{3}} boldsymbol{W} boldsymbol{b} / boldsymbol{m}^{mathbf{2}} ) respectively. Then its velocity is: A ( .1 .7 times 10^{6} mathrm{m} / mathrm{s} ) B . ( 6.8 times 10^{6} mathrm{m} / mathrm{s} ) ( c cdot 6.8 m / s ) D. ( 1.7 times 10^{8} mathrm{m} / mathrm{s} ) |
12 |

1120 | A rectangular loop, carrying current ( i, ) is lying near a long straight conductor PQ as shown in the figure in such way that the wire is parallel to one of the sides of the loop and is in the plane of the loop. If constant current ( I ) is passed in the wire then the loop will A. move towards the wire B. move away from the wire c. remain stationary D. rotate about an axis parallel to the wircre |
12 |

1121 | In cyclotron, for a given magnet, radius of the semicircle traced by positive ion is directly proportional to (v=velocity of positron ion) A ( cdot v^{-2} ) B . ( v^{-1} ) ( c ) ( D cdot v^{2} ) |
12 |

1122 | A planar coil of area ( 7 mathrm{m}^{2} ) carrying an anti-clockwise current 2 A is placed in an extemal magnetic field ( vec{B}=(0.2 hat{i}+ ) ( 0.2 hat{j}-0.3 hat{k}), ) such that the normal to the plane is along the ( operatorname{line}(3 hat{i}-5 hat{j}+ ) 4 ( hat{k} ) ). Select correct statements from the following. ( Consider Normal of the coil and Magnetic moment vectors to be in the same direction This question has multiple correct options A. The potential energy of the coil in the given orientation is 6.4 B. The angle between the normal (positive) to the coil and the external magnetic field is ( cos ^{-1}(0.57) ) c. The potential energy of the coil in the given orientation is 3.2 D. The magnitude of magnetic moment of the coil is about ( 14 A m^{2} ) |
12 |

1123 | Derive expression for the self inductance of a solenoid. What factors affect it? |
12 |

1124 | A long straight wire is carrying current ( boldsymbol{I}_{1}=mathbf{2} / mathbf{5} boldsymbol{A} ) in ( +mathbf{z} ) direction.The ( mathbf{x}-mathbf{y} ) plane contains a closed circular loop carrying current ( boldsymbol{I}_{2}=mathbf{5} / mathbf{2} boldsymbol{A} ) and not encircling the straight wire, then the force (in newton) on the loop will be ? (Radius of the circular loop ( boldsymbol{R}=mathbf{3} / mathbf{4 m} ) ). |
12 |

1125 | A small magnet is placed perpendicular to a uniform magnet field. The forces acting on the magnet will result in : A. Rotational motion B. Translatory motion c. No motion at al D. Translational and rotational motion both |
12 |

1126 | I wo very long stralght parallel wires having current ( I ) and ( 2 I ) as shown in the figure. A point charge ( q ) is at a point equidistant from the two wires in the plane of the wires. Its instantaneous velocity ( bar{v} ) is parallel to currents in the plane. The magnitude of force due to the magnetic field acting on the charge at this instant is: A ( cdot frac{q v mu_{0} l}{2 pi d} ) B. ( frac{2 q v mu_{0} l}{3 pi d} ) C. ( frac{6 q v mu_{0} l}{2 pi d} ) D. ( frac{q v mu_{0} l}{pi d} ) |
12 |

1127 | A current-carrying circular coil of magnetic moment ( M ) is situated in a magnetic field ( B ). The work done in deflecting it from an angle ( 0^{circ} ) to ( theta^{circ} ) will be : ( A . M B ) В. ( M B(1-cos theta) ) ( mathrm{c} cdot-M B ) D. ( M B(1-sin theta) ) |
12 |

1128 | Draw a neat and labelled diagram of suspended coil type moving coil galvanometer. |
12 |

1129 | If only ( 2 % ) of the main current is to be passed through a Galvanometer of resistance ( G, ) the resistance of shunt should be : A. ( G / 50 ) в. ( G / 49 ) c. ( 50 / G ) D. ( 49 G ) |
12 |

1130 | Two thin long parallel wires separated by a distance ( b ) are carrying a current ( I ) ampere each. The magnitude of the force per unit length exerted by one wire on the other is A ( frac{mu_{0} I^{2}}{b^{2}} ) в. ( frac{mu_{0} I^{2}}{2 pi b} ) c. ( frac{mu_{0} I}{2 pi b} ) D. ( frac{mu_{0} I}{2 pi b^{2}} ) |
12 |

1131 | The ratio of the magnetic field at the centre of a current carrying circular wire and the magnetic field at the centre of a square coil made from the same length of wire is A ( cdot frac{pi}{2 sqrt{2}} ) в. ( frac{pi}{4 sqrt{2}} ) c. ( frac{pi^{2}}{4 sqrt{2}} ) D. ( frac{pi^{2}}{8 sqrt{2}} ) |
12 |

1132 | When a galvanometer is shunted with a ( 4 Omega ) resistance, the deflection is reduced to one – fifth. If the galvanometer is further shunted with a ( 2 Omega ) wire, determine current in galvanometer now if initially current in galvanometer is ( I_{0} ) (given main current remain same). A ( cdot I_{0} / 13 ) the в. ( I_{0} / 5 ) c. ( I_{0} / 8 ) D. ( 5 I_{0} / 13 ) |
12 |

1133 | A wire of length ( l ) carries a current ( i ) along the ( x ) -axis.A magnetic field ( vec{B}= ) ( B_{o}(hat{j}+hat{k}) ) exists in the space.Find the magnitude of the magnetic force acting on the wire. |
12 |

1134 | A proton enters a magnetic field of flux density ( 1.5 W b / m^{2} ) with a speed of ( 2 times ) ( 10^{7} mathrm{m} / mathrm{s} ) at angle of ( 30^{circ} ) with the field. The force on a proton will be A. ( 0.44 times 10^{-12} N ) B . ( 2.4 times 10^{-12} N ) c. ( 24 times 10^{-12} N ) D. ( 0.024 times 10^{-12} N ) |
12 |

1135 | Can cyclotron accelerate uncharged particles?Why? |
12 |

1136 | The strength of magnetic field inside a long current carrying straight solenoid is: A. more at the ends than at the centre B. minimum in the middle c. same at all points D. found to increase from one end to the other |
12 |

1137 | A wire carrying current of ( 10 A ) supports a wire of ( 10 mathrm{cm} ) long and weighing ( 1 mathrm{g} ) vertically above it at a distance of ( 1 mathrm{cm} ) The current that is passing through the wire is : ( mathbf{A} cdot 490 A ) B . ( 205 A ) ( c cdot 408 A ) D. ( 316 A ) |
12 |

1138 | In an hydrogen atom, the electron is making ( 6.6 times 10^{15} )rps. If the radius of the orbit is ( 0.53 times 10^{-10} m, ) then the equivalent magnetic dipole moment is approximately ( mathbf{A} cdot 10^{-29} A m^{2} ) B . ( 10^{-27} mathrm{Am}^{2} ) c. ( 10^{-23} A m^{2} ) D. ( 10^{-19} mathrm{Am}^{2} ) |
12 |

1139 | A solenoid has a core of a material with relative permeability of 500. The windings of the solenoid are insulated from the core and carry a current of ( 2 mathrm{A} ) If the number of turns is 1000 per meter, then magnetisation will be then A . ( 7.78 times 10^{5} mathrm{Am}^{-1} ) В. ( 8.88 times 10^{5} mathrm{Am}^{-1} ) c. ( 9.98 times 10^{5} mathrm{Am}^{-} ) D. ( 10.2 times 10^{5} mathrm{Am}^{-1} ) |
12 |

1140 | A free charged particle moves through a magnetic field. The particle may undergo a change in A. Speed B. Energy c. Direction of motion D. None of these |
12 |

1141 | A uniformly charged ring of radius ( R ) is rotated about its axis with constant linear speed ( v ) of each of it’s particles. The ratio of electric field to magnetic field at a point ( boldsymbol{P} ) on the axis of the ring at a distant ( x=R ) from the centre of the ring is : ( (c text { is speed of light }) ) A ( frac{c^{2}}{v} ) в. ( frac{v^{2}}{c} ) c. ( frac{c}{v} ) ( D cdot underline{v} ) |
12 |

1142 | A solenoid of length ( 50 mathrm{cm}, ) having 100 turns carries a current of 2.5 A. The magnetic field at one end of the solenoid is: A. 3.14 ( times 10^{4} ) न B. 6.28 ( times 10^{4} ) Т c. ( 1.57 times 10^{4} ) न D. 9.42 ( times 10^{4} ) न |
12 |

1143 | Shunt wire should be ( A ). Thick and long B. Thick and short c. Thin and long D. Thin and short |
12 |

1144 | The magnetic field of a solenoid carrying a current is similar to that of a B. bar magnet c. toroid D. none |
12 |

1145 | toppr Q Type your question from point ( P ) to ( Q ) as shown in figure. The velocities at ( P ) and ( Q ) are respectively, ( boldsymbol{v} overrightarrow{boldsymbol{i}} ) and ( -2 v vec{j} . ) Then which of the following statements ( (A, B, C, D) ) are the correct? (Trajectory shown in schematic and not to scale) ( (mathbf{A}) boldsymbol{E}=frac{mathbf{3}}{mathbf{4}}left(frac{boldsymbol{m} boldsymbol{v}^{2}}{boldsymbol{q} boldsymbol{a}}right) ) (B) Rate of work done by the electric field at ( P ) is ( frac{3}{4}left(frac{m v^{3}}{a}right) ) (C) Rate of work done by both the fields at Qis zero (D) The difference between the magnitude of angular momentum of the particle at ( P ) and ( Q ) is 2 mav. ( A cdot(A),(B),(C),(D) ) B. ( (A),(C),(D) ) ( c cdot(B),(C),(D) ) D. ( (A),(B),(C) ) |
12 |

1146 | Two parallel wires ( 1 m ) apart carry currents of ( 1 A ) and ( 3 A ) respectively in opposite directions. The force per unit length acting between these two wires is A ( .6 times 10^{-7} mathrm{Nm}^{-1} ) repulsive B. ( 6 times 10^{-7} mathrm{Nm}^{-1} ) attractive c. ( 6 times 10^{-5} mathrm{Nm}^{-1} )repulsive D. ( 6 times 10^{-5} mathrm{Nm}^{-1} ) attractive |
12 |

1147 | Why does a current carrying freely suspended solenoid rest along a particular direction? A. It points towards the geometric poles of the earth B. A current carrying solenoid behaves like a bar magnet C. It points in the direction of the flow of current D. None of the above |
12 |

1148 | The work done in turning a magnet of magnetic moment ( M ) by an angle of ( 90^{circ} ) from the meridian is ( n ) times the corresponding work done to turn it through an angle of ( 60^{circ} ) from the meridian, where ( n ) is given by : A ( cdot frac{1}{2} ) B. 2 ( c cdot frac{1}{4} ) D. |
12 |

1149 | A long straight wire along the z-axis carries a current lin the negative z direction. The magnetic vector field ( bar{B} ) at a point having coordinates ( (x, y) ) in the z=0 plane is: A ( cdot frac{mu_{0} I(y hat{i}-x hat{j})}{2 pileft(x^{2}+y^{2}right)} ) B. ( frac{mu_{0} I(x hat{i}-y hat{j})}{2 pileft(x^{2}+y^{2}right)} ) c. ( frac{mu_{0} I(x hat{j}-y hat{i})}{4 pileft(x^{2}+y^{2}right)} ) D. ( frac{mu_{0} I(x hat{i}-y hat{j})}{4 pileft(x^{2}+y^{2}right)} ) |
12 |

1150 | An ( alpha ) – particle moves from ( mathrm{E} ) to ( mathrm{W} ) in a magnetic field perpendicular to the plane of the paper and into the paper. The particle is deflected towards: A. East B. west c. south D. North |
12 |

1151 | The force that a magnetic field exerts on a current is always perpendicular to A. Field B. Velocity c. current D. All of the above |
12 |

1152 | mounted on one end of a balance beam and introduced between the poles of an electromagnet as shown in fig. The area of the coil is ( S=1 c m^{2}, ) the length of the right arm of the balance beam is ( l= ) ( 30 mathrm{cm} . ) When there is no current in the coil the balance is in equilibrium. On passing a current ( I=22 m A ) through the coil, equilibrium is restored by putting an additional weight of mass ( boldsymbol{m}=mathbf{6 0} mathrm{mg} ) on the balance pan. Find the magnetic induction field (in terms of ( left.times 10^{-1} Tright) ) between the poles of the electromagnet, assuming it to be uniform: |
12 |

1153 | Identify the odd one out: Magnet, Solenoid, Compass needle, Oven. |
12 |

1154 | State Ampere’s circuital law and arrive at the expression for the magnetic field near a straight infinite current carrying wire. |
12 |

1155 | A magnetic field due to a long straight wire carrying a current I is proportional to ( A ) B . ( I^{2} ) c. ( I^{3} ) D. ( sqrt{I} ) |
12 |

1156 | Assertion no electric current will be present within a region having uniform and constant magnetic field. Reason Within a region of uniform and constant magnetic field ( vec{B} ), the path integral of magnetic field ( oint vec{B} cdot overrightarrow{d l} ) along any closed path is zero. Hence, from Ampere circuital law ( oint vec{B} cdot overrightarrow{d l}=mu_{0} I ) (where the given terms have usual meaning), no current can be present within a region having a uniform and constant magnetic field A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
12 |

1157 | A current carrying small loop of one turn behaves like a small magnet. If ( A ) be its area, ( M ) its magnetic moment, the current in the loop will be A ( cdot frac{M}{A} ) в. ( frac{A}{M} ) c. ( M A ) D. ( A^{2} M ) |
12 |

1158 | Two protons move parallel to each other, keeping distance r between them, both moving with same velocity ( overrightarrow{mathrm{v}} ). Then the ratio of the electric and magnetic force of interaction between them is: (c – Velocity of light) A ( cdot mathrm{c}^{2} / mathrm{v}^{2} ) B ( cdot 2 c^{2} / v^{2} ) c. ( c^{2} / 2 v^{2} ) D. none |
12 |

1159 | The unit of reduction factor of tangent galvanometer is A. Ampere B. Gauss c. Radian D. No units |
12 |

1160 | Under what conditions permanent electromagnet is obtained if a current carrying solenoid is used? Support your answer with the help of a labelled circuit diagram. |
12 |

1161 | If the galvanometer reading is zero in the gives circuit, the current passing through resistance ( 250 Omega ) is A . 0.016 A B. 0.16 A ( c cdot 0.032 mathrm{A} ) D. 0.042 A |
12 |

1162 | A wire loop ( P Q R S ) formed by joining two semi-circular wires of radii ( boldsymbol{R}_{1} ) and ( R_{2} ) carries a current ( I ) as shown in the following diagram. The magnetic induction at the centre ( O ) is A ( cdot frac{mu_{0} I}{4 R_{1}} ) в. ( frac{mu_{0} I}{4 R_{2}} ) c. ( frac{mu_{0}}{4 pi} Ileft(frac{1}{R_{1}}-frac{1}{R_{2}}right) ) D ( cdot frac{mu_{0}}{4} Ileft(frac{1}{R_{1}}+frac{1}{R_{2}}right) ) |
12 |

1163 | Assertion Magnetic force on a moving charge is always perpendicular to the magnetic field. Reason Electric force on a charge is along the direction of electric field. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
12 |

1164 | A given length of wire can be bent to form a circle or a square of single turn and a current may be established in it. The ratio of magnetic field at the centre of circle to that at the centre of square is : A ( cdot frac{pi^{2}}{8 sqrt{2}} ) B. ( frac{4 sqrt{2}}{pi^{2}} ) c. ( frac{pi}{2 sqrt{2}} ) D. |
12 |

1165 | Which of the following is likely to have the largest resistance? A. Voltmeter of range 10 v B. Moving coil galvanometer c. Ammeter of range 1 A D. A copper wire of length ( 1 mathrm{m} ) and diamete |
12 |

1166 | A magnetizing field of ( 1600 mathrm{A} / mathrm{m} ) producers a magnetic flux of ( 2 times 10^{-5} ) Wh in a bar of iron of cross section ( 0.2 x ) ( 10^{-4} m^{2} . ) Calculate the susceptibility of the bar. A . 596.8 B . 288.9 ( c cdot 2 ) D. 1328 |
12 |

1167 | Which of the following figures represents the magnetic lines of force due to an isolated north pole? ( A ) B. ( c . ) Both D. None |
12 |

1168 | A proton travels few distance in an electric field, then it enters a crossed magnetic field of ( 1 mathrm{T} ) and radius ( 0.2 mathrm{m} ) Find the velocity of proton. A ( cdot 0.2 times 10^{8} mathrm{ms}^{-1} ) В. ( 0.2 times 10^{7} mathrm{ms}^{-1} ) ( c cdot 0.2 times 10^{6} m s^{-1} ) ( – ) D. ( 2 times 10^{8} mathrm{ms}^{-1} ) |
12 |

1169 | Two circular coils of radii ( 5 mathrm{cm} ) and 10 cm carry currents of 2 A.The coils have 50 and 100 turns respectively and are placed in such a way that their planes as well as their centres coincide.Magnitude of magnetic field at the common centre of coil is This question has multiple correct options A. ( 8 pi times 10^{-4} T ) if currents in the coils are in same ser B . ( 4 pi times 10^{-4} T ) if currents in the coils are in opposite sense c. zero if currents in the coils are in opposite sense D. ( 8 pi times 10^{-4} T ) if currents in the coils are in opposite sense |
12 |

1170 | Show that in an ideal toroid the magnetic field outside the toroid at any point in the open space is zero. |
12 |

1171 | In order to increase the sensitivity of a moving coil galvanometer: A. the magnetic field should be increased B. the suspension wire should be made stiff. c. the area of the coil should be reduced D. the number of turns in the coil should be reduced |
12 |

1172 | Two parallel conductors ( P ) and ( Q ) of equal lengths carry currents I and ( 5 I ) respectively in the same direction, then. A. They will repel each other with the same force B. They will attract each other with the same force c. A will attract but B will repel D. B will attract but A will repel |
12 |

1173 | Figure below shows two infinitely long and thin current carrying conductors ( boldsymbol{X} ) and ( Y ) kept in vacuum, parallel to each other, at a distance ‘a Define ampere, in terms of force between two current carrying conductors |
12 |

1174 | In a tangent galvanometer a current of ( 0.1 A ) produces a deflection of ( 30^{circ} . ) The current required to produced a deflection of ( 60^{circ} ) is A . ( 0.2 A ) в. ( 0.3 A ) ( c .0 .4 A ) D. ( 0.5 A ) |
12 |

1175 | In terms of potential difference ( V ) electric current I, permittivity ( varepsilon_{0} ) permeability ( mu_{0} ) and speed of light ( c, ) the dimensionally correct equation(s) is(are). This question has multiple correct options A ( cdot mu_{0} I^{2}=varepsilon_{0} V^{2} ) В ( cdot varepsilon_{0} I=mu_{0} V ) c. ( I=varepsilon_{0} c V ) D. ( mu_{0} c l=varepsilon_{0} V ) |
12 |

1176 | Two very long, straight wires carrying currents as shown in figure. Find all locations where the net magnetic field is zero ( y=sqrt{2} x ) ( x ) в. ( y=x ) c. ( y=-x ) D. ( y=-(x / 2) ) |
12 |

1177 | Ampere rule is used to find the A. direction of current B. direction of magnetic field C. direction of motion of the conductor D. magnitude of current |
12 |

1178 | Which of the following is true for a toroid? A. low inductance and ( Q ) factor B. high inductance and Q factor c. high inductance and low ( mathrm{Q} ) -factor D. low inductance and high ( mathrm{Q} ) -factor |
12 |

1179 | In the shown figure a current 2i is flowing in a straight conductor and entering along the diameter of the circular loop of similar conductor through the point A. The current is leaving the loop along another similar semi-infinite conductor parallel to the plane of the loop through the other opposite end D of the diameter. |
12 |

1180 | The dipole moment of a current loop is independent of A. current in the loop B. number of turns c. area of the loop D. magnetic field in which it is situated |
12 |

1181 | A long wire carries a current of ( 20 A ) long the axis of a solenoid, the field due to the solenoid is 4 mT. The resultant field at a point 3 mm from the solenoid axis is : A. ( 1.33 mathrm{mT} ) в. ( 4.2 mathrm{mT} ) c. ( 2.1 m T ) D. ( 8.4 mathrm{mT} ) |
12 |

1182 | Let ( left[varepsilon_{o}right] ) denote the dimensional formula of the permittivity of the vacuum, and ( left[mu_{o}right] ) that of the permeability of the vacuum. If ( mathrm{M}= ) mass, ( mathrm{L}= ) length, ( mathrm{T}= ) time and I = electric current. This question has multiple correct options A ( cdotleft[mu_{o}right]=M^{-1} L^{-3} T^{2} I ) B . ( left[varepsilon_{o}right]=M^{-1} L^{-3} T^{4} I^{2} ) c. ( left[mu_{o}right]=M L T^{-2} I^{-2} ) ( mathbf{D} cdotleft[mu_{o}right]=M L^{2} T^{-1} I ) |
12 |

1183 | Assertion: When radius of a circular wire carrying current is doubled, its magnetic moment becomes four times Reason: Magnetic moment is directly proportional to area of the loop A. Both A and R are true and R is the correct explanation of A. B. Both ( A ) and ( R ) are true and ( R ) is not correct explanation of A. C. ( A ) is true, but ( R ) is false D. A is false, but R is true |
12 |

1184 | Ratio of electric and magnetic field due to moving point charge if its speed is ( 4.5 times 10^{5} mathrm{m} / mathrm{s} ) A ( .2 times 10^{1} ) B . ( 3 times 10^{11} ) ( c cdot 2 times 10^{8} ) D. ( 3 times 10^{12} ) |
12 |

1185 | A wire carrying a current of ( 5 mathrm{A} ) is placed perpendicular to a magnetic induction of 2T.The force on each centimeter of the wire is A . ( 0.1 mathrm{N} ) B. 10 N ( c cdot 100 N ) D. 1 N |
12 |

1186 | In Fleming’s left hand rule, thumb shows direction of A. current B. Field c. Motion D. charge |
12 |

1187 | Two wires are pictured below, both carrying current toward the east. What is the direction of the force exerted by wire 2 on wire ( 1 ? ) North West A. north B. south c. up D. down E. east |
12 |

1188 | The magnetic moment of an electron with orbital angular momentum ( boldsymbol{J} ) will be: ( ^{mathbf{A}} cdot frac{e vec{J}}{m} ) B. ( frac{e vec{J}}{2 m} ) c. ( frac{2 m}{e bar{J}} ) D. zero |
12 |

1189 | Find out the following in the electric circuit given in Figure. Difference in reading of ammeter ( boldsymbol{A}_{mathbf{1}} ) |
12 |

1190 | A wire is placed to the lines of force in a magnetic field and a current flows in the wire. Then A. the wire will experience a force in the direction of magnetic field B. the wire will not experience any force at all C. the wire will experience a force in a direction opposite to the field D. it experiences a force in a direction perpendicular to lines of force |
12 |

1191 | A long solenoid has 200 turns per cm and carries a current ( I ). The magnetic field at its centre is ( 6.28 times ) ( 10^{-2} W b / m^{2} . ) Another long solenoid has 100 turns per cm and it carries a current ( I / 3 . ) The value of the magnetic field at its centre is A ( cdot 1.05 times 10^{-2} mathrm{Wb} / mathrm{m}^{2} ) B . ( 1.05 times 10^{-5} mathrm{Wb} / mathrm{m}^{2} ) c. ( 1.05 times 10^{-3} mathrm{Wb} / mathrm{m}^{2} ) D. ( 1.05 times 10^{-4} mathrm{Wb} / mathrm{m}^{2} ) |
12 |

1192 | Two circular coils made up of identical wires of length ( 40 mathrm{cm} ) have respectively 8 and 4 turns and the current flowing through the second coil is 4 times greater than in the first coil. The ratio of magnetic induction at their centres is : A . 2: 3 B. 3: ( c cdot 1: ) D. 1: 2 |
12 |

1193 | A proton and an ( alpha ) -particle, accelerated through the same potential difference, enter a region of uniform magnetic field normally. If the radius of the proton orbit is ( 10 c m, ) the radius of ( alpha ) -orbit is ( mathbf{A} cdot 10 mathrm{cm} ) в. ( 10 sqrt{2} mathrm{cm} ) ( c cdot 20 c m ) ( D .5 sqrt{2} c m ) |
12 |

1194 | A current-carrying wire in a magnetic field is subject to a magnetic force. If the current in the wire is doubled, what happens to the magnetic force acting on the wire? A. It is quartered B. It is halved c. It is unchange D. It is doubled E. It is quadrupled |
12 |

1195 | The radius of the curved part of the wire is ( R=100 m m, ) the linear parts of the wire are very long. Find the magnetic induction at the point ( O ) if the wire carrying a current ( I=8.0 A ) has the shape shown in figure. A ( .0 .34 mu T ) в. ( 0.11 mu T ) c. ( 1.1 mu T ) D. ( 34 mu ) 7 |
12 |

1196 | What can be the causes of helical motion of a charged particle? |
12 |

1197 | A current ( I ) flows in a long single-layer solenoid with cross-sectional radius ( boldsymbol{R} ) The number of turns per unit length of the solenoid equals ( n ). If the limiting current at which the winding may rupture if the tensile strength of the wire is equal to ( boldsymbol{F}_{text {lim }} ) is ( boldsymbol{I}_{text {lim }}= ) ( sqrt{frac{x F_{l i m}}{mu_{0} n R}} . ) Find ( x ) |
12 |

1198 | Two straight wires ( A ) and ( B ) of lengths 10m and 12m carrying currents of 4.0 A and 6.0 A respectively in opposite direction, lie parallel to each other at a distance of ( 3.0 mathrm{cm} . ) The force on a ( 15 mathrm{cm} ) section of the wire ( mathrm{B} ) near its centre is A. 2.4 ( times 10^{-5} N ), attractive B. 2.4 ( times 10^{-5} N ), repulsive C. ( 1.2 times 10^{-5} N ), attractive D ( cdot 1.2 times 10^{-5} N, ) repulsive |
12 |

1199 | Potential energy of a current loop placed inside some magnetic field does not depend upon magnetic moment of the loop.Enter 1 if True and 0 if False. |
12 |

1200 | Ampere’s circuital law is given by: A ( cdot oint bar{H} cdot overline{d l}=mu_{0} I_{e n c} ) B . ( oint bar{B} . overline{d l}=mu_{0} I_{e n c} ) ( mathbf{c} cdot oint bar{B} cdot bar{d} l=mu_{0} I ) D . ( oint bar{H} . overline{d l}=mu_{0} I ) |
12 |

1201 | A straight magnetised wire of magnetic moment ‘ ( M^{prime} ) is bent as shown. Find resultant magnetic moment in each case. |
12 |

1202 | An electron of charge e and mass ( mathrm{m} ) is moving in circular path of radius r with a uniform angular speed. Then which of the following statements are correct? This question has multiple correct options A. The equivalent current flowing in the circular path is proportional to ( r^{2} ) B. The magnetic moment due to circular current loop is independent of C. The magnetic moment due to circular current loop is equal to ( 2 mathrm{e} / mathrm{m} ) time the angular momentum of the electron D. The angular momentum of the particle is proportional to the areal velocoty of electron. |
12 |

1203 | Two long wires are hanging freely. They are joined first in parallel and then in series and then are connected with a battery. In both cases which type of force acts between the two wires? A. Attraction force when in parallel and repulsion force when in series B. Repulsion force when in parallel and attraction force when in series c. Repulsion force in both cases D. Attraction force in both cases |
12 |

1204 | Which of the following effects of current does not depend on the direction of current? A. Lighting and chemical effects B. Heating and lighting effects c. Heating and magnetic effects D. Magnetic and chemical effects |
12 |

1205 | A galvanometer of 50 gives full scale deflection with 2 mA current as to convert it into ammeter range of 10 A is connected with it then shunt resistance will be A . ( 0.1 Omega ) B. ( 0.2 Omega ) c. ( 0.01 Omega ) D. ( 0.001 Omega ) |
12 |

1206 | Two long thin parallel conductor are kept very close to each other without touching. One carries a current ( i ) and the other has charge ( lambda ) per unit length. An electron moving parallel to the conductor is undeflected. If ( c ) is the velocity of light. then : This question has multiple correct options A ( cdot v=frac{lambda c^{2}}{i} ) B. ( v=frac{i}{lambda} ) c. ( c=frac{i}{lambda} ) D. the electron may be at any distance from the conductor |
12 |

1207 | Two long parallel wires ( P ) and ( Q ) are held perpendicular to the plane of the paper at a acceptance of ( 5 mathrm{m} ) between them. If ( P ) and ( Q ) carry currents of 2.5 and 5 amp respectively in the same direction, then the magnetic field at a point half way between the wire is ( mathbf{A} cdot frac{mu_{0}}{pi} ) B. ( frac{sqrt{3} mu_{0}}{pi} ) ( c cdot frac{mu_{0}}{2 pi} ) D. ( frac{3 mu_{0}}{2 pi} ) |
12 |

1208 | A thin conducting strip of width ( h= ) ( 2.0 mathrm{cm} ) is tightly wound in the shape of a very long coil with cross-section radius ( R=2.5 mathrm{cm} ) to make a single- layer straight solenoid. A direct current ( boldsymbol{I}=mathbf{5 . 0} boldsymbol{A} ) flows through the strip. Find the magnetic induction inside and outside the solenoid as a function of the distance ( r ) from its axis. |
12 |

1209 | A long solenoid has 200 turns per ( mathrm{cm} ) and carries a current ( i . ) The magnetic field at its centre is ( 6.28 times ) ( 10^{-2} W b m^{-2} . ) Another solenoid has 100 turns per ( c m ) and it carries a current ( frac{i}{3} ) The value of the magnetic field at its centre : A . ( 1.05 times 10^{-4} mathrm{Wbm}^{-2} ) B. ( 1.05 times 10^{-2} mathrm{Wbm}^{-2} ) c. ( 1.05 times 10^{-5} mathrm{Wbm}^{-2} ) D. ( 1.05 times 10^{-3} mathrm{Wbm}^{-2} ) |
12 |

1210 | A rectangular loop of wire is oriented with the left corner at the origin, one edge along X-axis and the other edge along Y-axis as shown in the figure. A magnetic field is into the page and has a magnitude that is given by ( beta=alpha y ) where ( alpha ) is constant. Find the total magnetic force on the loop if it carries current ( i ) |
12 |

1211 | Biot-Savart law indicates that the moving electrons (velocity ( overline{boldsymbol{v}} ) ) produce a magnetic field ( bar{B} ) such that: ( mathbf{A} cdot bar{B} perp bar{v} ) B . ( bar{B} | bar{v} ) C . it obeys inverse cube law. D. it is along the line joining the electron and point of observation. |
12 |

1212 | A current ( i ) ampere flows along an infinitely long straight thin walled tube, then the magnetic induction at any point inside the tube is ( A cdot infty ) в. zero c. ( frac{mu_{0}}{4 pi} cdot frac{2 i}{r} ) tesla D. ( frac{2 i}{r} ) tesla |
12 |

1213 | A circular loop of wire has current going through it in the clockwise direction. What is the direction of the magnetic field that is caused by this current through the wire? A. Inside the loop: out of the screen Outside the loop: into the screen B. Inside the loop: out of the screen Outside the loop: out of the screen C. Inside the loop: into the screen Outside the loop: out of the screen D. Inside the loop: into the screen Outside the loop: into the screen |
12 |

1214 | You are provided with one low resistance ( R_{L} ) and one high resistance ( R_{H} ) and two galvanometers. One galvanometer is to be converted to an ammeter and the other to a voltmeter. Show how you will do this with the help of simple, labelled diagrams |
12 |

1215 | A galvanometer having a resistance of ( 120 Omega ) is shunted by ( 5 Omega ) resistance. What is the ratio of current in shunt to the current in galvanometer? |
12 |

1216 | A long solenoid has 200 turns per cm and carries a current i.The magnetic field at its centre is ( 6.28 times ) ( 10^{-2} W b / m^{2} . ) Another long solenoid has 100 turns per ( mathrm{cm} ) and it carries a current i/3.The value of magnetic field at its centre is: A ( cdot 1.05 times 10^{-2} mathrm{Wb} / mathrm{m}^{2} ) в. ( 1.05 times 10^{-5} mathrm{Wb} / mathrm{m}^{2} ) c. ( 1.05 times 10^{-3} mathrm{Wb} / mathrm{m}^{2} ) D. ( 1.05 times 10^{-4} mathrm{Wb} / mathrm{m}^{2} ) |
12 |

1217 | State and explain Ampere’s circuital law. |
12 |

1218 | On what factors does the force experienced by a current carrying conductor placed in a uniform magnetic field depend? A. Magnetic field B. current c. Length of the conductor D. All |
12 |

1219 | Compare the magnetic field produced by a solenoid with that of bar magnet by drawing respective diagrams. | 12 |

1220 | Draw the magnetic field lines due to a current passing through a long solenoid. Use Ampere’s circuital law, to obtain the expression for the magnetic field due to the current I in a long solenoid having n number of turns per unit length. | 12 |

1221 | The force experience by charged ‘q’ moving with velocity with ‘v’ in magnetic filled be is given by ( mathrm{F}=mathrm{qvB} ) Find the dimension of mag field. | 12 |

1222 | Two circular coil 1 and 2 are made from the same wire but the radius of the 1 st coil is twice that of the ( 2 n d ) coil. What potential difference in volts should be applied across them so that the magnetic field at their centres is the same- A . 3 B. 4 ( c cdot 6 ) D. 2 |
12 |

1223 | A charged particle is projected in a plane perpendicular to uniform magnetic field. The areal velocity (area swept per unit time) of the particle is : This question has multiple correct options A. directly proportional to kinetic energy of particle B. directly proportional to momentum of the particle c. inversely proportional to magnetic field strength D. inversely proportional to charge on particle |
12 |

1224 | Particles having positive charge occasionally come with high velocity from the sky towards the earth on account of magnetic field of earth, they would be deflected towards: A. North B. South ( c . ) East D. west |
12 |

1225 | The magnetic field due to a current carrying circular loop of radius ( 3 mathrm{m} ) at a point on the axis at a distance of ( 4 mathrm{m} ) from the centre is ( 54 mu T . ) What will be its value at the centre of the loop? A. ( 250 mu T ) в. ( 150 mu T ) c. ( 125 mu T ) D. ( 75 mu T ) |
12 |

1226 | A magnetic field of ( 100 mathrm{G}left(1 mathrm{G}=10^{-4} mathrm{T}right) ) is required which is uniform in a region of linear dimension about ( 10 mathrm{cm} ) and area of cross-section about ( 10^{-3} m^{2} . ) The maximum current-carrying capacity of a given coil of wire is 15 A and the number of turns per unit length that can be wound round a core is at most 1000 turns ( m^{-1} . ) Suggest some appropriate design particulars of a solenoid for the required purpose. Assume the core is not ferromagnetic. |
12 |

1227 | What are the units of magnetic moments and magnetic induction? | 12 |

1228 | If ( 2 % ) of the main current is to be passed through a galvanometer of resistance ( G ), then resistance of the shunt required is A ( cdot frac{G}{50} ) в. ( frac{G}{49} ) c. ( 49 G ) D. ( 50 G ) |
12 |

1229 | If the direction of the current changes in the current carrying loop placed in some magnetic field perpendicular to loop, then Potential energy of loop is not effected because current is a scalar quantity.Enter 1 if true and 0 if False. |
12 |

1230 | In cyclotron the charged particle may be accelerated upto energies A. several ev B. Mev c. Bev D. Kev |
12 |

1231 | Match the following. ( mathbf{A} cdot A-H, B-G, C-E, D-F ) ( mathbf{B} cdot A-G, B-H, C-E, D-F ) ( mathbf{c} cdot A-E, B-H, C-G, D-F ) ( mathbf{D} cdot A-F, B-G, C-H, D-F ) |
12 |

1232 | If a charged particle is projected perpendicular to uniform magnetic field, then a) force experienced will be perpendicular to the magnetic field and initial velocity. b) force experienced will be perpendicular to the magnetic field and instantaneous velocity c) the work done by the magnetic field is zero. d) the particle experiences both radial and tangential accelerations. A. a, b, c are correct d is wrong B. all are correct c. a, b are correct, c, d are wrong D. a, b, c are wrong, d is correct |
12 |

1233 | A solenoid of ( 0.4 mathrm{m} ) length with 500 turns carries a current of ( 3 mathrm{A} ). A coil of 10 turns and of radius ( 0.01 mathrm{m} ) carries a current of 0.4 A. The torque required to hold the coil with its axis at right angle to that of the solenoid in the middle part of it, is: A ( cdot 6 pi^{2} times 10^{-7} N m ) В. ( 3 pi^{2} times 10^{-7} mathrm{Nm} ) c. ( 9 pi^{2} times 10^{-7} N m ) D. ( 12 pi^{2} times 10^{-7} mathrm{Nm} ) |
12 |

1234 | The magnetic induction due to circular current-carrying conductor of radius ( a ) at its centre is ( B_{c} ). The magnetic induction on its axis at a distance ( a ) from its centre is ( B_{a} . ) The value of ( B_{c}: ) ( boldsymbol{B}_{boldsymbol{a}} ) will be : A ( cdot sqrt{2}: 2 ) B. ( 1: 2 sqrt{2} ) c. ( 2 sqrt{2}: 1 ) D. ( 2: sqrt{2} ) |
12 |

1235 | Q Type your question. ( n=v ) an with its centre al origin. Current ( I=1 A ) is lead to the sphere in one of the wires lying (on y-axis) and in the other wire (on x-axis) it is lead away from the sphere. A uniform and constant external magnetic field exists in positive z-direction and has magnitude ( B_{o}=2 T . ) Then find the magnitude of magnetic force (in newtons) on the solid sphere due to external magnetic field. ( A ) B. 4 ( c .5 ) ( D ) |
12 |

1236 | A copper wire of cross sectional area ( 3 m m^{2} ) carrying a current of ( 4 A ) has ( 10^{29} ) free electrons ( / m^{3} . ) If this wire is now placed in a field of induction ( 0.15 T ) perpendicular to wire. The force on each electron is : A . ( 20 times 10^{-25} mathrm{N} ) В. ( 37.5 times 10^{-25} N ) ( begin{array}{ll}text { С } & 10 times 10^{-25} Nend{array} ) D. ( 41.7 times 10^{-25} N ) |
12 |

1237 | A long straight wire of radius R carries a current distributed uniformly over its cross-section. The magnitude of the magnetic field is This question has multiple correct options A. maximum at the axis of the wire B. minimum at the axis of the wire c. maximum at the surface of the wire D. minimum at the surface of the wire |
12 |

1238 | begin{tabular}{l} ( E ) \ ( L ) \ ( L ) \ hline end{tabular} |
12 |

1239 | A solenoid of length ( 1.5 m ) and ( 4 c m ) in diameter possesses 10 turns per metre. A current of ( 5 A ) is flowing through it. The magnetic induction at a point inside the solenoid along the axis is ( _{-}——left(mu_{0}=4 pi timesright. ) ( mathbf{1 0}^{-mathbf{7}} boldsymbol{W b} / mathbf{A . m} ) A ( cdot pi times 10^{-5} T ) В. ( 2 pi times 10^{-5} T ) c. ( 3 pi times 10^{-5} T ) D . ( 4 pi times 10^{-5} T ) |
12 |

1240 | A coil of metal wire is kept stationary in a non-uniform magnetic field. An emf is induced in the coil. A. True B. False |
12 |

1241 | Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by strong magnetic field to your right side. What is the direction of magnetic field? |
12 |

1242 | Two long parallel conductors are placed at right angles to a metre scale at the ( 2 c m ) and ( 4 c m ) marks, as shown in the figure. They carry currents of ( 1 A ) and ( 3 A ) respectively. They will produce zero magnetic field at the (ignore the Earth’s magnetic field) A. ( 0.5 mathrm{cm} ) mark B. ( 2.5 mathrm{cm} ) mark c. ( 1 mathrm{cm} ) mark D. ( 8 mathrm{cm} ) mark |
12 |

1243 | To know the resistance ( G ) of a galvanometer by half deflection method, a battery of emf ( V_{E} ) and resistance ( R ) is used to deflect the galvanometer by angle ( theta . ) If a shunt of resistance ( S ) is needed to get half deflection the ( G, R ) and ( S ) are related by the equation: A. ( S(R+G)=R G ) B. ( 2 S(R+G)=R G ) ( mathrm{c} cdot 2 G=S ) D. ( 2 S=G ) |
12 |

1244 | A rectangular coil of 500 turns and of ( operatorname{area} 6 times 10^{-4} m^{2} ) is suspended inside a radial magnetic field of induction ( 10^{-4} T ) by a suspension wire of torsional constant ( 5 times 10^{-10} N m ) per degree Calculate the current required to produce a deflection of ( 10^{circ} ) |
12 |

1245 | Proton, denteron and alpha particles of the same kinetic energy and moving in circular trajectories in a constant magnetic field. The radii of proton, denteron and alpha particles are respectively ( r_{p}, r_{d} ) and ( r_{alpha} . ) Which one of the following relations is correct? A ( cdot r_{alpha}=r_{p}=r_{d} ) B . ( r_{alpha}=r_{p}r_{d}>r_{p} ) D ( cdot r_{alpha}=r_{d}>r_{p} ) |
12 |

1246 | The value of intensity of magnetic field at a point due to a current carrying conductor depends A. on the value of current B. On a small part of length of conductor c. on angle between the line joining the given point to the mid point of small length and the distance between the small length of the point D. On all and the above |
12 |

1247 | In the adjacent circuit a resistance ( mathrm{R} ) is used. Initially with ‘wire ( A B^{prime} ) not in the circuit, the galvanometer shows a deflection of d divisions. Now, the ‘wire ( A B^{prime} ) is connected parallel to the galvanometer and the galvanometer shows a deflection nearly ( boldsymbol{d} / 2 ) division. Therefore current sensitivity of the galvanometer is about: |
12 |

1248 | In a region, steady and uniform electric and magnetic fields are present. These two fields are parallel to each other. A charged particle is released from rest in this region. The path of the particle will be a A. helix B. straight line c. ellipse D. circle |
12 |

1249 | Two ( 2 mathrm{m} ) long parallel wires are placed in vacuum at a distance ( 0.2 mathrm{m} ). If current ( 0.2 mathrm{A} ) flows in both the wires in the same direction, calculate the force acting per unit length between them. |
12 |

1250 | Write an underlying principle of the moving coil galvanometer? | 12 |

1251 | A wire lying along y-axis from ( y=0 ) to ( y=1 ) m carries a current of ( 2 mathrm{mA} ) in the negative y-direction.The wire lies in a non-uniform magnetic field given by ( vec{B}=(0.3 T / m) y hat{i}+(0.4 T m) y hat{j} . ) The magnetic force on the entire wire is A ( cdot-3 times 10^{-4} hat{j} N ) В. ( 6 times 10^{-3} hat{k} N ) c. ( -3 times 10^{-4} hat{k} N ) D. ( 3 times 10^{-4} hat{k} N ) |
12 |

1252 | Give two characteristics of magnetic field lines. | 12 |

1253 | The magnetic field produced by a current-carrying wire at a given point depends on A. the current passing through it B. the voltage across it c. the power through it D. all |
12 |

1254 | A solenoid is a coil of insulated or enameled wire wound on a rod-shaped form made of solid iron, solid steel, or powdered iron. State whether this statement is true or |
12 |

1255 | Maximum P.E. of magnet of moment M situated in a magnetic field of induction ( mathrm{B}, ) is ( ^{mathbf{A}} cdot frac{1}{2} M B ) в. ( frac{M}{B} ) ( mathbf{c} .2 M B ) D. ( M B ) |
12 |

1256 | In a cyclotron, magnetic field of ( 3.5 W b / m^{2} ) is used to accelerate protons.What should be the time interval in which the electric field between the Dees be reversed? (Mass of proton ( =1.67 times 10^{-27} k g ) charge on proton ( =mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} mathbf{C} ) ). |
12 |

1257 | The magnetic moment of a bar magnet is 0.256 amp.m ( ^{2} ). Its pole strength is 400 milli amp. m. It is cut into two equal pieces and these two pieces are arranged at right angles to each other with their unlike poles in contact (or like poles in contact). The resultant magnetic moment of the system is A ( cdot sqrt{2} times 256 times 10^{-3} A m^{2} ) B . ( 250 times 10^{-3} mathrm{Am}^{2} ) c. ( frac{256}{sqrt{2}} times 10^{-3} mathrm{Am}^{2} ) D ( cdot frac{128}{sqrt{2}} times 10^{-3} mathrm{Am}^{2} ) |
12 |

1258 | A uniformly charged ring of radius R carrying q is rotating with angular speed ( omega . ) The magnetic field at the centre of ring is: A ( cdot frac{mu_{o} q omega}{2 pi R} ) в. ( frac{mu_{0} q omega}{4 pi R} ) c. ( frac{mu_{q} q omega}{8 pi R} ) D. zero |
12 |

1259 | Assertion Amperes circuital law holds for steady currents which do not fluctuate with time. Reason Amperes circuital law is similar to that of Biot-savarts law. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |

1260 | A long solenoid is fabricated to closely winding wire of radius ( 0.5 mathrm{mm} ) over a cylinderical frame, so that the successive turns nearly touch each other. The magnetic field at the centre of solenoid, if it carries a current of 5 A is? ( mathbf{A} cdot 2 pi times 10^{-2} mathbf{T} ) В . ( 2 pi times 10^{-3} mathrm{T} ) с. ( 2 pi times 10^{-4} mathrm{T} ) D. ( 2 pi times 10^{-5} mathrm{T} ) |
12 |

1261 | A current of 3 A is flowing in a linear conductor having a length of ( 40 mathrm{cm} . ) The conductor is placed in a magnetic field of strength 500 gauss and makes an angle ( 30^{circ} ) with the direction of the field. It experiences a force of magnitude ( mathbf{A} cdot 3 times 10^{-4} N ) B. ( 3 times 10^{-2} N ) c. ( 3 times 10^{2} N ) D. ( 3 times 10^{4} N ) |
12 |

1262 | A magnet of magnetic moment 20 CGS units is freely suspended in a uniform magnetic field of intensity ( 0.3 mathrm{CGS} ) units. The moment of work done in deflecting it by an angle of ( 30^{circ} ) in ( C G S ) units is A . 6 B. ( 3 sqrt{3} ) c. ( 3(2-sqrt{3}) ) D. 3 |
12 |

1263 | Two wires of same length are shaped into square and a circle. if they carry same current ratio of magnetic moment is A . ( 2: pi ) в. ( pi: 3 ) ( c cdot pi: 4 ) D. ( 1: pi ) |
12 |

1264 | A circular coil of radius ( 4 mathrm{cm} ) and of 20 turns carries a current of 3 amperes. It is placed in a magnetic field of intensity of 0.5 weber ( / m^{2} . ) The magnetic dipole moment of the coil is A. 0.15 ampere ( -m^{2} ) B. 0.3 ampere ( -m^{2} ) c. 0.45 ampere ( -m^{2} ) D. 0.6 ampere ( -m^{2} ) |
12 |

1265 | A straight wire of mass ( 200 g ) and length ( 1.5 m ) carries a current of ( 2 A . ) It is suspended in mid air by a uniform horizontal magnetic field ( B ). The magnitude of ( B ) (in tesla) is : A . 0.65 в. 0.55 c. 0.75 D. 0.45 |
12 |

1266 | State the underlying principle of a cyclotron. Write briefly how this machine is used to accelerate charged particles to high energies. | 12 |

1267 | A helium nucleus makes a full rotation in a circle of radius ( 0.8 m ) in two seconds. The value of the magnetic field B at the centre of the circle will be ( mathbf{A} cdot 10^{-19} / mu_{0} ) B . ( 10^{-19} ) p ( _{0} ) c. ( 2 times 10^{-19} mu_{0} ) D. ( 2 times 10^{-19} / mu_{0} ) |
12 |

1268 | A current of 0.24 A flows through a circular coil of 72 turns, the average diameter of the coil being ( 20 mathrm{cm} . ) What is the strength of field produced at the centre of the coil? |
12 |

1269 | The pole is pieces of a horse-shoe magnet are made cylindrical so that the deflection of the coil is proportional to A. the current flowing in the coil в. ( frac{1}{text { current flowing in the coil }} ) c. the magnetic field D. the square of current flowing in the coil |
12 |

1270 | Two conductors each of length ( 12 m ) lie parallel to each other in air. The centre to centre distance between the two conductors is ( 15 times 10^{-2} m ) and the current in each conductor is ( 300 A ). The force in newton tending to pull the conductors together is: A . ( 14.4 N ) B. ( 1.44 N ) c. ( 144 N ) D. ( 0.144 N ) |
12 |

1271 | A current ( I=1.00 A ) circulates in a round thin-wire loop of radius ( boldsymbol{R}= ) 100 ( m m ). Find the magnetic induction at the centre of the loop. A. ( 7.3 mu T ) B. ( 3.7 mu T ) c. ( 3.6 mu T ) D. ( 6.3 mu T ) |
12 |

1272 | A particle is moving with velocity ( vec{v}= ) ( hat{mathbf{i}}+mathbf{3} hat{mathbf{j}} ) and it produces an electric field at that point equal to ( 2 hat{k} ), find the magnetic field at that point (all) quantities are in Sl units) A ( cdot(6 hat{i}-2 hat{j}) mu_{0} varepsilon_{0} ) B . ( (6 hat{i}+2 hat{j}) mu_{0} varepsilon_{0} ) c. zero D. cannot be determined from the given data |
12 |

1273 | A charged particle of unit mass and unit charge moves with velocity ( vec{v}= ) ( (8 hat{i}+6 hat{j}) m s^{-1} ) in a magnetic field of ( vec{B}=2 hat{k} T . ) Choose the correct alternative(s). This question has multiple correct options A ( cdot ) the path of the particle may be ( x^{2}+y^{2}-4 x-21=0 ) B. the path of the particle may be ( x^{2}+y^{2}=25 ) c. the path of the particle may be ( y^{2}+z^{2}=25 ) D. the time period of the particle will be 3.14 s |
12 |

1274 | The radius of the curved part of the wire is ( R, ) the linear parts are assumed to be very long. Find the magnetic induction of the field at the point ( O ) if a current- carrying wire has the shape shown in figure above. ( ^{mathbf{A}} cdot B=frac{mu_{0}}{4 pi} frac{I}{R}left[1+frac{3 pi}{2}right] ) в. ( B=frac{mu_{0}}{pi} frac{I}{R}left[1+frac{3 pi}{2}right] ) c. ( _{B}=frac{mu_{0}}{2 pi} frac{I}{R}left[1+frac{3 pi}{2}right] ) D. ( B=0 ) |
12 |

1275 | A moving charge will produce A. No field B. An electric field only C. A magnetic field only D. Both (b) and (c) |
12 |

1276 | The electric permittivity nad magnetic permeability of free space are ( varepsilon_{0} ) and ( mu_{0} ) respectively. The index of refraction of the medium, if ( varepsilon ) and ( mu ) are the electric permittivity and magnetic permeability in a medium is : A ( cdot frac{varepsilon mu}{varepsilon_{0} mu_{0}} ) ( ^{text {В }}left(frac{varepsilon mu}{varepsilon_{0 mu_{0}}}right)^{1 / 2} ) c. ( frac{varepsilon_{0} mu_{0}}{varepsilon_{mu}} ) ( ^{mathrm{D}}left(frac{varepsilon_{0} mu_{0}}{varepsilon mu}right)^{1 / 2} ) |
12 |

1277 | Write the definition of figure of merit of Galvanometer. |
12 |

1278 | Electrons traveling at a velocity of ( 2.4 times 10^{6} m s^{-1} ) enter a region of cross electric and magnetic fields as shown in fig. If the electric field is ( 3.0 x ) ( 10^{6} V m ) and the flux density of the magnetic field is ( 1.5 mathrm{T} ), the electron upon entering the region of the crossed fields will A. continue to travel undeflected in their original direction c. be deflected downward on the plane of the diagram D. none of the above |
12 |

1279 | An electric current through a metallic conductor produces around it. A. Magnetic field B. Mechanical force c. Induced current D. None |
12 |

1280 | A vertical wire carrying current in the downward direction is placed in a horizontal magnetic field directed northwards. The direction of the force on the wire is A. Eastward c. Upwards D. Westward |
12 |

1281 | Find the mobility of the conduction electrons in a copper conductor if in Hall effect measurements performed in the magnetic field of induction ( boldsymbol{B}= ) 100 ( m T ) the transverse electric field strength of the given conductor turned out to be ( eta=3.1 times 10^{3} ) less than that of the longitudinal electric field. |
12 |

1282 | If ( mu_{0} ) is absolute permeability of vacuum and ( mu_{r} ) is relative magnetic permeability of another medium, then permeability ( mu ) of the medium is A . ( mu_{0} mu_{r} ) B. ( mu_{0} / mu_{r} ) ( mathbf{c} cdot mu_{r} / mu_{0} ) D. ( I / mu_{0} mu_{r} ) |
12 |

1283 | In the given arrangement, the loop is moved with constant velocity ( v ) in a uniform magnetic field ( B ) in a restricted region of width ( a ). The time for which the emf is induced in the circuit is A ( -frac{2 b}{v} ) в. ( frac{2 a}{v} ) c. ( frac{(a+b)}{v} ) D. |
12 |

1284 | The direction of force on a current carrying conductor placed in a magnetic field is given by : A. Fleming’s Left Hand Rule B. Fleming’s Right Hand Rule c. End Rule D. Right Hand Palm Rule |
12 |

1285 | A current carrying small loop behaves like a small magnet. If ( A ) be its area and ( M ) its magnetic moment, the current in the loop will be A. ( M / A ) в. ( A / M ) ( c . M A ) D. ( A m^{2} ) |
12 |

1286 | An electron is projected into a magnetic field along the lines of force. Then A. there will be no effect on its motion B. the electron will travel along a circle and its speed remains unchanged C. the electron will follow the path of a parabola and its speed will increase D. the velocity will increase in magnitude but its direction will remain unchanged. |
12 |

1287 | Magnetic field at point ( ^{prime} boldsymbol{P}^{prime} ) due to given current distribution is: A ( cdot frac{mu_{0} I}{4 pi r}(1+sqrt{2}) odot ) В ( cdot frac{mu_{0} I}{2 pi r}(1+sqrt{2}) odot ) c. ( frac{mu_{0} I}{4 pi r}(1+sqrt{2}) otimes ) D. ( frac{mu_{0} I}{2 pi r}(1+sqrt{2}) otimes ) |
12 |

1288 | carrying a current ( boldsymbol{I} ) A. Three circular Amperian loops 1,2 and 3 are shown by dashed lines. Point ( P ) is an interior point. Point ( Q ) is an exterior point. What is the magnetic field due to the toroid at points ( P ) and ( Q ) respectively? A . 0,0 В ( cdot 0, mu_{o}, n ) C ( cdot mu_{o} n I, mu_{o} n I ) ( mathbf{D} cdot mu_{o} n I, 0 ) |
12 |

1289 | To obtain maximum intensity of magnetic field at a point the angle between position vector of point and small elements of length of the conductor is A. 0 в. ( pi / 4 ) c. ( pi / 2 ) D. |
12 |

1290 | An electron is moving in a perpendicular magnetic field of strength ( 4 times 10^{-3} T ) with a velocity of ( 4 times 10^{7} m / s . ) The radius of electron path will be ( mathbf{A} cdot 0.56 m ) B. ( 0.056 m ) ( c .56 m ) D. ( 5.6 m ) |
12 |

1291 | A long circular tube of length ( 10 m ) and radius ( 0.3 mathrm{m} ) carries a current I along its curved surface as shown. A wire-loop of resistance 0.0005 ohm and of radius 0.1 ( mathrm{m} ) is placed inside the tube with its axis coinciding with the axis of the tube. The current varies as ( boldsymbol{I}=boldsymbol{I}_{0} cos (boldsymbol{3} boldsymbol{0} boldsymbol{0} boldsymbol{t}) ) where ( I_{0} ) is constant. If the magnetic moment of the loop is ( N mu_{0} I_{0} sin (300 t) ) then ‘N’ is |
12 |

1292 | Find the ratio of magnetic dipole moment to angular momentum in a hydrogen like atom: A ( cdot frac{e}{m} ) B. ( frac{e}{2 m} ) c. ( frac{e}{3 m} ) D. ( frac{2 e}{m} ) E ( cdot frac{3 e}{m} ) |
12 |

1293 | Which of the following is based on mechanical effect of electric current? A. AC Dynamo B. DC Dynamo c. AC or DC motor D. Electric Geyser |
12 |

1294 | The ends of a coil are connected to a galvanometer. When current suddenly I starts flowing in a neighbouring circuit, the instantneous deflection in the galvanometer is ( +7^{circ} . ) If now the coil be quickly rotate through ( 180^{circ}, ) what will be the maximum deflection in the galvanometer? A ( cdot 7^{circ} ) B. ( 14^{circ} ) ( c cdot 21^{0} ) ( D cdot 28^{circ} ) |
12 |

1295 | Find the concentration of the conduction electrons. A ( cdot 2.5 times 10^{20} mathrm{m}^{-3} ) В. ( 2.5 times 10^{26} mathrm{m}^{-3} ) c. ( 2.5 times 10^{28} mathrm{m}^{-3} ) D. ( 2.5 times 10^{30} m^{-3} ) |
12 |

1296 | A neutral particle is at rest in a uniform magnetic field ( vec{B} ). At time ( t=0 ) it decays into two charged particles,each of mass m.The two particles move off in seperate paths,both of them lie in the plane perpendicular to ( vec{B} ). At a later time the particles collide.Express the time from decay until collison in terms of ( mathrm{m}, mathrm{B} ) and ( mathbf{q} ) |
12 |

1297 | The current in an ideal, long solenoid is varied at a uniform rate of ( 0.01 A / s . ) The solenoid has 2000 turns/m and its radius is ( 6.0 mathrm{cm} ) (a) Consider a circle of radius ( 1.0 mathrm{cm} ) inside the solenoid with its axis coinciding with the axis of the solenoid. Write the change in the magnetic flux through this circle in 2.0 seconds. (b) Find the electric field induced at a point on the circumference of the circle. (c) Find the electric field induced at a point outside the solenoid at a distance ( 8.0 mathrm{cm} ) from its axis. |
12 |

1298 | An electric current is flowing through a circular coil of radius ( mathrm{R} ). The ratio of the magnetic field at the center of the coil and that at a distance ( 2 sqrt{2} R ) from the center of the coil and on its axis is: |
12 |

1299 | A solenoid has a core of a substance with relative permeability ( 600 . ) What is the magnetic permeability of the given substance? A ( cdot 20 pi times 10^{-5} N A^{-2} ) B. ( 21 pi times 10^{-5} N A^{-2} ) c. ( 22 pi times 10^{-5} N A^{-2} ) D. ( 24 pi times 10^{-5} N A^{-2} ) |
12 |

1300 | A charged particle is moving through uniform magnetic field, then magnetic field : A. Always exerts a force on the particle B. Never exerts a force on the particle c. Exerts a force, if the particle is moving along the field. D. Exerts a force, if the particle is moving perpendicular to the direction of the field |
12 |

1301 | Each of the following particles is projected with the same speed into a uniform magnetic field ( B ) such that the particle’s initial velocity is perpendicular to ( B ). Which one would move in a circular path with the largest radius? A particle is projected at a given speed into a uniform magnetic field ( B ) and perpendicular to it. Choose the particle that will have the largest radius. |
12 |

1302 | The ratio of magnetic field at the centre of a current carrying coil to its magnetic moment is ( x ). If the current and radius both are doubled, the new ratio will become: A ( .2 x ) B. ( 4 x ) c. ( x / 4 ) D. ( x / 8 ) |
12 |

1303 | A closely wound solenoid ( 80 mathrm{cm} ) long has 5 layers of windings of 400 turns each. The diameter of the solenoid is 1.8 ( mathrm{cm} . ) If the current carried is ( 8.0 mathrm{A} ) estimate the magnitude of B inside the solenoid near its centre : A ( .1 .5 times 10^{-2} T ), opposite to the axis of solenoid B . ( 2 times 10^{-2} T ), along the axis of solenoid C . ( 3.5 times 10^{-2} T ), along the axis of solenoid D. ( 1.5 times 10^{-2} T ) along the axis of solenoid |
12 |

1304 | The value of ( mu_{o} ) is ( mathbf{A} cdot 2 pi times 10^{-7} H m^{-1} ) B ( cdot 4 pi times 10^{-7} mathrm{Hm}^{-1} ) ( mathbf{c} cdot 8 pi times 10^{-7} mathrm{Hm}^{-1} ) D ( cdot pi times 10^{-7} mathrm{Hm}^{-1} ) |
12 |

1305 | What happens to energy when a charged particle moving in a magnetic field although a magnetic force is acting on it? A . remains constant B. increases c. decreases D. none of these |
12 |

1306 | Magnetic lines of force A. form closed circuits B. cannot intersect C . are crowded together near the poles D. all the above are correct |
12 |

1307 | Induced electromotive force in a coil does not depend on A. Number of turns in the coil B. Intensity of the magnetic field c. Relative speed between coil and the magnet D. Resistance of the coil |
12 |

1308 | A long straight conductor carrying ( boldsymbol{I}_{1} ) is placed in the plane of ribbon at a distance a from the near edge of a ribbon of width b, which carries ( boldsymbol{I}_{2} ) parallel to the wire. Find the force of attraction per unit length between the two. |
12 |

1309 | A moving coil galvanometer, having a resistance ( G ), produces full scale deflection when a current ( I_{g} ) flows through it. This galvanometer can be converted into (i) an ammeter of range ( mathbf{0} operatorname{to} boldsymbol{I}_{mathbf{0}}left(boldsymbol{I}_{mathbf{0}}>boldsymbol{I}_{boldsymbol{g}}right) ) by connecting a shunt resistance ( boldsymbol{R}_{boldsymbol{A}} ) to it and (ii) into a voltmeter of range 0 to ( Vleft(V=G I_{0}right) ) by connecting a series resistance ( boldsymbol{R}_{boldsymbol{V}} ) to it. Then ( mathbf{A} cdot_{R_{A} R_{V}}=G^{2}left(frac{I_{g}}{I_{0}-I_{g}}right) ) and ( frac{R_{A}}{R_{V}}=left(frac{I_{0}-I_{g}}{I_{g}}right) ) ( ^{mathrm{B}} R_{A} R_{V}=G^{2} ) and ( frac{R_{A}}{R_{V}}=left(frac{I_{g}}{I_{0}-I_{g}}right)^{2} ) ( ^{mathbf{c}} cdot_{R_{A} R_{V}}=G^{2} ) and ( frac{R_{A}}{R_{V}}=frac{I_{g}}{I_{0}-I_{g}} ) ( ^{mathrm{D}} R_{A} R_{V}=G^{2}left(frac{I_{0}-I_{g}}{I_{g}}right) ) and ( frac{R_{A}}{R_{V}}=left(frac{I_{g}}{I_{0}-I_{g}}right)^{2} ) |
12 |

1310 | A long thin walled hollow cylinder of radius r is carrying a current I. A very long current carrying straight conductor is passing through the axis of the hollow cylinder, carrying a current ( i_{0} . ) Find the tension per unit length developed in the hollow cylinder due to the interaction of the straight current carrying conductor. |
12 |

1311 | A circular coil of wire of ( n ) turns has a radius ( r ) and carries a current ( i ). Its magnetic dipole moment is ( M . ) Now the coil is unwound and again rewound into a circular coil of half the initial radius and the same current is passed through it, then the dipole moment of this new coil is : A ( cdot frac{M}{2} ) в. ( frac{M}{4} ) c. ( M ) D. 2 ( M ) |
12 |

1312 | A circular coil of one turn in formed by a ( 6.28 mathrm{m} ) length wire, which carries a current of 3.14 A. the magnetic field at the center of coil is :- A ( cdot 1 times 10^{-6} T ) В. ( 4 times 10^{-6} T ) c. ( 0.5 times 10^{-6} T ) D. ( 2 times 10^{-6} T ) |
12 |

1313 | Figure shows a some of the equipotential surface of the magnetic scalar potential. The magnetic field at a point in the region is : A ( cdot 2 times 10^{-5} T ) B ( cdot 10^{-5} T ) ( mathbf{c} cdot 10^{-4} T ) D. ( 2 times 10^{-4} T ) |
12 |

1314 | An electron revolving in an orbit of radius ( 0.5 mathrm{A} ) in a hydrogen atom executes 10 revolutions per second. The magnetic moment of electron due to its orbital motion will be A ( cdot 1256 times 10^{-37} ) amp.m ( ^{2} ) B. ( 653 times 10^{-26} ) amp.m ( ^{text {2 }} ) c. zero D. ( 256 times 10^{-26} ) amp.m ( ^{2} ) |
12 |

1315 | The ratio of the magnetic field at the centre of a circular loop to the magnetic field at the centre of the square loop, which is made by a constant length current carrying wire is: A ( cdot frac{pi^{2}}{16} ) в. ( frac{pi^{2}}{8 sqrt{2}} ) c. ( frac{pi^{2}}{4 sqrt{2}} ) D. ( frac{pi^{2}}{2 sqrt{2}} ) |
12 |

1316 | State the advantages and disadvantages of a moving coil galvanometer. A moving coil galvanometer (M.C.G.) has 10 turns each of length ( 12 mathrm{cm} ) and breadth ( 8 mathrm{cm} . ) The coil of M.C.G. carries a current of ( 125 mu A ) and is kept perpendicular to the uniform magnetic field of induction ( 10^{-2} ) T. The twist constant of phosphor bronze fibre is ( 12 times 10^{-9} mathrm{Nm} / ) degree. Calculate the deflection produced. |
12 |

1317 | Two coaxial solenoids of different radii carry current I in the same direction. Let ( vec{F}_{1} ) be the magnetic force on the inner solenoid due to the outer one and ( vec{F}_{2} ) be the magnetic force on the outer solenoid due to the inner one. Then ( A cdot vec{F}_{1}=vec{F}_{2}=0 ) B . ( vec{F}_{1} ) is radially inwards and ( vec{F}_{2} ) is radially outwards C ( cdot vec{F}_{1} ) is radially inwards ( vec{F}_{2}=0 ) D. ( vec{F}_{1} ) radially outwards and ( vec{F}_{2}=0 ) |
12 |

1318 | If the direction of the initial velocity of the charged particle is perpendicular to the magnetic field, the orbit of charged particle will be A. a straight line B. a cycloid c. a circle D. a helix |
12 |

1319 | A single-layer coil (solenoid) has length and cross-section radius ( R ) A number of turns per unit length is equal to ( n ) The magnetic induction at the centre of the coil when a current ( I ) flows through it is given as ( B=frac{x mu_{0} n I}{sqrt{1+left(frac{2 R}{l}right)^{2}}} . ) Find ( boldsymbol{x} ) |
12 |

1320 | Amperes circuital law is given by A ( cdot oint bar{H} cdot overline{d l}=mu_{0} I_{e n c} ) B . ( oint bar{B} . overline{d l}=mu_{0} I ) C ( . oint bar{B} . overline{d l}=mu_{0} J ) D ( cdot oint bar{H} cdot bar{d} l=mu_{0} J ) |
12 |

1321 | A charged particle of specific charge (charge/mass) ( alpha ) is released from origin at time ( t=0 ) with velocity ( vec{v}= ) ( v_{0}(hat{i}+hat{j}) ) in a uniform magnetic field ( vec{B}=B_{0} hat{i} . ) Coordinates of the particle at time ( t=frac{pi}{B_{0} alpha} ) are A ( cdotleft(frac{v_{0}}{2 B_{0} alpha}, frac{sqrt{2} v_{0}}{alpha B_{0}}, frac{-v_{0}}{B_{0} alpha}right) ) В ( cdotleft(frac{-v_{0}}{2 B_{0} alpha}, 0,0right) ) ( ^{mathbf{C}} cdotleft(0, frac{2 v_{0}}{B_{0} alpha}, frac{v_{0} pi}{2 B_{0} alpha}right) ) D ( cdotleft(frac{v_{0} pi}{B_{0} alpha}, 0, frac{-2 v_{0}}{B_{0} alpha}right) ) |
12 |

1322 | In a long straight solenoid with cross- sectional radius ( a ) and number of turns per unit length, ( n ), the current varies with the rate ( boldsymbol{I} boldsymbol{A} / boldsymbol{s} ). The magnitude of the induced current field strength as a function of distance ( r ) from the solenoid axis is A ( cdot frac{1}{2} frac{n I a^{2}}{mu_{0} r} ) В ( cdot frac{1 I a^{2}}{2 mu_{0} r} ) С ( cdot frac{n I a^{2}}{mu_{0} r} ) D. ( frac{1}{2} frac{mu_{0} n I a^{2}}{r} ) |
12 |

1323 | A circular current loop of magnetic moment M is in an arbitrary orientation in an external magnetic field ( bar{B} ). The work done to rotate the loop by 30 about an axis perpendicular to its plane is: ( A . M B ) в. ( sqrt{3} frac{M B}{2} ) c. ( frac{M B}{2} ) D. zero |
12 |

1324 | Write the name of fields produced by a moving charged particles. | 12 |

1325 | Two long straight parallel wires separated by a distance, carrying equal currents exert a force ( F ) per unit length on each other. If the distance of separation is doubled, and the current in each is halved, the force per unit length, between them will be : ( A cdot F ) B. F/2 ( c cdot F / 4 ) D. F/ |
12 |

1326 | The distance between two thin long straight parallel conducting wires is ( b ) On passing the same current ( i ) in them, the force per unit length between them will be A ( cdot frac{mu_{0} i}{2 pi b} ) В. ( frac{mu_{0} i^{2}}{2 pi} ) c. ( frac{mu_{0} i^{2}}{2 pi b} ) D. zero |
12 |

1327 | A proton of mass ( m ) and charge ( q ) is moving in a plane with kinetic energy ( boldsymbol{E} ) If there exists a uniform magnetic field ( B, ) perpendicular to the plane of the motion the portion will move in a circular path of radius A ( cdot frac{2 E m}{q B} ) в. ( frac{sqrt{2 E m}}{q B} ) c. ( frac{sqrt{E m}}{2 q B} ) D. ( sqrt{frac{2 E q}{m B}} ) |
12 |

1328 | A horizontal wire carries 200 amp current below which another wire of linear density ( 20 times 10^{-3} k g m^{-1} ) carrying a current is kept at ( 2 mathrm{cm} ) distance. If the wire kept below hangs in air. The current in this wire is : A. ( 100 A ) B. ( 9.8 mathrm{A} ) ( c cdot 98 A ) ( D cdot 48 A ) |
12 |

1329 | A pair of stationary and infinitely long bent wires is placed in the ( x ) -y plane as shown in figure. Each wire carries current of ( 10 A . ) Segments ( L ) and ( M ) are along the x-axis.Segments ( P ) and ( Q ) are parallel to the y-axis such that ( O S= ) ( O R=0.02 m . ) Find the magnitude and direction of the magnetic induction at origin ( O ) in the form of ( x times 10^{-4} ). What is ( x ) |
12 |

1330 | large metal sheet carries an electric current along its surface. Current per unit length is ( lambda . ) Magnetic field near the metal sheet is (0)(0)(0)(0)(0)(0)(0)(0) ( A cdot frac{lambda mu}{2} ) B. ( frac{lambda mu}{2 pi} ) c. ( lambda mu_{0} ) ( D cdot frac{mu}{2 pi pi} ) |
12 |

1331 | ( N=2.5 times 10^{3} ) wire turns are uniformly wound on a wooden toroidal core of very small cross-section. A current ( I ) flows through the wire. If the ratio ( eta ) of the magnetic induction inside the core to that at the centre of the toroid is ( x times ) ( 10^{2} . ) Find ( x ) |
12 |

1332 | A circular coil of radius ( R ) carries an electric current. The magnetic field due to the coil at a point on the axis of the coil located at a distance ( r ) from the centre of the coil, such that ( r>>R ) varies as A. ( 1 / r ) B . ( 1 / r^{3 / 2} ) c. ( 1 / r^{2} ) D. ( 1 / r^{3} ) |
12 |

1333 | An electron is projected in the same direction of uniform magnetic field. Then A. the electron turns to right B. the electron turns to left C. the electron velocity remains constant D. the electron velocity decreases in magnitude |
12 |

1334 | The ends of a circular coil of radius ( r ) and number of turns ( n ) is connected to the two terminals of a cell. The magnetic field at the centre of the coil is ( B ). If the number of turns be made ( 2 n ) keeping the radius same, the magnetic field at the centre of the coil will be: A. ( B ) в. ( 2 B ) ( c .3 B ) D. ( 4 B ) |
12 |

1335 | A circular loop of radius ( 3 mathrm{cm} ) is having a current of 12.5 A. The magnitude of magnetic field at a distance of ( 4 mathrm{cm} ) on its axis is В ( cdot 5.27 times 10^{-5} T ) ( mathrm{c} cdot 6.54 times 10^{-5} T ) D. ( 9.20 times 10^{-5} T ) |
12 |

1336 | A solenoid of length 1 m, area of crosssection ( 4.0 mathrm{cm}^{2} ) and having 4000 turns is placed inside another solenoid of 2000 turns having a cross-sectional ( operatorname{area} 6 mathrm{cm}^{2} ) and length 2 m. The mutual inductance between the solenoids is ( x pi times 10^{-5} H . ) Findout the value of ( x ) |
12 |

1337 | A drop of oil of mass 2 ng is kept stationary in between two plates ( 2 mathrm{cm} ) apart. A potential difference is 2 kV is applied. The number of electrons it gained is A . 16 B. 160 ( c cdot 4 ) D. 1600 |
12 |

1338 | Q Type your question the dids ul divig sultilulu dis shuwn III fig. The ring has a narrow gap of width ( d ) in its circumference. The solenoid has cross sectional area ( A ) and a uniform internal field of magnitude ( B_{0} . ) Now beginning at ( t=0, ) the solenoid current is steadily increased so that the field magnitude at any time ( t ) is given by ( boldsymbol{B}(boldsymbol{t})=boldsymbol{B}_{0}+boldsymbol{alpha} ) where ( boldsymbol{alpha}>0 . ) Assuming that no change can flow across the gap, the end of ring which has excess of positive charge and the magnitude of induced e.m.f in the ring are respectively A. ( X, A alpha ) В. ( X, pi R^{2} alpha ) c. ( Y, pi A^{2} alpha ) D. ( Y, pi R^{2} alpha ) |
12 |

1339 | In a given region a charge particle is moving under the effect of electric and magnetic field with uniform velocity ( vec{v}=(hat{i}+hat{j}-hat{k}) mathrm{m} / mathrm{s} ) and magnetic field is given as ( vec{B}=(2 hat{i}+hat{j}-2 k) ) T. The electric field is given as? ( mathbf{A} cdot(i+j-k) mathrm{V} / mathrm{m} ) B. ( (i-j+k) vee / m ) c. ( (i+k) vee / m ) D. ( (-i-k) vee / ) m |
12 |

1340 | Find the mechanical work to be performed in order to turn the frame through ( 180^{circ} ) about its axis, with the currents maintained constant. A. ( 1.0 mu J ) B. ( 0.1 mu J ) c. ( 10 mu J ) D. ( 0 mu J ) |
12 |

1341 | Some equipotential surfaces of the magnetic scalar potential are shown in figure.Magnetic field at a point in the region is A ( cdot 10^{-4} ) न B . ( 0.5 times 10^{-4} ) T c. ( 2 times 10^{-4} ) न D. None of these |
12 |

1342 | Assertion A soft iron core is used in a moving coil galvanometer to increase the strength of magnetic field. Reason From soft iron more number of the magnetic lines of force passes. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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1343 | Which of the following statements is true? A. A stationary charge will experience a force in both a magnetic and electric field B. A charge moving parallel to field lines will experience a force in both magnetic and electric fields. C. A charge moving perpendicular to field lines will experience a force in both magnetic and electric fields. D. It is impossible for a charge to move with constant velocity through an area that has both electric and magnetic fields |
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1344 | State whether true or false: The pattern of the magnetic field around a conductor due to electric current flowing through it depends on the shape of the conductor A. True B. False |
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1345 | What will be the path of a charged particle moving along the direction of a uniform magnetic field? |
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1346 | topp 0 Fill in the blanks in the following passage(s) from the words given above. The magnetic field produced around a straight current carrying conductor is in the form of with the lying on the straight conductor. Take a copper wire AB. Pass it through a cardboard. Connect the wire to a battery through a key. Sprinkle some iron filings on the cardboard. Switch on the key and tap the cardboaro gently. You will find that the iron filings arrange themselves in the form of concentric circles. Reverse the direction of current by changing the of the battery. You will find that this time too, the iron filings arrange themselves in concentric circle but in direction. Hence, the magnetic field lines of force around a carrying electric current are concentric circles with the conductor at the centre. The direction of magnetic field changes if the direction of current is |
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1347 | The dimension of ( 1 / 2 varepsilon_{o} E^{2}left(varepsilon_{o}right. ) permittivity of free space; E: electric field) is? A . ( M L T^{-} ) В. ( M L^{2} T^{-2} ) c. ( M L^{-1} T^{-2} ) D. ( M L^{2} T^{-1} ) |
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1348 | A ( 200 M e V ) proton enters a region of the magnetic field of intensity 5 T. The magnetic field points from south to north and the proton in moving along the vertical. The value of the force acting on the proton will be A. zero В. ( 1.8 times 10^{-10} N ) c. ( 3.2 times 10^{-18} N ) D. ( 1.6 times 10^{-6} N ) |
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1349 | A magnet of moment ( 1.2 A m^{2} ) is kept suspended in a magnetic field of induction ( 2 times 10^{-6} ). The work done in rotating it through ( 120^{circ} ) is: A ( cdot 2.4 times 10^{-6} J ) B . ( 4.8 times 10^{-6} J ) c. ( 1.2 times 10^{-6} J ) D. ( 3.6 times 10^{-6} J ) |
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1350 | A tightly-wound, long solenoid carries a current of ( 2.00 A ). An electron is found to execute a uniform circular motion inside the solenoid with a frequency of ( 1.00 times 10^{8} ) rev ( s^{-1} ).Find the number of turns per metre in the solenoid. |
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1351 | Two particles ( X ) and ( Y ) having equal charges, after being accelerated through the same potential differences, enter in a region of uniform magnetic field and describe circular paths of radii ( R_{1} ) and ( R_{2} ) respectively. The ratio of the mass of ( X ) to that of ( Y ) is : ( ^{A} cdotleft(frac{R_{1}}{R_{2}}right)^{1 / 2} ) ( ^{text {в. }}left(frac{R_{1}}{R_{2}}right)^{-1} ) ( ^{c} cdotleft(frac{R_{1}}{R_{2}}right)^{2} ) D. ( left(frac{R_{1}}{R_{2}}right) ) |
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1352 | If magnetic field produced by a straight current carrying wire at a distance 10cm from it is X. Then the magnetic field produced at a distance ( 29 mathrm{cm} ) will be ( A cdot>x ) B. D. all December 27, 2019 Anjan Chatterjee ( B ) Share Save |
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1353 | Two parallel straight conductors, in which current is flowing in the same direction, attract each other. The cause of it is A. magnetic force between the two B. electric force between the two c. potential difference between the two D. mutual induction between the two |
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1354 | Consider the three long,straight,parallel wires as shown in figure.Find the force experienced by a ( 25 mathrm{cm} ) length of wire ( mathrm{C} ) A ( cdot 2 times 10^{-4} N ) B. ( 3 times 10^{-4} N ) c. ( 5 times 10^{-4} N ) D. ( 6 times 10^{-4} N ) |
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1355 | Assertion Force experienced by moving charge will be maximum if direction of velocity of charge is perpendicular to applied magnetic field. Reason Force on moving charge is independent of direction of applied magnetic field. A. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion. B. Both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion. C. Assertion is correct but Reason is incorrect. D. Assertion is incorrect but Reason is correct. |
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1356 | Current ( I_{o} ) flows through the solenoid of length ( L ) having ( N ) number of turns when its connected to DC. A charged particle is projected along the axis of the solenoid with a speed ( v_{0}, ) then the force on the charged particle in the solenoid is: A. Becomes zero B. Remains same c. Decreases D. Increases |
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1357 | A bar magnet of magnetic moment ( M ) is divided into ‘ ( n ) ‘ equal parts by cutting parallel to length. Then one part is suspended in a uniform magnetic field of strength ( 2 T ) and held making an angle ( 60^{0} ) with the direction of the field. When the magnet is released, the kinetic energy of the magnet in the equilibrium position is: A. ( frac{M}{n} ) B. ( M n ) J c. ( frac{M}{n^{2}} ) D. ( M n^{2} ) |
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1358 | Magnetic field at point ‘O’ due to given current distribution. If 5 A current is flowing in this system and the diameter of the loop is ( 10 mathrm{cm} ) A ( cdot 2 times 10^{-5} T, otimes ) B ( cdot 10^{-5} T, odot ) ( mathbf{c} cdot 10^{-5} T, otimes ) D. ( 2 times 10^{-5} T, odot ) |
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1359 | Two identical loops ( P ) and ( Q ) each of radius ( 5 mathrm{cm} ) are lying in perpendicular planes such that they have a common centre as shown in the figure. Find the magnitude and direction of the net magnetic field at the common centre of the two coils, if they carry currents equal to ( 3 A ) and ( 4 A ) respectively. |
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1360 | Magnetic moment of bar magnet is ( M ) The work done in turning the magnet by ( 90^{circ} ) in direction of magnetic field ( B ) will be A. zero в. ( frac{1}{2} M B ) c. ( 3 M B ) D. ( M B ) |
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1361 | The magnetic field inside a solenoid is: A . infinite B. zero c. uniform D. non-uniform |
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1362 | Complete the following statements with an appropriate word / term to be filled in the blank space(s).
Magnetic field lines emerge from the pole of a solenoid or a |
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1363 | While keeping area of cross-section of a solenoid same, the number of turns and length of solenoid one both doubled. The self inductance of the coil will be? A. Halved B. Doubled c. ( 1 / 4 ) times the original value D. Unaffected |
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1364 | Find an expression for the magnetic dipole moment and magnetic field induction at the centre of a Bohr’s hypothetical hydrogen atom in the ( n^{t h} ) orbit of the electron in terms of universal constants. |
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1365 | Two moving coil meters, ( M_{1} ) and ( M_{2} ) have the following particulars: ( boldsymbol{R}_{1}=mathbf{1 0} boldsymbol{Omega}, boldsymbol{N}_{mathbf{1}}=mathbf{3 0} ) ( boldsymbol{A}_{mathbf{1}}=mathbf{3 . 6} times mathbf{1 0}^{-mathbf{3}} boldsymbol{m}^{mathbf{2}}, boldsymbol{B}_{mathbf{1}}=mathbf{0 . 2 5} boldsymbol{T} ) ( boldsymbol{R}_{2}=mathbf{1 4} boldsymbol{Omega}, boldsymbol{N}_{2}=boldsymbol{4} boldsymbol{2} ) ( boldsymbol{A}_{2}=mathbf{1 . 8} times mathbf{1 0}^{-mathbf{3}}, boldsymbol{B}_{mathbf{2}}=mathbf{0 . 5 0} boldsymbol{T} ) (The spring constants are identical for the two meters).Determine the ratio of (a) current sensitivity and (b) voltage sensitivity of ( M_{2} ) and ( M_{1} ) |
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1366 | Figure shows two long wires carrying equal currents ( I_{1} ) and ( I_{2} ) flowing in opposite directions.Which of the arrows labeled ( A, B, C ) and ( D ) correctly represents the direction of the magnetic field due to the wires at a point located at an equal distance ( d ) from each wire? A . ( A ) B. ( B ) c. ( C ) ( D . D ) |
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1367 | Assertion The sensitivity of a moving coil galvanometer is increased by placing a suitable magnetic material as a core inside the coil. Reason Soft iron has a high magnetic permeability and cannot be easily magnetized or demagnetized. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
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1368 | The radius of each coil of a Helmholtz galvanometer is ( 0.1 m ) and number of turns in each is ( 25 . ) When a current is passed in it then the deflection of magnetic needle observed as ( 45^{circ} . ) If the horizontal component of earth’s magnetic field is ( 0.314 times 10^{-4} T ) then the value of current will be ( mathbf{A} cdot 0.14 A ) B. ( 0.28 A ) c. ( 0.42 A ) D. ( 0.07 A ) |
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1369 | An electron is moving in a cyclotron at a speed of ( 3.2 times 10^{7} m s^{-1} ) in a magnetic field of ( 5 times 10^{-4} ) T perpendicular to it. What is the frequency of this electron? ( left(boldsymbol{q}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} boldsymbol{C}, boldsymbol{m}_{boldsymbol{e}}=mathbf{9 . 1} timesright. ) ( left.10^{-31} k gright) ) A ( .1 .4 times 10^{5} mathrm{Hz} ) B. ( 1.4 times 10^{7} mathrm{Hz} ) c. ( 1.4 times 10^{6} mathrm{Hz} ) D. ( 1.4 times 10^{9} mathrm{Hz} ) |
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1370 | A long, straight metal has a long hole of radius a drilled parallel to the rod axis with cross-sectional view as shown. If the rod carries a current ( I ), the value of the magnetic field on the axis of the rod is: A ( quad B=frac{mu_{0} I a^{2}}{2 pi cleft(b^{2}-a^{2}right)} ) B. ( B=frac{mu_{0} I}{2 pi c} ) c. ( quad B=frac{mu_{0} I a^{2}}{4 pi cleft(b^{2}-a^{2}right)} ) ( mathbf{D} cdot B=z e r o ) |
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1371 | freely slide on a pair of parallel smooth horizontal rails placed in vertical magnetic field ( B ). The rails are connected by a capacitor of capacitance ( C . ) The electric resistance of the rails and the wire is zero. If a constant force ( F ) acts on the wire as shown in the figure. Then, the acceleration of the wire can be given as ( ^{mathbf{A}} cdot_{a}=frac{C^{2} B^{2} l-F}{m} ) ( ^{mathbf{B}} cdot_{a}=frac{F}{m+C B l} ) ( ^{mathbf{C}} cdot_{a}=frac{F C^{2} B^{2} l}{m} ) D. ( a=frac{F}{m+C B^{2} l^{2}} ) |
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1372 | An electron moves at right angle to a magnetic field of ( 15 times 10^{-2} T ) with a speed of ( 6 times 10^{7} m / s . ) If the specific charge of the electron is ( 1.7 times ) ( 10^{11} C / k g . ) The radius of the circular path will be ( mathbf{A} cdot 2.9 mathrm{cm} ) в. ( 3.9 mathrm{cm} ) ( c .2 .35 mathrm{cm} ) D. ( 2 c m ) |
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1373 | Electric current is passed through a straight conductor passing through the centre of a piece of cupboard. Some iron filings are sprinkled on the cardboard and tapped. How will the iron filings spread out around the conductor? A. settle as parallel lines B. settle as circles c. settle at one point D. do not acquire any regular pattern |
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