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

#### List of electromagnetic induction Questions

Question No | Questions | Class |
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1 | The total charge induced in a conducting loop when it is moved in magnetic field depends on A. The rate of change of magnetic flux B. Initial magnetic flux only c. The total change in magnetic flux D. Final magnetic flux only |
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2 | A small circular ring is kept inside a larger loop connected to a switch and a battery as shown. The direction of induced current when the switch is made (i) ON (ii) OFF after it was ON for a long time is: A. clockwise, anti-clockwise B. clockwise, clockwise C. anti-clockwise, clockwise D. anti-clockwise, anti-clockwise |
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3 | A rectangular coil of 200 turns and area ( 100 mathrm{cm}^{2} ) is kept perpendicular to a uniform magnetic field of induction ( 0.25 T . ) If the field is reversed in direction in 0.01 second, the average induced emf in the coil is : A ( cdot 10^{6} V ) B . ( 10^{4} V ) ( mathbf{c} cdot 10^{2} V ) D. zero |
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4 | A square frame with side ( a ) and a long straight wire carrying a current ( i ) are located in the same plane as shown in figure. The frame translates to the right with constant velocity ( v . ) Find the emf induced in the frame as a function of distance ( boldsymbol{x} ) A ( cdot frac{mu_{0}}{7 pi} frac{2 i a^{3} v}{x(x+a)} ) В. ( frac{mu_{0}}{4 pi} frac{2 i a^{2} v}{x(x+a)} ) c. ( frac{mu_{0}}{2 pi} frac{2 i a^{4} v}{x(x+a)} ) D. ( frac{mu_{0}}{3 pi} frac{7 i a^{2} v}{x(x+a)} ) |
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5 | A long solenoid of radius 2 cm has 100 turns/cm and is surrounded by a 100 turn coil of radius ( 4 mathrm{cm} ) having a total resistance ( 20 Omega ). If the current changes from ( 5 A ) to ( -5 A ), find the charge through the galvanometer. A . zero в. ( 800 mu ) с c. ( 400 mu ) с D. ( 600 mu ) C |
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6 | Which device uses slip rings? A. A d.c electric motor B. A relay C. A transformer D. An a.c. generator |
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7 | Using ( varepsilon=-frac{d phi}{d t} ) and ( varepsilon=i R ) find the current in the loop after the external field has stopped changing. A ( cdot frac{d i}{d t}=-left(frac{2 R}{mu_{0} pi a}right) ) в. ( frac{d i}{d t}=-frac{R}{mu_{0} a} ) c. ( frac{d i}{d t}=frac{-2 R}{mu_{0} a} i ) D. ( frac{d i}{d t}=frac{-2 R}{3 mu_{0} pi a} ) |
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8 | A wire shaped as a circle of radius ( mathrm{R} ) rotates about the axis ( 00^{prime} ) with an angular velocity ( omega ) as shown in figure. Resistance of the circuit is ( R ). Find the mean thermal power generated in the loop during a period of a rotation. A ( cdot frac{left(B pi a^{2} omegaright)^{2}}{4 R} ) B. ( frac{left(B pi a^{2} omegaright)^{2}}{2 R} ) ( ^{mathbf{C}} cdot frac{left(3 B pi a^{2} omegaright)^{2}}{2 R} ) D. None of these |
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9 | A metal rod ( frac{1}{sqrt{pi}} m ) long rotates about one of its ends perpendicular to a plane whose magnetic induction is ( 4 times ) ( 10^{-3} T . ) Calculate the number of revolutions made by the rod per second if the e.m.f induced between the ends of the rod is ( 16 m V ) |
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10 | Consider the time interval ( t=2.0 s ) to ( boldsymbol{t}=mathbf{4} . mathbf{0} boldsymbol{s} ) The magnetic field is perpendicular to the plane of the loop. |
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11 | (d) rR 47. A circuit contains two inductors of self-inductance L, and L2 in series (figure). If M is the mutual inductance, then the effective inductance of the circuit shown will be 0000000 0000000 L2V (a) L+L, (C) L + L +M (b) L. +L2-2M (d) L + L + 2M 40 TI.. c . |
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12 | The current passing through a choke coil of ( 5 H ) is decreasing at the rate of ( 2 A / s . ) The e.m.f. developed across the coil is A . ( 10 V ) в. ( -10 V ) ( mathrm{c} .2 .5 mathrm{V} ) D. ( -2.5 V ) |
12 |

13 | What is electromagnetic induction? Give an experiment which demonstrate this phenomenon. | 12 |

14 | In figure, if the current ( i ) decreases at a rate ( alpha, ) then ( V_{A}-V_{B} ) is A. zero в. ( -alpha L ) ( c cdot alpha L ) D. No relation exists |
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15 | Two circular coils ‘X’ and ‘Y’ are placed closed to each other. If the current in the coil ‘X’ is changed, will some current be induced in the coil ‘Y’? Give reason. |
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16 | Explain self-induction of a coil. Arrive at an expression for the induced emf in a coil and the rate of change of current in ¡t |
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17 | Name four appliances wherein an electric motor, a rotating device that converts electrical energy to mechanical energy, is used as an important component. In what respect motors are different from generators? |
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18 | 20. A boat is moving due east in a region where the earth’s magnetic field is 5.0 x 10-5 NA-‘m-‘ due north and horizontal. The boat carries a vertical aerial 2 m long. If the speed of the boat is 1.50 ms, the magnitude of the induced emf in the wire of aerial is (a) 1 mV (b) 0.75 mV (c) 0.50 mV (d) 0.15 mV (AIEEE 2011) |
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19 | Describe the working of an AC generator with the help of a labelled circuit diagram. What changes must be made in the arrangement to convert it to a DC generator? |
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20 | Some magnetic flux is changed from a coil of resistance ( 10 Omega ). As a result, an induced current is developed in it, which varies with time as shown in the figure. The magnitude of change in flux through the coil in webers is: ( A ) B. 4 ( c .6 ) ( D ) |
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21 | At ( t=0, ) when the magnetic field is switched on tehe conducting rod is moved to the left at constant speed ( 5 c m / s ) by some external means. At ( t= ) ( 2 s, ) net induced emf has magnitude A . ( 0.12 V ) B. ( 0.08 V ) c. ( 0.04 V ) D. ( 0.02 V ) |
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22 | A 100 millihenry coil carries a current of ampere. Energy stored in its magnetic field is A . 0.5 B . 1 J c. 0.05 D. 0.1 |
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23 | Which of the following is not correct about cyclotron.? A. It is a machine to accelerate charged particles or ions to high energies. B. Cyclotron uses both electric and magnetic fields in combination to increase the energy of charged particles. C. The operation of the cyclotron is based on the fact that the time for one revolution of an ion is independent of its speed or radius of its orbit D. The charged particles and ions in cyclotron can move on any arbitary path |
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24 | Write Faraday’s laws of electro magnetic induction. | 12 |

25 | Consider the situation shown in figure. The wire ( A B ) slides on the fixed rails with a constant velocity. If the wire ( A B ) is replaced by a semicircular wire, the magnitude of the induced current will A. Increase B. Remain the same c. Decrease D. Increase or decrease depending on whether the semicircle bulges towards the resistance or away from it. |
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26 | A generator with a circular coil of 100 turns of area ( 2 times 10^{-2} m^{2} ) is immersed in a ( 0.01 T ) magnetic field and rotated at a frequency of ( 50 H z . ) The maximum emf which is produced during a cycle is ( mathbf{A} cdot 6.28 V ) B . ( 3.44 V ) ( c cdot 10 V ) D. ( 1.32 V ) |
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27 | An athlete with ( 3 mathrm{m} ) long iron rod in hand runs towards east with a speed of 30 kmph. The horizontal component of earth’s magnetic field is ( 4 times ) ( 10^{-5} W b / m^{2} . ) If he runs with the rod in horizontal and vertical positions then the induced emf generated in the rod in two cases will be A. zero in vertical position and volt in horizonta position. B. 1 ( times 10 ) volt in vertical position and zero volt in in horizontal position c. zero in both positions D. ( 1 times 10^{-3} ) volt in both positions |
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28 | Two inductors ( L_{1} ) and ( L_{2} ) are connected in parallel and a time varying current i flows as shown. The ratio of currents ( mathbf{i}_{i} / mathrm{l}_{2} ) at any time ( mathrm{t} ) is ( A cdot L_{1} / L_{2} ) B . ( L_{2} / L_{1} ) ( mathbf{C} cdot frac{L_{1}^{2}}{left(L_{1}+L_{2}right)^{2}} ) ( D ) |
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29 | An AC generator is a device which converts: A. Electrical energy to mechanical energy. B. Heat energy to electrical energy c. Heat energy to light energy. D. Mechanical energy to electrical energy |
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30 | The magnetic flux through a coil is ( 4 x ) ( 10^{-4} W / b / m^{2} ) at time ( t=0 . ) It reduces to ( 10 % ) of its original value in ‘t’ seconds.If the induced e.m.f is ( 0.72 m V ) then the time ( t ) is: ( mathbf{A} cdot 0.25 s ) B. ( 0.05 s ) c. ( 0.75 s ) D. ( 1 s ) |
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31 | If strength of magnetic field ( vec{B}=2 hat{i}+ ) ( hat{boldsymbol{j}}-hat{boldsymbol{k}} ) and area vector is ( overrightarrow{boldsymbol{A}}=mathbf{3} hat{boldsymbol{i}}-hat{boldsymbol{j}} ) then find the magnetic flux link with area vector A. 4 wber B. 6 weber c. 7 weber D. 5 weber |
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32 | Magnetic flux passing through a coil is initially ( 4 times 10^{-4} ) Wh. It reduces to ( 10 % ) of its original value in ‘t’ second. If the e.m.f. induced is ( 0.72 mathrm{mV} ) then ‘t’ in second is: A . 0.3 B. 0.4 c. 0.5 D. 0.6 |
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33 | ( P Q ) is an infinite current carrying conductor. ( A B ) and ( C D ) are smooth conducting rods on which a conductor ( E F ) moves with constant velocity ( v ) as shown. The force needed to maintain constant speed to ( boldsymbol{E} boldsymbol{F} ) is ( ^{mathbf{A}} cdot frac{1}{v R}left[frac{mu_{0} I v}{2 pi} ln frac{(b)}{(a)}right]^{2} ) ( ^{mathrm{B}} cdot frac{v}{R}left[frac{mu_{0} I v}{2 pi} ln frac{(a)}{(b)}right]^{2} ) ( ^{mathrm{c}} cdot frac{v}{R}left[frac{mu_{0} I v}{2 pi} ln frac{(b)}{(a)}right]^{2} ) D. None of these |
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34 | The essential difference between AC and DC generator is: A. AC generator has an electromagnet while DC generator has permanent magnet. B. DC generator will generate high voltage. C. AC generator will generate high voltage. D. AC generator has slip rings while DC generator has a commutator |
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35 | The self inductance of a coil is ( 5 mathrm{m} ) H. If a current of 2 A is flowing in it then the magnetic flux produced in the coil will be A . 0.01 Weber B. 10 Weber c. zero D. 1 Weber |
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36 | A solenoid of inductance ( L ) carrying a certain current is linked with a total magnetic flux ( phi ). Now it is connected to a condenser with which it shares half of its initial energy. The total flux now linked with the solenoid is: ( A cdot frac{phi}{2} ) в. ( frac{phi}{sqrt{2}} ) ( c cdot frac{phi}{2 sqrt{2}} ) D. |
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37 | A conducting rod of length ( boldsymbol{L}=mathbf{0 . 1 m} ) is moving with a uniform speed ( boldsymbol{v}= ) ( 0.2 m / s ) on conducting rails in a magnetic field ( B=0.5 T ) as shown. On one side, the end of the rails is connected to a capacitor of capacitance ( C=20 mu F . ) Then the charges on the capacitor plates are : A ( cdot q_{A}=0=q_{B} ) B ( cdot q_{A}=+20 mu C ) and ( q_{B}=-20 mu C ) ( mathbf{c} cdot q_{A}=+0.2 mu C ) and ( q_{B}=-0.2 mu C ) ( mathbf{D} cdot q_{A}=-0.2 mu C ) and ( q_{B}=-0.2 mu C ) |
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38 | (a) How are eddy currently generated in a conductor which is subjected to ( n ) magnetic field? (b) Write two examples of their useful applications. (c) How can the disadvantages of eddy currents be minimized? |
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39 | Epilepsy can be diagnosed using A. ECG B. ultrasound c. ЕEG D. x-ray |
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40 | The four wire loops shown in figure have vertical edge lengths of either ( L, 2 L ) or 3 ( L ). They will move with the same speed into a region of uniform magnetic field ( vec{B} ) directed out of the page. Rank them according to the maximum magnitude of the induced emf greatest to least. A. 1 and 2 tie, then 3 and 4 tie B. 3 and 4 tie, then 1 and 2 tie c. 4,2,3,1 D. 4 then 2 and 3 tie, and then 1 E. answer required |
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41 | What is motional emf? State any two factors on which it depends. |
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42 | An electricity generating machine consists of a turbine and a A. Dynamo B. core c. Heat D. sun |
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43 | A plot of magnetic flux ( (phi) ) versus current (I) is shown in the figure, for two inductors ( A ) and ( B ). Which of the two has the larger value of self-inductance? |
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44 | A non-conducting ring having charge ( q ) uniformly distributed over its circumference is placed on a rough horizontal surface. A vertical time varying magnetic field ( B=4 t^{2} ) is switched on at time ( t=0 . ) Mass of the ring is ‘m’ and radius is R. The ring starts rotating after 2 s. The coefficient of friction between the ring and the table is: A ( cdot frac{4 q m R}{g} ) в. ( frac{2 q m R}{g} ) c. ( frac{8 q R}{m g} ) D. ( frac{q R}{2 m g} ) |
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45 | The figure shows four wire loops, with edge lengths of either I or 21. All four loops will move through a region of uniform magnetic field ( g ) at the same constant velocity. In which loop the emf induced is maximum: ( A ) B. I c. III D. IV |
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46 | The unit of inductance is equivalent to A. ( frac{text { volt } times text { ampere }}{text { second }} ) в. ( frac{text { ampere }}{text {volt } times text { second }} ) c. ( frac{v o l t}{text { Ampere } times text { second }} ) D. ( frac{text {volt } times text { second }}{text { ampere }} ) |
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47 | Assertion Induced potential across a coil and therefore induced current is always opposite to the direction of current due to external source. Reason Lenz’s law states that induced emf always opposes the cause due to which it is being produced. 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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48 | Alternating current of peak value ( left(frac{2}{pi}right) ) ampere flows through the primary coil of the transformer. The coefficient of mutual inductance between primary and secondary coil is 1 henry. The peak e.m.f. induced in secondary coil is (Frequency of a.c. ( =50 mathrm{Hz}) ) ( A cdot 100 v ) B. 200 V c. 300 D. 400 |
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49 | Q Type your question- speed of ( 2 mathrm{cms}^{-1} ) on a ( mathrm{V} ) -shaped conductor each prong of which is ( 50 mathrm{cm} ) in length immersed in a uniform magnetic field ( mathbf{B}=mathbf{0 . 4 T}, ) perpendicular and into the ( V ) -plane shown in the Figure. To start with, at time ( mathbf{t}=mathbf{0} s, ) the |
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50 | A conducting rod of length ( l ) is hinged at point ( 0 . ) It is free to rotate in a vertical plane. There exists a uniform magnetic field ( vec{B} ) in horizontal direction. The rod is released from the position shown. The potential difference between the two ends of the rod is proportional to: This question has multiple correct options ( A cdot l^{3 / 2} ) B ( cdot l^{2} ) ( c cdot sin theta ) D. ( (sin theta)^{1 / 2} ) |
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51 | The magnetic potential energy stored in a certain inductor is ( 25 mathrm{mJ} ), when the current in the inductor is ( 60 mathrm{mA} ). This inductor is of inductance. A . 1.389 н В. 0.138 н c. 13.89 н D. ( 138.88 mathrm{H} ) |
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52 | An inductor is connected to a direct voltage source through a switch. Now A. Very large emf is induced in inductor when switch is closed B. Larger emf is induced when switch is opened C. Large emf is induced whether switch is closed or opened D. No emf is induced whether switch is closed or opened |
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53 | A conducting rod of length ( l ) is moving in a transverse magnetic field of strength ( B ) with velocity ( v ). The resistance of the rod is ( R ). The current in the rod is A ( cdot frac{B l v}{R} ) в. ( B l v ) c. ( Z e r o ) D. ( frac{B^{2} v^{2} l^{2}}{R} ) |
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54 | A bicycle is resting on its stand in the east-west direction and the rear wheel is rotated at an angular speed of 50 revolutions per minute. If the length of each spoke is ( 30.0 mathrm{cm} ) and the horizontal component of the earth’s magnetic field is ( 4 times 10^{-5} T ), find the emf induced between the axis and the outer end of a spoke. Neglect centripetal force acting on the free electrons of the spoke. |
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55 | Three identical wires are bent into semi-circular arcs each of radius ( boldsymbol{R} ) These arcs are connected with each other to form a closed mesh such that one of them lies in x-y plane, one in ( y-z ) plane and the other in z-x plane as shown in figure. In the region of space, a uniform ( vec{B}=B_{0}(hat{i}+hat{j}) ) exists, whose magnitude increases at a constant rate ( boldsymbol{d} boldsymbol{B} / boldsymbol{d} boldsymbol{t}=boldsymbol{alpha} . ) Calculate the magnitude of emf induced in the mesh and mark direction of flow of induced current in the mesh. |
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56 | When the current in a coil changes from 2 amp. to 4 amp. in 0.05 sec., an e.m.f. of 8 volt induced in the coil. The coefficient of self inductance of the coil is A. 0.1 henry B. 0.2 henry c. 0.4 henry D. 0.8 henry |
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57 | In a ( D C ) generator, the induced e.m.f, in the armature is A ( . D C ) в. ( A C ) c. Fluctuating ( D C ) D. Both ( A C ) and ( D C ) |
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58 | Current in a coil of self-inductance ( 2.0 H ) is increasing as ( i=2 sin t^{2} . ) The amount of energy spent during the period when the current changes from 0 to ( 2 A ) is: A . 15 в. 2 J ( c .3 J ) D. ( 4 J ) |
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59 | Name and state the principle of a simple a.c. generator. What is its use? | 12 |

60 | A solenoid ( 30 c m ) long is made by winding 2000 loops of wire on an iron rod whose cross-section is ( 1.5 mathrm{cm}^{2} ). If the relative permeability of the iron is ( 6000, ) what is the self-inductance of the solenoid? ( mathbf{A} cdot 15 H ) в. ( 2.5 H ) ( c .3 .5 H ) D. ( 0.5 H ) |
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61 | What experiment do you suggest to understand Faradays law?What items are required? What suggestions do you give to get good results of the experiment? Give precautions also. | 12 |

62 | A charged particle oscillates about its equilibrium position with an frequency of ( 100 M H z . ) What is the frequency of electromagnetic waves produced by the oscillator? |
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63 | Some magnetic flux is changed in a coil of resistance 10 ohm. As a result an induced current is developed in it, which varies with time as shown in figure. The magnitude of change in flux through the coil in Webers is (Neglect self inductance of the coil) ( A cdot 2 ) ( B .4 ) ( c cdot 6 ) ( D ) |
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64 | Explain ‘Electric generator’ with the help of the following points : i. Principle of an electric generator. ii. Function of slip rings. iii. Any two uses of a generator. |
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65 | A rod AB moves with a uniform velocity ( v ) in a uniform magnetic field as shown in figure. ( begin{array}{llllll}mathbf{X} & mathbf{X} & mathbf{X} & mathbf{A} & mathbf{X} & mathbf{X} & mathbf{X} \ mathbf{X} & mathbf{X} & mathbf{X} & mathbf{n} & mathbf{X} & mathbf{X} & mathbf{X} \ mathbf{X} & mathbf{X} & mathbf{X} & mathbf{n} & mathbf{X} & mathbf{X} & mathbf{X} \ mathbf{X} & mathbf{X} & mathbf{X} & mathbf{B} & mathbf{X} & mathbf{X} & mathbf{X}end{array} ) A. The rod becomes electrically charged B. The end A becomes positively charged c. The end B become positively charged |
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66 | Electromagnetic induction is the: A. charging of a body with a positive charge B. production of current by relative motion between a magnet and a coil C. rotation of the coil of an electric motor D. generation of magnetic field due to a current carrying solenoid |
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67 | The coefficients of self induction of two coils are ( L_{1}=8 mathrm{mH} ) and ( L_{2}=2 mathrm{mH} ) respectively. The current rises in the two coils at the same rate. The power given to the two coils at any instant is same. The ratio of energies stored in the coils will be: A. ( frac{W_{1}}{W_{2}}=4 ) B. ( frac{W_{1}}{W_{2}}=frac{1}{4} ) ( mathbf{c} cdot frac{W_{1}}{W_{2}}=frac{3}{4} ) D. ( frac{W_{1}}{W_{2}}=frac{4}{3} ) |
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68 | Match column I with column II and select the correct option from the codes given below |
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69 | A ( 200 k m ) long telegraph wire has a capacitance of ( 0.014 mu F / k m . ) If it carries an ac of ( 5 k H z, ) what should be the inductance required to be connected in series, so that the impedance is minimum? Take ( pi=sqrt{10} ) | 12 |

70 | Constant magnetic field in the coil induces A . high B. low ( c cdot n o ) D. alternating |
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71 | State Faraday’s laws of electromagnetic induction and Lenz’s law. | 12 |

72 | at opposite sides of an infinitely long straight conducting wire as shown in the figure. If current in the wire is slowly decreased, then the direction of the nduced current will be : A. clockwise in ( A ) and anticlockwise in ( B ) 3. anticlockwise in ( A ) and clockwise in ( B ) c. clockwise in both ( A ) and ( B ) D. anticlockwise in both ( A ) and ( B ) |
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73 | The Sl unit of inductance is | 12 |

74 | A circular coil of conducting wire has an area ( A ) and number of turns ( N . ) It is lying in a vertical plane in a region where uniform magnetic field B exist with field direction normal to the coil plane. If the coil is rotated about a vertical axis by an angle ( pi ) in 0.5 seconds, then the value of the emf induced at the ends of the coil is ( A ). 4 NAB B. ( 4 pi ) NAB c. 8 NAB D. 8 ( pi ) NAB |
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75 | A flat circular coil of ( n ) turns, area ( A ) and resistance ( boldsymbol{R} ) is placed in a uniform magnetic field ( B ). The plane of coil is initially perpendicular to ( B ). When the coil is rotated through an angle of ( 180^{circ} ) about one of its diameter, a charge ( Q_{1} ) flows through the coil. When the same coil after being brought to its initial position, is rotated through an angle of ( 360^{circ} ) about the same axis a charge ( Q_{2} ) flows through it. Then ( Q_{2} / Q_{1} ) A . 1 B . 2 c. ( 1 / 2 ) D. |
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76 | 15. A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be (a) halved (b) the same (c) doubled (d) quadrupled |
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77 | Find the current through the conductor during its motion |
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78 | A conducting rod ( P Q ) of length ( L= ) 1.0 ( m ) is moving with a uniform speed ( boldsymbol{v}=20 boldsymbol{m} / boldsymbol{s} ) in a uniform magnetic field ( B=4.0 T ) directed into the paper ( A ) capacitor of capacity ( boldsymbol{C}=mathbf{1 0} boldsymbol{mu} boldsymbol{F} ) is connected as shown in figure. Then ( mathbf{A} cdot q_{A}=+800 mu C ) and ( q_{B}=-800 mu C ) B ( cdot q_{A}=-800 mu C ) and ( q_{B}=+800 mu C ) ( mathbf{c} cdot q_{A}=0=q_{B} ) D. charged stored in the capacitor increases exponentially with time |
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79 | In an inductance coil the current increases from zero to ( 6 A ) in 0.3 second by which an induced e.m.f. of ( 60 mathrm{V} ) is produced in it. The value of coefficient of self-induction of coil is : A. ( 1 H ) в. ( 0.5 H ) ( c .2 H ) D. ( 3 H ) |
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80 | are connected on the top by a capacitor C. A sliding conductor AB of length L slides with its ends in contact with the bars. The arrangement is placed in a uniform horizontal magnetic field directed normal to the plane of the figure. The conductor is released from rest. The displacement ( (x) ) in meter of the conductor at time ( t=2 ) sec is: ( left(text { Given } boldsymbol{m}=mathbf{1 0 0} boldsymbol{g} boldsymbol{m}, boldsymbol{g}=mathbf{1 0 m} / boldsymbol{s}^{2}, boldsymbol{B}=right. ) 100Tesla, ( boldsymbol{L}=mathbf{1} boldsymbol{m}, boldsymbol{a} boldsymbol{n} boldsymbol{d} boldsymbol{C}=mathbf{1 0} boldsymbol{mu} boldsymbol{F}) ) A . 10 B. 14 ( c cdot 7 ) ( D ) |
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81 | 8 the magnetic field changes at the rate of ( d B / d t . A B=B C . ) Calculate the induced emf between the ends of length ( A B, ) if ( A C ) and ( B C ) were removed from the circuit. ( ^{mathbf{A}} cdot R^{2}left(frac{d B}{d t}right) ) ( ^{mathbf{B}} cdot 4 R^{2}left(frac{d B}{d t}right) ) ( ^{mathbf{C}} cdot frac{1}{2} R^{2}left(frac{d B}{d t}right) ) ( ^{mathrm{D}} 2 R^{2}left(frac{d B}{d t}right) ) E. None of the above |
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82 | State Faraday’s laws of electromagnetic induction. |
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83 | Flux density under trailing pole tips in case of generator will : A. increase B. decrease c. either increase or decrease D. none of the above |
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84 | Define electromagnetic induction? | 12 |

85 | A long wire carrying current ( i ) is placed close to a U-shaped conductor (of negligible resistance). A wire of length ( l ) as shown in figure slides with a velocity v. Find the current induced in the loop as a function of distance ( x ) from the current carrying wire to slider. A ( cdot frac{mu_{0} i l u}{R x} ) в. ( frac{mu_{0} i l u}{2 pi R x} ) c. ( frac{mu_{0} i l u}{2 R x} ) D. ( frac{mu_{0} i l u}{4 pi R x} ) |
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86 | The magnitude of induced current in a closed coil increases with the increase in the ( ldots ldots . . . . . . . . . . ) of magnetic lines of force. A. strength B. alternating c. magnetic field D. less |
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87 | To convert mechanical energy into electrical energy, one can use This question has multiple correct options A. ( D C ) dynamo B. ( A C ) dynomo c. motor D. transformer |
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88 | The mutual inductance between two coils when a current of 5 A changes to ( 10 mathrm{A} ) in ( 1 mathrm{s} ) and induces an emf of ( 100 mathrm{m} ) Vin the secondary is A . ( 20 mathrm{m} ) н B. ( 10 mathrm{mH} ) c. ( 30 mathrm{mH} ) D. ( 15 mathrm{mH} ) |
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89 | A rod of length ( L ) rotates in the form of a conical pendulum with an angular velocity ( omega ) about its axis as shown in figure. The rod makes an angle ( boldsymbol{theta} ) with the axis. The magnitude of the motional emf developed across the two ends of the rod is ( A ) в. ( ^{mathrm{c}} cdot frac{1}{2}^{B omega L^{2} cos ^{2} theta} ) D. E. answer required |
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90 | An inductor is connected to a battery through a switch. The emf induced in the inductor is much larger when the switch is opened as compared to the emf induced when the switch is closed. Is this statement true or false? |
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91 | Collect information of experiments done by Faraday. | 12 |

92 | – 17. A long solenoid having 200 turns per centimeter carries a current of 1.5 A. At the center of the solenoid is placed a coil of 100 turns of cross-sectional area 3.14 x 10-4 m² having its axis parallel to the field produced by the solenoid. When the |
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93 | Study involving both electricity and magnetism is called A. electromagnetism B. magnetoelectricism c. electricmagnetism D. magneticelectromerism |
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94 | Two coils ( P ) and ( Q ) are kept near each other. When no current flows through coil ( P ) and current increases in coil ( Q ) at the rate ( 10 A / s ), the e.m.f. in coil ( P ) is ( 15 m V . ) When coil ( Q ) carries no current and current of ( 1.8 A ) flows through coil ( P, ) the magnetic flux linked with the coil ( Q ) is A. ( 1.4 mathrm{m} mathrm{Wb} ) B . ( 2.2 mathrm{m} mathrm{Wb} ) ( mathbf{c} .2 .7 mathrm{m} mathrm{Wb} ) D. ( 2.9 mathrm{m} mathrm{Wb} ) |
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95 | Pick out the wrong statement. A. Gauss’s law of magnetism is given by ( alpha phi B . d s=0 ) B. An EM wave is a wave radiated by a charge at rest and propagates through electric field only C. A time varying electric field is a source of changing magnetic field D. Faraday’s law of EM induction is ( phi E . d I=-frac{d phi_{B}}{d t} ) |
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96 | In what direction does the induced current in coil flow ( A cdot A ) to ( B ) B. в to A c. No current D. cant say |
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97 | A coil of resistance ( 400 Omega ) is placed in a magnetic field. If the magnetic flux ( phi(W b) ) linked with the coil varies with time ( t(sec ) ) as ( Phi=50 t^{2}+4 ) The current in the coil at ( t=2 sec ) is A. 2A B. 1A ( c .0 .5 A ) D. 0.1A |
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98 | D 211 x x 9. A wire is bent to form the double loop shown in figure. There is a uniform magnetic field directed into the plane of the loop. If the magnitude xa X X X bx of this field is decreasing, the cur- rent will flow from (a) a to b and c to do x x (b) b to a and d to c (c) a to b and d to c art х Хd x (d) b to a and c to d x x x x |
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99 | An ac generator produced an output voltage ( boldsymbol{E}=mathbf{1 7 0} sin mathbf{3 7 7 t} ) volts, where ( t ) is in seconds. The frequency of ac voltage is ( mathbf{A} cdot 50 H z ) в. ( 110 H z ) ( mathbf{c} cdot 60 H z ) D. ( 230 H z ) |
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100 | The value of mutual inductance can be increased by A. decreasing N B. increasing c. winding the coil on wooden frame D. winding the coil on china clay |
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101 | x x x x 6. A thin semicircular conducting ring of radius R is falling with its plane vertical in a horizontal magnetic induction B B. At the position MNQ, the speed of the ring is v and the potential difference developed across the ring is (a) zero (b) ByteR-/2 and Mis at higher potential (c) TRBv and Q is at higher potential (d) 2RBV and Q is at higher potential (d) Poto of de M |
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102 | Direction of induced EMF can be found from A. Lenz law B. Laplace law c. Fleming law D. None of the above |
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103 | The coil ( X ) and ( Y ) have the same number of turns and length. Each has a flux density ( B ) in the middle and a flux density ( 0.5 B ) at the ends when carrying the same current. When the coils are joined to form a long coil of twice the length of ( X ) or ( Y ) and the current ( I ) is sent through the coil, the flux density in the middle is given by: A. 0 в. ( 0.5 B ) c. ( 2 B ) D. ( B ) |
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104 | The current flowing through resistance ( R ) if the rod ( M N ) moves toward left and the rod ( M^{prime} N^{prime} ) moves toward the right is ( A ) [ frac{B l v}{R+(r / 2)} ] в. ( frac{2 B l v}{R+r} ) c. zero ( D ) [ frac{3 B l v}{2(R+r)} ] |
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105 | A conducting wire of length ( ell ) and mass ( m ) can slide without friction on two parallel rails and is connected to capacitance ( C . ) Whole system lies in a magnetic field ( B ) and a constant force ( F ) is applied to the rod. Then This question has multiple correct options A. the rod moves with constant velocity B. the rod moves with an acceleration of ( frac{F}{m+B^{2} ell^{2} c} ) c. there is constant charge on the capacitor D. charge on the capacitor increases with time E. answer required |
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106 | A coil of insulated Copper wire is connected to a Galvanometer. What happens, if a bar magnet is: (i) pushed into the coil? (ii) withdrawn from inside the coil? (iii) held stationary inside the coil? |
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107 | Assertion: When two coils are wound on each other, the mutual induction between the coils is maximum. Reason: Mutual induction does not depend on the orientation of the coils. A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion. B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion. c. Assertion is true but Reason is false D. Assertion is false but Reason is true |
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108 | Whenever there is a change in the magnetic flux linked with a closed circuit, an emf and a current are induced in the circuit. This statement is referred to as: A. Lenz’s law B. Faraday’s second law of electromagnetic induction C. Faraday’s first law of electromagnetic induction D. Laplace’s law |
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109 | What is the self inductance of a coil in which an induced emf of ( 2 V ) is set up, when the current is changing at the rate of ( 4 A s^{-1} ) A . ( 0.5 mathrm{mH} ) в. ( 0.05 mathrm{H} ) ( c cdot 2 H ) D. ( 0.5 H ) |
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110 | The out put of a dynamo using a split ring commutator is A . dc B. ac c. fluctuating dc D. half wave rectified da |
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111 | Figure shows a point ( mathrm{P} ) near a long conductor XY carrying a current 1. MN is a short current carrying conductor, kept at the point ( P, ) parallel to the conductor ( mathbf{X Y} ) (i) What is the direction of magnetic flux density ‘B’ at the point P due to the current flowing through XY? (ii) What is the direction of the force experienced by the conductor MN due to the current flowing through XY? |
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112 | A conducting disc of radius r rotates with a small constant angular velocity ( omega ) about its axis. A uniform magnetic field B exists parallel to the axis of rotations. Find the motional emf between the center and the periphery of the disc. |
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113 | Two coils have a mutual inductance ( 0.55 H . ) The current changes in the first coil according to equation ( boldsymbol{I}=boldsymbol{I}_{0} sin omega boldsymbol{t} ) where, ( I_{0}=10 A ) and ( omega=100 pi r a d / s ) The maximum value of emf in the second coil is A . ( 2 pi ) в. ( 5 pi ) c. ( pi ) D. ( 4 pi ) |
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114 | What are Eddy currents? Describe the ways in which they are used to advantage. |
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115 | In alternative current generator, ( A C ) current reverses its direction: A. 20 times per second B. 50 times per second c. once per second D. twice per second |
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116 | Lenz’s law is a consequence of the law of conservation of A. charge B. mass c. energy D. momentum |
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117 | A metallic rod of ( ^{prime} boldsymbol{L}^{prime} ) length is rotated with angular frequency of ( ^{prime} omega^{prime} ) with one end hinged at the centre and the other end at the circumference of a circular metallic ring of radius ( L ) about an axis passing through the centre and perpendicular to the plane of the ring. ( mathbf{A} ) constant and uniform magnetic field ( boldsymbol{B} ) parallel to the axis is present everywhere. Deduce the expression for the emf between the centre and the metallic ring. (a) ( (b) ) |
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118 | A conducting disc of radius R is rotating with angular velocity ( omega . ) Mass of electron is and charged e. If electrons are the current carries in a conductor, the potential difference between the center and the edge of the disc is: ( ^{A} cdot frac{m omega^{2} R^{2}}{e} ) B. ( frac{m omega^{2} R^{2}}{4 e} ) c. ( frac{m omega^{2} R^{2}}{3 e} ) D. ( frac{m omega^{2} R^{2}}{2 e} ) |
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119 | In electromagnetic induction, the induced charge in a coil is independent of A . Time B. Change in flux c. Resistance in the circuit D. None of the above |
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120 | In the process of electromagnetic induction, the magnitude of the induced emf does not depend on A. The number of turns of the coil B. The magnetic flux linked with the coil c. The rate of change of magnetic flux linked with the coil D. Area of the coil |
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121 | Assertion In the phenomenon of mutual induction, self Induction of each of the coil persists. Reason Self induction arises when strength of current in one coil changes. In mutual induction, current is changing in both the individual coils. 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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122 | A circular coil of mean radius of ( 7 mathrm{cm} ) and having 4000 turns is rotated at the rate of 1800 revolutions per minute in the earth’s magnetic field ( (mathrm{B}=mathbf{0 . 5} ) gauss), the peak value of emf induced in coil will be? A . ( 1.158 mathrm{v} ) B. ( 0.58 mathrm{V} ) c. ( 0.29 v ) D. ( 5.8 v ) |
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123 | A square wire frame of side ( a ) is placed a distance ( b ) away from a long straight conductor carrying current ( I ). The frame has resistance ( R ) and self inductance ( L ) The frame is rotated by ( 180^{circ} ) about ( 00^{prime} ) as shown in figure. Find the electric charge flown through the frame. ( ^{A} cdot frac{2 mu_{0} i a^{2}}{2 pi R b} ) В. ( frac{mu_{0} i}{2 pi R} log _{e} frac{b+a}{b-a} ) c. ( frac{mu_{0} i a}{2 pi R} log _{e} frac{b+a}{b-a} ) D. none of thes |
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124 | The magnetic field is varying as ( boldsymbol{B}(boldsymbol{t})= ) ( B_{o} t ) in the circuit as shown in the figure Then the emf induced in the circuit will be ( mathbf{A} cdot 2 pi a^{2} B_{0} ) В . ( pi a^{2} B_{0} ) c. ( frac{a^{2} B_{0}}{2} ) D. ( frac{pi a^{2} B_{0}}{2} ) |
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125 | Suppose the loop in Exercise is stationary but the current feeding the electromagnet that produces the magnetic field is gradually reduced so that the field decreases from its initia value of ( 0.3 mathrm{T} ) at the rate of ( 0.02 mathrm{T} s^{-1} . ) If the cut is joined and the loop has a resistance of 1.6 ohm , how much power is dissipated by the loop as heat? What is the source of this power? Exercise : I A rectangular wire loop of sides ( 8 mathrm{cm} ) and ( 2 mathrm{cm} ) with a small cut is moving out of a region of uniform magnetic field of magnitude ( 0.3 mathrm{T} ) directed normal to the loop. What is the emf developed across the cut if the velocity of the loop is ( 1 mathrm{cm} ) ( s^{-1} ) in a direction normal to the (a) longer side, (b) shorter side of the loop? For how long does the induced voltage last in each case? |
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126 | (a) ZM 46. A small coil of radius r is placed at the center of a large coil of radius R, where R>>r. The two coils are coplanar. The mutual inductance between the coils is proportional to (a) r/R (b) r/R (c) r-/R2 (d) r/R |
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127 | A dynamo does not consist of A. a bar magnet B. two carbon brushes c. the external circuit D. all of these |
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128 | When an electric cell drives current through load resistance, its back emf, A. Supports the original emf B. opposes the original emf c. supports if internal resistance is low D. Opposes if load resistance is large |
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129 | Whenever current is changed in a coil an induced e.m.f. is produced in the same coil, This property of the coil is due to A. mutual induction B. self induction c. eddy currents D. hysteresis |
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130 | Two identical conductors ( P ) and ( Q ) are placed on two frictionless rails ( R ) and ( S ) in a uniform magnetic field directed into the plane. If ( P ) is moved in the direction shown in figure with a constant speed, then rod ( Q ) begin{tabular}{c|c|c} & ( P ) & ( Q ) \ & & \ ( times ) & ( times ) & ( times ) \ hline( times ) & ( widehat{V} ) & ( times ) & ( times ) \ hline( s ) & & & \ hline( times ) & ( times ) & ( times ) \ hline end{tabular} A. will be attracted toward ( P ) B. will be repelled away from ( P ) c. will remain stationary D. may be repelled away or attracted toward ( P ) E. answer required |
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131 | The two rails of a railway track, insulated from each other and the ground, are connected to millivoltmeter. What is the reading of the millivoltmeter when a train passes at a speed of ( 180 mathrm{km} / mathrm{hr} ) along the track, given that the vertical component of earth’s magnetic field is ( 0.2 times ) ( 10^{-4} w b / m^{2} ) and rails are separated by 1 metre A ( cdot 10^{-1} ) volt B. ( 10 mathrm{mV} ) c. 1 volt ( mathbf{D} cdot 1 m V ) |
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132 | A solid metal cube of edge length ( 2 mathrm{cm} ) is moving in a positive ( y ) direction at a constant speed of ( 6 m / s . ) There is a uniform magnetic field of ( 0.1 T ) in the positive ( z- ) direction. The potential difference between the two faces of the cube perpendicular to the ( x- ) axis, is: ( mathbf{A} cdot 6 m V ) B. ( 1 mathrm{mV} ) c. ( 12 mathrm{mV} ) D. ( 2 m V ) |
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133 | The coil is rotated in a clockwise direction in the magnetic field at a constant rate to induce a current in the wire. If the direction of rotation of the coil is reversed and coil remains rotating at the same constant rate, Identify the correct statement. A. The current in the coil will reverse its direction B. The current in the coil will stop flowing c. The current in the coil will continue to flow in the same direction as before D. The current in the coil will decrease steadily E. The current in the coil will increase steadily |
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134 | A long solenoid with 10 turns per ( mathrm{cm} ) has a small loop of area ( 3 mathrm{Cm}^{2} ) placed inside, normal to the axis of the solenoid. If the current carried by the solenoid changes steadily form ( 2 A ) to ( 4 A ) in ( 0.2 s, ) what is the induced voltage in the loop, while the currect is changing? A ( cdot 4.2 times 10^{-8} ) B. ( 2.8 times 10^{-8} ) C ( .7 .3 times 10^{-6} ) D. ( 3.8 times 10^{-6} ) |
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135 | Whenever the magnetic flux linked with a coil changes, an induced e.m.f. is produced in the circuit. The e.m.f. lasts A. for a short time B. for a long time c. for ever D. so long as the change in flux takes place |
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136 | Whenever the magnetic flux linked with a coil changes, then there is an induced emf in the circuit. This emf lasts: A. for a short time B. for a long time ( c . ) for ever D. so long as the change in the flux takes place |
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137 | There are two thin wire rings, each of radius R, whose axes coincide. The charges on the rings are ( mathrm{q} ) and q.Evaluate the potential difference between the centers of the rings separates by a distance a. A ( cdot frac{q}{pi varepsilon_{0}}left[frac{1}{R}+frac{1}{sqrt{R^{2}+a^{2}}}right] ) B ( cdot frac{q}{2 pi varepsilon}left[frac{1}{R}+frac{1}{sqrt{R^{2}+a^{2}}}right] ) c. ( frac{q}{2 pi varepsilon_{0}}left[frac{1}{R}-frac{1}{sqrt{R^{2}+a^{2}}}right] ) D. ( frac{2 q}{pi varepsilon_{0}}left[frac{1}{R}-frac{1}{sqrt{R^{2}+a^{2}}}right] ) |
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138 | Two coils of self inductances ( 2 mathrm{mH} ) and ( 8 mathrm{mH} ) are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils is: ( A cdot 10 mathrm{mH} ) B. ( 6 mathrm{mH} ) ( c cdot 4 m H ) D. 16 mH |
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139 | A rectangular coil ( A B C D ) is rotated anticlockwise with a uniform angular velocity about the axis shown in figure. The axis of rotation of the coil as well as the magnetic field ( B ) is horizontal. The induced emf in the coil would be minimum when the plane of the coil A. is horizontal B. makes and angle ( 45^{circ} ) with direction of magnetic field ( mathrm{c} ). is at right angle to the magnetic field D. makes and angle of ( 30^{circ} ) with the magnetic field E. answer required |
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140 | 5. A and B are two metallic rings placed at opposite sides of an infinitely long straight conducting wire as shown in figure. If current in the wire is slowly decreased, the direction of the induced current will be (a) clockwise in A and anticlockwise in B (b) anticlockwise in A and clockwise in B (c) clockwise in both A and B (d) anticlockwise in both A and B |
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141 | Will the current be time dependent? | 12 |

142 | The flux linked with a coil of any instant ( t ) is given by ( phi=t^{2}-5 t+25 . ) The induced emf ( operatorname{at} t=4 s ) is? A ( .2 v ) B. ( -3 v ) c. ( 4 v ) D. – ( 4 v ) |
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143 | A rod lies across frictionless rails in uniform magnetic field ( vec{B} ) as shown in Fig. The rod moves to the right with speed ( V . ) In order to make the induced emf in the circuit to be zero, the magnitude of the magnetic field should. begin{tabular}{|l|l|} hline & \ hline(8) & 8 \ hline & ( bigotimes ) \ hline \ hline end{tabular} |
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144 | If the coil in a simple generator is wound around a soft iron core then: A. strength of magnetic field increases. B. current produced will be increased. c. voltage produced will be increased. D. all |
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145 | a. Redraw the diagram! b. This diagram represents c. Label the parts of the diagram. d. Mention the principle used in the device denoted by this diagram |
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146 | The dimensions of self- induction are : ( mathbf{A} cdotleft[M L T^{-2}right] ) B . ( left[M L^{2} T^{-1} A^{-2}right. ) ( mathbf{c} cdotleft[M L^{2} T^{-2} A^{-2}right. ) D・ ( left[M L^{2} T^{-2} A^{2}right] ) |
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147 | Q Type your question placed near a long straight current- carrying wire. The dimensions are shown in the figure. The lone wire lies in the plane of the loop. The current in the long wire varies as ( boldsymbol{I}=boldsymbol{I}_{mathbf{0}}(boldsymbol{t}) . ) The mutual inductance of the pair is A ( cdot frac{mu_{0} a}{2 pi} ln left(frac{2 a+l}{l}right) ) B. ( frac{mu_{0} a}{2 pi} ln left(frac{2 a-l}{l}right) ) c. ( frac{2 mu_{0} a}{2 pi} ln left(frac{a+l}{l}right) ) D. ( frac{mu_{0} a}{2 pi} ln left(frac{a+l}{l}right) ) |
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148 | The two rails of a railways track, insulated from each other and the ground, are connected to a milli voltmeter. What is the reading of the milli voltmeter when a train travels at a speed of ( 20 mathrm{ms}^{-1} ) along the track, given that the vertical component of the earth’s magnetic field is ( 0.2 times 10^{-4} ) ( mathrm{Wbm}^{-2} ) and the rails are separated by 1 ( mathrm{m} ? ) A. 4 mv B. ( 0.4 mathrm{mv} ) c. ( 80 mathrm{mv} ) D. 10 mv |
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149 | Magnetic flux through a circuit of resistance ( 20 Omega ) is changed from 20 Wb to ( 40 mathrm{Wb} ) in ( 5 mathrm{ms} ). Charge passed through the circuit during this time is A . ( 1 mathrm{c} ) B. 2 c. zero D. ( 0.5 mathrm{c} ) |
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150 | The magnetic flux through a circular carrying a current of ( 2.0 A ) is 0.8 weber. If the current reduces to ( 1.5 A ) in ( 0.1 s ) the induced emf be A . ( 2.0 V ) в. ( 4.0 V ) ( c .8 .0 V ) D. None of the above |
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151 | toppr Q Type your question uniform speed ( 20 mathrm{m} / mathrm{sec} . ) Size of magnet is ( 2 times 1 times 2 mathrm{cm} ) and size of coil ( 4 times 6 mathrm{cm} ) as shown in figure. The correct variation of induced emf with time is : (Assume at ( t=0, ) the coil enters in the magnetic field) 4 3 ( c ) ( D ) |
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152 | topp Q Type your question the same wire as shown in figure. ( A E F D ) is a square of side ( 1 m ) and ( boldsymbol{E B}=boldsymbol{F C}=mathbf{0 . 5 m .} ) The entire circuit is placed in a steadily increasing, uniform magnetic field directed into the plane of paper and normal to it. The rate of change of the magnetic field is ( 1 T s^{-1} ) The resistance per unit length of the wire is ( 1 Omega m^{-1} ). Find the magnitude ano direction of the current in the segment ( A E, B E ) and ( E F ) ( ^{mathbf{A}} cdot frac{6}{22} A, E ) to ( A ; frac{7}{22} A, B ) to ( E ; frac{1}{22} A, F ) to ( E ) B. ( frac{1}{22} A, ) E to ( A ; frac{6}{22} A, E ) to ( B ; frac{7}{22} A, F ) to ( E ) c. ( frac{7}{22} A, ) E to ( A ; frac{6}{22} A, B ) to ( E ; frac{1}{22} A, F ) to ( E ) |
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153 | A wire in the shape of an equilateral triangle with sides of length ( 1.00 m ) is kept in a magnetic field of ( 2.00 T ) pointing to the right. Find out the magnitude of the magnetic flux passing through the triangle? A. ( 0 W b ) в. ( 1.00 mathrm{Wb} ) c. ( 1.73 W b ) D. 2.00Wb E. ( 3.46 W b ) |
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154 | Choose the correct options This question has multiple correct options A. Sl unit of magnetic flux is henry-ampere B. SI unit of coefficient of self-inductance is ( J / A ) C. Sl unit of coefficient of self inductance is ( frac{v o l t-s e c o n d}{a m p e r e} ) D. Sl unit of magnetic induction is weber |
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155 | Two similar circular loops carry equal currents in the same direction. On moving the coils further apart, the electric current will A. increase in both B. decrease in both C. remain unaltered D. increases in one and decreases in the second |
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156 | Give one example in which 10 V may be fatal This question has multiple correct options A. when touched to tongue B. when touched with wet hand C. when touched with unaided hand D. when it is a storage battery |
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157 | Self inductance of long solenoid is directly proportional to- ( (A ) is area of cross section) A. ( A ) B . ( A^{2} ) c. ( A^{3} ) D. ( A^{4} ) |
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158 | Light with energy flux of 18 w ( / mathrm{cm}^{2} ) falls on a non reflecting surface of area 20 ( mathrm{cm}^{2} ) at normal incidence the momentum delivered in 30 minutes ise A ( cdot 1.2 times 10^{-6} mathrm{kgms}^{-1} ) B . ( 2.16 times 10^{-3} mathrm{kgms}^{-1} ) C. ( 1.8 times 10^{-3} mathrm{kgms}^{-1} ) D. ( 3.2 times 10^{-3} mathrm{kgms}^{-1} ) |
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159 | A conducting circular loop is placed in a uniform magnetic field ( mathrm{B}=0.025 mathrm{T} ) with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at ( 1 mathrm{mm} mathrm{s}^{-1} ). The induced emf in the loop when the radius is ( 2 mathrm{cm} ) is: A. ( 2 pi mu V ) в. ( pi mu V ) c. ( frac{pi}{2} mu V ) D. ( 3.2 pi mu V ) |
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160 | A square loop of side ( 10 mathrm{cm} ) and resistance ( 0.5 Omega ) is placed vertically in the east-west plane. A uniform magnetic field of ( 0.10 mathrm{T} ) is set up across the plane in the north-east direction. The magnetic field is decreased to zero in 0.70 s at a steady rate. The magnitudes of induced emf and current during this time-interval is then ( A cdot 1 mathrm{mV}, 2 mathrm{mA} ) B. ( 1 mathrm{mV}, 1 mathrm{ma} ) c. ( 2 mathrm{mv}, 2 mathrm{mA} ) D. ( 2 mathrm{mV}, 1 mathrm{mA} ) |
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161 | Flux ( phi( ) in webers) in a closed circuit of resistance 10 ohm varies with time ( t ) (in seconds according to the equation ( phi=6 t^{2}-5 t+1 . ) What is the magnitude of the induced current in 0.25 second : A. ( 0.8 mathrm{A} ) B. 1.2 A c. 0.6 A D. ( 0.2 mathrm{A} ) |
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162 | When a voltage source that is inducing voltage into a large number of coils is disconnected, and a switch that is in series with the coils of wire is also opened, a spark is observed to jump across the switch terminals as the switch begins to open up. Identify the cause of this spark? A. Free electrons from the voltage source B. Free electrons from the coils of wire c. collapse of the magnetic field in the coils D. Secondary electron flow from the source E. Stored voltage in the coils of wire |
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163 | If the voltage applied to a motor is 200 volt and back emf is 160 volt, then the efficiency of the motor will be : A. ( 100 % ) B. 80% c. ( 50 % ) D. 25% |
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164 | A coil of inductance ( 1 H ) and resistance ( 10 Omega ) is connected to a resistanceless battery of emf ( 50 V ) at time ( t=0 . ) The ratio of the rate at which magnetic energy is stored in the coil to the rate at which energy is supplied by the battery at ( t=0.1 s ) is ( frac{37}{n} . ) Find ( x ) |
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165 | Dimension of ( frac{text { magnetic flux }}{text { electric flux }} ) are ( mathbf{A} cdotleft[L T^{-1}right] ) B cdot ( left[T L^{-1}right] ) ( mathbf{c} cdotleft[L^{3} T^{2} A^{-2}right] ) D cdot ( left[L^{0} T^{0} A^{0}right] ) |
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166 | What is an a.c. generator or Dynamo used for? Name the principle on which it works. |
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167 | A semicircular wire of radius ( boldsymbol{R} ) is rotated with constant angular velocity about an axis passing through one end and perpendicular to the plane of the wire. There is a uniform magnetic field of strength ( B ). The induced emf between the ends is ( mathbf{A} cdot B omega R^{2} / 2 ) в. ( 2 B omega R^{2} ) C. is variable D. none of these |
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168 | Which of the following is/are correct statement(s)? This question has multiple correct options A. The motional EMF generated by a magnetic force on a moving wire is case of Lorentz force B. The transformer EMF generated by an electric force due to a changing magnetic field is the result of Faraday law. C. The motional EMF generated by a magnetic force on a moving wire is case of Faraday’s law. D. Both B and C are correct. |
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169 | A coil has self inductance of 0.01 H. The current through it is allowed to change at the rate of ( 1 A ) in ( 10^{-2} ) s. The induced emf is A . ( 1 V ) B. 2 ( c .3 V ) D. ( 4 V ) |
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170 | When a coil rotated in magnetic field induced current in it : A. continuously changes B. remains same c. becomes zero D. becomes maximum |
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171 | Identify which of the following best describe the Mutual inductance? A. the ability of a current carrying conductor to induce a voltage in another conductor through a mutual magnetic field. B. the ability of current carrying conductor to produce a changing magnetic field. C. the ability of a conductor to induce a magnetic field in another current carrying conductor D. the ability of a current carrying conductor to induce a current in another conductor through a mutual magnetic field. E. the ability of a magnetic field to induce a voltage in a current carrying conductor. |
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172 | The wire is found to vibrate in the third harmonic.The time when the emf becomes maximum for the first time is A ( cdot frac{2 pi}{omega} ) B. ( frac{pi}{omega} ) c. ( frac{pi}{2 omega} ) ( D cdot 2 pi ) 1 |
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173 | A 50 turn circular coil has a radius of 3 ( mathrm{cm}, ) it is kept in a magnetic field acting normal to the area of the coil. The magnetic field B is increased from ( 0.10 T ) to ( 0.35 T ) in 2 milli second, the average induced emf will be A. ( 177 V ) B. ( 1.77 V ) c. ( 0.177 V ) D. ( 17.7 V ) |
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174 | The production of an electromotive force across an electrical conductor in a changing magnetic field is known as an Electromagnetic induction. Enter 1 for True and 2 for False. |
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175 | A rectangular loop of wire of size ( 4 c m times 10 c m ) carries steady current of 2 A. A straight long wire carrying 5 A current is kept near the loop as shown. If the loop and the wire are coplanar, find the magnetic flux through the rectangular loop. |
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176 | The frequency of generator ( (mathrm{AC}) ) is measured using: A. multimeter B. AVO meter c. tachometer D. speedometer |
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177 | From which of the following case, the induced current in the loop will not be obtained? A. The loop is moved in the direction of the magnet B. The loop and magnet are moved in the opposite direction with the same speed C. The magnet is moved in the direction of the loop D. The loop and magnet are moved in one direction with the same speed |
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178 | A transformer has 50 turns in primary and 100 turns in secondary. If the primary is connected to 220 V d.c. supply, then the voltage across the secondary will be : A . ( 440 mathrm{V} ) B. 220 ( c cdot 110 v ) D. o v |
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179 | Mark the incorrect statement. A. electric current produces magnetism. B. magnets can produce electric current. C. magnets can’t produce electric current. D. a and b |
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180 | Dynamo produces: A. Charge B. Electromotive force C . Electric field D. Magnetic field |
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181 | When the number of turns per unit length in a solenoid is doubled then its coefficient of self induction will become A . half B. double c. four times D. unchanged |
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182 | Two circular coils can be arranged in any of three situations as shown in the figure. Their mutual inductance will be: A. maximum in situation (i) B. maximum in situation (ii) c. maximum in situation (iii) D. same in all situation |
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183 | A thin wire of length ( 2 m ) is perpendicular to the ( x-y ) plane. It is moved with velocity ( overrightarrow{boldsymbol{v}}=(2 hat{boldsymbol{i}}+boldsymbol{3} hat{boldsymbol{j}}+ ) ( hat{k}) m / s ) through a region of magnetic induction ( vec{B}=(hat{i}+2 hat{j}) W b / m^{2} . ) Then potential difference induced between the ends of the wire is A . ( 2 V ) B. ( 4 V ) ( c .0 V ) D. none of these |
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184 | The phenomena of a electromagnetic induction is A. The process of charging a body B. The process of generating magnetic field due to current passing through a coil C. Producing induced current in a coil due to relative motion between a magnet and a coil D. All the above |
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185 | The Sl unit of inductance, the henry, can be written as : This question has multiple correct options A. weber / ampere B. volt second / ampere C . joule / ampere ( ^{2} ) D. ohm second |
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186 | In figure, there is a conducting ring having resistance ( R ) placed in the plane of paper in a uniform magnetic field ( B_{0} ) If the ring is rotating in the plane of paper about an axis passing through point ( boldsymbol{O} ) and perpendicular to the plane of paper with constant angular speed ( omega ) in clockwise direction, then A. point ( O ) will be at higher potential than ( A ) B. the potential of point ( B ) and ( C ) will different c. the current in the ring will be zero D. the current in the ring will be ( 2 B_{0} omega r^{2} / R ) E. answer required |
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187 | A transformer core is laminated to A. reduce hysteresis loss B. reduce eddy current loss c. reduce copper loss D. reduce all of the above loss |
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188 | In the magnet and coil experiment, the magnet and the coil are moved in the same direction with same speed, the emf induced in the coil is A. Maximum B. Minimum c. Either (1) or (2) D. zero |
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189 | An equilateral triangular conducting frame is rotated with angular velocity ( omega ) in uniform magnetic field ( B ) as shown. Side of triangle is ( l ). Choose the correct options This question has multiple correct options A. ( V_{a}-V_{c}=0 ) B. ( v_{a}-V_{c}=frac{B omega l^{2}}{2} ) c. ( _{V_{a}-V_{b}}=frac{B omega l^{2}}{2} ) D. ( V_{c}-V_{b}=-frac{B omega l^{2}}{2} ) |
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190 | A ( 100 m H ) coil carries ( 1 A ) current. Energy stored in its magnetic field is. A. 0.15 J ( 5.1 .5 . ) B. ( 0.05 J ) ( c .0 .5 J ) D. ( 1 . ) |
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191 | A rectangular coil has 60 turns and its length and width is ( 20 mathrm{cm} ). and ( 10 mathrm{cm} ) respectively. The coil rotates at a speed of 1800 rotation per minute in a uniform magnetic field of ( 0.5 T ) about its one of the diameter. Calculate maximum induced emf will be |
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192 | The value if power ( boldsymbol{P}_{2} ) is A. ( 10000 W ) B. ( 975 W ) ( c .25 W ) D. ( 200 W ) |
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193 | 1,2,3 and 4 are the four stages of ( a ) rotating armature coil placed between the poles of a filed magnet. (a) In which stage / stages will the emf be maximum? (b) Represent graphically the relation between induced emf and angle of rotation of the coils in stages 1,2,3 and 4 |
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194 | A small magnet M is allowed to fall through a fixed horizontal conducting ring R. Let ( g ) be the acceleration due to gravity. The acceleration of M will be This question has multiple correct options A. ( g when it is above R and moving towards R c. g ) when it is below ( R ) and moving away from ( R ) |
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195 | A uniform magnetic field of induction ( boldsymbol{B} ) is confined to a cylindrical region of radius ( R ). The magnetic field is increasing at a constant rate of ( boldsymbol{d B} / boldsymbol{d t T} ) ( s^{-1} . ) An electron placed at the point ( P ) on the periphery of the field, experiences an acceleration: ( ^{mathbf{A}} cdot frac{1}{2} frac{e R}{m} frac{d B}{d t} ) toward left B. ( frac{1}{2} frac{e R}{m} frac{d B}{d t} ) toward right c. ( frac{e R}{m} frac{d B}{d t} ) toward left D. zero |
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196 | What will be the self inductane of a coil of 100 turns if a current of ( 5 A ) produces a magnetic flux ( 5 times 10^{-5} ) Wb? ( mathbf{A} cdot 1 m H ) в. ( 10 mathrm{mH} ) ( c cdot 1 mu H ) D. ( 10 mu H ) |
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197 | The polarity of induced emf is given by A. Ampere’s circuital law B. Biot-Savant’s law C. Lenz’s law D. Remlng’s right hand rule E. Flemhg’s left hand rule |
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198 | A metal disc of radius R rotates with an angular velocity, ( omega=1 r a d / s ) about an axis perpendicular to its plane passing through its centre in a magnetic field of induction B acting perpendicular to the plane of the disc. The induced e.m.f. between the rim and axis of the disc is: A ( . B R^{2} ) B ( cdot 2 B^{2} R^{2} ) ( c cdot B R^{3} ) D. ( B R^{2} / 2 ) |
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199 | When the plane of the armature of an a.c generator is parallel to the field, in which it is rotating A. both the flux linked and induced emf in the coil are zero B. the flux linked with it is zero, while induced emf is maximum c. flux linked is maximum while induced emf is zero D. both the flux and emf have their respective maximumm values |
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200 | What is eddy current? Mention two applications of eddy current. |
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201 | A bar magnet is moved along the axis of a copper ring placed far away from the magnet. Looking from the side of the magnet, an anti-clockwise current is found to be induced in the ring. Which of the following may be true? This question has multiple correct options A. The south pole faces the ring and the magnet moves towards it B. The north pole faces the ring and the magnet moves towards it. c. The south pole faces the ring and the magnet moves away from it. D. The north pole faces the ring and the magnet moves away from it. |
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202 | The phenomenon of electromagnetic Induction is : A. The process of charging a sphere B. The process of producing magnetic field in a coil C. The process of producing induced current in a coil whenever there is a relative motion between the coil and the magnet D. The process of producing cooling effect |
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203 | The induced voltage across a stationary conductor in a stationary magnetic field is A. zero B. reversed in polarity c. increased D. decreased |
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204 | The magnetic field ( B=2 t^{2}+4 t^{2} ) (where ( t= ) time ) is applied perpendicular to the plane of a circular wire of radius ( r ) and resistance ( R ). If all the units are in SI the electric charge that flows through the circular wire during ( t=0 s ) to ( t=2 s ) is A ( cdot frac{6 pi r^{2}}{R} ) в. ( frac{24 pi r^{2}}{R} ) c. ( frac{32 pi r^{2}}{R} ) D. ( frac{48 pi r^{2}}{R} ) |
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205 | The conductor AD moves to the right in a uniform magnetic field directed into the paper: ( (x) ) This question has multiple correct options A. The free electrons in AD will move towards A B. D will acquire a positive potential with respect to A C. If ( D ) and ( A ) are joined by a conductor externally, a current will flow from A to D in AD D. The current in AD flows from lower to higher potential |
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206 | At the instant when the current in an inductor is increasing at a rate of ( mathbf{0 . 0 6 4 0} boldsymbol{A} / boldsymbol{s}, ) the magnitude of the self- induced emf is ( 0.0160 V . ) If the inductor is a solenoid with 400 turns, what is the average magnetic flux through each turn when the current is ( 0.720 A ? ) |
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207 | A magnet is taken towards a conducting ring in such a way that a constant current of ( 10 m A ) is induced in it. The total resistance of the ring is ( 0.5 Omega . ln 5 s, ) the magnetic flux through the ring changes by ( mathbf{A} cdot 0.25 m W b ) B. ( 25 m ) Wb ( mathbf{c} .50 m W b ) D. ( 15 mathrm{m} mathrm{Wb} ) |
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208 | A coil with an area of ( 0.50 m^{2} ) and a resistance of 7 ohms is completely in a changing magnetic field. If the current in the coil is 2.0 Amps, what is the rate of change of the magnetic field? A. ( 3.5 T / s ) в. ( 7 T / s ) c. ( 14 T / s ) D. ( 28 T / s ) |
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209 | Th circular arc (in ( x-y ) plane) shown in figure rotates (about ( z- ) axis ) with a constant angular velocity ( omega . ) Time in a cycle for which there will be induced emf in the loop is: A ( cdot frac{pi}{2 omega} ) B. ( frac{pi}{omega} ) c. ( frac{2 pi}{3 omega} ) D. ( frac{3 pi}{2 omega} ) |
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210 | A loop of area ( 0.5 m^{2} ) is placed in a magnetic field of strength ( 2 T ) in direction making an angle of ( 30^{circ} ) with the field. The magnetic flux linked with the loop will be A ( cdot frac{1}{2} W b ) в. ( sqrt{frac{3}{2}} W b ) c. ( 2 mathrm{Wb} ) D. ( frac{sqrt{3}}{2} W b ) |
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211 | 541 negligible resistance and radius ( a ). It is hinged at the center of the ring and rotated about this point in clockwise direction with a uniform angular velocity ( omega . ) There is a uniform magnetic field of strength ( B ) pointing inward and ( r ) is a stationary resistance. Then This question has multiple correct options A. current through ( r ) is zero B. current through ( r ) is ( left(2 B omega a^{2}right) / 5 r ) c. direction of current in external resistance ( r ) is from center to circumference D. direction of current in external resistance ( r ) is from circumference to center E. answer required |
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212 | In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are A. friction and windage losses B. copper losses c. hysteresis and eddy current losses D. none of the above |
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213 | In the circuit shown (fig), the coil has inductance and resistance. When X is joined to ( Y ), the time constant is ( tau ) during the growth of current. When the steady state is reached, heat is produced in the coil at a rate P. ( X ) is now joined to Z. After joining ( X ) and ( Z ) A. the total heat produced in the coil is ( P tau ) B. the total heat produced in the coil is ( frac{1}{2} P tau ) ( c . ) the total heat produced in the coil is ( 2 P tau ) D. the data given are not sufficient to reach a conclusion |
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214 | 43. A rectangular loop of sides a and b is placed in xy plane. A very long wire is also placed in xy plane such that side of length a of the loop is parallel to the wire. The distance between the wire and the nearest edge of the loop is d. The mutual inductance of this system is proportional to (a) a (b) b (c) 1/d (d) current in wire |
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215 | 77. An inductor coil stores 32 J of magnetic field energy and dissipates energy as heat at the rate of 320 W when a current of 4 amp is passed through it. Find the time constant of the circuit when it is formed across an ideal battery. (a) t= 0.2 sec (b) t= 0.32 sec (c) T=0.5 sec (d) t= 1 sec |
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216 | The current flowing in the circuit is ( mathbf{A} cdot 2.5 A ) B. ( 5 A ) ( c cdot 1 A ) ( mathbf{D} cdot 2 A ) |
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217 | A proton of mass ‘m’ moving with a speed ( v(<<c, ) velocity of light in vacuum) completes a circular orbit in time 'T' in a uniform magnetic field. If the speed of the proton is increased to ( sqrt{2} v, ) what will be time needed to complete the circular orbit? A ( cdot sqrt{2} T ) в. T c. ( frac{T}{sqrt{2}} ) D. ( frac{T}{2} ) |
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218 | A proton (mass ( m ) ) accelerated by a potential difference ( V ) files through a uniform transverse magnetic filed ( boldsymbol{B} ) The field occupies a region of space by width ‘ ( d^{prime} . ) If ( ^{prime} alpha^{prime} ) be the angle of deviation of proton from initial direction of motion (see figure), the value of ( sin alpha ) will be A ( cdot frac{B}{2} sqrt{frac{e d}{m V}} ) B. ( e V sqrt{frac{B d}{2 m}} ) ( ^{c} cdot frac{B}{2} sqrt{frac{e}{2 m V}} ) D ( cdot B d sqrt{frac{e}{2 m V}} ) |
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219 | What determines the frequency of a.c. produced in a generator? A. The number of rotations of the coil in one second. B. the speed of rotation of the coil ( c cdot ) both ( A & B ) D. None of the above |
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220 | Work done by all forces in ring in 0 to ( left(frac{n}{omega}right) ) time interval is ( A ) в. ( frac{1}{8} frac{left(B_{0} Q Rright)^{2}}{m} ) c. ( frac{1}{4} frac{left(B_{0} Q Rright)^{2}}{m} ) D. ( frac{1}{2} frac{left(B_{0} Q Rright)^{2}}{m} ) |
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221 | In a transformer, coefficient of mutual inductance between primary and secondary coil is ( 0.2 mathrm{H} ). When current changes by 5 Na in the primary, then: the induced era in the secondary will be A. ( 0.5 mathrm{v} ) B. 1 ( c cdot 1.5 v ) D. 2.0 |
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222 | Draw a neat diagram of AC dynamo and represent the current in it in the external circuit by a graph. |
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223 | Figure shows a square loop of side ( 5 mathrm{cm} ) being moved towards right at a constant speed of ( 1 mathrm{cm} / mathrm{sec} ). The front edge just enters the ( 20 mathrm{cm} ) wide magnetic field at ( t=0 . ) Find the induced emf in the loop at ( t=2 s ) and ( t=10 s ) |
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224 | An equilateral triangle frame PQR of mass ( mathrm{M} ) and side a is kept under the influence of magnetic force due to inward perpendicular magnetic field B and gravitational field as shown in the figure.The magnitude and direction of current in the frame so that the frame remains at rest is ( A ) [ I=frac{2 M g}{a B} ; text { anticlockwise } ] в. [ I=frac{2 M g}{a B} ; text { clockwise } ] ( c ) [ I=frac{M g}{a B} ; text {anticlockwise} ] ( D ) [ I=frac{M g}{a B} ; text { clockwise } ] |
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225 | What does an electric generator generate? A. current B. Magnetism c. Gravity D. Light |
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226 | Write the Faraday’s law of electromagnetic induction. |
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227 | A small generator is called a A. AC generator B. DC generator c. Dynamo D. All |
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228 | What amount of power is generated in that resistance? ( P=frac{2 v^{2} B^{2} d^{2} R}{left(R+frac{2 rho d}{S}right)^{2}} ) ( P=frac{2 v^{2} B^{2} d^{2} R}{left(R+frac{rho d}{S}right)^{2}} ) ( mathbf{C} cdot p=frac{v^{2} B^{2} d^{2} R}{left(R+frac{2 rho d}{S}right)^{2}} ) ( P=frac{v^{2} B^{2} d^{2} R}{left(R+frac{rho d}{S}right)^{2}} ) |
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229 | toppr Q Type your question generated across the coil during one cycle is ( A ) B. ( c ) ( D ) |
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230 | The area of the coil must be. A . ( 1.8 m^{2} ) B. ( 18 m^{2} ) ( c cdot 8 m^{2} ) D. none of these |
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231 | A cyclist riding a bicycle fitted with dynamo to a tyre gets bright light from the bulb connected when he s fast. this is because A. magnet becomes powerful, when wheel rotates faster and current flows fast B. current flows easly when cycle goes down c. more magnetic lines of force change with respect to the coil and leading more current D. coil become hot due to friction and produces more current |
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232 | A coil of cross-sectional area ( boldsymbol{A} ) having ( boldsymbol{n} ) turns is placed in a uniform magnetic field ( B ). When it is rotated with an angular velocity ( omega, ) the maximum e.m.f. induced in the coil will be ( mathbf{A} cdot n B A omega ) В ( cdot frac{3}{2} n B A omega ) ( c .3 n B A omega ) D. ( frac{1}{2} n B A ) |
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233 | A machine is run such that electrical current is input and as a result rotation is achieved in the rotor. If current is turned off and rotation is forced in the machine A. current is produced B. Rotor motion faces resisting force c. Machine acts as a generator D. All of the above |
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234 | Two concentric coils each of radius equal to ( 2 pi mathrm{cm} ) are placed at right angles to each other. 3 ampere and 4 ampere are the currents flowing in each coil respectively. The magnetic induction in ( w e b e r / m^{2} ) at the centre of the coils will be ( left(mu_{0}=4 pi times 10^{-7} w b / A . mright) ) A ( cdot 10^{-5} ) B . ( 12 times 10^{-5} ) C ( .7 times 10^{-5} ) D. ( 5 times 10^{-5} ) |
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235 | allu 4. A conducting wire frame is placed in a magnetic field which is directed into the paper. The magnetic field is increasing at a constant rate. x The directions of induced current in wires AB and CD are x A x (a) B to A and D to C (b) A to B and C to D X BX (c) A to B and D to C (d) B to A and C to D |
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236 | Find the inductance ( L ) of a solenoid of length I whose windings are made of material of density D and resistivity ( rho ) The winding resistance is ( mathrm{R} ) : A ( cdot frac{mu_{0}}{4 pi l} cdot frac{R_{m}}{rho D} ) в. ( frac{mu_{0}}{4 pi R} cdot frac{l_{m}}{rho D} ) c. ( frac{mu_{0}}{4 pi l} cdot frac{R^{2} m}{rho D} ) D. ( frac{mu_{0}}{2 pi R} cdot frac{l_{m}}{rho D} ) |
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237 | Two coils have self-inductance ( boldsymbol{L}_{mathbf{1}}=mathbf{4} ) ( boldsymbol{m} boldsymbol{H} ) and ( boldsymbol{L}_{2}=mathbf{1} boldsymbol{m} boldsymbol{H} ) respectively. The currents in the two coils are increased at the same rate. At a certain instant of time both coils are given the same power. If ( i_{1} ) and ( i_{2} ) are the currents in the two coils, at that instant of time respectively, then the value of ( left(i_{1} / i_{2}right) ) is A ( cdot frac{1}{8} ) в. ( frac{1}{4} ) ( c cdot frac{1}{2} ) D. |
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238 | In one second, a current of 10 A changes through a coil. The induced emf is ( 10 v ) then, self-inductance of the coil is A . २ B. 5H c. ( 1 mathrm{H} ) D. 0.5H |
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239 | AUUU 2015 22. A metallic rod of length ‘l’ is tied to a string of length 21 and made to rotate with angular speed O on a horizontal table with one end of the string fixed. If there is a vertical magnetic field ‘B’ in the region, the e.m.f. induced across the ends of the rod is 3 Bol2 4 Bol? 2 (a) (b) = 2 5 Bol (d) 2 Bor (JEE Main 2013) |
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240 | The self inductance of a coil having 500 turns is 50 mH. The magnetic flux through the cross-sectional area of the coil while current through it is 8 mA is found to be A ( cdot 4 times 10^{-4} W b ) в. ( 0.04 W b ) c. ( 4 mu W b ) D. ( 40 m W b ) |
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241 | The co-efficient of mutual induction between primray and secondary coil is 2H. Calculate induced e.m.f. if current of 4A is cut off in ( 2.5 times 10^{-4} ) seconds. |
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242 | An electrical generator works on the principle of electromagnetic induction A. True B. False |
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243 | A rectangular coil of single turn, having area ( A, ) rotates in a uniform magnetic field B with an angular velocity ( omega ) about an axis perpendicular to the field. If initially the plane of the coil is perpendicular to the field, then the average induced emf when it has rotated through ( 90^{circ} ) is: ( mathbf{A} cdot frac{omega B A}{pi} ) в. ( frac{omega B A}{2 pi} ) c. ( frac{omega B A}{4 pi} ) D. ( frac{2 omega B A}{pi} ) |
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244 | ( mathbf{A} ) D.C. generator is based on the principle of A. magnetic effect ofcurrent B. lighting effect ofcurrent c. electrochemical induction D. electromagnetic induction |
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245 | ( x ) cnanges Its pıtch so that It IS rIyıng ( 100 m / s ) in an area of the Earth’s magnetic field that is perpendicular to the plane and equal to ( 5.010^{5} T ) What is the emf induced between the |
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246 | Give reasons for the following. Split rings are used instead of slip rings to construct DC dynamo. | 12 |

247 | A thin semicircular conducting ring of radius ( mathrm{R} ) is falling with its plane vertical in a horizontal magnetic field B. At the position MNQ, the speed of the ring is ( mathbf{v} ) and the potential difference across the ring is A. zero B ( cdot frac{1}{2} B v pi R^{2} ) and ( mathrm{M} ) is at higher potential ( mathrm{c} . pi R B v ) and ( mathrm{Q} ) is at higher potential D. ( 2 R B v ) and ( Q ) is at higher potential |
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248 | Find the induced emf about ends of the rod in each case. (ii) |
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249 | ( A ) and ( B ) are two concentric circular conductors of centre ( boldsymbol{O} ) and carrying currents ( I_{1} ) and ( I_{2} ) as shown in the adjacent figure. If ratio of their radii is 1 : 2 and ratio of the flux densities at ( O ) due to ( A ) and ( B ) is ( 1: 3, ) then the value of ( boldsymbol{I}_{1} / boldsymbol{I}_{2} ) is: |
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250 | In an AC generator, maximum number of lines of force pass through the coil when the angle between the plane of coil and lines of force is | 12 |

251 | A ( 10 m ) long horizontal wire extends from North East to South West. It is falling with a speed of ( 5.0 m s^{-1}, ) at right angles to the horizontal component of the earth’s magnetic field, of ( 0.3 x ) ( 10^{-4} W b / m^{2} . ) The value of the induced emf in wire is: A ( cdot 2.5 times 10^{-3} V ) В. ( 1.1 times 10^{-3} V ) c. ( 0.3 times 10^{-3} V ) D. ( 1.5 times 10^{-3} V ) |
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252 | Complete the following sentence: The current is induced in a closed circuit only if there is A. change in number of magnetic field lines linked with the circuit. B. no change in number of magnetic field lines linked with the circuit C. change in number of gravitational field lines linked with the circuit. D. no change in number of gravitational field lines linked with the circuit. |
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253 | Which one of the following can produce maximum induced emf? A. 50 ampere DC B. 50 ampere, ( 50 H z ) AC c. 50 ampere, ( 500 mathrm{Hz} ) АС D. 100 ampere DC |
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254 | A thin copper wire of length ( 100 mathrm{m} ) is wound as a solenoid of length ( l ) and radius ( r . ) Its self-inductance is found to be L. Now if the same length of wire is wound as a solenoid of length ( l ) but of radius ( r / 2, ) then its self- inductance will be : A . ( 4 L ) B. 2L ( c cdot L ) D. L/2 |
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255 | State whether given statement is True or False A device which receives and then transmits electromagnetic signal in an artificial satellite is called transponder. A. True B. False |
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256 | What energy conversion takes place in a generator? A. mechanical energy into magnetic energy. B. mechanical energy into chemical energy. C. mechanical energy into electric energy. D. electrical energy into mechanical energy |
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257 | The conducting rod ( a b ), as shown in figure makes contact with metal rails ( c a ) and ( d b . ) The apparatus is in a uniform magnetic field of ( 0.800 T, ) perpendicular to the plane of the figure. In what direction does the current flow in the rod? ( A cdot b ) to ( a ) B. a to ( c . ) a to b and then b to a D. a to |
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258 | Assertion When number of turns in a coil is doubled, coefficient of self-inductance of the coil becomes 4 times. Reason This is because ( L alpha N^{2} ) 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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259 | An electromagnetic field exists only when there is A. an increasing current B. decreasing current c. voltage D. current |
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260 | A circular loop of radius ( boldsymbol{R} ), carrying current ( I ), lies in ( x-y ) plane with its center at the origin. The total magnetic flux through ( x-y ) plane is This question has multiple correct options A. directly proportional to ( l ) B. directly proportional to ( R ) c. inversely proportional to ( R ) D. zero |
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261 | Two identical circular loops of metal wire are lying on a table without touching each other. Loop – ( A ) carries a current which increases with time. In response, the loop-B A. remains stationary B. is attracted by the loop ( A ) c. is repelled by the loop ( A ) D. rotates about its ( C M ) with ( C M ) fixed E. none of these |
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262 | The essential difference between an AC generator and a DC generator is that: A. AC generator has an electromagnet while a DC generator has permanent magnet. B. DC generator will generate a higher voltage. C. AC generator will generate a higher voltage. D. AC generator has slip rings while DC generator has a commutator. |
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263 | ( boldsymbol{y}=boldsymbol{x}^{4}, ) is moving with velocity ( boldsymbol{V}=boldsymbol{V}_{0} boldsymbol{i} ) in a non-uniform magnetic field ( vec{B}= ) ( boldsymbol{B}_{0}left(1+left(frac{boldsymbol{y}}{boldsymbol{L}}right)^{beta}right) hat{boldsymbol{k}}, ) as shown in figure. If ( V_{0}, B_{0}, L ) and ( beta ) are positive constants and ( Delta phi ) is the potential difference developed between the ends of the wire, then the correct statement(s) is/are? This question has multiple correct options A ( cdot|Delta phi|=frac{4}{3} B_{0} V_{0} L ) for ( beta=2 ) B. ( |Delta phi| ) remains same if the parabolic wire is replaced by a straight wire, ( y=x, ) initially, of length ( sqrt{2} l ) C ( cdot|Delta phi|=frac{1}{2} B_{0} V_{0} L ) for ( beta=0 ) D. ( |Delta phi| ) is proportional to the length of wire projected on y-axis |
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264 | Read the following statements and answer whether the given statement is true or false.
The number of magnetic lines of force passing through a surface is called magnetic flux linked with that surface. |
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265 | The magnetic flux linked with a coil is changing with time ( t(text { second }) ) according to ( phi=6 t^{2}-5 t+1 . ) Where ( phi ) is in ( mathrm{Wb} ) At ( t=0.5 mathrm{S}, ) the induced current in the coil is The resistance |
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266 | Q Type your questior perpendicular to a constantmagnetic field of magnitude ( 1 mathrm{T} ) as shown in figure. One end of a resistanceless rod is hinged at thecentre of ring 0 and other end is placed on the ring. Now rod is rotated with constant angular velocity ( 4 mathrm{rad} / mathrm{s} ) by some external agent and circuit is connected as shown in the figure, initially switch is open andcapacitor is uncharged. If switch S is closed at ( t=0, ) then calculate heat ( operatorname{loss}(operatorname{in} mu mathrm{J}) ) from the resistor ( boldsymbol{R}_{1} ) from ( mathrm{t} ) ( =0 ) to the instant when voltage across the capacitor becomes half of steady state voltage. (Assume plane of ring to be horizontal and friction to be absent at all the contacts) |
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267 | Electromagnetic induction is not used in A. Transformer B. Room heater c. Ac generator D. Choke coil |
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268 | Which of the following statements is not correct? A. Whenever the amount of magnetic flux linked with a circuit changes, an emf is induced in the circuit. B. The induced emf lasts so long as the change in magnetic flux continues. C. The direction of induced emf is given by Lenz’s law. D. Lenz’s law is a consequence of the law of conservation of momentum. |
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269 | BN 59. The magnetic induction at P, for the arrangement shown in the figure, when two similar short magnets of magnetic moment M are joined at the middle so that they are mutually perpendicular will be (b) Ho 3M 4T ² (a) Ho M√3 41 d3 (c) Ho MV5 41 ď (d) M2M 41 d3 |
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270 | The laws of electromagnetic induction have been used in the construction of a A. galvanometer B. voltmeter c. electric motor D. electric generator |
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271 | Calculate the induced emf in the loop if the current in both the wires is changing at the rate ( boldsymbol{d} boldsymbol{i} / boldsymbol{d} boldsymbol{t} ) |
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272 | The number of turns in a coil of wire of fixed radius is 600 and its self inductance is 108 mH. The self inductance of a coil of 500 turns will be A. 74 mH B. 75 mH c. ( 76 mathrm{mH} ) D. 77 mH |
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273 | A coil having an area ( A_{0} ) is placed in a magnetic field which changes from ( boldsymbol{B}_{mathbf{0}} ) to ( 4 B_{0} ) in time interval t. The e.m.f. induced in the coil will be A ( cdot 3 A_{0} B_{0} / t ) в. ( 4 A_{0} B_{0} / t ) c. ( 3 B_{0} / A_{0} t ) D ( cdot 4 A_{0} / B_{0} t ) |
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274 | What is back emf in a DC motor? | 12 |

275 | Two coils of self inductances ( 6 m H ) and ( 8 m H ) are connected in series and are adjusted for highest co-efficient of coupling. Equivalent self inductance ( L ) for the assembly is approximately ( mathbf{A} cdot 50 m H ) в. ( 36 m H ) ( mathrm{c} cdot 28 m H ) D. ( 18 m H ) |
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276 | The inductance is measured in A. ohm B. farad c. henery D. none of these |
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277 | In which of the following cases does the electromagnetic induction occur? This question has multiple correct options A. A current is started in a wire held near a loop of wire. B. The current is stopped in a wire held near a loop of wire C. A magnet is moved through a loop of wire. D. A loop of wire is held near a magnet |
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278 | The current in a coil changes from ( 1 m A ) to ( 5 m A ) in 4 milli second. If the coefficient of self-induction of the coil is ( 10 m H ) the magnitude of the “self- induced” emf is: A . ( 10 mathrm{mV} ) B. ( 5 mathrm{mV} ) c. ( 2.5 mathrm{mV} ) D. ( 1 mathrm{mV} ) |
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279 | 1. The inductance between A and D is (a) 3.66 H (b) 9 H (c) 0.66 H (d) 1H (AIEEE 2002) |
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280 | U TO 69. A bar magnet was pulled away from a hollow coil A as she in figure. As the south pole came out of the coil, the magnet next to hollow coil B experienced a magnetic force Up Left Right Down I NORDS (a) to the right (c) upward (b) to the left (d) equal to zero |
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281 | A generator has an e.m.f. of 440 volt and internal resistance of 400 ohm. Its terminals are connected to a load of 4000 ohm. The voltage across the load is: A . 220volt B. 440volt c. ( 200 v o l t ) D. 400volt |
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282 | Figure as shown a rod ( P Q ) of length ( 20.0 mathrm{cm} ) and mass ( 200 mathrm{g} ) suspended through a fixed point ( O ) by two threads of length ( 20.0 mathrm{cm} ) each. A magnetic field of strength ( 0.500 T ) exists in the vicinity of the wire ( P Q ) as shown in the figure. The wires connecting with ( P Q ) with the battery are loose and exert no force on ( P Q ) (a) Find the tension in the threads when the switch ( S ) is open.(b) A current of ( 2.0 A ) is established when the switch ( S ) is closed. Find the tension in the thread. |
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283 | The net magnetic flux through any closed surface, kept in a uniform magnetic field is? A. zero в. ( frac{mu_{o}}{4 pi} ) c. ( 4 pi mu_{o} ) D. ( frac{4 mu_{o}}{pi} ) |
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284 | Magnitude of e.m.f. produced in a coil when a magnet is inserted into it does not depend upon: A. Number of turns in the coil B. Speed of the magnet c. Magnetic strength of magnet D. Temperature of coil |
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285 | A wooden stick of length ( 3 l ) is rotated about an end with constant angular velocity ( omega ) in a uniform magnetic field ( B ) perpendicular to the plane of motion. If the upper one-third of its length is coated with copper, the potential difference across the whole length of the stick is ( A ) [ frac{9 B omega l^{2}}{2} ] в. [ frac{4 B omega l^{2}}{2} ] c. [ frac{5 B omega l^{2}}{2} ] D. [ frac{B omega l^{2}}{2} ] |
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286 | f cross section area and length of a long solenoid are increased 3 times then its self-inductance will be changed how many times- A. B. 2 ( c cdot 3 ) ( D ) |
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287 | At large distances from source ( vec{E} ) and ( vec{B} ) are in phase and the decrease in their magnitude is comparatively slower with distance r as per A ( cdot r^{-1} ) B. ( c cdot r^{-3} ) D ( cdot r^{2} ) |
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288 | A loop of area ( 4 m^{2} ) is placed flat in the x-y plane.There is a constant magnetic field ( 4 hat{j} ) in the region. Find the flux through the loop A . 2 units B. 4 units c. 6 units D. 0 units |
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289 | Which of the following statement is correct? This question has multiple correct options A. when the magnetic flux linked with conducting loop is zero then emf induced is always zero B. when the emf induced in conducting loop is zero, then the magnetic flux linked with the loop must be zero C. transformer works on mutual induction D. all of these |
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290 | A constant current i is maintained in a solenoid. Which of the following quantities will increase if an iron rod is inserted in the solenoid along its axis? This question has multiple correct options A. Magnetic field at the centre B. Magnetic flux linked with the solenoid c. self-inductance of the solenoid D. Rate of Joule heating |
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291 | A frame ( C D E F ) is laced in a region where a magnetic field ( vec{B} ) is present. ( mathbf{A} ) rod of length one metre moves with constant velocity ( 20 m / s ) and strength of magnitude field is one tesia. The power spent in the process is (take ( R=0.2 Omega ) and all other wires and rod have zero resistance) ( mathbf{A} cdot 1 k W ) ( mathbf{B} cdot 2 k W ) ( mathbf{c} .3 k W ) ( mathbf{D} cdot 4 k W ) |
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292 | The back emf in a DC motor is maximum when A. the motor has picked up maximum speed. B. the motor has just started moving. C. the speed of motor is still on increase. D. the motor has just been switched off. |
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293 | Figure shows a square loop of resistance ( 1 Omega ) of side ( 1 m ) being moved towards right at a constant speed of 1 ( boldsymbol{m} / boldsymbol{s} ). The front edge enters the ( boldsymbol{3} boldsymbol{m} ) wide magnetic field ( (B=1 T) ) at ( t=0 ) Draw the graph of current induced in the loop as time passes. (Take anticlockwise direction of current as positive) [ x ] |
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294 | From which of the following case, the current in the loop will not be induced? A. The loop is moved in the direction of the magnet. B. The magnet is moved in the direction of the loop. C. The loop and magnet are moved in the opposite direction with the same speed. D. The loop and magnet are moved in one direction with the same speed. |
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295 | A square metal loop of side ( 10 mathrm{cm} ) and resistance ( 1 Omega ) is moved with a constant velocity partly inside a uniform magnetic field of ( 2 W b m^{-2} ) directed into the paper, as shown in the figure. The loop is connected to a network of five resistors each of value ( 3 Omega ). If a steady current of 1 m ( A ) flows in the loop, then the speed of the loop is A ( cdot 0.5 mathrm{cms}^{-1} ) B. ( 1 mathrm{cms}^{-1} ) ( mathrm{c} cdot 2 mathrm{cms}^{-1} ) D. ( 4 mathrm{cms}^{-1} ) |
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296 | When a conducting ring is moved in a magnetic field then the total charge induced in it depends on A. initial magnetic flux B. final magnetic flux c. the rate of change of magnetic flux D. the total change in magnetic flux |
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297 | Explain in detail the principle, construction and working of a single phase AC generator. | 12 |

298 | A conducting rod of length Lis falling with velocity ( V ) in a uniform horizontal magnetic field B normal to the rod. The induced emf between the ends the rod will be : ( A cdot 2 B V l ) B. zero c. вlv D. ( frac{B V l}{2} ) |
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299 | If the number of turns and length of the long solenoid are doubled without changing the area, then its self- inductance ( L ) will be: A . same B. 2 times c. 3 times D. 4 times |
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300 | toppr LOGIN Q Type your question_ What is ( y ) support. A uniform magnetic field of ( 0.4 T ) is directed perpendicular and into the plane of the spring-rod system. At ( t=0, ) the rod is released with the springs extended by ( 20 c m . ) If the spring constant of each spring is ( 2 N m^{-1} ) then This question has multiple correct options A. the maximum value of emf induced across the rod is ( 64 m V ) B. the induced emf across the rod is reduced to zero in ( frac{pi}{8} ) S after releasing the rod. C. the induced emf across the rod reaches maximum first time in ( frac{pi}{8} mathrm{S} ) after releasing the rod D. the maximum value of induced emf is ( 32 m V ) |
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301 | A wire as a parabola ( y=4 x^{2} ) is located in a uniform magnetic field of inductance B perpendicular to the XY plane. At t=0 a connection starts translation wise from the parabola apex with constant acceleration ( alpha ). The induced emf in the loop, thus formed, as a function of y is: A ( e=sqrt{2 alpha} cdot B y ) ( y ) в. ( e=B y sqrt{frac{alpha}{2}} ) c. ( e=frac{B y sqrt{a}}{2 sqrt{2}} ) D. ( e=frac{B y sqrt{alpha}}{4} ) |
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302 | Assertion When two coils are wound on each other, the mutual induction between the coils is maximum. Reason Mutual induction does not depend on the orientation of the coils. 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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303 | Read the following statements and answer whether the given statement is true or false. An electric generator works on the principle of electromagnetic induction A. True B. False |
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304 | A very long cylindrical wire of radius ( mathrm{R} ) carries a current ( boldsymbol{I}_{mathbf{0}} ) uniformly distributed across the cross-section of the wire, calculate the magnetic flux through a rectangle that has one side of length w s running down the centre of the wire and another side of length ( R ), shown in figure A ( cdot frac{mu_{0} I_{0} times w R}{4 pi} ) B. ( frac{mu_{0} I_{0} w}{4 pi} ) с. ( frac{mu_{0} I_{0} R}{4 pi w} ) D. None of these |
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305 | Derive expression for self inductance of a long air-cored solenoid of length ( L ) cross- sectional area ( A ) and having number of turns N. |
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306 | A flat coil, ( C, ) of ( n ) turns, area ( A ) and resisitance ( R ) is placed in a uniform magnetic field of magnitude B. The plane of the coil is initially perpendicular to B. If the coil is rotated by an angle about the axis ( mathrm{XY} ), charge of amount Q flows through it. if the coil rotates about XY with a constant angular velocity ( omega, ) the emf induced in ¡t. This question has multiple correct options A. is zero B. changes nonlinearly with time c. has a constant value ( =mathrm{BAn} omega ) D. has a maximum value ( = ) BAn |
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307 | A conduction loop of area ( 5 mathrm{cm}^{2} ) is placed in a magnetic field which varies sinusoidally with time as ( B= ) ( 0.2 sin 300 t . ) The normal to the coil makes an angle of ( 60^{circ} ) with the field. The emf induced at ( t=(pi / 900) ) s is? A ( .7 .5 times 10^{-3} mathrm{v} ) B. zero c. ( 15 times 10^{-3} v ) D. ( 20 times 10^{-3} mathrm{V} ) |
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308 | A coil of 100 turns and 5 square centimeter is placed in a magnetic field ( mathrm{B}=0.2 mathrm{T} . ) The normal to the plane of the coil makes an angle of 60 with the direction of the magnetic field. The magnetic flux linked with the coil is : A ( cdot 5 times 10^{-3} mathrm{wb} ) B. ( 5 times 10^{-5} mathrm{wb} ) ( c cdot 10^{-2} w b ) D. ( 10^{-4} mathrm{wb} ) |
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309 | What is an electromagnetic? | 12 |

310 | A magnetic field directed along ( Z ) axis varies as ( mathrm{B}=mathrm{BO} times mathrm{aB}=mathrm{BOxa} ) directed along ( X ) axis, the induced emf (in volts) in the loop is A . 3 B . 2 ( c .5 ) D. 6 |
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311 | A bar magnet moves toward two identical parallel circular loops with a constant velocity ( v ) as shown in figure This question has multiple correct options A. Both the loops will attract each other B. Both the loops will repel each other C. The induced current in ( A ) is more than that in ( B ) D. The induced current is same in both the loops E. answer required |
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312 | A wire loop that encloses an area of ( 20 mathrm{cm}^{2} ) has a resistance of ( 10 Omega ). The loop is placed in a magnetic field of ( 2.4 T ) with its plane perpendicular to the field. The loop is suddenly removed from the field. How much charge flows past a given point in the wire? ( mathbf{A} cdot 12 times 10^{-4} C ) B. ( 10^{-1} C ) c. ( 4.8 times 10^{-4} C ) D. ( 2.4 times 10^{-3} C ) |
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313 | Voltage in the secondary coil of a transformer does not depend upon: A. frequency of the source B. voltage in the primary coil c. ratio of number of turns in the two coils ( D . ) both ( (b) ) and ( (c) ) |
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314 | A square loop is placed in ( x-y ) plane as shown in figure. Magnetic field in the region is ( vec{B}=-B_{0} x hat{k} . ) The induced current in the loop is anticlockwise. Reason f inward magnetic field from such a loop increases, then current should be anticlockwise 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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315 | X X 1 X X X X X 34. A square non-conducting loop, X X X X 20 cm, on a side is placed in a (x x x x x x magnetic field. The centre of side (X x XOX X X AB coincides with the centre of magnetic field. The magnetic field xxxx is increasing at the rate of 2 T/s. The potential difference between B and D C C is (a) 30 m V (b) zero (c) 10 mV (d) 20 mV X X X X X X X X X |
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316 | toppr Q туре уо inductance to determine the height of the liquid level in the tank. The inductance of the tank changes from a value of ( L_{0} ) corresponding to a relative permeability of 1 when the tank is empty to value ( L_{f} ) corresponding to a relative permeability ( boldsymbol{X}_{m} ) (relative permeability of liquid) when the tank is full. The appropriate electronic circuit can determine the inductance correct upto 5 significant figures and thus the effective relative permeability of the combined air and liquid within the rectangular has height ( D ). The height of the liquid level in the tank is ( d ) Ignore the fringing effects. Assume tank is fitted with ( boldsymbol{H} boldsymbol{g} boldsymbol{X}_{boldsymbol{H} boldsymbol{g}}=boldsymbol{2} . boldsymbol{9} times mathbf{1 0}^{5} ) Express ( d ) as a function of ( L ), inductance corresponding to a certain liquid height ( boldsymbol{L}_{0}, boldsymbol{L}_{f} ) and ( boldsymbol{D} ) A ( cdot d=frac{left(L-L_{0}right) D}{L_{f}-L_{0}} ) в. ( _{d}=frac{L D}{L_{f}-L_{0}} ) c. ( _{d=} frac{left(L-L_{0}right) D}{L_{f}} ) D. None of these |
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317 | The inductive reactance of a coil of ( 0.2 H ) inductance at a frequency of ( mathbf{6 0} boldsymbol{H} boldsymbol{z} ) is: A . ( 7.54 Omega ) в. ( 0.754 Omega ) c. ( 75.4 Omega ) D. ( 7.54 times 10^{-3} Omega ) |
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318 | Pick up the correct statements: This question has multiple correct options A. The changing (with time) magnetic field need not be in existence at the location of induced electric field. B. A uniform magnetic field increasing at constant rate, induces an electric field which is constant and non conservative C. Non zero force exerted by uniform and constant magnetic field on a moving charged particle does no work but always changes momentum of the particle. D. All the above statements are wrong. |
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319 | A coil having resistance ( 20 Omega ) and inductance ( 2 H ) is connected to a battery of emf ( 4.0 % ). Find (a) the current at ( 0.20 s ) after the connection is made and (b) the magnetic field energy in the coil at the instant |
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320 | In an a.c. generator the speed at which the coil rotates is doubled. How would this affect the frequency of output voltage? A. frequency is doubled B. frequency is halvedd c. frequency remains same D. cant say |
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321 | Assertion The coil in the resistance boxes are made by doubling the wire. Reason Thick wire is required in resistance box. 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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322 | Interpret ( mathrm{K}^{prime}-mathrm{K} ) | 12 |

323 | The split-ring type commutator is used in generators to: A. Convert AC to DC B. Convert DC to ACC c. Induce emf D. Induce magnetism |
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324 | Ampere. A “S” shaped conducting rod AB consisting of two semicircles each of radius ( r ) is placed in such a way that the centre ( C ) of the conducting wire is at a distance ( 2 r ) from the end of the wire.The rod ( A B ) moves with velocity of ( 5 m s^{-1} ) along the direction of the current flow as shown in the figure. If the line joining the ends of the rod makes an angle ( 60^{circ} ) with the wire then, This question has multiple correct options A. the emf induced between the ends of the rod is ( (ln 4) ) ( mu V ) B. the end ( A ) is at higher potential than end ( B ). c. the end ( A ) is at lower potential than end ( B ). D. the emf induced between the ends of the rod is ( (ln 3) ) ( mu V ) |
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325 | A conducting rod ( P Q ) of length ( l=2 m ) is moving at a speed of ( 2 m s^{-1} ) making an angle of ( 30^{circ} ) with its length. uniform magnetic field ( B=2 T ) exists in a direction perpendicular to the plane of motion. Then ( mathbf{A} cdot V_{P}-V_{Q}=8 V ) B. ( V_{P}-V_{Q}=4 V ) C ( . V_{Q}-V_{P}=8 V ) ( mathbf{D} cdot V_{Q}-V_{P}=4 V ) |
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326 | 7. The figure shows four wire loops, with edge lengths of either L or 2L. All four loops will move through a region of uniform magnetic field B (directed out of the page) at the same constant velocity. Rank the four loops according to the maximum magnitude of the e.m.f. induced as they move through the field, greatest first (a) (x = £j)(&q=&) (c) Ę > Ed > & > Ey (d) x < £; <& < En |
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327 | The magnitude of the induced electric field in the orbit at any instant of time during the time interval of the magnetic field change, is A ( cdot frac{B R}{4} ) в. ( frac{B R}{2} ) c. ( B R ) D. ( 2 B R ) |
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328 | Assertion An electric motor converts electrical energy to mechanical energy. Reason The working of the motor is based on mutual induction. 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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329 | A millivoltmeter is connected in parallel to an axle of the train running with a speed of ( 180 mathrm{km} / ) hour. If the vertical component of earth’s magnetic field is ( 0.2 times 10^{-4} W b / m^{2} ) and the distance between the rails is ( 1 mathrm{m} ), then the reading of voltmeter will be : A ( cdot 10^{-2} ) volt B. ( 10^{-4} ) volt c. ( 10^{-3} ) volt D. 1 volt |
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330 | describe briefly any one way of inducing e.m.f. |
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331 | Find the induced emf. Will the induced emf be time dependent? |
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332 | n a coil of resistance ( 100 Omega ), a current is induced by changing the magnetic flux through it as shown in the figure. The magnitude of change in flux through the coil is: A ( .275 mathrm{Wb} ) В. ( 200 mathrm{Wb} ) ( c .225 W b ) D. ( 250 mathrm{Wb} ) |
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333 | YSICS dqE ILLUSTRATION 23.6 What is the mutual inductance of a sys of coaxial cables carrying current in opposite direction shown in figure. Their radii are a and b, respectively. putran the anace of |
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334 | Read the following statements and answer whether the given statement is true or false. S.I. unit of magnetic flux is weber. It is a vector quantity A. True B. False |
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335 | Explain the underlying principle and working of electric generator by drawing a labelled diagram. What is the function of brushes? |
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336 | Which of the following units denotes the dimension ( frac{M L^{2}}{Q^{2}} ) where ( Q ) denotes the electric charge? A ( cdot W b / m^{2} ) в. henry( (H) ) c. ( H / m^{2} ) D. weber ( (W b) ) |
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337 | Assertion An AC generator is which converts mechanical energy into electrical energy (alternating emf). It works on the principle of electromagnetic induction the magnet generates an emf (current) in the coil. Reason The property of coil by which an emf is induced in it when the current flowing through it changes is mutual inductance 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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338 | Find the inductance of a solenoid of length ( l_{0}, ) made of Cu windings of mass m. The winding resistance is equal to ( R ) The diameter of solenoid ( <<l . rho_{0} ) is resistivity of Cu and ( rho ) is density of the Cu. ( ^{text {A }} cdot frac{mu_{0} R m}{2 pi l_{0} rho rho_{0}} ) в. ( frac{mu_{0} R m}{4 pi l_{0} rho rho_{0}} ) c. ( frac{mu_{0} R m}{3 pi l_{0} rho rho_{0}} ) D. ( frac{2 mu_{0} R m}{3 pi l_{0} rho rho_{0}} ) |
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339 | A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will A. increase B. decrease c. remain constant D. be excessive |
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340 | Q Type your question connected to a resistance ( R ) and two ideal inductors ( L_{1} ) and ( L_{2} ) through a switch ( S ) as shown. There is no mutual inductance between the two inductors. The switch ( S ) is initially open. At ( t=0 ) the switch is closed and current begins to flow. Which of the following options is/are correct? This question has multiple correct options A ( cdot ) At ( t=0, ) the current through the resistance ( R ) is ( frac{V}{R} ) B. After a long time, the current through ( L_{2} ) will be ( frac{V}{R} frac{L_{1}}{L_{1}+L_{2}} ) C. After a long time, the current through ( L_{1} ) will be ( frac{V}{R} frac{L_{2}}{L_{1}+L_{2}} ) D. The ratio of the currents through ( L_{1} ) and ( L_{2} ) is fixed at all times ( (t>0) ) |
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341 | State Fleming’s right hand rule and give examples. Demonstrate the same with the help of an experiment. | 12 |

342 | A conductor of uniform resistance (per unit length) bent in the form of an equilateral triangle of side a. It is enclosing on inward magnetic field ( vec{B}=B_{0} cos ^{2} omega t(-hat{k}) . ) Then This question has multiple correct options A ( cdot ) During ( 0<t<frac{pi}{2 omega} ) an clockwise current is induced in the coil. B. During ( 0<t<frac{pi}{omega} ) an anticlockwise current is induced in the coil C . During ( frac{pi}{2 omega}<t<frac{pi}{omega} ) an anticlockwise current flows through it D. During ( frac{pi}{omega}<t<frac{3 pi}{2 omega} ) a clockwise current flows through it |
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343 | The current does not rise immediately in a circuit containing inductance A. because of induced emf B. because of high voltage drop c. because of low power consumption D. because of joule heating |
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344 | 13. A coil of wire having finite inductance and resistance has a conducting ring placed coaxially within it. The coil is connected to a battery at time t = 0, so that a time- dependent current 1/(t) starts flowing through the coil. If I (t) is the current induced in the ring. and B(t) is the magnetic field at the axis of the coil due to 1 (t), then as a function of time (t > 0), the product 12 (t) B(t) (a) Increases with time (b) Decreases with time (c) Does not vary with time (d) Passes through a maximum |
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345 | S.I. unit of Magnetic flux is: A. ampere-meter B. ampere ( m^{2} ) C. weber D. weber ( / mathrm{m}^{2} ) |
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346 | Two conducting rings ( P ) and ( Q ) of radi and ( r ) and ( 2 r ) rotate uniformly in opposite directions with centre of mass velocities ( 2 mathrm{v} ) and ( mathrm{v} ) respectively on a conducting surface S. There is a uniform magnetic field of magnitude B perpendicular to the plane of the rings. The potential difference between the highest points of the two rings is ( A cdot(a) ) zer ( B cdot(b) 4 B v ) ( c cdot(c) 8 ) Bv D. (d)16 Bv |
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347 | State whether following statements are True or False: (a) An electric motor converts mechanical energy into electrical energy (b) An electric generator works on principle of electromagnetic induction (c) The field at the center of a long circular coil carrying current will be parallel straight lines (d) A wire with a green insulation is usually the live wire of an electric supply |
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348 | In electromagnetic induction, the induced E.M.F is independent of A. Change of flux B. Time c. Tesla D. weber |
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349 | Calculate velocity at time | 12 |

350 | A metal disc of radius ( a ) rotates with a constant angular velocity ( omega ) about its axis. The potential difference between the center and the rim of the disc is ( boldsymbol{m}= ) mass of electron, ( boldsymbol{e}= ) charge on electron) ( ^{mathrm{A}} cdot frac{m omega^{2} a^{2}}{e} ) B. ( frac{1 m omega^{2} a^{2}}{2} ) ( ^{mathrm{c}} cdot frac{e omega^{2} a^{2}}{2 m} ) D. ( frac{e omega^{2} a^{2}}{m} ) |
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351 | What is the direction of force on the loop if ( frac{d i}{d t} ) is positive | 12 |

352 | A magnetic field ( B=2 t+4 t^{2} ) (where ( t=text { time }) ) is applied perpendicular to the plane of a circular wire of radius ( r ) and resistance ( R ). If all the units are in ( S I, ) the electric charge that flows through the circular wire during ( t=0 s ) to ( t=2 s ) is: ( mathbf{A} cdot frac{6 pi r^{2}}{R} ) В. ( frac{20 pi r^{2}}{R} ) ( ^{mathrm{c}} cdot frac{32 pi r^{2}}{R} ) D. ( frac{48 pi r^{2}}{R} ) |
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353 | A long solenoid of diameter 0.1 m has ( 2 times 10^{4} ) turns per metre.At the centre of the solenoid, a coil of 100 turns and radius ( 0.01 m ) is placed with its axis coinciding with the solenoid axis.The current in the solenoid reduces at a constant rate to ( 0 A ) from ( 4 A ) in 0.05 s. If the resistance of the coil is ( 10 pi^{2} Omega ) the total charge flowing through the coil during this time is. ( mathbf{A} cdot 32 pi mu C ) B. ( 16 mu C ) c. ( 32 mu C ) D. ( 16 pi mu C ) |
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354 | What is the Si unit of magnetic flux, is it vector or scalar quantity? | 12 |

355 | A square loop of side ( b ) is rotated in a constant magnetic field ( B ) at angular frequency ( omega ) as shown in figure. What is the emf induced in it? ( mathbf{A} cdot b^{2} B omega sin omega t ) ( mathbf{B} cdot b B omega sin ^{2} omega t ) ( mathbf{C} cdot b B^{2} omega cos omega t ) D. ( b^{2} B omega ) |
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356 | A varying current in a coil change from ( 10 A ) to 0 in 0.5 sec. If the average emf induced in the coil is ( 220 V ), the self inductance of the coil is : A . ( 5 H ) в. ( 6 H ) ( c .11 H ) D. ( 12 H ) |
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357 | n mutual induction A: when current in one coil increases, induced current in neighbouring coil flows in the opposite direction B: When current in one coil decreases, induced current in neighbouring coil flows in the opposite direction A. A is true, B is false B. A and B are false c. A and B are true D. A is false, B is true |
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358 | If a spark is produced on removing the load from an AC circuit then the element connected in the circuit is A. high resistance B. high capacitance c. high inductance D. high impedance |
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359 | Which of the following statement is correct? A. AC generator generates a higher voltage B. DC generator generates a higher voltage C. AC generator has a permanent magnet whereas a DC generator has an electromagnet D. There is a split-ring commutator in a DC generator but not in an AC generator |
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360 | In a coil of resistance ( 10 Omega ), the induced current developed by changing magnetic flux through it, is shown in figure as a function of time. The magnitude of change in flux through the coil in Weber is- |
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361 | In a motor, a rotor is fitted with the armature that has current of 10 A. The rotor rotates with angular speed of 3 rad/s.Magnetic field of magnitude 2 T varies in direction is such a way that it is always perpendicular to the loop area If the rotor coil has ( N ) number of turns and area of each loop is ( 0.45 m^{2} ) then find the value ( N . ) Given that motor consumes 2106 W power and there are no losses. |
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362 | Explain ( e . f . ) due to a uniformly charged plane sheet |
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363 | A conducting loop (as shown) has total resistance ( R ). A uniform magnetic field ( B=gamma t ) is applied perpendicular to plane of the loop where ( gamma ) is a constant and ( t ) is time. The induced current flowing through loop is: ( A ) B. ( frac{left(b^{2}-a^{2}right) gamma}{R} ) c. ( frac{left(b^{2}-a^{2}right) gamma t}{R} ) D. ( frac{left(b^{2}+a^{2}right) gamma}{R} ) |
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364 | In a magnetic field of ( 0.05 T ) area of coil changes from ( 101 mathrm{cm}^{2} ) to ( 100 mathrm{cm}^{2} ) without changing the resistance which is ( 2 Omega . ) The amount of charge that flow during this period is A ( .2 .5 times 10^{-6} mathrm{C} ) В. ( 2 times 10^{-6} C ) ( mathbf{c} cdot 10^{-6} C ) D. ( 8 times 10^{-6} C ) |
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365 | A current carrying infinitely long wire is kept along the diameter of a circular wire loop, without touching it. The correct statement(s) is(are) This question has multiple correct options A. The emf induced in the loop is zero if the current is constant B. The emf induced in the loop is finite if the current is constant c. The emf induced in the loop is zero if the current decreases at a steady rate. D. The emf induced in the loop is finite if the current decreases at a steady rate |
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366 | In figure, the wires ( P_{1} Q_{1} ) and ( P_{2} Q_{2} ) are made to slide on the rails with same speed of ( 5 c m s^{-1} . ) In this region, a magnetic field of ( 1 T ) exists. The electric current in the ( 9 Omega ) resistance is This question has multiple correct options A. zero if both wires slide toward left B. zero if both wires slide in opposite directions C. ( 0.2 m A ) if both wires move toward left D. ( 0.2 m A ) if both wires move in opposite directions |
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367 | If length of a solenoid is increased then what change should be made on no. of turns to keep self inductance constant- ( A ). increase B. remain same c. decrease D. none of these |
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368 | A horizontal metal wire is carrying an electric current from the north to the south. Using a uniform magnetic field, it is to be prevented from falling under gravity. The direction of this magnetic field should be towards the A . east B. west c. north D. south |
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369 | What is self inductance of a coil when a charge of current from 0 to 2 A in 0.05 second induces an emf of ( 40 mathrm{V} ) in it? A . ( 1 mathrm{H} ) B. 2H ( c . ) зн D. 44 |
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370 | When the normal to a coil points in the direction of magnetic field (B), then flux is A. a scalar quantity B. a vector quantity c. neither scalar nor vector D. uncertain |
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371 | Read the following statements and answer whether the given statement is true or false.
The induced e.m.f. depends only on the |
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372 | Which of the following devices works on the principle of electromagnetic induction? A. Ammeter B. Voltmeter c. Generator D. Galvanometer |
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373 | The direction of the induced e.m.f. is determined by : A. Fleming’s left hand rule B. Fleming’s right hand rule c. Maxwell’s right hand screw rule D. Ampere’s rule of swimming |
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374 | Assertion The back emf in a dc motor is maximum when the motor has just been switched on. Reason When motor is switched on it has maximum speed. 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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375 | Assertion Time-dependent magnetic field generates electric field Reason Direction of electric field generated from time variable magnetic field does obey Lenz’s 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. Assertion is incorrect but Reason is correct |
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376 | Self inductance of a long solenoid is directly proportional to(Where ( L ) is the length of solenoid) A. ( L ) B . ( L^{2} ) c. ( 1 / L ) D. ( 1 / L^{2} ) |
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377 | An induced emf has A. A direction same as field direction B. A direction opposite to the field direction C. No direction of its own D. Non of these |
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378 | ( 10 c m ) and ( 100 c m ) are placed on a horizontal plane as shown in the Figure. Outer loop is connected to a source of unknown emf through a key K. If a current of ( 2 A ) flows in the inner loop as shown aside, when the key k is closed at time ( t=0 s, ) then the emf of the source sending a current ( I ), should be [Take resistance of both wire per length ( left.operatorname{as} 10^{-4} Omega m^{-1}right) ) of unknow ( mathbf{A} cdot 4 V ) B. ( 4 t V ) ( mathbf{c} cdot 04 mathrm{t}^{2} mathbf{V} ) D. ( left(0.4 t^{2}+4 t+4right) V ) |
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379 | Magnetic flux ( phi ) linked with a stationary loop of resistance ( R ) vaires with time ( t ) as ( phi=a t(T-t) . ) Amount of heat generated in loop during time interval ( boldsymbol{T} ) is ( ^{mathbf{A}} cdot frac{a T}{3 R} ) ( ^{mathbf{B}} cdot frac{a^{2} T^{2}}{3 R} ) c. ( frac{a^{2} T^{2}}{R} ) D. ( frac{a^{2} T^{3}}{3 R} ) |
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380 | A conducting rod of length I and mass ( mathrm{m} ) is moving down a smooth inclined plane of inclination ( boldsymbol{theta} ) with constant velocity ( v . ) A current ( i ) is flowing in the conductor in a direction perpendicular to paper inward. A vertically upward magnetic field ( vec{B} ) exists in space. Then, magnitude of magnetic field ( vec{B} ) is: A ( cdot frac{m g}{i l} sin theta ) B. ( frac{m g}{i l} tan theta ) c. ( frac{m g cos theta}{i l} tan theta ) D. ( frac{m g}{text {ilsint}} ) |
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381 | A horizontal magnetic field B is produced across a narrow gap between the two square iron pole pieces. closed square loop of side a, mass ( mathrm{m} ) and resistance ( R ) is allowed to fall with the top of the loop in the field. The loop attains a terminal velocity equal to: A ( cdot frac{R m g}{B^{2} a^{2}} ) B. ( frac{mu_{0}}{4 pi} frac{R m g}{B a^{2}} ) c. ( frac{m g B}{R a^{2}} ) D. ( frac{mu_{0}}{4 pi} frac{R m B}{B a^{2}} ) |
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382 | The total magnetic induction at point 0 due to curved portions and straight portion in the following figure, will be A ( cdot frac{mu_{0} i}{2 pi r}[pi-phi+tan phi ) в. ( frac{mu_{0} i}{2 pi r} ) c. ( frac{mu_{0} i}{pi r}[pi-phi+tan phi ) D. |
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383 | toppr Q Type your question- the rails is ( 1 m . ) A conducting rod of mass ( 0.5 k g ) can slide on the rails frictionlessly. The rod is tied at midpoint to a light string passing over a smooth pulley fixed to the edge of the table. A mass of 0.5kg tied to the other end of the string hangs vertically as shown in the Figure. A uniform magnetic field of ( 0.5 T ) can be applied in vertically downward direction. If the system is released from rest, then, point out incorrect statements from the following: I be the acceleration due to gravity] This question has multiple correct options A. When the magnetic field is put on, the acceleration of the system increases from ( frac{g}{3} ) to ( frac{g}{2} ) B. Due to induction, the change in the acceleration of the system is same as that obtained by increasing the mass of the rod by ( 0.5 k g ) in the absence of the magnetic field. c. Due to induction, the change in the acceleration of the system is same as that obtained by decreasing the mass of the rod by ( 0.25 mathrm{kg} ) in the absence of magnetic field D. When the magnetic field is put on, the acceleration of the system decreases from ( frac{g}{2} ) to ( frac{g}{3} ) |
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384 | Read the following statements and answer whether the given statement is true or false. Energy stored in an inductor ( =frac{1}{2} L V^{2} ) |
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385 | Ine varıatıon or anoae current ın a triode valve corresponding to a change in grid potential at three different values of the plate potential is shown in the given figure. The mutual conductance of triode is ( mathbf{A} cdot 5 times 10^{-3} m h o ) B . ( 2.5 times 10^{-3} ) mho C. ( 7.5 times 10^{-3} ) mho D. ( 9.5 times 10^{-3} ) mho |
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386 | A copper wire of length ( l ) is bent into a semicircle. It is moved with a velocity ( boldsymbol{v} ) in a region where magnetic field is uniform and perpendicular to the plane of the wire. If the strength of the field is ( B ) then emf induced is ( mathbf{A} cdot B l v ) в. ( quad B frac{l}{pi} v ) c. ( _{B} frac{2 l}{pi} v ) D. none of these |
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387 | A simple pendulum with bob of mass ( m ) and conducting wire of length L swings under gravity through an angle ( 2 theta ). The earth’s magnetic field component in the direction perpendicular to swing is B. The maximum potential difference induced across the pendulum is? |
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388 | Match the statements in Column ( A ) | 12 |

389 | Two ends of an inductor of inductance ( L ) are connected to two parallel conducting wires. A rod of length ( l ) and mass ( m ) is given velocity ( v_{0} ) as shown. The whole system is placed in perpendicular magnetic field ( B ). Find the maximum current in the inductor. ( ^{A} cdot frac{m v_{0}}{L} ) в. ( sqrt{frac{m}{L}} v_{0} ) c. ( frac{m v_{0}^{2}}{L} ) D. None of these |
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390 | Define coefficient of self inductance and write its unit. |
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391 | An angular conductor is moving with velocity ( v ) along its angular bisector in a perpendicular magnetic field ( (B) ) as shown in the figure. The induced potential difference between its free ends will be ( A ) [ 2 B v l sin frac{theta}{2} frac{theta}{2} ] B. ( 2 B v l ) c. ( 2 B v l sin theta ) D. zero |
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392 | ILLUSTRATION 24.3 Suppose you want the current amplitude in a pure inductor in a radio receiver to be 250 uA when the voltage amplitude is 3.60 V at a frequency of 1.60 MHZ (corresponding to the upper is 3.60 V AM broadcast band). What inductive reactance is needed? What inductance is required? |
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393 | State Faraday’s law of electromagnetic induction. Apply the law to obtain an expression for the induced emf in a conducting rod of length ( a ) rotating about its one end with angular velocity ( omega ) in uniform magnetic field B. |
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394 | If coil is placed perpendicular to field lines then number of lines passing through coil are : ( A ). minimum B. maximum c. zero D. may be max. or min |
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395 | Two coils ( A ) and ( B ) having turns 300 and 600 respectively are placed near each other, on passing a current of 3.0 ampere in ( A ), the flux linked with ( A ) is 1.2 ( x 10^{-4} ) weber and with ( B ) it is ( 9.0 times 10^{-5} ) weber. The mutual induction of the system is: |
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396 | Q Type your question- to two ideal voltmeters ( V_{1} & V_{2} ) Assume that a voltmeter reads ( Delta V= ) ( -int_{a}^{b} vec{E} cdot d vec{ell} ) between its terminals. A time varying magnetic field ( B(t) ) exists in a circular region of radius a and it is directed into the plane of the figure ( B(t)=B_{0} t ) where ( B_{0} ) is a positive constant of proper dimensions and t is the time. The emf induced in the circuit is : ( A cdot 2 pi a^{2} B_{0} ) В ( cdot pi a^{2} B_{0} ) c. ( frac{a^{2} B_{0}}{2} ) D・ ( pi a^{2} B_{0} ) |
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397 | State whether true or false: A dynamo converts electric energy into mechanical energy. A. True B. False |
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398 | Q Type your question as on the same direction, while in 3 is in the opposite direction. Match the following table Table 1 Table – 2 (a) When the current in 1 is (p) current in 1 will increased increased i (b) When the current in 2 is (q) current in 2 will increase increased (r)Current in 3 will (c) When the current in 3 is increase increased ( A cdot a-r ; b-r ; c-p, q ) B. ( a-p ; b-p ; c-q ) ( mathrm{C} cdot mathrm{a}-mathrm{q} ; mathrm{b}-mathrm{q} ; mathrm{c}-mathrm{r} ) D. ( a-r ; b-q ; c-p ) |
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399 | toppr Q Type your question insulated from each other. The entire loop lies in the plane (of the paper). A uniform magnetic field ( 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 options is/are correct? This question has multiple correct options A. The amplitude of the maximum net ( e m f ) induced due to both the loops is equal to the amplitude of maximum ( e m f ) induced in the smaller loop alone B. The rate of change of the flux is maximum when the plane of the loops is perpendicular to plane of the paper c. The ( e m f ) induced in the loop is proportional to the surn of the areas of the two loops D. The net ( e m f ) induced due to both the loops is proportional to cos ( omega t ) |
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400 | A conductor ( A B ) of length ( l ) moves in ( x-y ) plane with velocity ( overrightarrow{boldsymbol{v}}=boldsymbol{v}_{0}(hat{boldsymbol{i}}-hat{boldsymbol{j}}) cdot boldsymbol{A} ) magnetic field ( vec{B}=B_{0}(hat{i}+hat{j}) ) exists in the region. The induced emf is A . zero в. ( 2 B_{0} ) lv ( _{0} ), c. ( B_{0} l v_{0} ) D. ( sqrt{2} B_{0} l v_{0} ) |
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401 | Principle behind electric generator is A. when a straight conductor is moved in the electric field, then current is induced in the conductor B. when a circular loop is moved in electric field, then current is induced in the conductor. C. when a straight conductor is moved in a magnetic field, the current is induced in the conductor. D. none |
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402 | A helicopter rises vertically with a speed of ( 100 mathrm{m} / mathrm{s} ). If helicopter has length ( 10 mathrm{m} ) and horizontal component of earth’s magnetic field is ( 5 times ) ( 10^{-3} W b / m^{2}, ) then the induced emf between the tip of nose and tail of helicopter is: A. ( 50 v ) B. 0.5 ( v ) ( c cdot 5 v ) D. 25 V |
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403 | State Lenz’s law. | 12 |

404 | A coil of insulating wire is connected to battery. If it is moved towards a galvanometer then its point gets deflected because A. the coil behaves like a magnettet B. induced current is produced in the coil C. the number of turns in the galvanometer coil remains constant D. none of the above |
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405 | A small straight condctor PQ is lying at right angles to an infinite current carrying conductor ( X Y ). If the conductor PQ is displaced on metallic rails parallel to the conductor ( X Y ), then the direction of induced emf in PQ will be: A. from Q to P B. from P to Q c. vertically downwards D. vertically upwards |
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406 | The mutual inductance ( M_{12} ) of a coil 1 with respect to coil 2 A. increases when they are brought nearer B. depends on the current passing through the coilss c. increases when one of them is rotated about an axis D. both (a) and (b) are correct |
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407 | Find the average of the squares of emf induced over a long period. | 12 |

408 | An e.m.f. of 5 volt is produced by a self inductance, when the current changes at a steady rate from 3 A to 2 A in 1 millisecond. The value of self inductance is A . zero в. 5 н c. 5000 н D. 5 mH |
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409 | rectangular conductor ( L M N O ) is placed in a uniform magnetic field of ( 0.5 T . ) The field is directed perpendicular to the plane of the conductor. When the arm ( M N ) of length ( 20 mathrm{cm} ) is moved towards left with velocity of ( 10 m s^{-1} ) calculate the emf induced in the arm. Given the resistance of the arm to be ( 5 Omega ) assuming that other arms are of regligible resistance) find the value of the current in the arm ( left.begin{array}{l}mathbf{X}_{mathrm{L}} mathbf{X}^{overrightarrow{mathbf{B}}} mathbf{X} & mathbf{X} times mathbf{X} \ mathbf{X} \ mathbf{X} \ mathbf{X} & mathbf{X} & mathbf{X} \ mathbf{X} & mathbf{X} & mathbf{X} mathbf{X} \ mathbf{X} & mathbf{X} & mathbf{X} mathbf{X} \ mathbf{X} & mathbf{X} & mathbf{X} \ mathbf{X} & mathbf{X} & mathbf{X} & mathbf{X} \ mathbf{X}^{mathbf{o}} & mathbf{X} & mathbf{X} & mathbf{X}end{array}right] underset{mathbf{X}}{mathbf{X}}_{mathbf{X}} mathbf{X}_{mathbf{X}} mathbf{X}_{mathbf{X}} mathbf{X} ) |
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410 | A current carrying wire produces a magnetic field in its surrounding space. The S.I. unit of magnetic flux density is A . Henry B. Tesla c. ( A M^{2} ) D. A-m |
12 |

411 | In the process of electromagnetic induction, the magnitude of the induced emf depends on: Select the correct options from the following This question has multiple correct options A. The number of turns of the coil B. The magnetic flux linked with the coil c. The rate of change of magnetic flux linked with the coi D. Area of the coil |
12 |

412 | A current ( I ) ampere flows along an infinitely long straight thin walked tube, then the magnetic induction at any point inside the tube is A . infinite B. zero c. ( frac{mu_{0}}{4 pi} frac{2 i}{r} ) tesla D ( frac{2 i}{r} ) tesla |
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413 | Give any two applications of Faraday’s law of Induction in daily life. | 12 |

414 | The magnetic field in a region is given by ( vec{B}=B_{0}left(1+frac{x}{a}right) hat{k} . ) A square loop of edge length ( d ) is placed with its edge along the ( x ) – and ( y ) -axes. The loop is moved with a constant velocity ( overrightarrow{boldsymbol{v}}=boldsymbol{v}_{mathbf{0}} hat{boldsymbol{i}} ) The emf induced in the loop is A ( cdot frac{v_{0} B_{0} d^{2}}{a} ) B. ( frac{v_{0} B_{0} d^{3}}{a^{2}} ) ( mathbf{c} cdot v_{0} B_{0} d ) ( mathbf{D} cdot 2 v_{0} B_{0} d ) E . zero |
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415 | A circular loop of radius ( 2 mathrm{cm} ), is placed in a time varying magnetic field with rate of ( 2 T / )sec. Then induced electric field in this loop will be: ( mathbf{A} cdot mathbf{0} ) в. ( 0.002 mathrm{V} / mathrm{m} ) c. ( 0.01 V / m ) D. ( 2 V / m ) |
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416 | A metal conductor of length 1 m rotates vertically about one of its ends at angular velocity 5 radians per second. If the horizontal component of earths magnetic field is ( 0.2 times 10^{-4} T, ) then the e.m.f. developed between the two ends of the conductor is A. depends on the nature of the metal used B. depends on the intensity of the radiation c. depends both on the intensity of the radiation and the metal used D. is the same for all metal and independent of the intensity of the radiation. |
12 |

417 | Two spherical bobs, one metallic and the other of glass, of the same size are allowed to fall freely from the same height above the ground. Which of the two would reach earlier and why? |
12 |

418 | Define the unit of self inductance. | 12 |

419 | For what angle ( theta ) does the induced emf have the largest amplitude? |
12 |

420 | A wire loop is rotated in a uniform magnetic field about an axis perpendicular to the field. The direction of the current induced in the loop reverse once each A . quarter revolution B. half revolution c. full revolution D. two revolution |
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421 | Q Type your question- uniformly distributed over its circumference is hanging by a insulated thread with the help of a small smooth ring (not rigidly fixed with bigger ring). A time varying magnetic field ( B=B_{0} sin omega t ) is switched on at ( t ) ( =0 ) and the ring is released at the same time.The average magnetic moment of Ring in time interval 0 to is A ( cdot frac{B_{0} q^{2} R^{2}}{2 pi m} ) B. ( frac{B_{0} q^{2} R^{2}}{4 pi m} ) c. ( frac{B_{0} q^{2} R^{2}}{pi m} ) D. zer |
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422 | Stepping up of voltage by a factor of 100, reduce the current by a factor of A . 10 B. 100 c. leaves the current unchanged D. increase the current by a factor of 100 |
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423 | Two identical conducting rings ( A ) and ( B ) of radius ( R ) are rolling over a horizontal conducting plane with same speed ( v ) but in opposite direction. A constant magnetic field ( B ) is present pointing into the plane of the paper. Then the potential difference between the highest points of the two rings is ( A ) в. ( 2 B v R ) c. ( 4 B v R ) D. none of these E. answer require |
12 |

424 | The voltage applied to a purely inductive coil of self inductance ( 15.9 m H ) is given by the equation ( V= ) ( 100 sin 314 t+75 sin 942 t+ ) ( 450 sin 1570 t ) Find the equation of current wave. |
12 |

425 | What is to be used to convert an AC generator into DC generator? A. split-ring type commutator must be used B. slip rings and brushes must be used C. a stronger magnetic field has to be used D. a rectangular wire loop has to be used |
12 |

426 | The current in the resistance ( R ) as a function of time. |
12 |

427 | – X X x X X x X x X X x || X X xxx xxxx X x 23. A conductor of length I and mass m x can slide without any friction along the two vertical conductors connected at the top through a capacitor (figure). A uniform magnetic field B is set up 1 to the plane of |
12 |

428 | An electric generator converts mechanical energy into energy. |
12 |

429 | A coil has 200 turns and area of ( 70 mathrm{cm}^{2} ) The magnetic field perpendicular to the plane of the coil is ( 0.3 W b / m^{2} ) and take ( 0.1 sec ) to rotate through ( 180^{circ} . ) The value of the induced e.m.f. will be A. ( 8.4 mathrm{v} ) B. 84 c. 42 v D. 4.2 v |
12 |

430 | The induction coil works on the principle of A. Self-induction B. Mutual induction c. Ampere’s rule D. Fleming’s right hand rule |
12 |

431 | 27. Figure shows a copper rod moving with velocity v parallel to a long straight wire carrying current=100 A. Calculate the induced emf in the rod, where y = 5 ms, a=1 cm, b= 100 cm. (a) 0.23 m V (b) 0.46 mV (c) 0.16 mV (d) 0.32 mV |
12 |

432 | The electric field of an electromagnetic wave in free space is given by ( vec{E} 10 cos left(10^{7} t ! k xright) hat{j} V / m ) where ( t ) and ( x ) are in seconds and metres respectively. It can be iferred that (i) the wavelength ( % ) is ( 188.4 mathrm{m} ) (ii) the wave number ( k ) is 0.33 rad/m (iii) the wave amplitude is ( 10 mathrm{V} / mathrm{m} ) (iv) the wave is propagating along ( +x ) direction Which one of the following pairs of statements is correct? A . (iii) and (iv) B. (i) and (ii) c. (ii) and (iii) D. (i) and (iii) |
12 |

433 | The property of a conductor which enables to induce an EMF due to change of current in the same coil is |
12 |

434 | EMF developed by generator depends upon: A. size of magnet B. length of rotating wire c. radius of wire D. none of these |
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435 | A coil having 100 turns is kept in a uniform magnetic field of induction 0.5 T. If its area changes from ( 0.3 m^{2} ) to 0.1 ( m^{2} ) in 10 s, then the emf induced is ( mathbf{V} ) ( A cdot 2 ) B. 1 ( c cdot 4 ) D. |
12 |

436 | The horizontal component of earth’s magnetic field at a place is ( 3 times 10^{-4} T ) and the dip is ( tan ^{-1}left(frac{4}{3}right) cdot A ) metal rod of length ( 0.25 m ) is placed in ( N-S ) direction and is moved at a constant speed of ( 10 mathrm{cm} s^{-1} ) towards the east The emf induced in the rod will be A ( .1 mu V ) B. ( 5 mu V ) c. ( 7 mu V ) D. ( 10 mu V ) |
12 |

437 | A uniform rod of mass ( 6 M ) and length ( 6 l ) is bent to make an equilateral hexagon. Its mutual inductance about an axis passing through the centre of mass and perpendicular to the plane of hexagon is ( A cdot 5 m l^{2} ) В ( .6 m l^{2} ) ( mathrm{c} cdot 4 m l^{2} ) ( mathbf{D} cdot 12 m l^{2} ) |
12 |

438 | The magnitude of the induced emf in a coil of inductance ( 30 m H ) in which the current changes from ( 6 A ) to ( 2 A ) in ( 2 s ) is: A ( .0 .06 mathrm{V} ) в. ( 0.6 mathrm{V} ) c. ( 1.06 V ) D. ( 6 V ) |
12 |

439 | A closed coil with a resistance R is placed in a magnetic field. The flux linked with the coil is ( phi ). If the magnetic field is suddenly reversed in direction, the charge that flows through the coil will be: A. ( frac{phi}{2 R} ) в. ( frac{phi}{R} ) c. ( _{2} frac{phi}{R} ) D. zero |
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440 | An electric bulb has a rated power of ( 50 W ) at ( 100 V . ) If it is used on an ( A C ) source ( 200 V, 50 H z, ) a choke has to be used in series with it. This choke should have an inductance of ( mathbf{A} cdot 0.01 m H ) в. ( 1 m H ) ( c .0 .1 H ) D. ( 1.1 H ) |
12 |

441 | A conductor is moving with the velocity v in the magnetic field and induced current is I. If the velocity of conductor becomes double, the induced current will be A. ( 0.5 I ) B. 1.5 ( I ) ( c cdot 2 I ) D. 2.5 I |
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442 | What is the magnetomotive force ( (m m f) ) of a wire with 8 turns carrying three amperes of current? A. 2,400 At B. 240 At ( c cdot 24 mathrm{At} ) D. 2.4 At |
12 |

443 | The magnetic flux linked with a coil of ( N ) turns of area of cross-section ( A ) held with its plane parallel to the field ( B ) is A. ( frac{N A B}{2} ) в. ( N A B ) c. ( frac{N A B}{4} ) D. 0 E . ( 2 N A B ) |
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444 | состолор 12. A square coil ACDE with its plane vertical is released from rest in a horizontal uniform magnetic field B of length 2L (figure). The X X X XE acceleration of the coil is (a) less than e for all the time 22 X X X X till the loop crosses the X X X X magnetic field completely (b) less than g when it enters the field and greater than g when it comes out of the field (c) g all the time (d) less than g when it enters and comes out of the field but equal to g when it is within the field |
12 |

445 | Current in a circuit falls from ( 5.0 A ) to ( 0.0 A ) in 0.1 sec. If an average emf of ( 200 V ) is induced, give an estimate of the self-inductance of the circuit. |
12 |

446 | Which of the following does not have the same dimensions as the Henry? A. ( frac{text { joule }}{(text { ampere })^{2}} ) B. ( frac{text { tesla }-m^{2}}{(text { ampere })^{2}} ) c. ohm-second D. ( frac{1}{text { Farad-second }} ) |
12 |

447 | (a) A rod of length ( l ) is moved horizontally with a uniform velocity’ ( v ) ‘ in a direction perpendicular to its length through a region in which a uniform magnetic field is acting vertically downward. Derive the expression for the emf induced across the ends of the rod. (b) How does one understand this motional emf by invoking the Lorentz force acting on the free charge carriers of the conductor? Explain. |
12 |

448 | A square loop of side ( 20 mathrm{cm} ) is initially kept ( 30 mathrm{cm} ) away from a region of uniform magnetic filed of ( 0.1 mathrm{T} ) as shown in the figure. It is then moved towards the right with a velocity of ( 10 mathrm{cm} mathrm{s}^{-1} ) till it goes out of the field. plot a graph showing the variation of (i) magnetic flux ( (phi) ) through the loop with time(t). (ii) induced emf ( (varepsilon) ) in the loop with time t. (iii) induced current in the loop, if it has resistance of ( 0.1 Omega ) |
12 |

449 | An alternating potential ( V=V_{0} sin omega t ) is applied across a circuit. As a result, the current ( boldsymbol{I}=boldsymbol{I}_{0} sin left(boldsymbol{omega} boldsymbol{t}-frac{boldsymbol{pi}}{2}right) ) flows in it. The power consumed in the circuit per cycle is: A . zero в. ( 0.5 I_{0} V_{0} ) с. ( 0.707 I_{0} V_{0} ) D. ( 1.414 I_{0} V_{0} ) |
12 |

450 | To measure the field ( B ) between the poles of an electromagnet, a small test loop of area ( 1 mathrm{cm}^{2} ), resistance ( 10 Omega ) and 20 turns is pulled out of it. A galvanometer shows that a total charge of ( 2 mu C ) passed through the loop. The value of ( B ) is A . ( 0.001 T ) в. ( 0.01 T ) ( c .0 .17 ) D. ( 1.0 T ) |
12 |

451 | The normal drawn to the surface of a conductor makes an angle ( theta ) with the direction of field ( vec{B}, ) the flux ( phi ) passing through the area ( vec{A} ) is given by A. ( phi=A B sin theta ) в. ( _{phi}=frac{B}{A} ) c. ( phi=B A ) D. ( phi=B A cos theta ) |
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452 | Which of the following best describe the electromagnetic induction? A. the ability of a changing magnetic field to induce a voltage in a conductor B. the ability of a conductor to generate a magnetic field C. the ability of a static magnetic field to induce a voltage in a conductor D. the ability of a permanent magnet to induce a voltage in a coil E. the ability of a conductor to induce a magnetic field |
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453 | A conducting circular loop is placed in a uniform magnetic field ( B=0.020 T ) with its plane perpendicular to the field. Somehow, the radius of the loop starts shrinking at a constant rate of ( 1 mathrm{mm} / mathrm{s} ) Find the induced current in the loop at an instant when the radius is ( 2 mathrm{cm} ) |
12 |

454 | Reactance of a coil is ( 157 Omega ). On connecting the coil across a source of frequency ( 100 H z ), the current lags behind e.m.f. by ( 45^{circ} . ) The inductance of the coil is A ( .0 .25 H ) в. ( 0.5 H ) ( c .4 H ) D. ( 314 H ) |
12 |

455 | The wire is found to vibrate in the third harmonic. The maximum emf induced is ( A ) B. [ frac{3(A B) omega}{k} ] ( c ) [ frac{2(A B) omega}{k} ] ( D ) [ frac{(A B) omega}{k} ] E. answer required |
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456 | Assertion An electric field ( vec{E} ) is induced in a closed loop where magnetic flux is varied.The induced ( overrightarrow{boldsymbol{E}} ) is not a conservative field Reason The line integral ( vec{E} . overrightarrow{d l} ) around the closed loop is nonzero 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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457 | The magnitude of the force required to move the conducting rod at constant speed ( 5 c m / s ) at the same instant ( t= ) ( 2 s, ) is equal to B. ( 0.12 N ) c. ( 0.08 N ) D. ( 0.64 N ) |
12 |

458 | Check the incorrect statement: When a magnet is moved into a coil the strength of the current depends on: A. The number of turns in the coil B. The speed with which the magnet moves c. The resistance of the coil D. None of the above |
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459 | The figure shows a square loop ( L ) of side ( 5 c m ) which is connected to a network of resistances. The whole setup is moving towards right with a constant speed of ( 1 mathrm{cm} s^{-1} . ) At some instant, a part of Lis in a uniform magnetic field of ( 1 T ) perpendicular to the plane of the loop. If the resistance of ( L ) is ( 1.7 Omega ), the current in the loop at that instant will be close to A . ( 115 mu A ) в. 170 иА ( c cdot 60 mu A ) D. ( 150 mu A ) |
12 |

460 | Consider the situation shown. The wire AB is sliding on fixed rails with a constant velocity. If the wire ( A B ) is replaced by semi-circular wire, the magnitude of induced e.m.f will A. increase B. decrease c. remain the same D. increase or decrease depending on whether the semicircle buldges towards the resistance or away from it |
12 |

461 | Find the maximum emf induced | 12 |

462 | The self inductance of two solenoids ( A ) ( & mathrm{B} ) having equal length are same. If the number of turns in two solenoids ( A & B ) are 100 and 200 respectively. The ratio of radii of their cross-section will be A . 2: 1 B. 1: 2 c. 1: 4 D. 4: 1 |
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463 | An electron moves on a straight line path ( Y Y^{prime} ) as shown in figure. A coil is kept in the right such that ( Y Y^{prime} ) is in the plane of the coil. At the instant when the electron gets closest to the coil (neglect self-induction of the coil), A. the current in the coil flows clockwise B. the current in the coil flows anticlockwise c. the current in the coil is zero D. the current in the coil does not change the direction as the electron crosses point ( O ) E. answer required |
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464 | along a diameter of a conducting ring of radius ( 0.1 m ) and lies on ( x ) -y plane. There is a magnetic field ( vec{B}=(50 T) hat{K} . ) The ring rotates with an angular velocity ( omega=20 r a d s^{-1} ) about its axis. An external resistance of ( 10 Omega ) is connected across the center of the ring and rim. The current through external resistance is: ( mathbf{A} cdot frac{1}{4} ) B. ( frac{1}{2} ) ( c cdot frac{1}{3} ) D. zero |
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465 | A thin semicircular conducting the ring ( (P Q R) ) of radius ( ^{prime} r^{prime} ) is falling with its plane vertical in a horizontal magnetic field ( B ), as shown in figure. The potentia difference developed across the ring when its speed is ( v ), is A. Zero B. ( B v pi r^{2} / 2 ) and ( P ) is at higher potential ( mathrm{c} . pi r B v ) and ( R ) is at higher potential D. ( 2 r B v ) and ( R ) is at higher potential |
12 |

466 | The direction of torque produced due to induced current is A . counter-clockwise B. clockwise C. lateral to produce precession D. none of these |
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467 | A train is moving from south to north with a velocity of ( 90 mathrm{km} / mathrm{h} ). The vertical component of earth’s magnetic induction is ( 0.4 times ) ( 10^{-4} W b / m^{2} . ) If the distance between the two rails is ( 1 m, ) what is the induced e.m.f. in its axle? A. ( 1 m V ) B. ( 0.1 m V ) ( mathrm{c} .10 mathrm{mV} ) D. ( 100 m V ) |
12 |

468 | On making a coil of copper wire of length I and coil radius ( r, ) the value of self inductance is obtained as ( L ). If the coil of same wire, but of coil radius r/2, is made, the value’ of self inductance will be- – A . 2L B. 4L ( c cdot L / 2 ) ( D cdot L / 3 ) |
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469 | Write an expression of magnetic flux density ‘B’ at a point in end-on position or an axial position of a magnetic dipole. (Derivation not required.) | 12 |

470 | Energy in a current carrying coil is stored in the form of A . electric field B. magnetic field c. dielectric strength D. heat |
12 |

471 | ( A, B ) and ( C ) are the three coils of conductor having different number of turns, wound around a soft iron ring as shown in the figure. Ends of coils ( B ) and ( C ) are connected to the galvanometers. The observation that can be made when ends of coil ( A ) are connected to an A.C. source is A. Same electric current is induced in ( B ) and ( C ) B. No electric current is induced in ( B ) and ( C ) c. Induced electric current is more in ( B ) than in ( C ) D. Induced electric current is less in ( B ) than in ( C ) |
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472 | a) Redraw the above diagram. b) This diagram represents c) Label the parts of the diagram d) Mention the working principle of the device denoted by this diagram. |
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473 | The magnetic field ( B=2 t^{2}+4 t^{2} ) (where ( t= ) time ) is applied perpendicular to the plane of a circular wire of radius ( r ) and resistance ( R ). If all the units are in SI the electric charge that flows through the circular wire during ( t=0 s ) to ( t=2 s ) is A ( cdot frac{6 pi r^{2}}{R} ) в. ( frac{24 pi r^{2}}{R} ) c. ( frac{32 pi r^{2}}{R} ) D. ( frac{48 pi r^{2}}{R} ) |
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474 | Dynamo converts: A. electric energy into magnetic energy B. magnetic energy into potential energy C. mechanical energy into electrical energy D. no energy |
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475 | A conducting loop of radius ( R ) is has a ( B ) -field directed through it at a downward angle as shown. Determine the amount of flux in the loop. ( mathbf{A} ) ( B ) ( mathbf{c} cdot B pi R^{2} sin theta ) ( mathbf{D} cdot B pi R^{2} cos theta ) |
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476 | A material of ( 0.25 mathrm{cm}^{2} ) cross sectional area is placed in a magnetic field of strength ( (H) 1000 A m^{-1} . ) Then the magnetic flux produced is: [Susceptibility of material is 314 and Permeability of free space, ( mu_{0}=4 pi times ) ( 10^{-7} H m^{-1} ) A . ( 8.33 times 10^{-8} mathrm{Wb} ) В. ( 1.84 times 10^{-6} mathrm{Wb} ) ( mathbf{c} cdot 9.87 times 10^{-6} mathrm{Wb} ) D. ( 3.16 times 10^{-8} mathrm{Wb} ) |
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477 | A solenoid is connected to a source of constant e.m.f. for a long time. A soft iron piece is inserted into it. Then, which of the following is/are correct? This question has multiple correct options A. Self-inductance of the solenoid gets increased B. Flux linked with the solenoid increases; hence, steady state current gets decreased C. Energy stored in the solenoid gets increased D. Magnetic moment of the solenoid gets increased |
12 |

478 | Self inductance ( L ) of long solenoid is being proportional to the number of turns ( N ) as- A . ( N ) В. ( N^{2} ) c. ( N^{3} ) D. ( N^{4} ) |
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479 | Which of the following can’t increase the voltage produced by the generator? A. Using a powerful electromagnet to make the magnetic field stronger in place of a permanent magnet. B. By winding the coil round a soft iron core to increase the strength of magnetic field. C. By using a coil with more turns. D. Changing the material of the coil. |
12 |

480 | The Sl unit of magnetic field induction is A. Tesla B. weber c. weber/m D. weber. m |
12 |

481 | In the given figure current from ( A ) to ( B ) in the straight wire is decreasing. The direction of induced current in the |
12 |

482 | An ac generator consists of a coil of 200 turns, ( 100 mathrm{cm} ) in diameter. If the coil rotates at 500 rpm in a magnetic field of ( 0.25 mathrm{T} ), then the maximum induced emf A . 20.6 ( v ) B. 51.7 c. 4.1 D. None of the above |
12 |

483 | The value of magnetic field induction which is uniform is 2 T. What is the flux passing through a surface of area ( 1.5 m^{2} ) perpendicular to the field? |
12 |

484 | 4. When the current changes from +2 A to -2 A in 0.05 s, an emf of 8 V is induced in a coil. The coefficient of self- induction of the coil is (a) 0.1 H (b) 0.2 H (c) 0.4 H (d) 0.8 H (AIEEE 2003) |
12 |

485 | Derive an expression for the force on current carrying in a magnetic field. | 12 |

486 | The figure shows a small circular coil of area A suspended from a point 0 by a string of length I in a uniform magnetic induction B in the horizontal direction. If the coil is set into oscillations likes simple pendulum by displacing it a small angle ( theta_{0} ) as shown, find emf induced in the coil as a function of time. Assume the plane of the coil is always in the plane of string. |
12 |

487 | Assertion (A) : The net magnetic flux coming out of a closed surface is always zero. Reason (R) : Unlike poles of equa strength exist together 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 c. A is true, But R is false D. A is false, But R is true |
12 |

488 | The value of coefficient of mutual induction for the arrangement of two coils shown in the figure will be : A. zero B. Maximum c. Negative D. Positive |
12 |

489 | Give a few applications of Faradays law of induction in daily life. | 12 |

490 | What is electromagnetic induction? | 12 |

491 | Explain the work of an Electric Generator with diagram. |
12 |

492 | The number of turns in the coil of an ( A C ) generator ar e100 and its cross- sectional area is ( 2.5 m^{2} . ) The coil is revolving in a uniform magnetic field of strength ( 0.3 T ) with the uniform angular velocity of 60 rad/s. The value of maximum value produced is ( mathbf{k V} ) A . 1.25 в. 4.50 c. 6.75 D. 2.25 |
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493 | Magnetic flux has the dimension ( mathbf{A} cdot M L^{2} A^{-2} ) B ( cdot M L^{2} T^{-2} A^{-1} ) ( mathbf{C} cdot M T^{-2} A^{-1} ) D. ( M L^{2} T^{-2} A^{-2} ) |
12 |

494 | When the flux linked with a coil changes: A. current is always induced B. an emf and a current are always induced c. an emf is induced but a current is never induced D. an emf is always induced and a current is induced when the coil is a closed one |
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495 | Two rail tracks are ( 1 m ) apart and insulated from each other and insulated from ground. A milli-voltmeter is connected across the rail-tracks. When a train travelling at ( 180 mathrm{km} / mathrm{h} ) passes through what will be the reading in milli-voltmeter? Given : horizontal component of earth’s field ( sqrt{3} times 10^{-4} T ) and dip at the place ( 60^{circ} ) A. ( 1.5 mathrm{mV} ) B. ( 15 mathrm{mV} ) c. ( frac{15}{sqrt{3}} m V ) D. ( frac{1.5}{sqrt{3}} m V ) |
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496 | Two circular coils are placed adjacent to each other. Their planes are paralle and currents through them ( i_{1} ) and ( i_{2} ) are in same directions. Choose the correct options This question has multiple correct options A. When ( A ) is brought near ( B ), current ( i_{2} ) will decrease B. When ( A ) is brought near ( B ), current ( i_{2} ) will increase C. When current ( i_{1} ) is increased, current ( i_{2} ) will decrease D. When current ( i_{1} ) is increased, current ( i_{2} ) will increase |
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497 | A conducting circular loop of area ( 1 mathrm{nm} ) is placed compulsary with a long, straight wire at a distance of current which changes from 10 A to zero in 0.1 s. Find the average emf induced in the loop in 0.1 s. |
12 |

498 | A square metal wire loop of side ( 10 mathrm{cm} ) and of resistance ( 2 Omega ) moves with constant velocity in the presence of a uniform magnetic field of induction ( 4 mathrm{T} ) perpendicular and into the plane of the loop. The loop is connected to a network of resistance as shown in the Figure. If the loop should have a steady current of ( 2 mathrm{mA} ), the speed of the loop must be (in ( left.mathrm{cm} mathrm{s}^{-1}right): ) 4 B. ( c ) ) |
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499 | A copper rod of length ( l ) is rotated about one end, perpendicular to the uniform magnetic field ( B ) with constant angular velocity ( omega . ) The induced emf between two ends of the rod is: A ( cdot frac{1}{2} B omega l^{2} ) в. ( B omega l^{2} ) c. ( frac{3}{2} B omega l^{2} ) D . ( 2 B omega l^{2} ) |
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500 | A dynamo is used to supply electric current to a small electric bulb, If the number of turns in the coil of this dynamo is doubled, then the voltage in the bulb. A. will decrease B. Remains unchanged c. will be doubled D. Will increase by a factor between 1 and 2 |
12 |

501 | A conducting rod ( mathrm{AB} ) moves parallel to X-axis in a uniform magnetic field, pointing in the positive X-direction. The end ( A ) of the rod gets A. positively charged B. negatively charged c. neutral D. first positively charged and then negatively charged |
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502 | The working of magnetic braking of trains is based on A. Steady current B. Eddy current c. Alternating current D. Pulsating current |
12 |

503 | A closely wound flat circular coil of 25 turns of wire has diameter of ( 5 mathrm{cm} ) which carries current of 4 amperes, the flux density at the centre of a coil will be A ( cdot 1.256 times 10^{-3} ) tesla В. ( 1.679 times 10^{-5} ) tesla c. ( 1.512 times 10^{-5} ) telsa D. ( 2.28 times 10^{-4} ) telsa |
12 |

504 | A square conducting coil of area ( = ) ( 100 mathrm{cm}^{2} ) is placed normally inside a uniform magnetic field of ( 10^{3} W b m^{-2} ) The magnetic flux linked with the coil is Wh. A . 10 B . ( 10^{-5} ) ( c cdot 10^{5} ) D. 0 |
12 |

505 | For a coil having ( boldsymbol{L}=2 boldsymbol{m} boldsymbol{H}, ) current flow through it is ( I=t^{2} e^{-t} ) then the time at which emf become zero: – ( mathbf{A} cdot 2 s ) B . ( 1 s ) c. ( 4 s ) D. ( 3 s ) |
12 |

506 | The induced emf developed across the rod must be A. ( 4.5 mathrm{V} ) with b at higher potential B. 1.5 V with a at higher potential c. 1.5 V with b at higher potential D. 4.5 V with a at higher potential |
12 |

507 | Two coils, ( A ) and ( B ), are lined such that emf ( epsilon ) is induced in ( B ) when the current in ( A ) is changing at the rate ( I ). If ( i ) current is now made to flow in ( mathrm{B} ), the flux linked with ( A ) will be : A. ( (epsilon / I) i ) i B. ( epsilon i I ) c. ( (epsilon I) ) D. ( i I / epsilon ) |
12 |

508 | A metallic rod of length ( l^{prime} ) is tied to a string of length ( 2 l ) and made to rotate with angular speed ( omega ) on a horizontal table with one end of the string fixed. If there is a vertical magnetic field ( B^{prime} ) in the region, the e.m.f. induced across the ends of the rod is: A ( cdot frac{3 B omega l^{2}}{2} ) в. ( frac{4 B omega l^{2}}{2} ) c. ( frac{5 B omega l^{2}}{2} ) D. ( frac{2 B omega l^{2}}{2} ) |
12 |

509 | An a.c. generator consists of a coil of 10,000 turns and of area ( 100 mathrm{cm}^{2} . ) The coil rotates at an angular speed of 140 rpm in a uniform magnetic field of ( 3.6 times 10^{-2} mathrm{T} . ) Find the maximum value of the emf induced. |
12 |

510 | toppr ( t ) Q Type your question emf induced with time ( s ) |
12 |

511 | A horizontal straight conductor when placed along south-north direction falls under gravity; there is A. an induced current from south-to-north direction B. an induced emf current from north-to-south direction c. no induced emf along the length of the conductor D. an induced emf along the length of the conducto |
12 |

512 | ( A B C ) is an equilateral triangle with ( O ) as its centre, ( vec{F}_{1}, vec{F}_{2} ) and ( vec{F}_{3} ) represent three forces acting along the sides ( A B, B C ) and ( A C ) respectively. If the total torque about ( O ) is zero then the magnitude of ( vec{F}_{3} ) is? A ( frac{F_{1}+F_{2}}{2} ) ( mathbf{B} cdot 2left(F_{1}+F_{2}right) ) ( c cdot F_{1}+F_{2} ) D. ( F_{1}-F_{2} ) |
12 |

513 | If the resistances of values ( R_{1} ) and ( R_{2} ) are connected on both ends as shown in figure, current ( I, ) flowing through resistance ( R_{1} ) is given by ( A ) [ frac{B l R_{2}left(v_{1} r_{2}-v_{2} r_{1}right)}{R_{1} R_{2}left(r_{1}+r_{2}right)+r_{2} r_{1}left(R_{1}+R_{2}right)} ] B. [ frac{B l R_{2}left(v_{1} r_{2}+v_{2} r_{1}right)}{R_{1} R_{2}left(r_{1}+r_{2}right)+r_{2} r_{1}left(R_{1}+R_{2}right)} ] ( c ) [ frac{B l R_{2}left(v_{1} r_{2}-v_{2} r_{1}right)}{R_{1} R_{2}left(r_{1}-r_{2}right)+r_{2} r_{1}left(R_{1}+R_{2}right)} ] D. [ frac{B l R_{2}left(v_{1} r_{2}-v_{2} r_{1}right)}{R_{1} R_{2}left(r_{1}+r_{2}right)-r_{2} r_{1}left(R_{1}+R_{2}right)} ] E . nont |
12 |

514 | Explain Faradays law of induction with the help of activity. | 12 |

515 | 42. A wire of fixed length is wound in such a way that it forms a solenoid of length ‘l’ and radius ‘r’. Its self-inductance is found to be L. Now if same wire is wound in such a way that it forms a solenoid of length 1/2 and radius r/2, then the self-inductance will be (a) 2L (b) L (c) 4L (d) 8 L |
12 |

516 | Describe the coil and magnet experiment to demonstrate electromagnetic induction. | 12 |

517 | A lossless coaxial cable has a capacitance of ( 7 times 10^{-11} mathrm{F} ) and an inductance of ( 0.39 mu H . ) Calculate characteristic impedance of the cable. A . 65 B. 75 ( c cdot 66 ) D. 77 |
12 |

518 | A straight conductor ( 0.1 mathrm{m} ) long moves in a uniform magnetic field 0.1 T. The velocity of the conductor is ( 15 mathrm{m} / mathrm{s} ) and is directed perpendicular to the field. The emf induced between the two ends of the conductor is: A . ( 0.10 mathrm{v} ) B. 0.15 ( v ) c. ( 1.50 v ) D. 15.00 |
12 |

519 | Two coils are placed close to each other. The mutual inductance of the pair of coils depend upon: A. the currents in the two coils B. the rates at which currents are changing in the two coils c. relative position and orientation of the two coils D. the materials of the wires of the coil |
12 |

520 | Two coils ( X ) and ( Y ) are placed in a circuit such that a current changes by ( 3 A ) in coil ( X ) and magnetic flux changes of ( 1.2 ~ W b ) occurs in ( Y ). The value of mutual inductance of the coils is : ( mathbf{A} cdot 0.2 H ) в. ( 0.4 mathrm{H} ) c. ( 0.6 H ) D. ( 3.6 H ) |
12 |

521 | A straight coaxial cable of negligible active resistance is receiving energy from a constant voltage source ( V ) Current consumed is ( I ). Find the energy flux across the cross-section. Assume conductive sheath to be thin. |
12 |

522 | When the number of turns per unit length in a solenoid is doubled then its coefficient of self induction will become A . half B. double c. four times D. unchanged |
12 |

523 | Who gave the principle of Electromagnetic Induction? A. Volta B. Ampere c. Faraday D. orested |
12 |

524 | A square loop of side a is rotating about its diagonal with angular velocity ( omega ) in perpendicular magnetic field ( overline{boldsymbol{B}}, ) figure It has 10 turns. The e.m.f. induced is? A. ( B a^{2} ) sinwt B. ( B a^{2} )coswt D. ( 10 B a^{2} omega ) sinw |
12 |

525 | Which of following can induce the maximum induced voltage? A. 1 amp dc. B. 1 amp 1 Н ( z ). c. 1 amp 100 н ( z ) D. 20 amp dc. |
12 |

526 | Discuss with theory the method of inducing emf in a coil by changing its orientation with respect to the direction of the magnetic field. | 12 |

527 | A semi-circular conducting ring acb of radius ( R ) moves with constant speed ( v ) in a plane perpendicular to uniform magnetic field ( B ) as shown in figure. Identify the correct statement A ( cdot V_{a}-V_{c}=B R v ) В. ( V_{b}-V_{c}=B R v ) c. ( V_{a}-V_{b}=0 ) D. None of these |
12 |

528 | The area of a coil is ( 500 c m^{2} ) and the number of turns in it is ( 2000 . ) It is kept perpendicular to a magnetic field of induction ( 4 times 10^{-5} W b / m^{2} . ) The coil is rotated through 180 in 0.1 second. If the resistance of the total circuit is ( 20 Omega ) then the value of the induced charge flowing in the circuit will be : A ( cdot 1 times 10^{-4} C ) В. ( 2 times 10^{-4} mathrm{C} ) c. ( 3 times 10^{-4} C ) D. ( 4 times 10^{-4} C ) |
12 |

529 | Gauss is unit of which quantity? A. ( H ) в. ( B ) ( c cdot phi ) D. ( I ) |
12 |

530 | The magnetic field inside a ( 2 m H ) inductor becomes 0.8 of its maximum value in ( 20 mu s ) when the inductor is joined to battery. Find resistance of the circuit. A . ( 160 Omega ) B. ( 80 Omega ) ( c .320 Omega ) D. ( 240 Omega ) E. none of these |
12 |

531 | A metallic ring is attached to the wall of the room.When the north pole of magnet is brought near the ring, the induced current in the ring is: A . zero B. in clockwise direction c. in anti-clockwise direction D. infinite |
12 |

532 | Which of the following determines the direction of magnetic field due to a current carrying conductor? A. Faraday’s law of electromagnetic induction B. Fleming’s left hand rule c. Lenz’s law D. Maxwell’s cork screw rule |
12 |

533 | A rectangular loop carrying a current 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 a steady current lis established in the wire as shown in the figure, the loop will: A. rotate about an axis parallel to the wire B. move away from the wire C. remain stationary D. move towards the wire |
12 |

534 | An inductor may store energy in A. its electric field B. its coils c. its magnetic field D. both in electric and magnetic fields |
12 |

535 | A coil and a magnet moves with their constant speeds ( 5 m / )sec and ( 3 m / )sec respectively, towards each other, then induced emf in coil is ( 16 m V . ) If both moves in the same direction, then induced emf in the coil: ( mathbf{A} cdot 15 m V ) в. ( 4 m V ) c. ( 64 m V ) D. zero |
12 |

536 | A square of side L meters lies in the ( x-y ) plane in a region where the magnetic field is given by ( overline{boldsymbol{B}}=boldsymbol{B}_{0}(mathbf{2} hat{boldsymbol{i}}+boldsymbol{3} hat{boldsymbol{j}}+ ) ( 4 hat{k}) T, ) where ( B_{0} ) is constant. The magnitude of flux passing through the square is: ( mathbf{A} cdot 8 B_{0} L^{2} W b ) B. ( 12 B_{0} L^{2} W b ) c. ( 4 B_{0} L^{2} W b ) D. ( sqrt{4 times 29} B_{0} W b ) |
12 |

537 | In shown fig. the circular loop of wire is moved with velocity towards the infinite current carrying wire. Then A. No current is induced in loop B. Current is induced in loop clockwise c. Current is induced in loop anticlockwise D. Extra charges are induced on the wire loop |
12 |

538 | A conducting loop is placed in a uniform magnetic field with its plane perpendicular to the field. An emf is induced in the loop if ( A ). it is translated B. it is rotated about its axis c. it is kept untouched for several minutes D. it is cut into two pieces |
12 |

539 | A long solenoid with 20 turns per ( c m ) has a small loop of area ( 2.0 mathrm{cm}^{2} ) placed inside the solenoid normal to its axis. If the current carried by the solenoid changes steadily from ( 2.0 A ) to ( 4.0 A ) in ( 0.1 mathrm{sec}, ) calculate the induced emf in the loop while the current is changing. |
12 |

540 | Flux associated with coil of unit area placed int he magnetic field of induction ( B ) is doubled in ( 0.2 s . ) The emf induced in the coil is: A . ( 5 V ) B. ( 10 B V ) ( mathrm{c} .5 B V ) D. ( 10 V ) |
12 |

541 | Describe the working of AC electric generator with diagram: | 12 |

542 | If strength of magnetic field ( bar{B}=2 hat{i}+ ) ( hat{boldsymbol{j}}-hat{boldsymbol{k}} ) and area vector is ( overline{boldsymbol{A}}=mathbf{3} hat{boldsymbol{i}}-hat{boldsymbol{j}} ) then find the magnetic flux link with area vector A. 4 weber B. 6 weber c. 7 weber D. 5 weber |
12 |

543 | Q Type your question. figure. The ring has a narrow gap f width ( delta ) in its circumference. The cross- sectional area of the solenoid is ( a ). The solenoid has a uniform internal field of magnitude ( B(t)=B_{0}+beta t, ) where ( beta> ) 0. Assume that no charge can flow across the gap, the face(s) accumulating an excess of positive charge is/are ( mathbf{A} cdot F_{1} ) B . ( F_{2} ) c. ( F_{1} ) and ( F_{2} ) D. difficult to conclude as data given are insufficient E. answer requirec |
12 |

544 | Energy in a current carrying coil is stored in the form of A . electric field B. magnetic field c. dielectric strength D. heat |
12 |

545 | 6. A coil having n turns and resistance R ohm is connected with a galvanometer of resistance 4R ohm. This combination is moved in time t second from a magnetic field W, weber to W, weber. The induced current in the circuit is W2 – W n(W2-W) (a) – 5 Rnt (b)- 5Rt (c) – W2-W Rnt n(W2-W) (d) – (AIEEE 2004) |
12 |

546 | A generator or dynamo works on the principle: A. Heating effect of electric current B. Electromagnetic induction c. chemical effect of electric current D. All of the above |
12 |

547 | toppr Q Type your question voltage with time in the coil? ( A ) B. ( c ) D. |
12 |

548 | The magnitude of the earths magnetic field at a place is ( B_{0} ) and the angle of dip is ( delta . A ) horizontal conductor of length lying along the magnetic north-south moves eastwards with a velocity ( v . ) The emf induced across the conductor is: A . zero B. ( B_{0} v l sin delta ) c. ( B_{0} l v ) D. ( B_{0} l cos delta ) |
12 |

549 | ( mathrm{cm} ) and having a resistance of 0.2 ohm is allowed to slide over two paralle thick metallic rails with uniform velocity of ( 0.2 mathrm{m} / mathrm{s} ) as shown in the figure. The rails are situated in a horizontal plane. If the horizontal component of earth’s magnetic field is ( 0.3 times 10^{-4} mathrm{T} ) and a steady state current of ( 3 mu A ) is induced through the rod. The angle of dip will be : A ( cdot tan ^{-1}left(frac{3}{4}right) ) B. ( tan ^{-1}left(frac{1}{sqrt{3}}right) ) ( mathbf{c} cdot tan ^{-1}(sqrt{3}) ) D ( tan ^{-1}left(frac{1}{3}right) ) |
12 |

550 | A rectangular loop of sides ( a ) and ( b ) is placed in ( boldsymbol{x}-boldsymbol{y} ) plane. A uniform but time varying magnetic field of strength ( vec{B}=20 t hat{i}+10 t^{2} hat{j}+50 hat{k} ) is present in the region. The magnitude of induced emf in the loop at time ( t ) is : A. ( 20+20 t ) B . 20 ( c .20 t ) D. zero |
12 |

551 | A uniform circular loop of radius ( a ) and resistance ( R ) is placed perpendicular to a uniform magnetic field ( B ). One half of the loop is rotated about the diameter with angular velocity ( omega ) as shown in figure. Then, the current in the loop is: This question has multiple correct options A. zero, when ( theta ) is zer B. ( frac{pi a^{2} B omega}{2 R}, ) when ( theta ) is zero c. zero, when ( theta=pi / 2 ) ( stackrel{pi a^{2} B omega}{2 R}, ) when ( theta=frac{pi}{2} ) |
12 |

552 | If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage A. remains unchanged B. reverses polarity c. increases D. decreases |
12 |

553 | If the speed of rotation of armature coil is increased in an AC generator A. Magnitude of current increases B. Frequency of current increases c. Both 1 and 2 D. Magnitude of current increases, frequency decreases |
12 |

554 | When the magnetic flux associated with a coil changes an emf is induced in the circuit. State Faraday’s law of electromagnetic induction. | 12 |

555 | (c) Vo-Vp = 8 V (U P 21. A wire is sliding as shown in figure. The angle between the acceleration and the velocity of the wire is 30° Tes (a) 30° (c) 120° (b) 40° (d) 90° liding onductor of length lis ed |
12 |

556 | A conducting ring of radius ( r ) is rolling without slipping with a constant angular velocity ( omega ) (figure). If the magnetic field strength is ( B ) and is directed into the page then the emf induced across ( P Q ) is A. ( B omega r^{2} ) в. ( frac{B omega}{2} ) c. ( 4 B omega r^{2} ) D. ( frac{B omega}{4} ) |
12 |

557 | The coefficient of self induction of a coil is given by ( ^{text {A }} cdot L=left(-frac{d I}{d t}right) ) B. ( L=-frac{e d I}{d t} ) c. ( _{L}=frac{d I}{e d t} ) D. ( L=frac{d I}{d t} e^{2} ) |
12 |

558 | Two circular conducting loops of radii ( R_{1} ) and ( R_{2} ) are laying concentrically in the same plane. If ( boldsymbol{R}_{1}>boldsymbol{R}_{2} ) then the mutual inductance (M) between them will be proportional to: A ( cdot frac{R_{1}}{R_{2}} ) в. ( frac{R_{2}}{R_{1}} ) c. ( frac{R_{1}}{R_{2}^{2}} ) D. ( frac{R_{2}^{2}}{R_{1}} ) |
12 |

559 | When the plane of the rectangular coil is parallel to the direction of the magnetic field in a dynamo, then A. Induced current will be zero B. Induced current is maximum c. AC is produced. D. DC is produced. |
12 |

560 | Find the emf induced as a function of time it is zero at ( t=0 ) and is increasing in positive direction |
12 |

561 | According to Faraday’s law, the total charge induced in a conductor that is moved in a magnetic field depends up on: A. Initial magnetic flux B. Final magnetic flux c. Rate of change of magnetic flux D. change in magnetic flux |
12 |

562 | ance к 14. An equilateral triangular loop ADC having some resistance is pulled with a constant velocity v out of a uniform magnetic field directed into the paper (figure). At time 1 = 0, side DC of the loop is at edge of the magnetic field x x x x x x x x x x x x xxxx, x xxxxx xxxx xxxxx x The induced current (i) versus time (t) graph will be as (а) 11 (b) (c) і 15 Eicure ohоua опашана Тали |
12 |

563 | A coil is placed in transverse magnet field of 0.02 T. If this coil starts shrinking at a rate of ( 1 mathrm{mm} / mathrm{sec}, ) while its radius remains ( 4 mathrm{cm}, ) then what is the value of induced emf? ( A cdot 2 mu V ) B . ( 2.5 mu V ) ( c .5 mu V ) D. ( 8 mu V ) |
12 |

564 | A rectangular coil of 300 turns has an average area of ( 25 mathrm{cm} times 10 mathrm{cm} . ) The coil rotates with a speed of 50 cps in uniform magnetic field of strength ( 4 times ) ( 10^{-2} T ) about an axis perpendicular to the field. The peak value of the induced emf is ( (text { in } v o l t) ) A. ( 300 pi ) B. 3000 ( pi ) ( c .3 pi ) D. ( 30 pi ) |
12 |

565 | In the figure shown, a T-shaped conductor moves with constant angular velocity ( omega ) in a plane perpendicular, to uniform magnetic field ( vec{B} ). The potential difference ( V_{A}-V_{B} ) is A. zero в. [ frac{1}{2} B omega l^{2} ] c. ( 2 B omega l^{2} ) D. Bomega ( l^{2} ) |
12 |

566 | The armature of a DC motor has ( 20 Omega ) resistance. It draws a current of 1.5 amp when run by ( 200 V ) DC supply. The value of back emf induced in it will be ( mathbf{A} cdot 150 V ) в. ( 170 V ) ( mathbf{c} cdot 180 V ) D. ( 190 V ) |
12 |

567 | An electric circuit is composed of three conducting rods ( M O, O N ) and ( P Q ) as shown in figure. The resistance of the rods per unit length is ( lambda ). The rod ( P Q ) slides, as shown in the figure, at a constant velocity ( v, ) keeping its tilt angle relative to ( O N ) and ( N=M O ) fixed ( 45^{circ} . ) At each instance, the circuit is closed. The whole system is embedded in a uniform magnetic field ( B, ) which is directed perpendicularly into the page. Compute the timedependent induced electric current induced in the rods? |
12 |

568 | The loop shown moves with a velocity ( v ) in a uniform magnetic field of magnitude ( B ), directed into the paper. The potential difference between points ( P ) and ( Q ) is ( e . ) Then This question has multiple correct options B. ( e=B l v ) C. ( P ) is positive with respect to ( Q ) D. ( Q ) is positive with respect to ( P ) |
12 |

569 | Draw a neat diagram of the following and label the parts. DC dynamo |
12 |

570 | A conducting circular loop is placed in a uniform magnetic field, ( B=.025 ) T with its plane perpendicular to the loop The radius of the loop is made to shrink at a constant rate of ( 1 mathrm{mms}^{-1} ). The induced e.m.f. when the radius is ( 2 mathrm{cm} ), is ( mathbf{A} cdot 2 pi mu V ) в. ( pi mu V ) c. ( frac{pi}{2} mu V ) D. ( 2 mu V ) |
12 |

571 | (a) Obtain an expression for the energy stored in a solenoid of self-inductance ( L^{prime} ) when the current though it grows from zero to ( ^{prime} I^{prime} ) (b) A square loop MNOP of side ( 20 mathrm{cm} ) is placed horizontally in a uniform magnetic field acting vertically downwards as shown in the figure. The loop is pulled with a constant velocity of ( 20 mathrm{cm} s^{-1} ) till it goes out of the field (i) Depict the direction of the induced current in the loop as it goes out of the field. For how long would the current in the loop persist? (ii) Plot a graph showing the variation of magnetic flux and induced emf as a function of time. [ x times x times x times x times x ] |
12 |

572 | A wheel with 10 spokes each of length ‘ ( L ) ( mathrm{m} ) is rotated with a uniform angular velocity ‘ ( omega ) ‘ in a plane normal to the magnetic field ‘ ( B ) ‘. The emf induced between the axle and the rim of the wheel. A ( cdot frac{1}{2} N omega B L^{2} ) B. ( frac{1}{2} omega B L^{2} ) ( mathrm{c} cdot omega b L^{2} ) D. ( N omega B L^{2} ) |
12 |

573 | Area of a long solenoid is doubled.So how many times we have to increase its length to keep its self inductance constant- A. B. 2 ( c cdot 3 ) ( D ) |
12 |

574 | yual diape ( P Q R S^{prime} ) of dimensions, ( l times l ) is placed inside a constant and uniform Magnetic Field ( vec{B}=B_{0}left(frac{1}{sqrt{2}} hat{i}+frac{1}{sqrt{2}} hat{j}right) ) as shown in the figure such that it’s sides are initially parallel to the ( X ) and ( Y ) axes. Which of the following is the value for the “magnetic flux” associated with the square loop initially (as in the figure above)? A ( cdot theta_{S}=frac{B_{0}}{sqrt{2}} l^{prime} ) В . ( theta_{s}=B_{0} l ) c. ( theta_{mathrm{s}}=0 ) D. ( theta_{S}=sqrt{2} B_{0} l^{2} ) |
12 |

575 | Two identical circular loops of ( A & B ) of metal wire are lying on a table without touching each other. Loop A carries a current which increases with time. In response, the loop B: A. Remains stationary B. Is attracted by the loop ( A ) C. Is repelled by the loop ( A ) D. Rotates about its CM, with CM fixed |
12 |

576 | Which of the following statements can help you to determine the direction of induced current in Electromagnetic Induction? A. Induced current flows such that it increase the total value of current B. Induced current flows such that it reduces the total value of current C. Induced current flows such that direction of magnetic field produced from induced current opposes change in external magnetic field D. Induced current flows such that direction of magnetic field produced from induced current opposes external magnetic field |
12 |

577 | Assertion: When number of turns in a coil is doubled, coefficient of self inductance of the coil becomes 4 times. Reason: This is because ( boldsymbol{L} propto boldsymbol{N}^{2} ) A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion. c. Assertion is true but Reason is false D. Assertion is false but Reason is true |
12 |

578 | A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is (i) pushed into the coil (ii) withdrawn from inside the coil (iii) held stationary inside the coil. |
12 |

579 | Force which is required to maintain the velocity of the rod at that instant. |
12 |

580 | A dynamo converts: A. electrical energy into mechanical energy B. electrical energy into heat energy C. mechanical energy into electrical energy D. heat energy into electrical energy |
12 |

581 | Two parallel rails with negligible resistance are ( 10.0 mathrm{cm} ) apart and are connected by a ( 5.00 Omega ) resistor. The circuit also contains two metal rods having resistance of ( 10.0 Omega ) and ( 15.0 Omega ) sliding along the rails. The rods are pulled away from the resistor at a constant speeds ( 8.00 m / s ) and ( 4.00 m / s ) respectively. A uniform magnetic field ( 0.010 T ) is applied perpendicular to the plane of the rails. Determine the current in the ( 5.00 Omega ) resistor. |
12 |

582 | A current of ( 2 A ) is passed through a coil of 1000 turns to produce a flux of ( 0.5 mu W b . ) Self inductance of the coil A ( .2 .5 times 10^{-4} H ) В. ( 2.5 times 10^{-5} H ) c. ( 2.5 times 10^{-6} H ) D. ( 2.5 times 10^{-7} H ) |
12 |

583 | Consider the time interval ( t=0 ) to ( t= ) ( mathbf{2 . 0 s} ) The magnetic field is perpendicular to the plane of the loop. |
12 |

584 | Assertion An electric motor will have maximum efficiency when back emf becomes equal to half of applied emf. Reason Efficiency of electric motor depends only on magnitude of back emf. 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 |

585 | x x X x x x x X x x (d) current Hows in anticlockwise wirection 31. A metallic ring of radius r with a uniform metallic spe of negligible mass and length ris rotated about its a with angular velocity o in a perpendicular uniform magnetic field B as shown in figure. The central end of the spoke is connected to the rim of the wheel through resistor R as shown. The X X X X X resistor does not rotate, its one end is always at the center of the ring and the other end is X always in contact with the ring. A force F as shown is needed to maintain constant X angular velocity of the wheel. F is equal to (the ring and the X X X X X spoke has zero resistance) B²wr² 8R B²wr3 C2R 4R A conducting ring + X x x (a) (b) Bor2 2R B²wr3 (d) AR 32 |
12 |

586 | When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage A . increases B. decreases c. remains constant D. reaches zero |
12 |

587 | ( ln operatorname{an} A C ) Generator, if the number of turns for the armature coil is doubled keeping all other specifications to be the same, which of the following applies to the voltage generated A. Peak Voltage will remain the same but the rms value of Voltage generated double B. Peak Voltage will double but the rms value of Voltage generated will remain the same c. Both the peak Voltage and the rms value of Voltage generated will double. D. Both the peak Voltage and the rms value of Voltage generated will reduce to half the original value |
12 |

588 | Assertion Electromotive force is a force which help the electrons to flow and produce current. Reason Electromotive force is independent of the voltage across the cell 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 |

589 | A long solenoid has 1000 turns. When a current of ( 4 A ) flows through it, the magnetic flux linked with each turn of the solenoid is ( 4 times 10^{-3} ) Wh. The self- inductance of the solenoid is: A. 4 н в. 3 н ( c .2 H ) D. 1 |
12 |

590 | The magnetic fields through two identical rings made of copper and wood are changing at the same rate. The induced electric field in copper ring will be : A. more than that in the wooden ring B. less than that in the wooden ring c. finite and that in the wooden ring will be zero D. same as that in the wooden ring |
12 |

591 | ( = ) ( b ) ( b ) ( b ) |
12 |

592 | coils which lie in a uniform magnetic field. Plane of the coils is perpendicular to the magnetic field as shown in figure. The coil is connected to a current integrator which measures the total charge passing through it. The coil is turned through ( 180^{circ} ) about the diameter. The charge passing through the coil is ( ^{mathbf{A}} cdot frac{N B A}{R} ) B. ( frac{sqrt{3} N B A}{2 R} ) c. ( frac{N B A}{sqrt{2} R} ) D. ( frac{2 N B A}{R} ) |
12 |

593 | Fleming’s right hand is also called as A. generator rule B. dynamo rule c. system rule D. none |
12 |

594 | The dimensional formula for magnetic flux is A ( cdotleft[M L^{2} T^{-2} A^{-1}right] ) B ( cdotleft[M L^{3} T^{-2} A^{-2}right] ) c. ( left[M^{0} L^{-2} T^{-2} A^{-2}right] ) D・ ( left[M L^{2} T^{-1} A^{2}right] ) |
12 |

595 | In a DC generator,the induced e.m.f in the armature is A. DC B. AC c. Fluctuating DC D. Both AC and DC |
12 |

596 | In a magnetic field of ( 0.05 T ) area of coil changes from ( 101 c m^{2} ) to ( 100 c m^{2} ) without changing the resistance which is ( 2 Omega . ) The amount of charge that flow during this period is A ( cdot 2.5 times 10^{-6} C ) B . ( 2 times 10^{-6} C ) c. ( 10 times 10^{-6} C ) D. ( 8 times 10^{-6} C ) |
12 |

597 | The electric flux through a certain area of dielectric is ( 8.76 times 10^{3} t^{4} ). The displacement current through the area is ( 12.9 p A ) at ( t=26.1 m s . ) Find the dielectric constant of the material. A ( .2 times 10^{-8} ) B. ( 4 times 10^{-8} ) c. ( 8 times 10^{-8} ) D. ( 2 times 10^{-7} ) |
12 |

598 | An emf will not be inducted in the coil, if ? | 12 |

599 | A loop of area ( 1 m^{2} ) is placed in a magnetic field ( B=2 T ), such that plane of the loop is parallel to the magnetic field. If the loop is rotated by ( 180^{circ}, ) the amount of net charge passing through any point of loop, if its resistance is ( 10 Omega ) is : A. ( 0.4 C ) B. ( 0.2 C ) ( c .0 .8 C ) D. ( 0 C ) |
12 |

600 | To convert mechanical energy into electrical energy, one can use A. DC dynamo B. AC dynamo c. motor D. (A) & (B) |
12 |

601 | Two parallel rails of a railway track insulated from each other and with the ground are connected to a millivoltmeter. The distance between the rails is one metre. A train is traveling with a velocity of ( 72 k m / h ) along the track. The reading of the millivoltmeter ( (text { in } boldsymbol{m} boldsymbol{V}) ) is : (Vertical component of the earths magnetic induction is ( left.2 times 10^{-5} Tright) ) A. 144 в. 0.72 c. 0.4 D. 0.2 |
12 |

602 | State True or False: Dynamo output can be coupled to a transformer. A. True B. False |
12 |

603 | To measure the field ( B ) between the poles of an electromagnet, a small test loop of area ( 1 mathrm{cm}^{2} ), resistance ( 10 Omega ) and 20 turns is pulled out of it. A galvanometer shows that a total charge of ( 2 mu C ) passed through the loop. The value of ( B ) is A . ( 0.001 T ) в. ( 0.01 T ) ( c .0 .17 ) D. ( 1.0 T ) |
12 |

604 | A conducting slider of resistance ( R(10 Omega), ) mass ( 50 g & ) length10cm is kept on a U-shaped frame as shown in figure. There is uniform magnetic field ( (B=0.1 T) ) perpendicular to plane of frame. The slider is attached to a spring ( (K=0.5 N / m) . ) The slider is displaced by an amount ( A_{0} & ) released. Time in which its amplitude become ( A_{0} / e ) is A . ( 9000 s ) B. 10000 s c. ( 12000 s ) D. 15000 s |
12 |

605 | If ( 0.1 J ) of energy is stored for the flow of current of ( 0.2 A ) in an inductor, then its inductance value is: A ( .5 H ) в. ( 0.5 H ) ( mathrm{c} cdot 5 m H ) D. ( 50 H ) E . ( 50 mathrm{mH} ) |
12 |

606 | A solenoid has 2000 turns wound over a length of ( 0.3 m . ) The area of its cross section is ( 1.2 times 10^{-3} m^{2} . ) Around its cross section a coil of 300 turns is wound. If an initial current of ( 2 A ) is reversed in ( 0.25 s, ) the emf induced in the coil is equal to A ( cdot 6 times 10^{-4} V ) В. ( 4.8 times 10^{-2} V ) c. ( 2.4 times 10^{-2} V ) D. ( 48 k V ) |
12 |

607 | In the figure shown ABCDEFGH is a square conducting frame of side ( 2 m ) and resistance ( 1 Omega / m . ) A uniform magnetic field B is applied perpendicular to the plane and pointing inwards. It increases with time at a constant rate of ( 10 T / s . ) Then: ( (A B=B C ) ( =C D=B H=1 m) ) rhis question has multiple correct options A. current in DH arm is zero B. power consumed as heat in the circuit 200 watt C. heat produced in DH and BF arm is zero D. current in AG and CB arm is equal and its magnitude ( 5 A ) |
12 |

608 | ( ln ) an ( A C ) generator, the rate of change of magnetic flux through the coil is maximum when the angle between the plane of the coil and the lines of force is A . ( 0^{circ} ) B. ( 60^{circ} ) ( c cdot 30^{circ} ) D. ( 90^{circ} ) |
12 |

609 | A thin circular ring of area ( A ) is held perpendicular to a uniform magnetic field of induction B. A small cut is made in the ring and a galvanometer is connected across the ends such that the total resistance of the circuit is ( mathrm{R} ). When the ring is suddenly squeezed to zero area, the charge flowing through the galvanometer is A. ( frac{B R}{A} ) в. ( frac{B A}{R} ) c. ABR D. ( frac{B^{2} A}{R^{2}} ) |
12 |

610 | What replacement is required to convert an AC generator to DC generator ? A. Armature with coil c. Slip rings with split rings D. All of the above |
12 |

611 | A metal rod moves at a constant velocity in a direction perpendicular to its length. A constant uniform magnetic field exists in space in a direction perpendicular to the rod as well as its velocity. Select the correct statement(s) from the following: A. The entire rod is at the same electric potentia B. There is an electric field in the rod c. The electric potential is highest at the center of the rod and decrease toward its ends D. The electric potential is lowest at the center of the rod and increases toward its ends |
12 |

612 | Two metallic rings of radius ( R ) are rolling on a metallic rod. A magnetic field of magnitude ( B ) is applied in the region. The magnitude of potential difference between points ( A ) and ( C ) on the two rings (as shown), will be: ( A ) в. ( 4 B omega R^{2} ) ( mathbf{c} cdot 8 B omega R^{2} ) ( D cdot 2 B omega R^{2} ) |
12 |

613 | Eddy currents are produced in a metallic conductor when A. The magnetic flux linked with it changes B. It is placed in a changing magnetic field C. It is placed in a magnetic field. D. Both A and B |
12 |

614 | If radius of long solenoid is reduced to half of original without changing other physical factor,then its self inductance will change- A. ( 1 / 3 ) times B. ( 1 / 2 ) times c. ( 1 / 5 ) times D. ( 1 / 4 ) times |
12 |

615 | Q Type your question constant angular velocity ( boldsymbol{omega}=frac{1}{sqrt{L C}} ) with the help of an external agent. A uniform magnetic field B exists in space and is directed into the plane of the figure. (circuit part remains at rest (left part is at rest) ). Then, This question has multiple correct options A the rms value of current in the circuit is ( frac{pi B a^{2}}{R sqrt{2 L C}} ) B. the rms value of current in the circuit is ( frac{pi B a^{2}}{2 R sqrt{L C}} ) c. the maximum energy stored in the capacitor is ( frac{pi^{2} B^{2} a^{4}}{8 R^{2} C} ) D. the maximum power delivered by the external agent is ( frac{pi^{2} B^{2} a^{4}}{4 L C R} ) |
12 |

616 | One conducting U tube can slide inside another as shown in figure, maintaining electric contacts between the tubes. The magnetic field B is perpendicular to the plane of the figure. If each tube moves towards the other at a constant speed ( v ) then the emf induced in the circuit in terms of ( mathrm{B}, l ) and ( mathrm{v} ) where ( l ) is the width of each tube, will be A . -Blv в. Вlv c. 2 вlv D. zero |
12 |

617 | Match column I and column II and select the correct answer using the codes given below: |
12 |

618 | (4) 2.0 X10 J 1 The four wire loops shown in figure have vertical edge lengths of either L, 2L, or 3L. They will move with the same speed into a region of uniform magnetic field B directed out of the page. Rank them according to the maximum magnitude of the induced emf greatest to least. BO 1 2 3 (a) 1 and 2 tie, then 3 and 4 tie (b) 3 and 4 tie, then 1 and 2 tie (c) 4, 2, 3,1 (d) 4 then 2 and 3 tie, and then 1 |
12 |

619 | As shown in above figure, a uniform magnetic field B, direction of magnetic field is outward of the plane of the page. Calculate the potential difference between point a and b if metal rod is pulled upward with constant velocity. A . B. ( frac{1}{2} v B L ), with point a at the higher potential C ( cdot frac{1}{2} v B L, ) with point ( b ) at the higher potential D. vBL, with point a at the higher potential E. vBL, with point b at the higher potential |
12 |

620 | Analyse the first pair and complete the second pair [ text { Battery: } overbrace{^{2}}{mid sqrt{mathrm{TIME}} longrightarrow} quad text { DC Generator: } ] |
12 |

621 | Assertion The coil in the resistance boxes are made by doubling the wire. Reason Thick wire is required in resistance box. 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 |

622 | The flux linked with a coil changes with time according to the equation ( phi=a t^{2} ) ( +b t+c . ) Then Sl unit of a is A. volt B. Volt/sec c. volt.sec D. weber |
12 |

623 | A pair of adjacent coil has a mutual inductance of ( 1.5 mathrm{H} ). If the current in one coil changes from 0 to ( 20 A ) in 0.5 sec, what is the change of flux linkage with the other coil? |
12 |

624 | Refer to the figure. When does the the galvanometer (G) deflect? A. The magnet is pushed into the coil B. The magnet is rotated into the coil c. The magnet is stationary at the centre of the coil. D. The number of turns in the coil is reduced |
12 |

625 | When a wire loop is rotated in a magnetic field, the direction of induced emf changes in every A. one revolution B. ( frac{1}{2} ) revolution c. ( frac{1}{4} ) revolution D. 2 revolution |
12 |

626 | In the given figure, a bar magnet is quickly moved towards a conducting loop having a capacitor. Predict the polarity of the plates ( A ) and ( b ) of the capacitor. |
12 |

627 | If we use a powerful electromagnet in place of permanent magnet in a generator, then: A. voltage produced by the generator increases B. current produced by the generator increases. c. Both A and B are true D. No effect on current or voltage occurs. |
12 |

628 | A dynamo consists of A. a horse-shoe magnet B. an armature coil C . two slip rings D. all of these |
12 |

629 | If the turns ratio of a transformer is 2 and the impedance of primary coil is 250 W then the impedance of secondary coil will be A . ( 1000 Omega ) B. 500 ( Omega ) ( c cdot 250 Omega ) D. 125 ( Omega ) |
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630 | 19. The network shown in the figure is a part of a compla circuit. If at a certain W h o novom instant the current i is 5 12 15 V 5 mH B A and is decreasing at the rate of 10° A/s then V-V. (a) 5V (b) 10 V (c) 15 V (d) 20 V |
12 |

631 | In a DC generator, induced emf in the armature is A. DC B. AC c. fluctuating DC D. both ( A C ) and ( D C ) |
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632 | Explain why an induced current must flow in such a direction so as to oppose the change producing it |
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633 | A solenoid coil is wound on a frame of rectangular cross section. If all the linear dimension of the frame are increased by a factor of two and the number of turns per unit length of the coil remains the same, the self- inductance increases by a factor of A .4 B. 8 c. 12 D. 16 |
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634 | Which end of the inductor, ( a ) or ( b ), is at a higher potential? |
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635 | What is an AC generator? Obtain an expression for the sinusoidal emf induced in the coil of ac generator, rotating with a uniform angular speed in a uniform magnetic field. |
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636 | Lenz’s law is a consequence of the law of conservation of A. charge B. mass c. energy D. momentum |
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637 | The magnetic flux in a coil of 100 turns increases by ( 12 times 10^{3} ) Maxwell in 0.2 second due to the motion of a magnet. The emf induced in the coil will be ( A cdot 6 v ) B. ( 0.6 v ) c. ( 0.06 v ) D. 60 V |
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638 | Consider the time interval ( t=2.0 s ) to ( boldsymbol{t}=mathbf{4} . mathbf{0} boldsymbol{s} ) The magnetic field is perpendicular to the plane of the loop. |
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639 | 3. Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon (a) the currents in the two coils. (b) the rates at which currents are changing in the two coils. (c) the relative position and orientation of the two coils (d) the material of the wire of the coils (AIEEE 2003) |
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640 | The self inductance of a motor of an electric fan is ( 10 H . ) In order to impart maximum power at ( 50 H z ), it should be connected to a capacitance of : A ( .4 mu F ) в. ( 8 mu F ) ( mathrm{c} cdot 1 mu F ) D. ( 2 mu F ) |
12 |

641 | The uniform magnetic field perpendicular to the plane of a conducting ring of radius a changes at the rate of ( alpha, ) then This question has multiple correct options A. all the points on the ring are at the same potential B. the emf induced in the ring is ( pi a^{2} alpha ) C. electric field intensity ( E ) at any point on the ring is zero ( mathbf{D} cdot E=(a alpha) / 2 ) E . answer required |
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642 | Crosses represent uniform magnetic field directed into the paper. A conductor XY moves in the field towards right side. Find the direction of induced current in the conductor. Name the rule you applied. What will be the direction of current if the direction of field and the direction of motion of the conductor both are reversed? |
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643 | The average induced emf in the circuit is ( mathbf{A} cdot 0.2 V ) B. ( 0.1 V ) ( mathbf{c} cdot 1 V ) D. ( 10 V ) |
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644 | toppr Q Type your question The space between the conductors is filled with air. The inner and outer conductors are carrying currents of equal magnitudes and in opposite directions Then the variation of magnetic field |
12 |

645 | A short magnet is allowed to fall from rest along the axis of a horizontal conducting ring. The distance fallen by the magnet in one second may be ( A cdot 5 m ) в. ( 6 m ) ( c .4 m ) D. None of these |
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646 | Match the following: Quantity Formula x linked a coil 1) Magnetic c flux with a) ( -N frac{d phi}{d t} ) 2) Induced emf b) ( mu_{r} mu_{0} n_{1} n_{2} pi r_{1}^{2} l ) 3) Force on a charged particle ( cdots ) moving in a electric and c) ( B A cos theta ) magnetic field ( f a ) 4) Mutual inductance of solenoid d) [ q(bar{E}+bar{v} times bar{B}) ] ( A cdot 1-c, 2-d, 3-b, 4-a ) B. ( 1-c, 2-a, 3-d, 4-b ) ( mathbf{C} cdot 1-mathbf{b}, 2-mathbf{a}, mathbf{3}-mathbf{c}, mathbf{4}-mathbf{d} ) D. ( 1-a, 2-b, 3-d, 4-c ) |
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647 | 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. ( frac{1}{4} ) times the original valu D. Unaffected |
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648 | An inductor may store energy in: A. its electric field B. its coil C . its magnetic field D. both electric and magnetic fields |
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649 | A triangular loop is placed in a dot ( Theta ) magnetic field as shown in figure. The direction of induced current is clockwise in the loop if magnetic field is |
12 |

650 | What is a generator state the principle on which generators work |
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651 | A conducting ring of radius ( r ) and resistance ( boldsymbol{R} ) rolls on a horizontal surface with constant velocity ( v ). The magnetic field ( B ) is uniform and is normal to the plane of the loop. Choose the correct option. A. The induced emf between ( O ) and ( Q ) is ( B r v ) B. ( _{text {An induced current } I}=frac{2 B v r}{R} ) flows in the clockwise direction Conduced current ( I=frac{2 B v r}{R} ) flows in the anticlockwise direction D. No current flows E. answer required |
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652 | What will be the magnitude of e.m.f. induced in a 200 turns coil with cross section area ( 0.16 m^{2} ? ) The magnetic field through the coil changes from 0.10 Wb ( m^{-2} ) to ( 0.30 mathrm{Wb} ), at a uniform rate over a period of ( 0.05 mathrm{s} ) A . ( 128 v ) B. 130v ( c cdot 118 v ) D. 1320 |
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653 | Which of the following statement is correct regarding induced electric field (symbols have their usual meanings)? This question has multiple correct options A. Work done in moving a test charge in an induced electric field can be zero B. Induced electric field is non-conservative is nature C. Induced electric lines of force form closed loops D. Induced e.m.f. in the loop in ( varepsilon=oint vec{E} . overline{d iota}=-frac{d phi}{d t} ) |
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654 | The radius of a coil decreases steadily at the rate of ( 10^{2} mathrm{m} / mathrm{s} ). A constant and uniform magnetic field of induction ( 10^{3} W b / m^{2} ) acts perpendicular to the plane of the coil. The radius of the coil when the induced e.m.f. in the coil is ( 1 mu ) ( v, ) is ( ^{A} cdot frac{2}{pi} mathrm{cm} ) в. ( frac{3}{pi} mathrm{cm} ) c. ( frac{4}{pi} mathrm{cm} ) D. ( frac{5}{pi} mathrm{cm} ) |
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655 | A square wire loop of ( 10.0 mathrm{cm} ) side lies at right angles to a uniform magnetic field of 7 T. A 10 V light bulb is in series with the loop as shown in figure. The magnetic field is decreasing steadily to zero over a time interval ( Delta t . ) For what value if ( Delta t(text { in } m s), ) the bulb will shine with full brightness? |
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656 | Determine the magnetic flux through the smaller loop as a function of ( x ) A ( cdot frac{mu_{0} i R^{2} pi r^{2}}{x^{3}} ) B. ( frac{mu_{0} i R^{2} pi r^{2}}{2 x^{3}} ) c. ( frac{2 mu_{0} i R^{2} pi r^{2}}{x^{3}} ) D. ( frac{sqrt{2} mu_{0} i R^{2} pi r^{2}}{x^{3}} ) |
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657 | A rectangular loop PQRS, is being pulled with constant speed into a uniform transverse magnetic fieldby a force (as shown). E.m.f. induced in side PS and potential difference between points Pand S respectively are (Resistance of the ( operatorname{loop}=r) ) A ( cdot ) zero, ( frac{F r}{B ell} ) B. Zero, zero c. zero, ( frac{F r}{6 B ell} ) D. ( frac{F r}{6 B ell}, frac{F r}{6 B ell} ) |
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658 | A square loop of side ( a ) and a straight long wire are placed in the same plane as shown in figure. The loop has a resistance ( boldsymbol{R} ) and inductance ( boldsymbol{L} ). The frame is turned through ( 18^{circ} ) about the axis ( O O^{prime} . ) What is the electric charge that flows through the loop? ( ^{mathbf{A}} cdot frac{mu_{0} I a}{2 pi R} ln left(frac{2 a+b}{b}right) ) в. ( frac{mu_{0} I a}{2 pi R} ln left(frac{b}{b^{2}-a^{2}}right) ) c. ( frac{mu_{0} I a}{2 pi R} ln left(frac{a+2 b}{b}right) ) D. None of these |
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659 | A long solenoid with length ( l ) and a radius ( R ) consists of ( N ) turns of wire,Neglecting the end effects, find the self-inductance. B . ( mu_{0} N pi R^{2} / l ) c. ( mu_{0} N^{2} pi R^{3} l ) D. ( mu_{0} N^{3} pi R^{2} l ) |
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660 | A conducting wire in the shape of ( Y ) with each side of length ( l ) is moving in a uniform magnetic field B, with a uniform speed v as shown in the figure. The induced emf at the two ends ( X ) and Y of the wire will be A. zero в. 2Blv ( c . ) 2Blv ( sin (theta / 2) ) D. 2Blv ( cos (theta / 2) ) |
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661 | Flux ( Phi ) (in weber) in a closed circuit of resistance 10 ohm varies with time ( t ) (in sec) according to the equation ( Phi=6 t^{2}- ) ( 5 t+1 . ) What is the magnitude of the induced current at ( t=1 ) sec? A . ( 0.5 A ) в. ( 0.6 A ) ( c .0 .7 A ) D. ( 0.8 A ) |
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662 | The Sl unit of inductance, the henry, can be written as: A. Weber ampere ( ^{-1} ) B. Volt-s ampere- c. Joule ampere- D. ohm ( s^{-1} ) |
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663 | A system ( S ) consists of two coils ( A ) and B. The coil ( A ) have a steady current ( I ) while the coils ( B ) is suspended near by as shown in figure. Now the system is heated as to raise the temperature of two coils steadily, then : A. the two coils show attraction B. the two coils show repulsion C. there is no change in the position of the two coils D. induced currents are not possible in coil ( B ) |
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664 | A coil of inductance ( L ) is carrying a steady current I what is the nature of its stored energy? A. Magnetic B. Electrical c. Both magnetic and electrical D. Heat |
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665 | A commutator changes the direction of current in the coil of A. a DC motor B. a DC motor and an AC generator c. a DC motor and a DC generator D. an Ac generator |
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666 | The horizontal component of the earth’s magnetic field at a place is ( 3 times 10^{-4} T ) and the dip is ( theta=tan ^{-1}(4 / 3) . ) A metal rod of length ( 0.25 mathrm{m} ) placed in the north south position is moved at a constant speed of ( 10 mathrm{cm} / mathrm{s} ) towards the east. The e.m.f induced in the rod will be: A. zero B. ( 1 mathrm{mV} ) ( c cdot 5 m v ) D. 10 mv |
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667 | A 10 V battery connected to ( 5 Omega ) resistance coil having inductance ( 10 mathrm{H} ) through a switch drives a constant current in the circuit. The switch is suddenly opened and the time taken to open it is 2 ms. The average emf induced across the coil is A ( cdot 4 times 10^{4} ) B ( .2 times 10^{4} ) ( c cdot 2 times 10^{2} ) D. ( 1 times 10^{4} ) |
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668 | Deflection in the galvanometer A. Towards right B. Left c. No defection D. None of these |
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669 | Current is induced in a coil by electromagnetic induction when: A. Only the coil moves in a magnetic field. B. Only the magnet moves towards the coil. C. Coil and the magnet move with respect to each other D. None of the above |
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670 | A coil of self inductance ( 2 cdot 5 H ) and resistance ( 20 Omega ) is connected to a battery of emf 120V having internal resistance of ( 5 Omega ). Find the current in the circuit in steady state. |
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671 | The figure given shows the variation of an alternating emf with time. What is the average value of the emf for the shaded part of the graph? A . 100 B. 200 ( c .300 ) D. 400 |
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672 | If the coil of the generator starts rotating faster then: A. voltage produced by the generator increases. B. current produced by the generator increases. c. Both A and B D. No effect on the value of current and voltage |
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673 | 74. In the given figure two concentric cylindrical region in which time varying magnetic field is present as shown. From the center to radius R magnetic field is perpendicular into the plane varying as dB/dt = 2ko and in a region from R to 2R magnetic field is perpendicular out of the plane varying as dB/ 3RB dt = 4ko. Find the induced emf across an arc AB of radius 3R. (a) 6Rºko (b) 5Rľke (c) 7Rºke (d) none of these |
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674 | The device which converts the mechanical energy in to electric energy is A . D.C. motor B. A.C. dynamo c. Transformer D. starter |
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675 | The self inductance of a coil having 400 turns is ( 10 mathrm{mH} ). The magnetic flux through the cross section of the coil corresponding to Current ( 2 mathrm{mA} ) is ( mathbf{A} cdot 4 times 10^{-5} mathbf{W} mathbf{b} ) B. ( 2 times 10^{-3} mathrm{wb} ) ( c cdot 3 times 10^{-5} w b ) D. ( 8 times 10^{-3} mathrm{wb} ) |
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676 | What will be the polarities at ( A & B ) if the direction of current is reversed in the circuit?? |
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677 | Strength of magnetic field is defined as A. Number of field lines passing normally through a unit surface B. Electric field lines passing the loop C. Current through surface D. Number of electrons passing a specific point per unit time |
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678 | Two inductance’s connected in parallel are equivalent to a single inductance of ( 1.5 H, ) and when connected in series are equivalent to a single inductance of ( 8 H . ) The difference in their inductance is:- ( mathbf{A} cdot 3 H ) в. ( 7.5 ~ H ) c. ( 2 H ) D. ( 4 H ) |
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679 | A rectangular copper coil is placed in uniform magnetic field of induction ( 40 m T ) with its plane perpendicular to the field. The area of the coil is shrinking at a constant rate of ( 0.5 m^{2} s^{-1} ). The emf induced in the coil is A . ( 10 mathrm{mV} ) в. ( 20 mathrm{mV} ) c. ( 80 m V ) D. ( 40 mathrm{mV} ) |
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680 | 21 UUUU (c) A 13. The flux linked with a coil at any instant t is given by 0= 10r – 50t + 250. The induced emf at t = 3 s is (a) 10 V (b) 190 V (c) -190 V (d) -10 V (AIEEE 2006) |
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681 | (AILLE 200) 2. A conducting square loop of side L and resistance R moves in its place with a uniform velocity v perpendicular to one of its sides. A magnetick induction B, constant in time and space, pointing perpendicular and into the plane at the loop, exists everywhere with half the loop outside the field, as shown in the figure. The induced emf is (a) zero (b) RvB (d) vBL (AIEEE 2002) R o VBL rout |
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682 | A rectangular frame of wire abcd has dimensions ( 32 mathrm{cm} times 8.0 mathrm{cm} ) and a total resistance of ( 2.0 Omega . ) It is pulled out of a magnetic field ( B=0.020 T ) by applying a force of ( 3.2 times 10^{-5} N ) (figure). It is found that the frame moves with constant speed. What is constant speed of the frame? |
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683 | A vertical rod of length ( l ) is moved with constant velocity ( v ) towards east. The vertical component of earth’s magnetic field is ( mathrm{B} ) and angle of dip is ( theta . ) The induced e.m.f. in rod is: A. ( B l v cot theta ) B. ( B l v sin theta ) c. ( B l v tan theta ) D. ( B l v cos theta ) |
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684 | A domestic electrical appliance requires alternating current of ( 15 mathrm{V} ). If ( 220 mathrm{V} ) of alternating current is supplied to the house, then the device that helps in the functioning of that electrical appliance is A. Induction coil B. Step-up transformer c. AC dynamo D. Step-down transformer |
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685 | Two coaxial coils are very close to each other and their mutual inductance is ( 5 m H . ) If a current 50 sin500t is passed in one of the coils then the peak value of induced emf in the secondary coil will be A . ( 5000 V ) B. ( 500 V ) ( mathbf{c} cdot 150 V ) D. ( 125 V ) |
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686 | Mention any two applications of eddy currents. |
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687 | Assertion It is more difficult to push a magnet into a coil with more loops. Reason Emf induced in the current loop resists the motion of the magnet. 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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688 | A ( 1.0 mathrm{m} ) long metallic rod is rotated with an angular frequency of 400 rad ( s^{-1} ) about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field of 0.5 T parallel to the axis exists everywhere. Calculate the emf developed between the centre and the ring. |
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689 | A coil of inductance 1 henry and resistance ( 10 Omega ) is connected to an ideal battery of emf ( 50 mathrm{V} ) at time ( t=0 ) Calculate the ratio of the rate at which |
12 |

690 | XX X X X X X (u) 90 22. A rectangular loop with a sliding conductor of length l is located in a uniform magnetic field perpendicular to the plane of the loop (figure). The magnetic induction is X B. The conductor has a X resistance R. The sides AB and CD have resistances R, and R2, respectively. Find the current through X the conductor during its motion to the right with a constant velocity v. Blv(R+R) BI? (b) R (R₂ + R₂) R₂ + R, R₂ Blv(R+R) BI? R, R₂ + R(R₂ + R₂) R, R₂ + R(R₂ + R₂) X X X X X X X X X X X X X X X X X X X X X mimo XXXXXXX (a) A vtola 1 |
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691 | A circular coil has 500 turns of wire and its radius is ( 5 mathrm{cm} ). The self inductance of the coil is:- A ( cdot 25 times 10^{-3} m H ) в. ( 25 m H ) c. ( 50 times 10^{-3} H ) D. ( 50 times 10^{-3} mathrm{mH} ) |
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692 | The coefficient of mutual inductance of the two coils is ( 5 H . ) The current through the primary coil is reduced to zero value from ( 3 A ) in 1 millisecond. The induced emf in the secondary coils is A. zero в. 1.67 Кル c. ( 15 K V ) D. ( 600 V ) |
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693 | The phenomenon of electromagnetic induction is : A. the process of charging a body B. the process of generating magnetic field due to a current passing through a coil C. producing induced current in a coil due to relative motion between a magnet and the coil D. the process of rotating a coil of an electric motor |
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694 | Draw a labelled diagram of an electric generator |
12 |

695 | When a rectangular coil is rotated in a uniform magnetic field about an axis passing through its centre and perpendicular to the field, the induced emf in the coil is maximum when the plane of the coil is A. Perpendicular to the field B. Parallel to the field c. Inclined at 60 with the field direction D. Inclined at 45 with the field direction |
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696 | A long solenoid of radius ( R ) carries a time (t)-dependent current ( boldsymbol{I}(boldsymbol{t})= ) ( boldsymbol{I}_{0} boldsymbol{t}(mathbf{1}-boldsymbol{t}) cdot mathbf{A} ) ring of radius ( 2 boldsymbol{R} ) is placed coaxially near its middle. During the time interval ( 0 leq t leq 1, ) the induced current ( left(I_{R}right) ) and the induced ( boldsymbol{E} boldsymbol{M} boldsymbol{F}left(boldsymbol{V}_{boldsymbol{R}}right) ) in the ring change as: ( mathbf{A} cdot ) At ( t=0.5 ) direction of ( I_{R} ) reverses and ( V_{R} ) is zero. B. Direction if ( I_{R} ) remains unchanged and ( V_{R} ) is zero at ( t=0.25 ) C . At ( t=0.25 ) direction of ( I_{R} ) reverses and ( V_{R} ) is maximum. D. Direction of ( I_{R} ) remains unchanged and ( V_{R} ) is maximum at ( t=0.5 ) |
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697 | There is a uniform (in spatial districution) magnetic filed B in a circular region of radius ( R ) as shown in the figure whose magnitude varies uniformly a the rate ( beta ) w.r.t. time. The emf induced across the ends of a circular concentric conducting arc of radius ( R_{1} ) having an agle ( theta ) as shown ( left(<boldsymbol{O} boldsymbol{A} boldsymbol{O}^{prime}=boldsymbol{theta}right) ) is ( ^{mathrm{A}} cdot frac{theta}{2 pi} R_{1}^{2} cdot beta ) B. ( frac{theta}{2} R^{2} cdot beta ) c. ( frac{theta}{2 pi} R^{2} . ). D. zero |
12 |

698 | p is shown in the 20. The current through a 4.6 H inductor is shown following graph. The induced emf during the time inte t = 5 milli-sec to 6 milli-sec will be (a) 10′ (b) – 23 x10 V (c) 23 x 10’v (d) Zero I (Amp) —– 5 6 (milli sec) |
12 |

699 | The electrical analog of mass is A . Diode B. Capacitance c. Inductance D. Resistance |
12 |

700 | The reading of ( V_{2} ) is : ( ^{mathbf{A}} cdot frac{-pi a^{2} B_{0} R_{1}}{R_{1}+R_{2}} ) ( ^{mathbf{B}} cdot frac{-pi a^{2} B_{0} R_{2}}{R_{1}+R_{2}} ) с. ( frac{pi a^{2} B_{0} R_{1}}{R_{1}+R_{2}} ) D. None of these |
12 |

701 | An inductor of inductance 100 m ( H ) is connected in series with a resistance, a variable capacitance and an AC source of frequency ( 2.0 mathrm{kHz} ); The value of the capacitance so that maximum current may be drawn into the circuit. ( A cdot 50 mathrm{nF} ) B. 60 nF ( c cdot 63 ) nf D. 79 nf |
12 |

702 | A conducting rod ( A B ) moves parallel to the x-axis in a uniform magnetic field pointing in the positive z direction. The end ( A ) of the rod gets positively charged. explain. |
12 |

703 | Production of electricity from magnetism is called A . electric field B. magnetic field lines c. electromagnetic induction D. magnetic induction |
12 |

704 | The magnitude of the EMF in a coil depends on A. flux density passing through it B. density of material c. amount of flux leakage D. rate of change of flux linkages |
12 |

705 | A solenoid of length ( 1 m ) and ( 0.05 m ) diameter has 500 turns. If a current of ( 2 A ) passes through the coil, calculate the co-efficient of self induction of the coil. |
12 |

706 | A straight conductor ( 0.1 mathrm{m} ) long moves in a uniform magnetic field ).1T. The velocity of the conductor is ( 15 mathrm{m} / mathrm{s} ) and is directed perpendicular to the field The e.m.f. induced between the two ends of the conductors is. A . ( 0.10 mathrm{v} ) B. 0.15 ( v ) c. ( 1.50 v ) D. 15.00 |
12 |

707 | Find the speed of the connector as a function of time if the force ( boldsymbol{F} ) is applied ( operatorname{at} t=0 ) |
12 |

708 | In the circuit shown in figure, a conducting wire ( H E ) is moved with a constant speed ( boldsymbol{v} ) toward left. The complete circuit is placed in a uniform magnetic field ( vec{B} ) perpendicular to the plane of the circuit inward. The current in ( boldsymbol{H} boldsymbol{K} boldsymbol{D} boldsymbol{E} ) is A . clockwise B. anticloclwise c. alternating D. zero E. answer required |
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709 | Which is the correct formula for calculating the power lost due to eddy currents per unit mass for a thin sheet or wire?? Where ( P ) is the power lost per unit mass ( (W / k g), B_{p} ) is the peak magnetic field ( (T), d ) is the thickness of the sheet or diameter of the wire ( (boldsymbol{m}), boldsymbol{f} ) is the frequency ( (H z), k ) is a constant equal to 1 for a thin sheet and 2 for a thin wire ( ^{mathrm{A}} cdot_{P}=frac{pi^{2} B_{p}^{2} d^{2} f^{2}}{6 k rho D} ) в. ( quad P=frac{pi^{2} B_{p}^{2} d^{2} f}{k rho D} ) ( ^{mathrm{C}} P=frac{pi^{2} B_{p}^{2} d^{2} f^{2}}{6 k rho D^{3}} ) D. ( P=frac{pi^{2} B_{p}^{2} d^{2} f}{6 k rho D^{2}} ) |
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710 | If emf induced in a coil is ( 2 V ) by changing the current in it from ( 8 A ) to ( 6 A ) in ( 2 times 10^{-3} s, ) then the coefficient of self induction is A ( cdot 2 times 10^{-3} H ) в. ( 10^{-3} H ) c. ( 0.5 times 10^{-3} H ) D. ( 4 times 10^{-3} H ) |
12 |

711 | Self inductance of a long solenoid depends upon following(s)This question has multiple correct options A. number of turns B. radius of solenoid c. length of solenoid D. none of these |
12 |

712 | Why self induction is called inertia of electricity? |
12 |

713 | 26 A ring of mass m, radius r having charge g uniformly distributed over it and free to rotate about its own axis is placed in a region having a magnetic field B parallel to its axis. If the magnetic field is suddenly switched off, the angular velocity acquired by the ring is (a) QB (b) 29B m m (c) 9B (d) none of these 2m lenn I nar unit length is |
12 |

714 | A feature common to both ( A C ) and ( D C ) generator is A. Split rings B. Electrical energy is converted to mechanical energy c. slip rings D. Mechanical energy is converted to electrical energy |
12 |

715 | 1 weber is equivalent of A ( cdot 10^{-8} ) Maxwell 1 B . ( 10^{12} ) Maxwell c. ( 10^{8} ) Maxwel D. ( 10^{4} ) Maxwell |
12 |

716 | The magnetic field perpendicular to the plane of a conducting ring of radius ( r ) changes at the rate ( frac{d B}{d t} ) This question has multiple correct options A ( cdot ) The emf induced in the ring is ( pi r^{2} frac{d B}{d t} ) B. The emf induced in the ring is ( 2 pi r frac{d B}{d t} ) C. The potential difference between diametrically opposite points on the ring is half of the induced emf. D. All points on the ring are at the same potential. |
12 |

717 | If area of a long solenoid is doubled,length is trippled and no. of turns are remained contant.Then its self-inductance will be changed how many times- A ( cdot 1 / 3 ) в. ( 2 / 3 ) ( c cdot 1 / 9 ) D. ( 4 / 3 ) |
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718 | There is no generator. A. ship rings B. electromagnets c. commulator D. generator coil |
12 |

719 | Electromagnetic induction is not used in : A. Transformer B. Room heater c. AC generator D. Choke coil |
12 |

720 | A flexible wire loop in the shape of a circle has a radius that grows linearly with time. There is a magnetic field perpendicular to the plane of the loop that has a magnitude inversely proportional to the distance from the center of the loop, ( B(r) propto frac{1}{r} . ) How does the emf vary with time? A. ( E propto r^{2} ) в. ( E propto t ) ( c cdot E propto sqrt{t} ) D. ( E ) is constant |
12 |

721 | The magnetic flux linked with a coil is ( phi leq 8 t^{2}+3 t+5 ) Weber. The induced emf in fourth second will be ( mathbf{A} cdot 16 V ) B. ( 139 V ) ( c .67 V ) D. ( 145 V ) |
12 |

722 | A rod lies across frictionless rails in a uniform magnetic field ( vec{B} ) as shown in figure. The rid moves to the right with speed ( V . ) In order to make the induced emf in the circuit to be zero, the magnitude of the magnetic field should A. not change B. increase linearly with time c. decrease linearly with time D. decrease nonlinearly with time E. answer required |
12 |

723 | The main difference between A.C. generator and D.C. generator is A. carbon brushes B. magnets c. coil D. commutator |
12 |

724 | The diagram shows two circular loops a wire(A and B) centred on and perpendicular to the ( x ) -axis, and oriented with their planes parallel to each other. The y-axis passes vertically through loop A(dashed line). There is a current ( I_{B} ) in loop ( mathrm{B} ) as shown. Possible actions which we might perform on loop ( mathbf{A} ) are A. Move A to the right along x axis closer to B B. Move A to the left along x axis away from B C. As viewed from above, rotate A clockwise about y-axis D. As viewed from above, rotate A anticlockwise about y axis |
12 |

725 | Which one of the following can produce maximum induced e.m.f.? A. 50 ampere DC B. 50 ampere 50 Hz AC c. 50 ampere 500 нz D. 100 ampere DC |
12 |

726 | A coil having 500 square loops each of side ( 10 mathrm{cm} ) is placed normal to a magnetic field which increases at the rate of ( 1 T s^{-1} . ) The induced e.m.f. is A . 0.1 B. 5.0 V ( c cdot 0.5 v ) D. 1.0 |
12 |

727 | Magnetic flux linked with a stationary loop resistance ( boldsymbol{R} ) varies with respect to time during the time period ( T ) as follows: ( phi=a t(T-t) ) The amount of heat generated in the loop during that time (inductance of the coil is negligible) is A ( cdot frac{alpha T}{3 R} ) В. ( frac{a^{2} T^{2}}{3 R} ) ( ^{mathbf{C}} cdot frac{a^{2} T^{2}}{R} ) D. ( frac{a^{2} T^{3}}{3 R} ) |
12 |

728 | A wire ( 88 mathrm{cm} ) long bent into a circular loop is placed perpendicular to the magnetic field of flux density 2.5 Wb ( m^{-2} . ) Within ( 0.5 mathrm{s} ), the loop is changed into a square and flux density is increased to ( 3.0 mathrm{Wb} mathrm{m}^{-2} ). The value of e.m.f. induced is : A . ( 0.018 v ) B. 0.016v c. ( 0.020 v ) D. 0.012V |
12 |

729 | Draw a labelled diagram of an ac generator. Obtain the expression for the emf induced in the rotating coil of ( mathrm{N} ) turns each of cross-sectional area ( A ), in the presence of a magnetic field ( vec{B} ). |
12 |

730 | Find the magnitude of the magnetic induction B of a magnetic field generated by a system of thin conductors (along which a current ( i ) is flowing) at a point ( A(0, R, 0), ) that is the centre of a circular conductor of radius ( R ). The circular part is in yz plane. |
12 |

731 | A device for producing electric current is A. Ammeter B. Voltmeter c. Generator D. Galvanometer |
12 |

732 | Which of the following electrical devices works on the principle of electromagnetic induction? A. Electric fan B. Electric bulb C. Electric cooker D. L.E.D. |
12 |

733 | The essential difference between an AC generator and a DC generator is that A. AC generator has an electromagnet while a DC generator has permanent magnet. B. DC generator will generate a higher voltage. C. AC generator will generate a higher voltage D. AC generator has slip rings while the DC generator has commutator |
12 |

734 | A coil has a self-inductance of 0.05 henry. Find magnitude of the emf induced in it when the current flowing through it is changing at the rate ( 100 A s^{-1} ) |
12 |

735 | The north pole of a magnet is moved into a coil through the end ( boldsymbol{A} ) Simultaneously the north pole of another magnet is moved into the coil through the end ( B ) as shown in the figure. The direction of induced emf will: A. Be in the anticlockwise direction as seen through the end ( A ) B. Be in the clockwise direction as seen through the end ( B ) c. Depend on the speed with which the two magnets are moved D. Depend on the speed with which the magnets are moved and the strengths of the magnets |
12 |

736 | A circular loop of wire is in the same place as an infinitely long wire carrying a constant current i. Four possible motion of the loop are marked by ( mathrm{N}, mathrm{E}, mathrm{W} ) and ( mathrm{S} ) as shown. A clockwise current is induced in the loop when loop is pulled towards ( A ) B. ( c cdot w ) ( D ) |
12 |

737 | Describe the construction and working of Van de graff generator making the labelled diagram. |
12 |

738 | Describe one experiment to demonstrate the phenomenon of electromagnetic induction. | 12 |

739 | If given arrangement is moving towards left with speed ( v, ) then potential difference between ( B ) and ( D ) and current in the loop are respectively. A. BvR and non-zero B. 2BvR and zero c. 4 Bv ( operatorname{R} ) and non-zer D. 4BvR and zero |
12 |

740 | Two circular loops ( P ) and ( Q ) are concentric and coplanar as shown in figure. The loop ( Q ) is smaller than ( P . ) If the current ( I_{1} ) flowing in loop is decreasing with time, then the current ( I_{2} ) in the ( operatorname{loop} Q ) A. flows in the same direction as that of ( P ) B. flows in the opposite direction as that of ( Q ) c. is zero D. None of these |
12 |

741 | A metal disc rotates freely, between the poles of a magnet in the direction indicated. Brushes ( P ) and ( Q ) make contact with the edge of the disc and the metal axle. What current, if any, flows through R? A. a current from P to Q B. a current from Q to P c. no current, because the emf in the disc is opposed by the back emf D. no current, because the emf induced in one side of the disc is opposed by the emf induced in the other side E. no current, because no radial emf is induced in the disc |
12 |

742 | Assertion The presence of large magnetic flux through a coil maintains a current in the coil if the circuit is continuous. Reason Magnetic flux is essential to maintain an Induced current 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 |
12 |

743 | The emf induced in the circuit is : ( mathbf{A} cdot 2 pi a^{2} B_{0} ) B . ( pi a^{2} B_{0} ) c. ( frac{a^{2} B_{0}}{2} ) D. ( frac{pi a^{2} B_{0}}{2} ) |
12 |

744 | A magnet is dropped free towards a loop of copper wire as shown in figure. The acceleration of magnet will be : A. Equal to g B. Greater than ( g ) c. Less than g D. zero |
12 |

745 | Two solenoids of equal number of turns having their length and the radii in the same ratio ( 1: 2 . ) The ratio of their self- inductance will be A .1: 2 B . 2: 1 c. 1: 1 D. 1: 4 |
12 |

746 | The mutual inductance of the system of two coils is ( 5 m H . ) The current in the first coil varies according to the equation ( boldsymbol{I}=boldsymbol{I}_{o} sin boldsymbol{w} boldsymbol{t} ) where ( boldsymbol{I}_{boldsymbol{o}}=mathbf{1 0} boldsymbol{A} ) and ( W=100 pi r a d / s . ) The value of maximum induced emf in the second coil is A ( .2 pi V ) в. ( pi V ) ( c .5 pi V ) D. ( 4 pi V ) |
12 |

747 | To obtain maximum EMF from a number of cells, they must be connected in A. Series B. Parallel c. Both (a) and (b) above D. None of these |
12 |

748 | Is this device feasible? A. Yes B. no C. depends on the availability of material D. maybe or may not be |
12 |

749 | netic poooooo 45. A mutual inductor consists of two coils X and Y as shown in figure in which one- quarter of the magnetic flux produced by X links with Y, giving a mutual Y inductance M. What will be the mutual inductance when Y is used as the primary? (a) M/4 (b) M/2 (c) M (d) 2M |
12 |

750 | The average induced emf in the circuit is ( mathbf{A} cdot 0.2 V ) B. ( 0.1 V ) ( mathbf{c} cdot 1 V ) D. ( 10 V ) |
12 |

751 | In figure a wire perpendicular to a long straight wire is moving parallel to the later with speed ( boldsymbol{v}=mathbf{1 0 m} / boldsymbol{s} ) in the direction of the current flowing in the later. The current is ( 10 A ). What is the magnitude of the potential difference between the ends of the moving wire? A ( cdotleft(5 times 10^{-4}right) ln (10) V ) B ( cdotleft(7 times 10^{-4}right) ln (10) V ) ( mathbf{c} cdotleft(2 times 10^{-4}right) ln (2) V ) D. ( left(2 times 10^{-5}right) ln (10) V ) |
12 |

752 | Assertion The direction of induced emf is always such as to oppose the change that causes it. Reason Conservation of energy applies to know the direction of induced emf. 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 |

753 | A circuit ( A B C D ) is held perpendicular to the uniform magnetic field of ( boldsymbol{B}= ) ( 5 times 10^{-2} T ) extending over the region ( P Q R S ) and directed into the plane of the paper. The circuit is moving out of the field at a uniform speed of ( 0.2 m s^{-1} ) for ( 1.5 s . ) During this time, the current in the ( 5 Omega ) resistor is ( mathbf{A} cdot 0.6 m A ) from ( B ) to ( C ) B. ( 0.9 m A ) from ( B ) to ( C ) c. ( 0.9 m A ) from ( C ) and ( B ) D. ( 0.6 m A ) from ( C ) to ( B ) E. ( 0.8 m A ) from ( C ) to ( B ) |
12 |

754 | A cylindrical bar magnet is lying along the axis of a circular coil. If the magnet is rotated about the axis of the coil then A. emf will be induced in the coil B. only induced current will be generate in the coil c. no current will be induced in the coil D. both emf and current will be induced in the coil |
12 |

755 | An aircraft having a wingspan of ( 20.48 m ) flies due north at a speed of ( 40 m s^{-1} . ) If the vertical component of earth’s magnetic field at the place is ( 2 times 10^{-5} T, ) calculate the emf induced between the ends of the wings. |
12 |

756 | The value of time when the current reverse its sign for the first time will be A. T/2 B. T/4 c. ( T / 6 ) D. ( T / 8 ) |
12 |

757 | the self inductance of the primary coil. | 12 |

758 | A coil having ( n ) turns and resistance ( boldsymbol{R} ) ( Omega ) is connected with a galvanometer of resistance ( 4 R Omega ). This combination is moved in time ( t ) seconds from a magnetic flux ( W_{1} ) to ( W_{2} ). The induced current in the circuit is A. ( -frac{W_{2}-W_{1}}{5 R n t} ) в. ( frac{nleft(W_{2}-W_{1}right)}{5 R t} ) c. ( -frac{left(W_{2}-W_{1}right)}{R n t} ) D. ( -frac{nleft(W_{2}-W_{1}right)}{R n t} ) |
12 |

759 | A magnet is dropped freely towards a loop of copper wire as shown in figure. The acceleration of magnet will be: A. equal to 9 B. greater than gless than ( g ) c. less than ( g ) D. zero |
12 |

760 | A conducting rod is moved with a constant velocity ( v ) in a magnetic field. A potential difference appears across the two ends ( mathbf{A} cdot ) if ( vec{v} | vec{l} ) B. if ( vec{v} | vec{B} ) c. if ( vec{l} mid vec{B} ) D. none of these |
12 |

761 | TU) 1 MTC , 1 W1lPold The graph shows the variation in magnetic flux o(t) with time through a coil. Which of the statements given below is not correct? (a) There is a change in the direction as well as magnitude of the induced emf between B and D (b) The magnitude of the induced emf is maximum between B and C (c) There is a change in the direction as well as magnitude of induced emf between A and C (d) The induced emf is zero at B |
12 |

762 | When a rod of magnetic material size ( 10 c m times 0.5 c m times 0.2 c m ) is located in magentic field of ( 0.5 times 10^{4} mathrm{A} / mathrm{m} ) then ( mathrm{a} ) magnetic moment of ( 5 A m^{2} ) is induced in it. Find out magnetic induction in rod. |
12 |

763 | A magnet is moved towards a coil, first quickly and then slowly. The induced e.m.f. produced is: A. Larger in first case B. Smaller in first case C. Equal in both cases D. Larger or smaller, depending upon resistance of the coil |
12 |

764 | Assertion Lenz’s law violates the principle of conservation of energy. Reason Induced emf always opposes the change in magnetic flux responsible for its production. 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 |

765 | 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 ( cdot frac{2 b}{v} ) B. ( frac{2 a}{v} ) c. ( frac{(a+b)}{v} ) D. ( frac{2(a-b)}{v} ) |
12 |

766 | Q Type your question uniformly distributed over its circumference is hanging by an insulated thread with the help of a small smooth ring (not rigidly fixed with bigger ring). A time varying magnetic field ( B=B_{0} sin omega t ) is switched on at ( t=0 ) and the ring is released at the same time. The induced EMF in loop at time ( t=2 pi / omega ) is: A . 0 в. ( frac{B_{0} pi omega R^{2}}{2} ) ( mathbf{c} cdot B_{0} pi omega R^{2} ) D. ( -frac{B_{0} pi omega R^{2}}{2} ) |
12 |

767 | ( = ) 0 0 0 |
12 |

768 | Two Circular cells can be arranged in any of the three following situations as shown in figure. Their mutual inductance will be Maximum in which arrangement ? ( A cdot(A) ) B. (B) ( c cdot(c) ) D. Same in all conditions |
12 |

769 | Generators uses the principle of to push electrons through a wire. A. electromagnetic induction B. electromagnetic reduction c. magnetoelectric conduction D. electric induction E. magnetic field contraction |
12 |

770 | The conductor ( A D ) moves to the right in a uniform magnetic field directed into the plane of the paper. This question has multiple correct options A. The free electron in ( A D ) will move toward ( A ) B. Dd will acquire a positive potential with respect to c. ( A ) current will flow from ( A ) to ( D ) in ( A D ) in closed loop D. The current in ( A D ) flows from lower to higher potential E. answer required |
12 |

771 | toppr ( t ) Q Type your question shown in figure. The graph of magnitude of induced emf in the coil is represented by ( A ) B. ( c ) D. |
12 |

772 | For the situation shown in the figure, flux through the square loop is ( mathbf{A} cdotleft(frac{mu_{0} i a}{2 pi}right) ln left(frac{a}{2 a-b}right) ) B ( cdotleft(frac{mu_{0} i b}{2 pi}right) ln left(frac{a}{2 b-b}right) ) ( left(frac{mu_{0} i b}{2 pi}right) ln left(frac{a}{b-a}right) ) ( left(frac{mu_{0} i a}{2 pi}right) ln left(frac{2 a}{b-a}right) ) |
12 |

773 | A coil having 200 turns has a surface area of ( 0.15 m^{2} . ) A magnetic field of strength ( 0.2 T ) applied perpendicular to this changes to ( 0.6 mathrm{T} ) in ( 0.4 mathrm{s} ), then the induced emf in the coil is A . 45 B. 30 c. 15 D. 60 |
12 |

774 | A square loop of side length ( a ) having ( n ) turns is kept in a horizontal plane. ( mathbf{A} ) uniform magnetic field ( B ) exists in vertical direction as shown in figure. Now, the loop is rotated with constant angular speed ( omega ) as shown below. Which of the following statement is correct? ( begin{array}{llllll}mathbf{X} & mathbf{X} & mathbf{X} & mathbf{X} & mathbf{X} & mathbf{X}end{array} ) ( mathbf{x} quad mathbf{x} quad mathbf{x} quad mathbf{x} quad mathbf{x} quad mathbf{x} quad mathbf{x} ) A. Same emf is induced in both cases (i) and (ii) B. Maximum emf is induced in case (i) c. Emf induced in case (ii) is more than (i) D. No emf induced in case (ii) |
12 |

775 | Electric charge is uniformly distributed along a long straight wire of a radius of 1 mm. The Charge per cm length of the wire is Q coulomb. Another cylindrical surface of radius ( 50 mathrm{cm} ) and length ( 1 mathrm{m} ) symmetrically encloses the wire as shown in fig. The total flux passing through the cylindrical surface is A ( cdot frac{Q}{epsilon_{0}} ) в. ( frac{100 Q}{epsilon_{0}} ) c. ( frac{10 Q}{pi epsilon_{0}} ) D. ( frac{100 Q}{pi epsilon_{0}} ) |
12 |

776 | When the current through the electromagnet of a relay reaches a particular value A. It breaks the circuit B. It open the circuit by pulling in an iron contact c. It closes the circuit by pulling in an iron contact D. Both A or C |
12 |

777 | In a coil of area ( 10 mathrm{cm}^{2} ) and 10 turns with magnetic field directed perpendicular to the plane and is changing at the rate of ( 10^{8} ) Gauss/second. The resistance of the coil is ( 20 Omega ). The current in the coil will be A. ( 0.5 mathrm{A} ) B. 5A ( c . ) 50 A D . ( 5 times 10^{8} A ) |
12 |

778 | Assertion: The induced emf and current will be same in two identical loops of copper and aluminium, when rotated with same speed in the same magnetic field. Reason: Mutual induction does not depend on the orientation of the coils. A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion c. Assertion is true but Reason is false D. Assertion and Reason both are false |
12 |

779 | The self inductance of a straight conductor is. A. zero B. Infinity c. Very large D. Very small |
12 |

780 | State Flemings right hand rule. For what purpose is it used? | 12 |

781 | X X X 13. A conducting wire frame is placed in a magnetic fiel which is directed into the plane of the paper (figure). Th magnetic field is increasing at a constant rate. The directions of induced currents in wires AB and X CD are (a) B to A and D to C (b) A to B and C to D x x x xь x (c) A to B and D to C (d) B to A and C to D 14. An equilateral triangular loop ADC having some resistance X xxxxx xВx xx X Y X |
12 |

782 | Two identical inductance carry currents that vary with time according to linear laws (as shown in figure). In which of two inductance is the self induction emf greater? ( A ) B. 2 ( c . ) same D. data are insufficient to decide |
12 |

783 | Whenever, current is changed in a coil, an induced e.m.f. is produced in the same coil. This property of the coil is due to A. mutual induction B. eddy currents c. self induction D. hysteresis |
12 |

784 | Two concentric and coplanar circular coils have radii ( a ) and ( b(>>a) ) as shown in figure. Resistance of the inner coil is ( R ) Current in the outer coil is increased from 0 to ( i ), then find the total charge circulating the inner coil : ( ^{text {A }} cdot frac{mu_{0} pi a^{2} i}{2 R b} ) в. ( frac{2 mu_{0} pi a^{2}}{2 R b} ) c. ( frac{mu_{0} pi a^{2} i}{4 R b} ) D. ( frac{mu_{0} pi a^{3} i}{4 R b} ) |
12 |

785 | toppr Q Type your question capacitor ( C ) as shown in the figure. Magnetic field ( B ) is into the plane. Consider the following statements: (i) Current in loop ( boldsymbol{A} boldsymbol{E} boldsymbol{F} boldsymbol{B} boldsymbol{A} ) is anticlockwise. (ii) Current in loop ( boldsymbol{A} boldsymbol{E} boldsymbol{F} boldsymbol{B} boldsymbol{A} ) is clockwise (iii) Current through the capacitor is zero. (iv) Energy stored in the capacitor is ( frac{1}{2} C B^{2} L^{2} V^{2} ) Which if the following options is correct? A. Statements (i) and (iii) are correct B. Statements (ii) and (iv) are correct c. Statements (i), (iii) and (iv) are correct D. None of these |
12 |

786 | Write a short note on: 1. Armature coil 2. Brushes 3. Commutator 4. Direct current |
12 |

787 | A flat coil, ( C ) of ( n ) turn, area ( A ) and resistance ( R ), is placed in a uniform magnetic field of magnitude ( B ). The plane of the coil is initially perpendicular to ( B ). The coil is rotated by an angle ( theta ) about a diameter and charge of amount ( Q ) flows through it. Choose the correct alternatives. This question has multiple correct options A ( cdot theta=90^{circ}, Q=(B A n / R) ) B . ( theta=180^{circ}, Q=(2 B A n / R) ) c. ( theta=180^{circ}, Q=0 ) |
12 |

788 | Fill in the blank. Electromagnetic induction occurs in a wire when a change occurs in in wire. A . current B. intensity of the electric field C . voltage applied D. magnetic field intensity applied E. resistance added to the wire |
12 |

789 | The phenomenon in which an emf is induced in a conductor kept just by the side of another conductor through which varying current is passed is called A. Magnetic effect B. Electromagnetic induction c. Photoelectric effect D. Mechanical effect |
12 |

790 | A circular metal plate of radius ( boldsymbol{R} ) is rotating with a uniform angular velocity ( omega ) with its plane perpendicular to a uniform magnetic field ( B ). Then the emf developed between the centre and the rim of the plate is A ( cdot pi omega B R^{2} ) B. ( omega B R^{2} ) ( mathbf{c} cdot pi omega B R^{2} / 2 ) D. ( omega B R^{2} / 2 ) |
12 |

791 | A long solenoid having 200 turns per ( mathrm{cm} ) carries a current of ( 1.5 a m p . ) At the centre of it is placed a coil of 100 turns of cross-sectional are ( 3.14 times 10^{-4} m^{2} ) having its axis parallel to the field produced by the solenoid. When the direction of current in the solenoid is reversed within 0.05 sec, the induced e.m.f. in the coil is A. ( 0.48 V ) в. ( 0.048 V ) ( begin{array}{ll}.0 .0048 V & V \ V V & 0.088end{array} ) D. ( 48 V ) |
12 |

792 | Two conducting rings of radii r and ( 2 r ) move in opposite directions with velocities ( 2 v ) and ( v ) respectively on a conducting surfaces S. There is a uniform magnetic field of magnitude B perpendicular to the plane of the rings. The potential difference between the highest points of the two rings is? ( A cdot ) zero B. 2rvB c. 4 rv ( B ) D. 8rvB |
12 |

793 | The magnetic flux through a circuit of resistance R changes by an amount ( Delta phi ) in time ( Delta t . ) Then the total quantity of electric charges ( Q ) that passes any point in the circuit during the time ( Delta t ) is represented by: A ( cdot Q=frac{Delta phi}{R} ) в. ( Q=frac{Delta phi}{Delta t} ) c. ( Q=R cdot frac{Delta phi}{Delta t} ) D. ( Q=frac{1}{R} cdot frac{Delta phi}{Delta t} ) |
12 |

794 | The emf of a genetator is 12 V and its internal resistance is 1 K( Omega .0 mathrm{m} ) measuring its emf with a voltmeter of ( 5 K Omega ) the reading will be:- A . ( 10 v ) B. 10 milli v c. 1 milliv ( D cdot 1 v ) |
12 |

795 | The diagram below show a coil connected to a centre zero galvanometer ( G . ) The galvanometer shows a deflection to the right when the ( N ) -pole of a powerful magnet is moved to the right as shown. Does the direction of the current in the coil appear clockwise or anticlockwise viewed from this end ( A ? ) A. The direction of induced current at end ( A ) is anti clockwise B. The direction of induced current at end ( A ) is clockwise c. The direction of induced current at end ( A ) is firsts clockwise and then anticlockwise D. The direction of induced current at end ( A ) cannot be determined |
12 |

796 | The coefficient of self induction of two inductor coils are ( 20 m H ) and ( 40 m H ) respectively. If the coils are connected in series so as to support each other and the resultant inductance is ( 80 m H ) then the value of mutual inductance between the coils will be ( mathbf{A} cdot 5 m H ) в. ( 10 m H ) c. ( 20 m H ) D. ( 40 m H ) |
12 |

797 | The law of electromagnetic induction has been used in the construction of A. Generator B. Electric motor c. Galvanometer D. None of these |
12 |

798 | Show the variation of the emf generated versus time as the armature is rotated with respect to the direction of the magnetic field. |
12 |

799 | Starter is used in A. high power electric motors B. low power electric motors C. transformers D. galvanometer |
12 |

800 | An electromagnetic wave has energy in the form of A. variable electric field B. variable magnetic field c. both A and B D. none of the above |
12 |

801 | The coefficients of self induction of two inductance coils arc ( 0.01 mathrm{H} ) and ( 0.03 mathrm{H} ) respectively. When they are connected in series so as to support each other then the resultant self inductance becomes 0.06 Henry. The value of coefficient of mutual induction will be- A . ( 0.02 mathrm{H} ) B. 0.05 c. ( 0.01 mathrm{H} ) D. ZERO |
12 |

802 | A circular loop of radius ( r, ) having ( N ) turns of a wire, is placed in a uniform and constant magnetic field ( boldsymbol{B} ). The normal loop makes an angle ( theta ) with the magnetic field. Its normal rotates with an angular velocity ( omega ) such that the angle ( theta ) is constant. Choose the correct statement from the following. This question has multiple correct options A . emf in the loop is ( N B omega r^{2} / 2 cos theta ) B. emf induced in the loop is zero c. emf must be induced as the loop crosses magnetic lines D. emf must not be induced as flux does not change with time E. answer required |
12 |

803 | A straight wire with a resistance of ( r ) per unit length is bent to form an angle 2 ( alpha ). A rod of the same wire perpendicular to the angle bisector (of ( 2 alpha) ) forms a closed triangular loop. This loop is placed in a uniform magnetic field of a induction ( B ). Calculate the current in the wires when the rod moves at a constant speed ( V ) |
12 |

804 | An average emf of ( 20 mathrm{V} ) is induced in an inductor when the current in it is changed from ( 2.5 A ) in one direction to the same value in the opposite direction in 0.1 s. The self-inuctance of the inductor is A . zero в. ( 0.2 H ) ( c .0 .4 H ) D. ( 1 H ) |
12 |

805 | 33. In the circuit shown in figure, a A H conducting wire HE is moved with a constant speed y toward R V >=0 left. The complete circuit is placed in a uniform magnetic field B perpendicular to the plane of the circuit inward. The current in HKDE is (a) clockwise (b) anticlock wise (c) alternating (d) zero |
12 |

806 | Which rule gives the direction of induced current due to electromagnetic induction? A. Fleming’s left hand rule B. Maxwell’s left hand rule c. Ampere’s rule D. Fleming’s right hand rule |
12 |

807 | The flux of magnetic field through closed conducting loop of resistance 0.4 Whanges with time according to the equation ( phi=0.20 t^{2}+0.40 t+0.60 ) where is time in seconds. Find (i) the induced emf at ( t=2 s . ) (ii) the average induced emf in ( t=0 ) to ( t=5 ) s. (iii) change passed through the loop in ( t=0 ) to ( t=5 s . ) (iv) average current in time interval ( t=0 ) to ( t=5 s ) (v) heat produced in ( t=0 ) to ( t=5 s ) |
12 |

808 | A long wire carries a current ( i . ) A rod of length ( l ) is moved with a velocity ( v ) in a direction parallel to the wire as shown in figure (a). Find the motional emf induced in the rod: A ( cdot frac{mu_{0} i}{2 pi x} l v ) В ( cdot frac{mu_{0} i}{2 pi} v log _{e} frac{x+l / 2}{x-l / 2} ) C ( frac{mu_{0} i}{2 pi} v log _{e} frac{x-l / 2}{x+l / 2} ) D. ( frac{mu_{0} i v}{2 pi} log _{e} frac{l+x}{x} ) |
12 |

809 | No. of magnetic lines of force present per unit volume is called A. Magnetic flux B. Magnetic line of force c. Magnetic Induction D. None of these |
12 |

810 | The current produced in a closed coil, where magnetic lines of force rapidly change within it is called: A. direct current B. alternating current c. induced current D. none of these |
12 |

811 | Two coils ( A ) and ( B ) have mutual inductance ( 2 times 10^{-2} ) henry. If the current in the primary is ( i= ) ( 5 sin (10 pi t) ) then the maximum value of e.m.f. induced in coil ( B ) is ( mathbf{A} cdot pi ) volt в. ( frac{pi}{2} ) volt c. ( frac{pi}{3} ) volt D. ( frac{pi}{4} ) volt |
12 |

812 | The device used for producing electric current is called a: A. generator. B. galvanometer. c. ammeter. D. motor |
12 |

813 | A jet plane is travelling towards west at a speed of ( 1800 mathrm{km} / mathrm{h} ). What is the voltage difference developed between the ends of the wing having a span of ( 25 m, ) if the Earth’s magnetic field at the location has a magnitude of ( 5 times ) ( 10^{-4} T ) and the dip angle is ( 30^{circ} ) ( begin{array}{ll}text { A } & text { 0.31 }end{array} ) в. 3.1 ( c cdot 5 v ) D. 10 |
12 |

814 | Two coils have mutual inductance ( 0.005 H . ) The current changes in the form coil according to equation, ( boldsymbol{I}= ) ( I_{0} sin omega t . ) Where ( I_{0}=10 A . ) and ( omega= ) ( 100 pi ) rads/s. The maximum value of emf in the second coil is : A . ( 12 pi ) B. ( 8 pi ) ( c .5 pi ) D. ( 2 pi ) |
12 |

815 | Principle behind the working of electric generator? A. When a conductor is moved in a magnetic field then voltage is induced in the conductor B. When a conductor is moved in a magnetic field then current is induced in the conductor ( c cdot ) both D. none |
12 |

816 | The length of side of a square coil is 50 ( mathrm{cm} ) and number of turns in it is ( 100 . ) If it is placed at right angles to a magnetic field which is changing at the rate of 4 Tesla/s, then induced emf in the coil will be: A . ( 0.1 mathrm{v} ) B. 1.0 ( c cdot 10 v ) D. 100 |
12 |

817 | The equivalent inductance of two inductor is ( 2.4 m H ) when connected in parallel and ( 10 m H ) when connected in series. The difference between two inductance is (neglecting mutual induction between coils) ( mathbf{A} cdot 3 m H ) в. ( 2 m H ) ( mathrm{c} .4 mathrm{mH} ) D. ( 16 m H ) |
12 |

818 | s nucuct length ( L=2 m, ) and a resistance ( r= ) ( 10 Omega ) is moving with velocity ( v= ) ( (2 m / s) hat{i} . ) Three mutually perpendicular sides are parallel to ( x, y ) and ( z ) axis as shown in figure. The corner A lies at origin at ( t=0 . ) There is a magnetic field in the region ( (mathbf{0} leq boldsymbol{x} leq boldsymbol{L}) ) is ( overrightarrow{boldsymbol{B}}= ) ( (-5 hat{k}) T ) and ( B=0, ) otherwise. Which of the following is correct? A. current through ( b c ) is ( 2 A ) at ( t=0.25 s ) B. current through ( f g ) is ( 1 A ) at ( t=0.25 s ) C. potential difference across ( g h ) is ( 20 V ) at ( t=0.25 s ) D. potential difference across ( d h ) is ( 5 V ) at ( t=0.25 s ) E. potential difference across ( d h ) is ( 10 V ) at ( t=0.25 ) |
12 |

819 | x x В x 9. A conducting U-tube can A x x x slide inside another as shown X in the figure maintaining electrical contacts between X the tubes. The magnetic field X B is perpendicular to the B X X Y C plane of the figure. If each tube moves towards the other at a constant speed v, then the emf induced in the circuit in terms of B, 1, and v, where I is the width of each tube, will be (a) 2Bly (b) zero (c) – Blv (d) Blv (AIEEE 2005) 10 The calf indiretonne of the motor of an electrin fon in |
12 |

820 | As shown in the figure, a rectangular loop of a conducting wire is moving away with a constant velocity ‘v’ in a perpendicular direction from a very long straight conductor a steady conductor carrying a steady current ‘I’. When the breadth of the rectangular loop is very small compared to its distance from the straight conductor. ( A ) [ E propto frac{1}{t^{2}} ] в. ( quad E propto frac{1}{t} ) c. ( E propto ln (t) ) D. [ E propto frac{1}{t^{3}} ] |
12 |

821 | A conductor is moved in a varying magnetic field. Name the law which determines the direction of current induced in the conductor: A. Fleming’s right hand rule B. Mohr’s right hand rule c. Fleming’s left hand rule D. Mohr’s left hand rule |
12 |

822 | Define the term ‘self-inductance’ of a coil. Write its S.I. unit. |
12 |

823 | A rectangular coil having 60 turns and area of ( 0.4 m^{2} ) is held at right angles to a uniform magnetic field of flux density ( mathbf{5} times mathbf{1 0}^{-5} mathbf{T} . ) Calculate the magnetic flux passing through it. |
12 |

824 | A circular copper disc ( 10 mathrm{cm} ) in diameter rotates at 1800 revolution per minute about an axis through its centre and at right angles to disc. A uniform field of induction ( B ) of 1 Wh ( m^{2} ) is perpendicular to disc. What potential difference is developed between the axis of the disc and the rim? A. 0.023 v v vas B. 0.23 ( c cdot 23 v ) D. 230 V |
12 |

825 | What is the working principle of generator? A. Attractive property of magnets. B. Conductors carrying current behave like magnets. C. Electromagnetic induction. D. none of the above |
12 |

826 | Comment on the statement given below: In self-induction When the current in a coil is increasing, induced emf opposes it |
12 |

827 | When the number of turns in a solenoid is doubled without any change in the length of the solenoid, its selfinductance becomes: A . Half B. Double c. Four times D. Eight times |
12 |

828 | toppr Q туре your question perpendicular to the plane of the triangle. The base of the triangle AB has a resistance ( 1 Omega ) while the other two sides have resistance ( 2 Omega ) each. The magnitude of potential difference between the points ( A ) and ( B ) will be ( 4 cdot 0.4 ) ( (mathrm{A}) ) 8. 0.6 v ( (mathrm{B}) ) c. ( 1.2 v ) ( (C) ) D. Non ( (mathrm{D}) ) |
12 |

829 | The figure shows a particle ( carrying change ( +q ) ) at the origin. A uniform magnetic field is directed into the plane of the paper. The particle can be projected only in the plane of paper and along positive or negative ( x ) -or ( y ) -axis. The particle moves with constant speed and has to hit target located in the third quadrant. There are two direction of projections, which can make it possible, these are then ( A cdot+x ) and ( +y ) B. ( +x ) and ( -y ) ( c .-x ) and ( +y ) D. – x and – y |
12 |

830 | 38. A thin non-conducting ring of mass m carrying a charge Q can freely rotate about its axis. Initially, the ring is rest and no magnetic field is present. Then a uniform field of magnetic induction was switched on, which was perpendicular to the plane of the ring and increased with time as a given function B(t). The angular velocity o(t) of the ring as a function of the field B(t) will be given by (a) 0(t) = 9B(t) (b) m(t) = qB(t) m 2m (c) (t) = 9B(1) (d) 0=0 2nm 30 Anomf coco |
12 |

831 | A dynamo dissipate 25 W when it supplies a current of 5 A through it. If the potential difference is 220 ( v, ) then the emf produced is A. ( 210 V ) B. ( 225 V ) ( mathbf{c} cdot 230 V ) D. ( 235 V ) |
12 |

832 | An emf can be induced between the two ends of straight copper wire when it is moved through a uniform magnetic field. A. True B. False |
12 |

833 | A solenoid of 500 turns, diameter ( 20 c m ) and resistance ( 2 Omega ) is rotated about its vertical diameter through ( pi ) radian in ( 1 / 4 ) s, when a horizontal field of ( 3 x ) ( 10^{-5} T ) acts normal to its plane. Find the emf induced and current thereof |
12 |

834 | The induced EMF in loop at time ( t= ) ( 2 pi / omega ) is : ( A cdot O ) B. ( frac{B_{0} pi omega R^{2}}{2} ) ( mathbf{c} cdot B_{0} pi omega R^{2} ) D. ( -frac{B_{0} pi omega R^{2}}{2} ) |
12 |

835 | A coil is needed to operate an arc lamp of ( 150 mathrm{V}, 50 mathrm{Hz} ). The lamp of resistance of 5 ohms when running at 10 A. Find inductance of the choke coil, if the same arc lamp is to be operated on 160 V, DC. What is the additional resistance required? A . ( 5 Omega ) B. ( 4.5 Omega ) c. ( 5.5 Omega ) D. 2.5Omega |
12 |

836 | uan 10. A plane loop, shaped as two squares of sides a = 1 m and b=0.4 m is introduced into a uniform magnetic field I to the plane of loop (figure). The magnetic field varies as B= 10-sin(100t) T. The amplitude of the current induced in the loop if its resistance per unit length is r= 5 m 2 m is (a) 2 A (b) 3A (c) 4A (d) 5 A 11. A long conducting wire AH is moved over a conductina |
12 |

837 | Magnetic flux during time interval ( tau ) varies through a stationary loop of resistance ( boldsymbol{R}, ) as ( boldsymbol{phi}_{boldsymbol{B}}=boldsymbol{a} boldsymbol{t}(boldsymbol{tau}-boldsymbol{t}) . ) Find the amount of heat generated during that time. Neglect the inductance of the loop. ( ^{text {A }} cdot frac{a^{2} tau^{3}}{R} ) в. ( frac{a^{2} tau^{2}}{2 R} ) c. ( frac{a^{2} tau^{3}}{3 R} ) D. ( frac{a^{2} tau^{3}}{4 R} ) |
12 |

838 | The induced emf produced when a magnet is inserted into a coil does not depend upon: A. The number of turns in the coil B. The resistance of the coil D. All the above |
12 |

839 | An induced e.m.f. is produced when a magnet is plunged into a coil. The strength of the induced e.m.f. is independent of A. the strength of the magnet B. number of turns of coil c. the resistivity of the wire of the coil D. speed with which the magnet is moved |
12 |

840 | The magnetic flux density ( B ) is changing in magnitude at a constant rate ( d B / d t . ) A given mass ( m ) of copper drawn into a wire of radius ( a ) and formed into a circular loop of radius ( r ) is placed perpendicular to the field ( B ). The induced current in the loop is ( i . ) The resistivity of copper is ( rho ) and density is d. The value of the induced current ( i ) is ( ^{mathbf{A}} cdot frac{m}{2 pi rho d} frac{d B}{d t} ) В. ( frac{m}{2 pi a^{2} d} frac{d B}{d t} ) c. ( frac{m}{4 pi a d} frac{d B}{d t} ) D. ( frac{m}{4 pi rho d} frac{d B}{d t} ) |
12 |

841 | Some physical quantities are given in list 1. The related units are given in list 2. Match the correct pairs List 1 List 2 a) Magnetic Field Intensity ( W b m^{-1} ) e) ) Magnetic Flux f) ( W b m^{-2} ) b) c Potential Magnetic ( W b ) c) g) h) ( A m^{-1} ) d) Magnetic Induction A. ( a-e, b-f, c-g, d-h ) B. a-h, b-g, c-e, d-f c. a-h, b-e, c-g, d-f D. a-f, b-g, c-e, d-h |
12 |

842 | The induced emf in the smaller loop is ( A ) B. ( ^{mathbf{c}} cdot frac{_{3 mu_{0} pi i} R^{2} r_{r}^{2}}{2} ) ( D ) E . none |
12 |

843 | A circular disc of radius 0.2 meter is placed in a uniform magnetic field of induction ( frac{1}{pi}left(W b / m^{2}right) ) in such way that its axis makes an angle of ( 60^{circ} ) with ( vec{B} ). The magnetic flux linked with the disc is A. ( 0.08 mathrm{wb} ) B. 0.01 Wb c. ( 0.02 mathrm{wb} ) D. ( 0.06 mathrm{wb} ) |
12 |

844 | Two coils have a mutual inductance ( 0.005 H . ) The current changes in the first coil according to the equation ( i= ) ( i_{m} sin omega t ) where ( i_{m}=10 A ) and ( omega= ) ( 100 pi ) rad ( s^{-1} . ) The maximum value of the emf induced in the second coil is A ( .2 pi ) в. ( 5 pi ) c. ( pi ) D. ( 4 pi ) |
12 |

845 | The coefficient of mutual inductance between two coils depends on A. medium between the coils B. separation between the two coils c. orientation of the two coils D. all of the above |
12 |

846 | A metal conductor of length ( 1 mathrm{m} ) rotates vertically about one of its ends at angular velocity 5 radians per second. If the horizontal component of earth’s magnetic field is ( 0.2 times 10^{-4} T ), then the e.m.f developed between the two ends of the conductor is ( A cdot 5 m v ) B. ( 50 mu V ) c. ( 5 mu V ) D. 50 mv |
12 |

847 | Back emf of a cell is due to A. Electrolytic polarization B. Peltier effect c. Magnetic effect of current D. Internal resistance |
12 |

848 | A magnet is allowed to fall through a copper circular wire. Then during fall: A. the electric current flows through the wire B. the acceleration of magnet is less than gravitational acceleration c. the acceleration of magnet is equal to gravitational acceleration D. the acceleration of magnet is greater than gravitational acceleration |
12 |

849 | The armature of a dc motor has ( 15 Omega ) resistance. It draws a current of ( 1.6 mathrm{A} ) when run by 220 V de supply. The value of back emf will be: A. 24 B. ( 196 v ) c. ( 220 v ) D. 244 V |
12 |

850 | If a magnetic field ( B ) points in the positive x direction, what is the magnitude of the emf developed in the wire when ( B ) increases at the rate of ( 3 m ) ( boldsymbol{T} boldsymbol{s}^{-1} ? ) |
12 |

851 | What does the negative sign indicate in Lenz’s law? | 12 |

852 | In the circuit shown here,cells ( A ) and ( B ) have emf ( 10 V ) each and the internal resistance is ( 5 Omega ) for ( A ) and ( 3 Omega ) for ( B ). For what value of ( R ) will the potential difference across the cell A will be zero? A . 0 B. 1 ohm c. 2 ohm D. 3 ohm |
12 |

853 | A magnetic flux of ( 500 mu W b ) passing through a 200 turns coil is reversed in ( 20 times 10^{-3} ) seconds. The average emf per unit area induced in the coil in ( V / m^{2} ) is A . 2.5 B. 5.0 ( c .7 .5 ) D. 10.0 |
12 |

854 | State one point of similarity and one point of difference between an A.C. generator ans a D.C. motor. | 12 |

855 | Dynamos is a device that A. reduces electric power B. generates electricity c. step down the voltage D. the voltage |
12 |

856 | A vertical ring of radius ( r ) and resistance ( boldsymbol{R} ) falls vertically. lt is in contact with two vertical rails which are joined at the top. The rails are without friction and resistance. There is a horizontal uniform magnetic field of magnitude ( B ) perpendicular to the plane of the ring and the rails. When the speed of the ring is ( v, ) the current in the top horizontal of the rail section is A . 0 B. ( frac{2 B r v}{R} ) ( ^{mathrm{c}} cdot frac{4 B r v}{R} ) D. ( frac{8 B r v}{R} ) |
12 |

857 | A current of 1 A through a coil of inductance of ( 200 mathrm{mH} ) is increasing at a rate of ( 0.5 mathrm{A} s^{-1} ). The energy stored in the inductor per second is then A. 0.5 J ( s^{-1} ) B. 5.0 Js ( ^{-1} ) c. ( 0.1 mathrm{Js}^{-1} ) D. 2.0 Js ( ^{-1} ) |
12 |

858 | op ( Q ) туре your question generated across the coil during on eycle is |
12 |

859 | The value of magnetic field induction which is uniform, is 2T. What is the flux passing through a surface of area ( 1.5 m^{2} ) perpendicular to the field. A. 3 Tesla В ( cdot 1 W b / m^{2} ) c. 2 Tesla D. None |
12 |

860 | An electron moves on a straight line path XY as shown. The abcd is a coil adjacent to the path of electron. What will be the direction of current, if any, induced in the coil? A. No current induced B. abcd ( c cdot ) adcb D. The current will reverse its direction as the electron goes past the |
12 |

861 | A helicopter rises vertically with a speed of ( 100 mathrm{m} / mathrm{s} ). If helicopter has length ( 10 mathrm{m} ) and horizontal component of earth’s magnetic field is ( 5 times ) ( 10^{-3} W b / m^{2}, ) then the induced emf between the tip of nose and tail of helicopter is: A. ( 50 v ) B. 0.5 ( v ) ( c cdot 5 v ) D. 25 V |
12 |

862 | Which rule determines the direction of current induced in a coil due to the rotation in a magnetic field. A. Maxwell right hand grip rule B. Fleming’s left hand rule c. Fleming’s right hand rule D. None |
12 |

863 | An emf of 100 millivolts is induced in a coil when the current in another nearby coil becomes ( 10 A ) from zero to 0.1 sec The corfficient of mutual induction between the two coils will be ( mathbf{A} cdot 1 m H ) в. ( 10 mathrm{mH} ) c. ( 100 mathrm{mH} ) D. ( 1000 m H ) |
12 |

864 | Figure shows a rectangular conductor PQRS in which the Conductor PQ is free to move in a uniform magnetic field perpendicular to the plane of the paper. The filed extends from ( x=0 ) to ( x=b ) and is zero for ( x>b ). Assume that only the arm PQ possesses resistance r. when the ( operatorname{arm} ) PQ is pulled outward from ( x=0 ) to ( x=2 b ) and is then moved back to ( x=0 ) with constant speed ( v, ) Determine the expression for the flux and induced emf Sketch the variations of these quantities with distance ( 0 leq x leq 2 b ) |
12 |

865 | A conducting loop in the form of a circle is placed in a uniform magnetic field with its plane perpendicular to the direction of the field. An e.m.f. will be induced in the loop if This question has multiple correct options A . I is translated parallel to itself B. It is rotated about one of its diameters. c. It is rotated about its own axis which is parallel to the field D. The loop is deformed from the original shape |
12 |

866 | A conducting circular loop is placed in a uniform magnetic field, ( B=.025 ) T with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of ( 1 mathrm{mm} ) s1. The induced e.m.f. when the radius is ( 2 mathrm{cm} ), is ( A cdot 2 mu V ) в. ( 2 pi mu V ) ( c . pi mu V ) D ( cdot frac{pi}{2} mu V ) |
12 |

867 | The figure shows a part of an electric circuit. The wires ( A B, C D ) and ( E F ) are long and have identical resistances. The separation between the neighboring wires is ( 1.0 mathrm{cm} ). The wires EA and BF have negligible resistance and the ammeter reads 30 A. Calculate the magnetic force per unit length on ( A B ) and ( C D ) |
12 |

868 | A closed circuit consists of a resistor ( boldsymbol{R} ) inductor of inductance ( L ) and a source of emf ( boldsymbol{E} ) are connected in series. If the inductance of the coil is abruptly decreased to ( L / 4 ) (by removing its magnetic core), the new current immediately after this moment is : (before decreasing the inductance the circuit is in steady state) A. Zero B. ( frac{E}{R} ) ( c cdot 4 frac{E}{R} ) D. ( frac{E}{4 B} ) |
12 |

869 | Read the following statements and answer whether the given statement is true or false. Lenz’s law is used to find out the magnitude of the induced e.m.f. A. True B. False |
12 |

870 | The rate of change of magnetic flux density through a circular coil of area 10 ( mathrm{m} ) and number of turns 100 is ( 10^{3} mathrm{Wb} / mathrm{m} ) 2 /s. The value of induced emf will be ( A cdot 10^{-2} v ) B. ( 10^{-3} v ) ( c cdot 10 v ) ( D cdot 10^{6} v ) |
12 |

871 | 8. A square loop of side 5 cm enters a magnetic field with 1 cms-1. The front edge enters the magnetic field at t=0 then which graph best depicts emf 5 cm * * * * * * B=0.6T 20 cm – 3×10 0 5 15 20 – 3×10 20 t(s) 0 5 3 x 10 (c) 15 2015) 3 x 10 (d) 15 20t(s) ol |
12 |

872 | The phenomenon of electromagnetic induction was discovered by A . Lenz B. Maxwell c. Fleming D. Faraday |
12 |

873 | Two conducting rings of radii r and 2 r move in opposite directions with velocities ( 2 v ) and ( v ) respectively on a conducting surface ( S ). There is a uniform magnetic field of magnitude ( B ) perpendicular to the plane of the rings. The potential difference between the highest points of the two rings is A . zero в. ( 2 r v B ) ( mathbf{c} cdot 4 r v B ) D. ( 8 r v B ) |
12 |

874 | Write Faraday’s laws of electromagnetic induction and obtain an expression of induced e.m.f. |
12 |

875 | t is desired to measure the magnitude of field between the poles of a powerful loud speaker magnet. A small flat search coil of area ( 2 mathrm{cm}^{2} ) with 25 closely wound turns, is positioned normal to the field direction, and then quickly snatched out of the field region. Equivalently, one can give it a quick ( 90^{circ} ) turn to bring its plane parallel to the field direction). The total charge flown in the coil (measured by a ballistic galvanometer connected to coil) is 7.5 mC. The combined resistance of the coil and the galvanometer is ( 0.50 Omega ) Estimate the field strength of magnet. |
12 |

876 | A conducting wire in the form of circular loop of radius ( sqrt{frac{2}{pi}} mathrm{m} ) is places normal to a uniform magnetic field of induction 2T. If the magnetic induction is uniformly reduced to T in 2s, the induced e.m.f in the loop is A. 4 volt B. 2volt c. 1 volt D. 0.4volt |
12 |

877 | A uniform magnetic field of induction ( mathrm{B} ) is confined to a cylindrical region of radius R. The magnetic field is increasing at a constant rate of ( frac{d B}{d t} T s^{-1} . ) An electron of charge ( e ) placed at the point ( P ) on the periphery of the field experiences an acceleration A ( cdot frac{1}{2} frac{e R}{m} frac{d B}{d t} ) toward left B. ( frac{1}{2} frac{e R}{m} frac{d B}{d t} ) toward right c. ( frac{e R}{m} frac{d B}{d t} ) toward left D. zero |
12 |

878 | Deduce an equation ( U=frac{1}{2} L I^{2} ) for an inductor. |
12 |

879 | The self induction of a coil having 400 turns is ( 10 mathrm{mH} ). The magnetic flux through the cross section of the coil corresponding to current ( 2 mathrm{mA} ) is : A ( cdot 2 times 10^{-5} mathrm{Wb} ) В. ( 8 times 10^{-3} mathrm{Wb} ) c. ( 4.3 times 10^{-5} mathrm{Wb} ) D. ( 4.8 times 10^{-3} mathrm{Wb} ) |
12 |

880 | A rectangular coil of area ( A ), having the number of turns ( N ) is rotated at ( f ) revolutions per second in a uniform magnetic field ( B ) the field is perpendicular to the coil. Prove that the maximum emf induced in the coil is ( 2 pi f N B A ) |
12 |

881 | What is the source of energy associated with the current obtained in part when a magnet is moved towards a coil having a galvanometer at its ends? |
12 |

882 | When a current of 5 A flows in the primary coil then the flux linked with the secondary coil is 200 weber. The value of coefficient of mutual induction will be A . 1000 н в. 40 c. ( 195 mathrm{H} ) D. 205 H |
12 |

883 | A coil of inductance ( 5 mathrm{H} ) is joined to a cell of emf ( 6 mathrm{V} ) through a resistance ( 10 Omega ) at time ( t=0 . ) The EMF across the coil at time ( t=ln sqrt{2} s ) is: ( A cdot 3 v ) B. 1.5 c. ( 0.75 v ) D. 4.5 |
12 |

884 | Fig shown below represents an area ( A=0.5 m^{2} ) situated in a uniform magnetic field ( B=2.0 w e b e r / m^{2} ) and making an angle of ( 60^{circ} ) with respect to magnetic field. The value of the magnetic flux through the area would be equal to: A. 2.0 weber B. ( sqrt{3} )weber c. ( sqrt{3} / 2 ) weber D. 0.5 weber |
12 |

885 | A coil of area ( A_{0} ) is lying in such a magnetic field whose value changes from ( B_{0} ) to ( 4 B_{0} ) in ( t ) seconds. The induced emf in the coil will be : A ( cdot frac{4 B_{0}}{A_{0} t} ) в. ( frac{4 B_{0} A_{0}}{t} ) c. ( frac{3 B_{0} A_{0}}{t} ) D. ( frac{3 B_{0}}{A_{0} t} ) |
12 |

886 | In given diagrams write the direction of magnetic field produced at point ( boldsymbol{P} ) in form of ( otimes ) and ( odot ) |
12 |

887 | Which of the following are not units of self inductance? This question has multiple correct options A. Weber / m ( ^{2} ) B. ( O h m- )second c. Joule – ampere D. Joule – ampere ( ^{-} ) |
12 |

888 | Derive expression for the self-induction of solenoid. What factors affect its value and how? |
12 |

889 | 68. In Figures (a) and (b), two air-cored solenoids P and o have been shown. They are placed near each other. In Figure (a), when Ip, the current in P, changes at the rate of 5 As), an emf of 2 mV is induced in Q. The current in P is then switched off, and the current changing at 2 AS! is fed through as shown in the figure. What emf will be induced in P? (a) (a) 8 x 10-4 v (c) 5 x 10-3v (b) (b) 2 x 10-V (d) 8 x 10-20 U m bollow cold as shown |
12 |

890 | In a coil of resistance ( 10 Omega ), the induced current developed by changing magnetic flux through it, is shown in figure as a function of time. The magnitude of change in flux through the coil in Weber is- |
12 |

891 | Find the approximate value of induced current assuming the resistance to the current is confined to the square. A ( cdot frac{B L omega d t}{rho} ) ( ^{text {В }} cdot frac{B L^{2} omega d t}{rho} ) ( ^{text {c. }} frac{B L^{2} omega d}{rho} ) ( frac{B L omega d^{2}}{rho} ) |
12 |

892 | If radius of long solenoid is doubled, then its self inductance will be : A. same B. doubled c. trippled D. quadrupled |
12 |

893 | A conducting wheel rim in which there we three conducting rods of each of length ( l ) is rotating with constant angular velocity ( omega ) in a uniform magnetic field Bas show in figure. The induced potential difference between its centre and rim will be : ( mathbf{A} cdot B omega l^{2} ) B. ( frac{3}{2} B omega l^{2} ) c. 0 D. ( frac{B omega l^{2}}{2} ) |
12 |

894 | X X X 26. A conducting ring of radius r X X X X is rolling without slipping with a constant angular velocity o (figure). If the magnetic field X strength is B and is directed into the page then the emf induced across PQ is X X X2x x Bor2 (a) Bor? (b) X X π2,2 Βω (c) 4Bor? (d) D: odmorit |
12 |

895 | The phenomenon of electromagnetic induction is A. the process of charging a sphere B. the process of producing magnetic field in a coil C. the process of producing induced current in a coil whenever there is a relative motion between the coil and the magnet D. the process of producing cooling effect |
12 |

896 | A wire in the form of a circular loop of radius ( 10 mathrm{cm} ) lies in a plane normal to a magnetic field of ( 100 T . ) If this wire is pulled to take a square shape in the same plane in ( 0.1 s, ) find the average induced emf in the loop. ( mathbf{A} cdot 8.99 V ) B. ( 4.33 V ) c. ( 7.77 V ) D. ( 6.74 V ) |
12 |

897 | toppr Q Type your question ( v_{0} . ) Which of the following graph truly depicts the variation of current through the conductor with time? 3 2 |
12 |

898 | Carbon brushes are not necessary in a dynamo, if the coil remains stationary and the magnet moves, because A. Current is drawn from a stationary source B. Current is drawn from a moving source c. Direct current is produced D. It is not necessary to reverse the direction of the current |
12 |

899 | A magnet is moved towards the coil (i) quickly in one case, and (ii) slowly in another case. Then the induced emf is : A. larger in case (i) B. smaller in case (i) c. equal in both D. larger or smaller depending upon the radius of the coil |
12 |

900 | 7. The figure shows four wire loops, with edge lengths of either L or 2L. All four loops will move through a region of uniform magnetic field B (directed out of the page) at the same constant velocity. Rank the four loops according to the maximum magnitude of the e.m.f. induced as they move through the field, greatest first (a) (x = £j)(&q=&) (c) Ę > Ed > & > Ey (d) x < £; <& < En |
12 |

901 | Q Type your question infinitely long wire carrying a constant current ( I . ) The sides ( P Q ) and ( R S ) are parallel to the wire. The wire and the loop are in the same plane. The loop is rotated by ( 180^{circ} ) about an axis parallel to the long wire and passing through the mid-points of the sides ( Q R ) and ( P S . ) The total amount of charge which passes through any point of the loop during rotation is A ( cdot frac{mu_{0} I a}{2 pi r} ln 2 ) B. ( frac{mu_{0} I a}{pi r} ln 2 ) c. ( frac{mu_{0} I a^{2}}{2 pi r} ln 2 ) D. cannot be found because time of rotation is not given E. answer required |
12 |

902 | The armature of a demonstrator generator consists of a flat square coil of side ( 4 c m ) and 200 turns. The coil rotates in a magnetic field of 0.75 T. The angular speed so that a maximum emf of ( 1.6 V ) is generated is: A ( cdot frac{20}{3} ) rad/s B. ( frac{10}{3} ) rotations/s c. ( frac{40}{3} ) rpm D. None of these |
12 |

903 | If ( mathrm{N} ) is the number of turns in a coil, the value of self-inductance varies are ( mathbf{A} cdot mathbf{N}^{mathbf{0}} ) B. c. ( N^{2} ) ( D cdot N^{-2} ) |
12 |

904 | As shown in the figure, ( P ) and ( Q ) are two coaxial conducting loops separated by some distance. When the switch ( S ) is closed, a clockwise current ( l_{p} ) flows in ( P ) (as seen by ( E ) ) and an induced current ( l_{Q 1} ) flows in ( Q . ) The switch remains closed for a long time. When ( S ) is opened, a current ( l_{Q 2} ) flows in ( Q ). Then the direction ( l_{Q 1} ) and ( l_{Q 2}(text { as seen by } E) ) are A. respectively clockwise and anti-clockwise B. both clockwise ( c . ) both anti-clockwise D. respectively anti-clockwise and clockwise |
12 |

905 | Q Type your question coll ana aırectea ınto the paper Is varying according to the relation ( phi= ) ( 6 t^{2}+7 t+1, ) where ( phi ) is in milliweber and ( t ) is in second. The magnitude of the emf induced in the loop at ( t=2 s ) and the direction of induce current through ( boldsymbol{R} ) are 8 A. 39 mV; right to left B. 39 mV; left to right c. ( 31 mathrm{mV} ; ) right to left D. 31 mV; left to right |
12 |

906 | A metallic wire bent into a right ( Delta ) abc moves with a uniform velocity ( boldsymbol{v} ) as shown in figure. B is the strength of uniform magnetic field perpendicular outwards the plane of triangle. The net emf is …………….. and emf along ab is A. zero, zero B. zero, ( B v(b c) ) with ( b ) positive C. zero, ( B v(b c) ) with ( a ) positive D. ( B v(b c) ) with ( c ) positive, zero E. ( B v(b c) ) with ( b ) positive, zero |
12 |

907 | The magnetic flans associated with a metal ring varies with time all. to ( phi= ) ( mathbf{3}left(boldsymbol{a} boldsymbol{t}^{3}-boldsymbol{b} boldsymbol{t}^{2}right) boldsymbol{T} boldsymbol{m}^{2}, boldsymbol{a}=boldsymbol{2} boldsymbol{s} boldsymbol{e} boldsymbol{c}^{-3}, boldsymbol{b}= ) ( 6 sec ^{-2} . ) If the resistance of the ring is ( 24 Omega, ) the current induced in the ring during the time ( t=2 sec ) is A. ( 2 a m p ) в. ( 4 a m p ) c. ( 6 a m p ) D. zero |
12 |

908 | A rod of length ( l ) rotates with a uniform angular velocity ( omega ) rad/s about an axis passing through its middle point but normal to its length in a uniform magnetic field of induction ( B ) with its direction parallel to the axis of rotation. The induced emf between the two ends of the rod is : ( ^{A} cdot frac{B l^{2} omega}{2} ) в. zero c. ( frac{B l^{2} omega}{4} ) D ( cdot 2 B l^{2} omega ) |
12 |

909 | A dynamo produces an electric current. It is based on the principle: A. magnets have attractive property B. conductors carrying current behave like magnets C. electromagnetic induction D. none of these |
12 |

910 | A coil of area ( 500 mathrm{cm}^{2} ) having 1000 turns is placed such that the plane of the coil is perpendicular to a magnetic field of magnitude ( 4 times 10^{-5} ) weber ( / m^{2} ). If it is rotated by 180 about an axis passing through one of its diameter in ( 0.1 mathrm{sec} ), find the average induced emf A. zero B. 30 mv c. ( 40 mathrm{mv} ) D. 50 mv |
12 |

911 | An e.m.f. of 5 millivolt is induced in a coil when in a nearby placed another coil, the current changes by 5 ampere in 0.1 second. The coefficient of mutual induction between the two coils will be : A. 1 Henry B. 0.1 Henry c. 0.1 millihenry D. 0.001 millihenry |
12 |

912 | A conducting loop is held above a current carrying wire ‘PQ’ as shown in the figure. Depict the direction of the current induced in the loop when the current in the wire ( P Q ) is constantly increasing. |
12 |

913 | Match the following Physical Quantity Unit in ¿uc is an a it ( begin{array}{l}text { a) Magnetic Moment } \ text { b) Magnetic Flux Density } \ text { c) Intensity of Magnetic Field } & text { e) } A m p-m \ text { d) Pole strength } & text { g) } N-m^{3} / W b \ text { h) Gauss }end{array} ) ( A cdot a-e, b-f, c-g, d-h ) B. ( a-g, b-h, c-f, d-e ) ( mathbf{C} cdot a-g, b-f, c-h, d-e ) D. a-e, b-f, c-h, d-g |
12 |

914 | While travelling back to his residence in the car, Dr. Pathak was caught up in a thunderstorm. It became very dark. He stopped driving the car and waited for thunderstorm to stop. Suddenly he noticed a child walking alone on the road. He asked the boy to come inside the car till the thunderstorm stopped. Dr. Pathak dropped the boy at his residence. The boy insisted that Dr. Pathak should meet his parents. The parents expressed their gratitude to Dr. Pathak for his concern for safety of the child. Answer the following questions based on the above information: |
12 |

915 | A uniform but time-varying magnetic field ( B_{(t)} ) exists in a circular region of radius a and is direction into the plane of the paper, as shown in the figure. The magnitude of the electric field at point ( P ) at a distance ( r ) from the centre of the circular region ( A ). is zero B. decreases as ( 1 / r ) c. increases as D. decrease as ( 1 / r^{2} ) |
12 |

916 | Two circular loops lie side by side in the same plane. One is connected to a source that supplies an increasing current, the other is a simple closed ring. Is the induced current in the ring is in the same direction as that in the loop connected to the source or opposite? What if the current in the first loop is decreasing? |
12 |

917 | Name two devices based on the magnetic effect of electricity. |
12 |

918 | A cylindrical bar magnet is kept along the axis of a circular coil. On rotating the magnet about its axis, the coil will have induced in it A . a current B. no current c. only an e.m.f. D. both an e.m.f. and a current |
12 |

919 | On what factors does the induced electromotive force depend? |
12 |

920 | Given below are the symbols of a few electronic components. Which of these components denote a variable inductor 7 ( A ) B. ( c ) D. |
12 |

921 | Generators used in power stations to generate electricity are A. DC generators B. AC generators ( c cdot ) Both D. None |
12 |

922 | Two coils ( A ) and ( B ) have mutual inductance ( 2 times 10^{-2} ) henry. If the current in the primary is ( i= ) ( 5 sin (10 pi t) ) then the maximum value of e.m.f. induced in coil B is: A . pivolt в. ( frac{pi}{2} ) volt c. ( frac{pi}{3} ) volt D. ( frac{pi}{4} ) volt |
12 |

923 | Draw a labeled diagram of AC generator.Derive the expression for the instantaneous value of the emf induced in the coil. |
12 |

924 | A wheel of radius ( 2 mathrm{m} ) having 8 conducting concentric spokes is rotating about its geometrical axis with an angular velocity of 10 rad/s in a uniform magnetic field of ( 0.2 T ) perpendicular to its plane. The value of induced emf between the rim of the wheel and centre is A . 2 B. 6 ( c cdot 4 ) D. 8 |
12 |

925 | The relation between ( [boldsymbol{E}] ) and ( [boldsymbol{B}] ) is ( mathbf{A} cdot[E]=[B][L][T] ) B . ( [E]=[B][L]^{-1}[T] ) c. ( [E]=[B][L][T]^{-1} ) D・ ( [E]=[B][L]^{-1}[T]^{-1} ) |
12 |

926 | The device used for producing current is called a |
12 |

927 | Assertion Mutual inductance of a pair of coils depend on their separation as well as their relative orientation. Reason Mutual inductance depend upon the length of the coil only. 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 |

928 | Explain the reasons for the following in a power generator. a.armature is used as stator. b. Strong electromagnets are used as field magnet. c. Three armature coil are arranged at ( 120^{circ} ) angular separation |
12 |

929 | Which statement is incorrect related to induced electric field due to changing magnetic flux? A. It varies with time B. It is non-conservative c. It forms closed loop D. Both (1) & (3) |
12 |

930 | If circular coil with ( N_{1} ) turns is changed in to a coil of ( N_{2} ) turns. What will be the ratio of self inductances in both cases. A ( cdot frac{N_{1}}{N_{2}} ) B. ( frac{N_{2}}{N_{1}} ) c. ( frac{N_{1}^{2}}{N_{2}^{2}} ) D. ( sqrt{frac{N_{1}}{N_{2}}} ) |
12 |

931 | When the number of turns in a coll is doubled without any change in the length of the coll, its self-inductance becomes A. four times B. Double c. Halved D. Not change |
12 |

932 | A conducting loop is pulled outward with a constant speed. The induced emf between the point ( A ) and B, just after the motion start is |
12 |

933 | A dynamo makes 100 cycles per second. The frequency of the AC is A. ( 100 mathrm{Hz} ) в. 200 нz c. 50 нz D. 400 нz |
12 |

934 | B 25. A wire of length 1. mass m, and resistance R slides without any friction down the parallel conducting rails of negligible resistance (figure). The rails are connected to each other at the bottom by a resistanceless rail parallel to the wire so that the wire and the rails form a closed rectangular conducting loop. The plane of the rails makes an angle e with the horizontal and a uniform vertical magnetic field of induction B exists throughout the region. Find the steady- state velocity of the wire. mg sine mg sine (a) RB21² cos²6 RB²1² cos² e sin e °B212 cose (c) mgr sine (d) mg B-12 cose |
12 |

935 | Mark the correct statement the magnitude of current induced in the coil can be increased A. by winding the coil on a soft iron core B. by increasing the number of turns in the coil. c. by increasing the strength of magnett D. all |
12 |

936 | A straight copper wire is moved in a uniform magnetic field such that it cuts the magnetic lines of force. Then A. emf will not be induced B. emf will be induced c. sometimes emf will be induced and sometimes not D. nothing can be predicted |
12 |

937 | Consider a current carrying coil placed in a magnetic field. What are the requirements for induced current to flow as per electromagnetic induction A . Coil of wire carrying current B. Change in magnetic field associated with the coil c. Both A and B D. None |
12 |

938 | In the space shown a non-uniform magnetic field ( overrightarrow{boldsymbol{B}}=boldsymbol{B}_{0}(boldsymbol{1}+boldsymbol{x})(-boldsymbol{k}) ) tesla is present. A closed loop of small resistance, placed in the ( x ) -y plane is given velocity ( V_{0} . ) The force due to magnetic field on the loop is A. zer B. along + x direction C. along ( -x ) direction D. along +y direction E. none of these |
12 |

939 | Fill in the blanks. Device that converts mechanical energy into electrical energy is |
12 |

940 | A uniform thin rod of length L is moving in a uniform magnetic field ( B_{0} ) such that velocity of its centre of mass is ( mathbf{v} ) and angular velocity is ( omega=frac{4 v}{L} ) Then A. e.m.f. between end ( mathrm{P} ) and ( mathrm{Q} ) of the rod is ( B_{0} l v ) B. end P of the rod is at higher potential than end Q of the rod C. end ( Q ) of the rod is at higher potential than end P of the rod D. the electrostatic field induced in the rod has same direction at all points along the length of rod |
12 |

941 | are used in making electric generators and electric motors. A. electric current B. magnetes c. cables D. all |
12 |

942 | The magnetic flux through a loop is varying according to a relation ( phi= ) ( 6 t^{2}+7 t+1 ) where ( phi ) is in milliweber and ( t ) is in second. What is the e.m.f. induced in the loop at ( t=2 ) second? |
12 |

943 | (d) UTOA 49. A long solenoid of length L, cross section A having N, turns has wound about its center a small coil of N, turns as shown in figure. The mutual inductance of two circuits is —— – – – – – – – – ba (a) MOA(N /N) | (b) (NN) L (c) Ho AN,N2L (2) MAN, ²N, ANNI |
12 |

944 | Assertion In a varying magnetic field the induced currents exhibit diamagnetic-like repulsion effects. A conductive object will experience a repulsion force. Reason Eddy currents produced in conductor will produce magnetic field to oppose the varying magnetic field according to faradays 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 |

945 | Define self inductance of a coil. Derive the expression for magnetic energy stored in the inductor of inductance ( L ) carrying current ( boldsymbol{I} ) |
12 |

946 | 48. The coefficient of mutual inductance of two circuits A and B is 3 mH and their respective resistances are 10 and 412. How much current should change in 0.02 s in circuit A, so that the induced current in B should be 0.0060 A? (a) 0.24 A (b) 1.6 A (c) 0.18 A (d) 0.16 A |
12 |

947 | A wheel with 4 spokes is placed with its plane perpendicular to a uniform magnetic field B of magnitude 0.5 T. The field is directed into the plane of the paper and is present over the entire region of the wheel as shown in fig. When the switch ( mathrm{S} ) is closed, there is initial current of 6 A between the axis and the rim and the wheel begins to rotate. Resistances of the spokes are 1 2,4 and ( 8 Omega, ) respectively. Resistance of rim is negligible If current in ( 1 Omega ) is ( 2 / X ) A. Find ( X ? ) |
12 |

948 | A horizontal straight wire ( 10 mathrm{m} ) long extending from east to west is falling with a speed of ( 5.0 m s^{-1}, ) at right angles to the horizontal component of the earth’s magnetic field 0.30 ( times 10^{-4} W B m^{-2} . ) (a) What is the instantaneous value of the emf induced in the wire?(b) What is the direction of the emf?(c) Which end of the wire is at the higher electrical potential? |
12 |

949 | A small, conducting circular loop is placed inside a long solenoid carrying a current. The plane of the loop contains the axis of the solenoid. If the current in the solenoid is varied. The current induced in the loop is A. clockwise B. anti-clockwise c. zero D. clockwise or anti-clockwise depending on whether the resistance is increased or decreased |
12 |

950 | (a) What are the defects of eye? How are these rectified? (b) Observe the figure and answer the following questions: (i) What does the given diagram represent? (ii) Write the principle of the device denoted in the given diagram. |
12 |

951 | Two identical coaxial coils ( P ) and ( Q ) carrying equal amount of current in the same direction are brought nearer. The current in A. ( P ) increases while in ( Q ) decreases B. ( Q ) increases while in ( P ) decreases c. Both ( P ) and ( Q ) increases D. Both ( P ) and ( Q ) decreases E. Both ( P ) and ( Q ) remains constant |
12 |

952 | The length of a thin wire require to manufacture a solenoid of length ( l= ) ( 100 mathrm{cm} ) and inductance ( L=1 m H, ) if the solenoid’s cross-sectional diameter is considerably less than its length is: A. ( 1 k m ) в. ( 0.10 mathrm{km} ) c. ( 0.010 mathrm{km} ) D. ( 10 mathrm{km} ) |
12 |

953 | Draw the diagram of a DC dynamo and label the following parts: a) Split rings b) Armature coil |
12 |

954 | A loop shown in the figure is immersed in the varying magnetic field ( B=B_{0} t ) directed into the page. If the total resistance of the loop is ( R ), then the direction and magnitude of induced current in the inner circle is : ( ^{mathrm{A}} cdot_{mathrm{clockwise}} frac{B_{0}left(pi a^{2}-b^{2}right)}{R} ) B. anticlockwise ( frac{B_{0}left(pi a^{2}+b^{2}right)}{R} ) c. ( _{text {clockwise }} frac{B_{0}left(pi a^{2}+4 b^{2}right)}{R} ) ” clockwise ( frac{B_{0}left(4 b^{2}-pi a^{2}right)}{R} ) |
12 |

955 | Two solenoids have identical geometrical construction but one is made of thick wire and the other of thin wire. Which of the following quantities are different for the two solenoids? This question has multiple correct options A. Self-inductance B. Rate of Joule heating if the same current goes through them c. Magnetic field energy if the same current goes through them D. Time constant if one solenoid it connected to one battery and the other is connected to another battery |
12 |

956 | When the acceleration of rod is zero, the charge on capacitor is : ( ^{text {A. }} frac{B^{2} L^{2} C Q_{0}}{M+B^{2} L^{2} C} ) ( ^{text {В }} frac{B^{2} R^{4} C^{3} Q_{0}}{M+B^{2} L^{2} C^{2}} ) c. ( frac{B^{2} R^{4} C^{3} Q_{0}}{M+B^{2} R^{4} C^{4}} ) D. ( frac{B^{2} L^{2} C Q_{0}}{M+B^{2} L^{2} C^{2}} ) |
12 |

957 | A coil with 100 turns has an inductance of ( 0.05 H ) and ( 0.02 A ) current is passed through it. Flux linked with the coil is A ( cdot 10^{-2} W b ) В ( cdot 10^{-3} W b ) ( mathbf{c} cdot 10^{-4} W b ) D. ( 10^{-5} W b ) |
12 |

958 | What do you mean by magnetic flux? | 12 |

959 | Assertion An emf is induced in a long solenoid by a bar magnet that moves while totally inside the solenoid along the axis of the solenoid. Reason As the magnet moves inside the solenoid the flux through individual turns of the solenoid changes. 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 |

960 | A metal rod moves at a constant velocity in a direction perpendicular to its length. A constant uniform magnetic field exists in space in a direction perpendicular to the rod as well its velocity. Select correct statements from the following A. the entire rod is at the same potential B. there is an electric field in the rod c. the electric potential is highest at the centre D. the electric potential is lowest at its centre and increases towards its ends |
12 |

961 | A solenoid has 2000 turns wound over a length of ( 0.3 m . ) Its cross-sectional area is equal to ( 1.2 times 10^{-3} m^{2} ). Around its central cross-section, a coil of 300 turns is wound. If an initial current of ( 2 A ) flowing in the solenoid is reversed in ( 0.25 s, ) the emf induced in the coil is A ( .0 .6 m V ) B. ( 60 m V ) c. ( 40.2 m V ) D. ( 0.48 m V ) |
12 |

962 | If an inductor of inductance ( L ), radius ( r ) current changes from ( I_{1} ) to ( I_{2} ). Find work done. |
12 |

963 | A solenoid ( 30 c m ) long is made by winding 2000 loops of wire on an iron rod whose cross-section is ( 1.5 mathrm{cm}^{2} ). If the relative permeability of the iron is 6000. What is the self-inductance of the solenoid? ( mathbf{A} cdot 15 H ) в. 25H ( c .35 H ) D. ( 5 H ) |
12 |

964 | Current in a coil is increased at a constant rate. The current in the second coil is also increased at the same rate. At a certain instant of time, the power given to the two coils is the same. At that time the current, the induced voltage and the energy stored in the first coil are ( I_{1}, V_{1}, ) and ( W_{1} ) respectively. Corresponding values for the second coil at the same instant are ( I_{2}, V_{2} ) and ( W_{2} ) respectively. Then A. ( frac{W_{2}}{W_{1}}=8 ) в. ( frac{W_{2}}{W_{1}}=frac{1}{8} ) c. ( frac{W_{2}}{W_{1}}=4 ) D. ( frac{W_{2}}{W_{1}}=frac{1}{4} ) |
12 |

965 | A circular ring is fixed in a gravity free space and one point of the ring is earthed. Now a magnet is placed along axis of the ring at a distance from its centre such that the nearer pole is north pole as shown in figure. A sharp impilse is applied on the magnet so that it starts to move towards the ring. Then, A. Initially magnet experiences an acceleration and then it retards to come to an instantaneous rest. B. Magnet starts to oscillate about centre of the ring C. Magnet continues to move along the axis with constant velocity D. The magnet retards and comes to rest finally |
12 |

966 | A conducting disc of radius ( r ) spins about its axis with an angular velocity ( omega . ) There is a uniform magnetic field of magnetude B perpendicular to the plane of the disc. ( C ) is the centre of the ring. This question has multiple correct options A. No emf is induced in the disc. B. The potential difference between C and the rim is ( frac{1}{3} B r^{2} omega ) c. ( c ) is at a higher potential than the rim D. Current flows between c and the rim |
12 |

967 | Draw a labelled diagram of an electric generator |
12 |

968 | Q Type your question Inglictic ilciu I mu paper.Wire ( C D ) is in the shape of an arc and is fixed. ( O A ) and ( O B ) are the wires rotating with angular velocity ( omega ) as shown in the figure in the same plane as that of the arc about point ( O . ) If at some instant, ( O A=O B=1 ) and each wire makes angle ( theta=30^{circ} ) with ( y ) -axis, then the current through resistance ( boldsymbol{R} ) is (wire ( O A ) and ( O B ) have no resistance) A . 0 B. ( frac{B omega l^{2}}{R} ) c. ( frac{B omega l^{2}}{2 R} ) D. ( frac{B omega l^{2}}{4 R} ) E . answer |
12 |

969 | If a Bismuth rod is introduced in the air coil as shown then current in the coil A. increases B. remains unchanged c. decrreases D. none of these |
12 |

970 | There are two long co-axial solenoids of same length ( l ). the inner and outer coils have radii ( r_{1} ) and ( r_{2} ) and number of turns per unit length ( n_{1} ) and ( n_{2} ) respectively. The rate of mutual inductance to the self-inductance of the inner-coil is : ( mathbf{A} cdot frac{n_{2}}{n_{1}} cdot frac{r_{2}^{2}}{r_{1}^{2}} ) B. ( frac{n_{2}}{n_{1}} cdot frac{r_{1}}{r_{2}} ) c. ( frac{n_{1}}{n_{2}} ) D. ( frac{n_{2}}{n_{1}} ) |
12 |

971 | Mutual inductance of two coils can be increased by A. decreasing the number of turns in the coils B. increasing the number of turns in the coils c. winding the coils on wooden cores D. none of these. |
12 |

972 | Output emf in a dynamo is generated on A. Magnettet B. Armature coil c. slip rings D. Carbon brushes |
12 |

973 | 41. A magnetic flux of 5 104 Wb is associated with every 10 turns of a 500 turns coil. The electric current flowing through the wire is 5 A. What is the self-inductance of the coil? (a) 0.5 H (b) 5 x 10-²H (c) 5.0 H (d) 5 x 10-2H |
12 |

974 | A small conduction loop is in a magnetic field pointing out of the screen.Which of the following would produce a counter-clockwise current in the loop? I. Moving the coil out of the field. II. Increasing the strength of the field. III. Rotating the coil on its center axis. A. I only B. I and III only c. Il only D. I, II, and III |
12 |

975 | Which of the following defines electromagnetic induction: A. When magnetic field associated with a coil changes, an induced electric current flows through the coil B. Electric current induces magnetic field near the wire carrying current. C. Two permanent magnets exert force on each other D. Electrolyte disintegrates into ions in a battery. |
12 |

976 | Two circular coils can be arranged in any of the three situations shown in the figure. Their mutual inductance will be A. maximum in situation ( (a) ) B. maximum in situation ( (b) ) C. maximum in situation ( (c) ) D. the same in all situations |
12 |

977 | In the field of electromagnetism, the term ‘EMI’ stands for: A. Electromotive Impact B. Electromagnetic Induction c. Electromotive inertia D. none of these |
12 |

978 | The current in a coil of inductance ( 2 mathrm{H} ) is changing according to varying current ( boldsymbol{I}=sin (2 t) . ) The amount of magnetic energy in the inductor during ( t=0 ) to ( boldsymbol{t}=frac{boldsymbol{pi}}{boldsymbol{4}} boldsymbol{s} ) is: A . 4 B . 3J c. 1 J D. 2 |
12 |

979 | A circular loop of radius ( 0.3 mathrm{cm} ) lies parallel to a much bigger circular loop of radius ( 20 mathrm{cm} . ) The centre of the small loop is on the axis of the bigger loop. The distance between their centres is ( 15 mathrm{cm} ) If a current of ( 2.0 A ) flows through the smaller loop, then flux liked with bigger loop is: A ( cdot 6 times 10^{-11} ) weber В. ( 3.3 times 10^{-11} ) weber c. ( 6.6 times 10^{-9} ) weber D. ( 9.1 times 10^{-11} ) weber |
12 |

980 | A square loop is placed near a long straight current carrying wire as shown Match the following two columns | 12 |

981 | (a) Draw a labelled diagram of an electric generator. Explain its construction and working in brief. (b) Write down any two characteristics of magnetic field lines of a bar magnet. |
12 |

982 | with an angular frequency ( omega ) with one end hinged at the centre and the other end at the circumference of a circular metallic ring of radius ( R, ) about an axis passing through the centre and perpendicular to the plane of the ring.There is a magnetic field B, perpendicular to the plane of the ring. The emf induced between the centre and the metallic ring is A. ( B ) sinwt ( ^{mathbf{B}} cdot frac{B R^{2} omega}{2} ) ( mathbf{c} cdot 2 B R^{2} omega ) D. ( B R^{2} omega ) |
12 |

983 | The dimensions of self-inductance L are ( mathbf{A} cdotleft[M L^{2} T^{-2} A^{-2}right] ) B. ( left[M L^{2} T^{-1} A^{-2}right] ) ( mathbf{c} cdotleft[M L^{2} T^{-1} A^{-1}right] ) D. ( left[M L^{-2} T^{-2} A^{-2}right] ) |
12 |

984 | Identify the wrong statement A. Eddy currents are produced in a steady magnetic field B. Eddy currents can be minimized by using laminated core C. Induction furnace uses eddy current to produce heat D. Eddy current can be used to produce breaking force in moving vehicles E. Power meters are working on the principle of eddy currents |
12 |

985 | A wheel with 10 metallic spokes each ( 0.5 mathrm{m} ) long rotated with a speed of 120 rpm in a plane normal to the horizontal component of earth’s magnetic field ( B_{h} ) at a place. If ( B_{h}=0.4 mathrm{G} ) at the place. What is the induced emf between the axle and the rim of the wheel? ( left(1 mathrm{G}=10^{4}right. ) ( T ) A. o v B. 0.628 mV c. ( 0.628 mu v ) D. 62.8 ( mu ) V |
12 |

986 | the number of turn of primary and secondary coil of the transformer is 5 and 10 respectively ad the mutual inductance is 25 H. if the number ( f ) turns of the primary and secondary is made 10 and ( 5, ) then the mutual inductance of the coils will be A . ( 6.25 mathrm{H} ) B. 12.5 c. 25 D. 50 |
12 |

987 | An average emf of ( 32 V ) is induced in a coil in which the current drops from ( 10 A ) to ( 2 A ) in ( 0.1 s . ) The inductance of the coil is: A ( .0 .32 H ) в. ( 0.4 H ) ( c .4 H ) D. ( 0.04 H ) |
12 |

988 | An airplane with wingspan ( 50 m ) is flying horizontally with a speed of ( 360 k m h r^{-1} ) over a place where the vertical component of the earth’s magnetic field is ( 2 times 10^{-2} ). The potential difference between the tips of the wings would be A. ( 100 V ) в. ( 1.0 V ) ( c .0 .2 V ) D. ( 0.01 V ) |
12 |

989 | Describe the construction of direct current dynamo drawing labelled diagram. Explain its working. What is the difference between direct current and alternating current? Explain it. |
12 |

990 | A rod ( A B ) moves with a uniform velocity ( boldsymbol{v} ) in a uniform magnetic field as shown in figure : [ begin{array}{llllll} x & x & x & x & x & x \ x & x & x & A & x & x \ x & x & x & x & x & x \ x & x & x & B x & x & x end{array} ] A. The rod becomes electrically charged B. The end A becomes positively chargedd C. The end B becomes positively charged D. The rod becomes hot because of Joule heating |
12 |

991 | Dynamo is A. a device B. a typr of magnet C . a current carrying wire D. none of these |
12 |

992 | 40. Two single-turn circular loops of wire have radii R and r, with R>>r. The loops lie in the same plane and are concentric. The mutual inductance of the pair is (approximately) Mor? 2 Mar (b) R 3 Mar? HOT2 2R (d) 2R 10-4 W i nted with ou |
12 |

993 | Two concentric circular coils one of small radius ( r_{1} ) and the other of large radius ( r_{2} ) such that ( r_{1}<<r_{2} ) are placed co-axially with centres coinciding. Obtain the mutual inductance of the arrangement. |
12 |

994 | Suggest one way to strengthen the magnetic field in the electromagnet. | 12 |

995 | Two large vertical and parallel metal plates having a separation of ( 1 mathrm{cm} ) are connected to a DC voltage source of potential difference ( X . ) A proton is released at rest midway between the two plates. It is found to move at 45 to the vertical JUST after release. Then X is nearly ( mathbf{A} cdot 1 times 10^{-5} V ) B . ( 1 times 10^{-7} V ) C . ( 1 times 10^{-9} V ) D. ( 1 times 10^{-10} V ) |
12 |

996 | Figure shows a long straight wire carrying current ( l ) and a square conducting wire loop of side ( I ), at a distance ‘a’ from current wire. Both the current wire and loop are in the plane of paper.Find the flux of magnetic field of current wire,passing through the loop. |
12 |

997 | The armature of a dc motor has ( 20 Omega ) resistance. It draws a current of ( 1.5 mathrm{A} ) when run by a ( 220 mathrm{V} ) dc supply. The value of the back emf induced in it is ( A cdot 150 V ) B. 170 V c. ( 180 v ) D. ( 190 mathrm{v} ) |
12 |

998 | The time constant of an inductance coil is ( 2 times 10^{-3} ) s. When a ( 90 Omega ) resistance is joined in series, the same constant becomes ( 0.5 times 10^{-3} ) s. The inductance and resistance of the coil are A. ( 30 m H ; 30 Omega ) в. ( 60 m H ; 30 Omega ) c. ( 30 m H ; 60 Omega ) D. ( 60 m H ; 60 Omega ) |
12 |

999 | The magnetic field in the cylindrical region shown in figure increases at a constant rate of ( 10.0 m T s^{-1} ). Each side of the square loop abcd and defa has a length of ( 20.0 mathrm{cm} ) and a resistance of ( 2.00 Omega . ) Correctly match the current in the wire ( a d ) in four different situations as listed in column I with the values given in column II. |
12 |

1000 | Define coefficient of mutual induction. If in the primary coil of a transformer, the current decreases from ( 0.8 A ) to ( 0.2 A ) in 4 milliseconds, calculate the induced e.m.f in the secondary coil. Mutual inductance is ( 1.76 H ) |
12 |

1001 | A bar magnet is dropped along the axis of copper ring held horizontally. The acceleration of fall is A. equal to g at the place. B. less than ( g ) c. more than ( g ) D. depends upon diameter of the ring and length of the magnet |
12 |

1002 | The magnetic flux linked with a coil satisfies the relation ( phi=4 t^{2}+6 t+9 ) Wh, where t is the time in second. The emf induced in the coil at ( t=2 s ) is A 22 V V ( V ) ) 22 в. ( 18 V ) ( mathrm{c} .16 mathrm{V} ) D. ( 40 V ) |
12 |

1003 | An electron accelerated by ( 200 mathrm{V} ) enters a magnetic field .If its velocity is ( 100 mathrm{m} / mathrm{sec} ). then ( (mathrm{e} / mathrm{m}) ) for it will be: ( (mathrm{C} / mathrm{Kg}) ) A. ( 1.75 times 10^{10} ) B. ( 1.75 times 10^{11} ) c. ( 1.75 times 10^{9} ) D. ( 1.75 times 10^{6} ) |
12 |

1004 | A conducting rod PQ of length ( L=1.0 mathrm{m} ) is moving with a uniform speed ( v=2.0 mathrm{m} / mathrm{s} ) in a uniform field ( B=4.0 ) T directed into the paper. A capacitor of capacity ( mathrm{C}=10 mu ) Fis connected as shown in the figure. Then charge on the capacitor is ( 10 alpha mu mathrm{C} ) Find the value of ( boldsymbol{alpha} ) ( A cdot 7 ) B. 8 ( c cdot s ) D. 10 |
12 |

1005 | If a bar magnet is dropped vertically into a, long copper tube then its final acceleration will be ( A cdot a=g ) B. a>g ( c cdot a ) December 26, 2019 Dipesh Bhutada (B) ( square ) Share Save |
12 |

1006 | Define:- Electromagnetic induction. |
12 |

1007 | Two coils ( P ) and ( Q ) are lying parallels and very close to each other. Coil P is connected to an AC source whereas Q is connected to a sensitive galvanometer. On pressing key ( mathrm{K} ) A. small variations are observed in the galvanometer for applied 50 Hz voltage B. deflections in the galvanometer can be observed for applied voltage of 1 Hz to 2 Hz. c. no deflection in the galvanometer will be observed D. constant deflection will be observed in the galvanometer for 50 Hz supply voltage |
12 |

1008 | ( A B ) and ( C D ) are two parallel conductors kept ( 1 mathrm{m} ) apart and connected by a resistance ( R ) of ( 6 Omega ) as shown in figure. They are placed in a magnetic field ( B= ) ( 3 times 10^{-2} mathrm{T} ) which is perpendicular to the plane of the conductors and directed into the paper. A wire MN is placed over ( A B ) and ( C D ) and then made to slide with velocity ( 2 m s^{-1} . ) (Neglect the resistance of ( A B, C D, ) and ( M N ) ). Calculate the induced current flowing through the resistor R. |
12 |

1009 | AC generator means A. Acquired continuity generator B. Assistant current generator C . Alternating current generator D. none |
12 |

1010 | A satellite orbiting the Earth at ( 400 mathrm{km} ) above the surface of the Earth has a ( 2 m ) long antenna oriented perpendicular to the Earth’s surface. At the equator the Earth’s magnetic field is ( 8 times 10^{-5} T ) and is horizontal. Assuming the orbit to the circular, find emf induced across the ends of the antenna.(Given radius of ( left.operatorname{earth} R_{e}=6400 K mright) ) A. ( 1.3 V ) В. ( 1.2 V ) c. ( 1.0 V ) D. ( 0.12 V ) |
12 |

1011 | When a straight wire is moved up and down rapidly between two poles of a horseshoe magnet then is produced in the wire. A. magnetic field B. magnetic current c. electric current D. none |
12 |

1012 | The self induction takes place when magnetic flux through a coil: A. Remains steady B. Decreases c. Increases D. Either (B) or (C) |
12 |

1013 | The relation between ( left[in_{0}right] ) and ( left[mu_{0}right] ) is A ( cdotleft[mu_{0}right]=left[epsilon_{0}right][L]^{2}[T]^{-2} ) B . ( left[mu_{0}right]=left[epsilon_{0}right][L]^{-2}[T]^{2} ) C ( cdotleft[mu_{0}right]=left[epsilon_{0}right]^{-1}[L]^{2}[T]^{-2} ) D ( cdotleft[mu_{0}right]=left[epsilon_{0}right]^{-1}[L]^{-2}[T]^{2} ) |
12 |

1014 | Complete the sentence by using the correct words given in the brackets: ( A_{-}-_{-}-_{-}-_{-} ) (generator ( / ) transformer/motor/transducer) is a source of electricity that generates large amount of electricity in a power house. A. Motor B. Generator c. Transducer D. Transformer |
12 |

1015 | Two coils have a mutual inductance of ( 0.005 H . ) The current changes in the first coil according to equation ( boldsymbol{I}= ) ( I_{0} )sin( omega t, ) where ( I_{0}=10 A ) and ( omega= ) 100 ( pi ) rad / s. The maximum value of emf (in volt) in the second coil is. A . ( 2 pi ) в. ( 5 pi ) c. ( pi ) D. ( 4 pi ) |
12 |

1016 | The instrument which works on the principle of mutual inductance is A. Galvanometer B. Ammeter c. Potentiometer D. Transformer |
12 |

1017 | 61. Switch S shown in figure is closed for t < 0 and is opened at t= 0. When currents through L, and L, are equal, their common value is 2 LR 8 L2 E(L₂+4) S RL EL R(L + L₂) E (4 + L2) R L2 |
12 |

1018 | If the self inductance of 500 turns coil is ( 125 mathrm{mH} ), then the self inductance of the similar coil of ( 800 mathrm{mH} ) A. ( 48.8 mathrm{mH} ) B. 200 mH c. ( 290 mathrm{mH} ) D. 320 mH |
12 |

1019 | Figure shows a fixed square frame of wire having a total resistance r placed coplartarly with a long, straight wire The wire carries a current i given by ( i= ) ( i_{2} cos (2 pi t / T), ) Find ( (a) ) the flux of the magnetic field through the square frame (b) the emf induced in the frame and (c) the heat developed in the frame in the time interval 0 to 10 T. |
12 |

1020 | What will be the magnitude of e.m.f. induced in a 200 turns coil with cross section area ( 0.16 m^{2} ? ) The magnetic field through the coil changes from ( 0.10 W b m^{-2} ) to ( 0.30 W b m^{-2}, ) at a uniform rate over a period of 0.05 s ( mathbf{A} cdot 128 V ) B. ( 130 V ) c. ( 118 V ) D. ( 132 V ) |
12 |

1021 | A conductor ABOCD moves along its bisector with a velocity of ( 1 mathrm{ms}^{-1} ) through a perpendicular magnetic field of ( 1 mathrm{Wbm}^{-2} ), as shown in the figure. If all the four sides are of ( 1 mathrm{m} ) length each, then the induced emf between point ( A ) and D is : A. zero в. 1.41 ( c cdot 0.71 v ) D. none of the above |
12 |

1022 | An aluminum ring B faces an electromagnet A. The current I through A can be altered Front side Observer Rear side (a) whether I increases or decreases, B will not experience any force (b) if I decrease, A will repel B (c) if I increases, A will attract B (d) if I increases, A will repel B 11 od |
12 |

1023 | Select the incorrect option A. Luminous flux and radiant flux have same dimensions B. Luminous flux and luminous intensity have same dimensions C. Radiant flux and power have same dimension D. Relative luminosity is a dimensionless quantity |
12 |

1024 | (a) A rod of length I is moved horizontally with a uniform velocity ‘v’ in a direction perpendicular to its length through a region in which a uniform magnetic field is acting vertically downward. Derive the expression for the emf induced across the ends of the rod. (b) How does one understand this motional emf by invoking the Lorentz force acting on the free charge carriers of the conductor? Explain. |
12 |

1025 | In a circuit a coil of resistance ( 2 Omega ), then magnetic flux charges from 2.0 ( W ) b to 10.0 ( W b ) in 0.2 sec. The charge flow in the coil during this time is: ( mathbf{A} cdot 5.0 C ) в. ( 4.0 C ) c. ( 1.0 C ) D. ( 0.8 C ) |
12 |

1026 | Fill in the blanks. The type of electric current that changes its direction twice during one cycle of the dynamo is called |
12 |

1027 | Current in a circuit falls from ( 5.0 A ) to ( 0.0 A ) in ( 0.1 s . ) If an average emf of ( 200 V ) induced, find an estimate of the selfinductance of the circuit. |
12 |

1028 | R 14 76. Two identical inductance carry currents that vary with time according to linear laws (as shown in figure). In which of two inductance is the self- induction emf greater? (a) 1 (b) 2 (c) same (d) data are insufficient to decide |
12 |

1029 | A conducting rod of length ( l ) falls vertically under gravity in a region of uniform magnetic field ( vec{B} ). The field vectors are inclined at an angle ( boldsymbol{theta} ) with the horizontal as shown in figure. If the instantaneous velocity of the rod is ( boldsymbol{v} ) the induced emf in the rod ( a b ) is: ( mathbf{A} cdot B l v ) B. ( B l v cos theta ) c. ( B l v sin theta ) D. zero |
12 |

1030 | The equivalent quantity of mass in electricity is : A. current B. self inductance c. potential D. charge |
12 |

1031 | A field of strength ( 5 times 10^{4} / pi ) ampere turns / meter acts at right angles to the coil of 50 turns of area ( 10^{-2} m^{2} . ) The coil is removed from the field in 0.1 second. Then the induced e.m.f. in the coil is : A . ( 0.1 V ) B. ( 0.2 V ) c. ( 1.96 V ) ( mathbf{D} cdot 0.98 V ) |
12 |

1032 | Assertion Two coaxial conducting rings of different radii are placed in space. The mutual inductance of both the rings is maximum if the rings are also coplanar Reason For two coaxial conducting rings of different radii, the magnitude of magnetic flux in one ring due to current in the other is maximum when both the rings are coplanar. 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 |

1033 | What do you mean by electric generator? Differentiate between a.c. and d.c generators on the basis of construction. |
12 |

1034 | ( begin{array}{ll}text { Table } 1 & text { Table } 2 \ begin{array}{l}text { (a) If current is } \ text { increased }end{array} & begin{array}{l}text { (p) Induced current in } \ text { loop is clockwise }end{array} \ begin{array}{l}text { (b) If current is } \ text { decreased }end{array} & begin{array}{l}text { (q) Induced current in } \ text { loop is anticlockwise }end{array} \ begin{array}{l}text { (c) If loop is moved } \ text { away from the wire }end{array} & begin{array}{l}text { (r) Wire will attract the } \ text { loop }end{array} \ begin{array}{l}text { (d) If loop is moved } \ text { towards the wire }end{array} & begin{array}{l}text { (s) wire will repel the } \ text { loop }end{array}end{array} ) A square loop is placed near a long straight current carrying wire as shown, match the following table 1 ( A cdot a-q, s ; b-p, r ; c-q, s ; d-p, r ) B. ( a-p, r ; b-q, s ; c-p, r ; d-q, s ) c. ( a-q, s ; b-p, r ; c-q, r ; d-p, q ) D. ( a-q, s ; b-p, r ; c-p, r ; d-q, s ) |
12 |

1035 | Q Type your question y ( D-D_{0}lfloorbar{a} / ) kappa. bo 14 ( d ) is placed with it’s edges on the ( x ) and ( y ) axis. The loop is moved with a constant velocity ( vec{v}=v_{0} hat{i} . ) The emf induced in the loop is : A ( cdot B_{0} v_{0} d ) B. ( frac{B_{0} v_{0} d^{2}}{2 a} ) c. ( frac{B_{0} v_{0} d^{3}}{a^{2}} ) D. ( frac{B_{0} v_{0} d^{2}}{a} ) |
12 |

1036 | The figure shows a conducting ring of radius ( R ). A uniform steady magnetic field ( B ) lies perpendicular to the plane of the ring in a circular region of radius ( r(<R) . ) If the resistance per unit length of the ring is ( lambda ), then the current induced in the ring when its radius gets doubled is ( ^{A} cdot frac{B R}{lambda} ) B. ( frac{2 B R}{lambda} ) ( mathbf{c} . ) zero D. ( frac{B r^{2}}{4 R lambda} ) |
12 |

1037 | A coil of area ( 5 mathrm{cm}^{2} ) with 20 turns is kept under the magnetic field of ( 10^{3} ) Gauss. Normal to the plane of coil makes an angle ( 30^{circ} ) with the magnetic field. The flux through the coil is A ( cdot 6.67 times 10^{-4} mathrm{Wb} ) B. ( 3.2 times 10^{-5} mathrm{Wb} ) ( mathbf{c} cdot 5.9 times 10^{-4} W b ) D. ( 8.65 times 10^{-4} W b ) |
12 |

1038 | The north pole of a bar magnet is moved towards a coil along the axis passing through the centre of the coil when viewed in the direction of the motion of the magnet direction of induced current is: A. clockwise B. Anti – Clockwise c. No current in the coil D. Either clockwise or anti-clockwise |
12 |

1039 | Q Type your question parallel smooth conducting rails. A conducting rod lies on these fixed horizontal rails and a uniform constant magnetic field ( B ) exists perpendicular to the plane of the rails as shown in the figure. If the rod is given a velocity ( v ) and released as shown in figure, it will stop after some time. The total work done by magnetic field is negative STATEMENT – 2 : If force acts opposite to direction of velocity its work done is negative. |
12 |

1040 | Lenz’s law is a consequence of law of conservation of A. momentum в. energy c. charge and mass D. angular momentum |
12 |

1041 | Two coils ( A ) and ( B ) are separated by a certain distance. If a current of ( 4 mathrm{A} ) flows through ( A, ) a magnetic flux of ( 10^{-3} ) Wh passes through B (no current through B).If no current passes through A and a current of 2 A passes through ( B ), then the flux through ( A ) is then A ( .5 times 10^{-3} ) B . ( 4 times 10^{-4} ) c. ( 5 times 10^{-4} ) D. ( 2 times 10^{-3} ) |
12 |

1042 | A body enters in MRI machine in 10 sec If the magnetic field is ( 1.5 T ) and circumference of MRI machine is ( 0.9 m ) then find out emf induced in the body. A . ( 0.96 V ) B. ( 9.6 V ) c. ( 9.6 m V ) D. ( 96 m V ) |
12 |

1043 | When a coil of cross-sectional area ( A ) and number of turns N is rotated in a uniform magnetic field B with angular velocity ( omega, ) then the maximum emf induced in the coil will be A. BNA в. ( frac{B a omega}{N} ) c. BNAomega D. zero |
12 |

1044 | A circular coil of ( n ) turns is kept in a uniform magnetic field such that the plane of the coil is perpendicular to the field. The magnetic flux associated with the coil is now ( phi . ) Now the coil is opened and made into another circular coil of twice the radius of the previous coil and kept in the same field such that the plane of the coil is perpendicular to the field. The magnetic flux associated with this coil now is: ( A cdot phi ) B. 2 ( c cdot frac{phi}{4} ) D. ( frac{phi}{2} ) |
12 |

1045 | A small coil is introduced between the poles of an electromagnet so that its axis coincides with the magnetic field direction. The cross-sectional area of the coil is equal to ( S=3.0 m m^{2}, ) the number of turns is ( N=60 . ) When the coil turns through ( 180^{circ} ) about its diameter, a galvanometer connected to the coil indicates a charge ( boldsymbol{q}=mathbf{4 . 5} boldsymbol{mu} boldsymbol{C} ) flowing through it. Find the magnetic induction magnitude between the poles, provided the total resistance of the electric circuit equals ( R=40 Omega ) |
12 |

1046 | 73 PO is an infinite current carrying conductor. AB and CD are smooth conducting rods on which a conductor EF moves with constant velocity v as shown. The force needed to maintain constant speed of EF is. PL ano I EF ol B To a OJĂ w |
12 |

1047 | Weber ( / m^{2} ) is equal to A. dyne B. tesla c. watt D. henry |
12 |

1048 | A rod of length ( 50 mathrm{cm} ) moves with a speed of ( 10 mathrm{cm} / mathrm{s} ), in a uniform magnetic field of strength ( 10 G ) at an angle of ( 30^{circ} ) with the field. The emf induced across the ends of the rod is : A. 5000 CGS unit B. ( 2500 mathrm{CGS} ) unit c. 7500 CGS unit D. ( 1000 mathrm{CGS} ) unit |
12 |

1049 | toppr OGII Q Type your question ( +y^{prime}=4 ) where ( x ) and ( y ) are in meters. wire frame ( A_{1} A_{2} A_{4} A_{3} A_{1} ) is placed in the magnetic field as shown. Segment ( mathbf{A} ) ( A_{2} ) and ( A_{3} A_{4} ) are identical quarter circles parallel to each other with axis along z-axis.The induced current flowing in the wire frame is equal to : (The total length of the loop of wire frame is ( 10 mathrm{m}, ) radius of arc ( mathrm{A}_{3} mathrm{A}_{4} ) and arc ( A_{1} A_{2} ) is ( 1 mathrm{m} ) each and resistance per unit length is ( 1 Omega / m ) ): ( A cdot ) zero В. ( frac{B_{0} pi}{10} ) c. ( frac{B_{0} pi}{5} ) D. ( frac{B_{0} pi}{20} ) |
12 |

1050 | If a magnet is dropped through a vertical hollow copper tube, then? A. The time taken to reach the ground is longer than the time taken, if the tube was made out of plastic B. The magnet will get attracted and stick to the copper tube C. The time taken to reach the ground is longer than the time taken, if the tube was made out of stainless steel D. The time taken to reach the ground does not depend on the radius of the copper tube E. The magnet will be repelled away by the tube |
12 |

1051 | A circular loop of radius ( r ) is placed at the centre of current carrying conducting square loop of side ( a . ) If both loops are coplanar and ( a>>r, ) then the mutual inductance between the loops will be: A ( frac{mu_{0} r^{2}}{2 sqrt{2}(a)} ) B. ( frac{mu_{0} r^{2}}{4 a} ) c. ( frac{2 sqrt{2} mu_{0} r^{2}}{pi a} ) D. ( frac{mu_{0} r^{2}}{4 sqrt{2} a} ) |
12 |

1052 | The magnetic flux linked with a coil setisfies the relation ( phi=4 t^{2}+6 t+ ) ( 9 W b, ) where ( t ) is the time (in ( s ) ). The emf indused in the coilat ( t=2 s ) is, (in ( mathbf{V}) ) ( mathbf{A} cdot 22 ) B . 18 c. 16 D. 40 |
12 |

1053 | A current of ( 3.14 A ) flows in an infinitely long wire with cross section in the form of a semicircular ring of radius ( 5 mathrm{cm} ) The magnitude of magnetic induction on its axis is : A . ( 8.0 times 10^{-6} T ) В. ( 1.6 times 10^{-5} T ) c. ( 2.0 times 10^{-5} T ) D. ( 4.0 times 10^{-6} T ) |
12 |

1054 | For a coil having ( L=2 m H, ) current flow through it is ( I=t^{2} e^{-t} ) then the time at which emf becomes zero: ( mathbf{A} cdot 2 sec ) B. 1 sec ( mathbf{c} cdot 4 sec ) D. 3 sec |
12 |

1055 | What is the unit for EMF? A. Ampere B. Potential c. watt D. volt |
12 |

1056 | What is the Sl unit of self-inductance? A. Henry B. Tesla c. weber D. Gauss |
12 |

1057 | If a current carrying coil is close to a magnet and both are moving with the same speed in same direction, what is the effect on induced current? A. Induced current increases B. Induced current decreases c. Induced current flows to oppose motion D. Induced current remains equal to zero |
12 |

1058 | by 6. A thin semicircular conducting ring of radius R is falling with its plane vertical in a horizontal magnetic induction B B. At the position MNQ, the speed of the ring is v and the potential difference developed across the ring is (a) zero (b) ByaR-/2 and Mis at higher potential (c) TRBv and Q is at higher potential (d) 2RBv and Q is at higher potential man of the camicircular ring |
12 |

1059 | Assertion When the electric current in a loop of wire changes, the changing current creates a changing magnetic field. Reason Magnetic field lines of a circular loop of wire is same as a magnet. 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 |

1060 | Current ( i ) is flowing in each of the two similar coaxial circular coils in the same direction. If the loops are moved towards each other, the following phenomenon will happen: A. current in each loop will remain same B. current in each loop will increase c. current in each loop will decrease D. current in one loop will increase and that in another loop will decrease |
12 |

1061 | An alternating current can be produced by: A. transformer B. generator c. turbine D. electric motor |
12 |

1062 | (i) Define mutual inductance. (ii) A pair of adjacent coils has a mutual inductance of 1.5 H. If the current in one coil changes from 0 to ( 20 A ) in ( 0.5 s, ) what is the change of flux linkage with the other coil? |
12 |

1063 | According to Faraday’s law, the total charge induced in a conductor that is moved in a magnetic field depends upon A. Initial magnetic flux B. Final magnetic flux c. Rate of change of magnetic flux D. change in magnetic flux |
12 |

1064 | In a circuit the coil of a choke: A. Decreases the current B. Increases the current C. Has high resistance to D. C. circuit D. No effect with the current |
12 |

1065 | Figure shows a conducting loop placed near a long straight wire carrying a current ( i ) as shown. If the current increases continuously, then the direction of the induced current in the loop is clockwise. True or false? |
12 |

1066 | The emf induced in the circuit is A. ( 125 mu V ) B. ( 250 mu V ) c. ( 100 mu V ) ( mathbf{D} cdot 300 mu V ) |
12 |

1067 | Current 1 in a long ( 4 y- ) axis is paced through a square metal frame of side ( 2 a ) oriented in the ( y-z ) p[lane a shown. The linear mass density of the frame is ( lambda . ) A uniform magnetic field ( B ) is now switched on along ( x- ) axis. Then the instantaneous angular acceleration of the frame will be: A ( cdot frac{4 I B}{lambda_{n}} ) В. ( frac{12 I B}{lambda a} ) c. ( frac{4 I B}{3 lambda a} ) ( D ) |
12 |

1068 | A coil of wire of a certain radius has 100 turn and a self-inductance of 15 mH. The self-inductance of a second similar coil of 500 turns will be : ( mathbf{A} cdot 75 m H ) в. 375 тН c. ( 15 m H ) D. none of these |
12 |

1069 | A copper ring is moved towards the north pole of a bar magnet. Then A. the ring will not be affected B. the ring all tend to get warm c. an alternating current will flow in the ring D. the ring will be positively charged |
12 |

1070 | On what principle ( A C ) generator works? | 12 |

1071 | Draw a labelled diagram of an alternating current Generator. Determine the induced electromotive force by the rotation of coil in it. |
12 |

1072 | If ( N ) is the number of turns in a circular coil then the value of self inductance varies as A . ( N^{0} ) в. ( N ) ( c cdot N^{2} ) D. ( N^{-2} ) |
12 |

1073 | Derive the expression for motional EMF induced in a conductor moving in a uniform magnetic field. | 12 |

1074 | What is the effect on self inductance of a solenoid, if a core of soft iron is placed in it? |
12 |

1075 | In the figure magnetic field points into the plane of paper and the conducting rod of length ( l ) is moving in this field such that the lowest point has a velocity ( boldsymbol{v}_{1} ) and the topmost point has the velocity ( v_{2}left(v_{2}>v_{1}right) . ) The emf induced is given by: [ begin{array}{cccc} x & x & x & x \ x & x & x_{2} & x \ x & x & x & x \ x & vec{x} & v_{1} & x & x end{array} ] ( mathbf{A} cdot B v_{1} l ) B. ( B v_{2} l ) ( c ) [ frac{1}{2} Bleft(v_{2}+v_{1}right) l ] D. [ frac{1}{2} Bleft(v_{2}-v_{1}right) l ] |
12 |

1076 | Lenz’s law is in accordance with the law of conservation of A. electric current B. energy c. electro motive force D. electric charge |
12 |

1077 | The voltage induced across a certain coil is ( 200 m V . A 120 Omega ) resistor is connected to the coil terminals. The induced current is A ( .1 .7 m A ) в. ( 16 m A ) c. ( 12 m A ) D. ( 120 m A ) |
12 |

1078 | A long coaxial cable consists of two thin-walled conducting cylinders with inner radius ( 2 c m ) and outer radius ( 8 c m ) The inner cylinder carries a steady current ( 0.1 A ), and the outer cylinder provides the return path for that current. The current produces a magnetic field between the two cylinders. Find the energy stored in the magnetic field for length ( 5 m ) of the cable. Express answer in ( n J ) (use ( ln 2=0.7) ) |
12 |

1079 | A cnarge + ( ell ) Is locatea somewnere inside a vertical cone such that the dept of the charge from the free surface of the cone is ( H . ) It is formed that the flux associated with the cone with thw curved surface is ( frac{3 Q}{5 epsilon_{0}} ) If the charge is raised vertically through a height ( 2 H ) then the flux through the curved surface is |
12 |

1080 | and conducting (c) 1.001 71. A simple pendulum with bob of mass m and condu wire of length L swings under gravity through an anal 20. The earth’s magnetic field component in the directi perpendicular to swing is B. Maximum potential differen induced across the pendulum is (a) 2BL sin)(82)2 (6) BL sin (8L) (C) BLsin)(8L)2 (a) BLsin) (8L)? |
12 |

1081 | Fill in the blanks. In Flemings rule the middle finger indicates the direction of |
12 |

1082 | Who gave the principle of Electromagnetic induction? A. Volta B. Oerstead c. Ampere D. Faraday |
12 |

1083 | A conducting straight wire ( P Q ) of length is fixed along a diameter of a nonconducting ring as shown in the figure. The ring is given a pure rolling motion on a horizontal surface such that its centre of mass has a veleocity ( v ). There exists a uniform horizontal magnetic field ( B ) in horizontal direction perpendicular to the plane of ring. The magnitude of induced emf in the wire ( P Q ) at the position shown in the figure will be : A. ( B v ) в. 2 Ву c. ( 3 B v l / 2 ) D. zer |
12 |

1084 | A coil of insulated copper wire is connected to a galvanometer. What would happen if a bar magnet is (i) Pushed into the coil? A. The galvanometer shows deflection B. The galvanometer do not show any deflection c. Current increases inside the coil D. none |
12 |

1085 | The coefficient of mutual induction between two coils is ( 4 mathrm{H} ). If the current in the primary reduces from 5 A to zero in ( 10^{-3} ) second then the induced emf in the secondary coil will be A ( cdot 10^{4} v ) B . ( 25 times 10^{3} mathrm{V} ) C ( cdot 2 times 10^{4} mathrm{V} ) ( mathbf{D} cdot 15 times 10^{3} mathbf{v} ) |
12 |

1086 | Assertion: Magnetic flux is a vector quantity Reason: Value of magnetic flux can be positive, negative or zero A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion. B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion c. Assertion is true but Reason is false D. Assertion is false but Reason is true |
12 |

1087 | A conducting loop rotates with constant angular velocity about its fixed diameter in a uniform magnetic field, whose direction is perpendicular to that fixed diameter This question has multiple correct options A. The emf will be maximum at the moment when flux is zero B. The emf will be 0 at the moment when flux is maximum C. The emf will be maximum at the moment when plane of the loop is parallel to the magnetic field D. The phase difference between the flux and the emf is ( pi / 2 ) E . answer required |
12 |

1088 | Distinguish between electric motor and electric generator | 12 |

1089 | A closed coil consists of 500 turns on a rectangular frame of area ( 4.0 mathrm{cm}^{2} ) and has a resistance of 50 ohms. The coil is kept with its plane perpendicular to a uniform magnetic field of ( 0.2 mathrm{wb} / mathrm{m}^{2} ) the amount of charge flowing through the coil if it is turned over. (rotated through ( 180^{0} ) ): A ( cdot 1.6 times 10^{-3} mathrm{c} ) B. ( 16 times 10^{-3} mathrm{C} ) c. ( 0.16 times 10^{-3} mathrm{c} ) D. ( 160 times 10^{-3} mathrm{c} ) |
12 |

1090 | Through an inductance coil of ( boldsymbol{L}= ) ( 0.2 H, ) an ac current of 2 ampere is passed first with frequency ( n_{1} ) and then with frequency ( n_{2} ). The ratio of the maximum value of induced emf ( left(e_{1} / e_{2}right) ) in the coil, in the two cases is A. ( n_{1} / n_{2} ) в. ( n_{2} / n_{1} ) c. ( n_{1}^{2} / n_{2}^{2} ) D ( cdot n_{2}^{2} / n_{1}^{2} ) |
12 |

1091 | Assertion An emf ( vec{E} ) is induced in a closed loop where magnetic flux is varied. The induced ( vec{E} ) is not a conservative field. Reason The line integral ( overrightarrow{boldsymbol{E}} cdot boldsymbol{d l} ) around the closed loop is nonzero. 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 |

1092 | The rate of change of current needed to induce an emf of ( 8 V ) in ( 0.1 H ) coil is A . ( 0.8 A / s ) В. ( 0.125 A / s ) c. ( 80 A / s ) D. ( 8 A / s ) |
12 |

1093 | A loop made of straight edges has six corners at ( A(0,0,0), B(L, 0,0), c(L, L, 0) ) ( mathrm{D}(0, mathrm{L}, 0), mathrm{E}(0, mathrm{L}, mathrm{L}) ) And ( F(0,0, mathrm{L}) ) A magnetic field ( bar{B}=B_{0}(hat{i}+hat{k}) T ) is present in the region.The flux passing through the loop ABCDEFA (in the order) is A. ( B_{0} L^{2} W b ) В ( cdot 2 B_{0} L^{2} W b ) c. ( sqrt{2} B_{0} L^{2} W b ) D. ( 4 B_{0} L^{2} W b ) |
12 |

1094 | The magnetic induction at the centre 0 is? |
12 |

1095 | 8. A thin circular ring of area A is perpendicular to uniform magnetic field of induction B. A small cut is made in the ring and a galvanometer is connected across the ends such that the total resistance of circuit is R. When the ring is suddenly squeezed to zero area, the charge flowing through the galvanometer is (a) BR (b) AB A (c) ABR R (d) B-A/R2 |
12 |

1096 | A ( 1.2 mathrm{m} ) wide railway track is parallel to magnetic meridian. The vertical component of earth’s magnetic field is 0.5 Gauss. When a train runs on the rails at a speed of ( 60 mathrm{Km} / mathrm{hr} ), then the induced potential difference the ends of its axle will be ( A cdot 10^{-4} v ) B . ( 2 times 10^{-4} mathrm{V} ) c. ( 10^{-3} mathrm{v} ) D. zero |
12 |

1097 | Henry, the Sl unit of inductance can be written as : A. weber ampere- B. volt second ampere ( ^{-1} ) c. joule ampere ( ^{-1} ) D. ohm s ( ^{-1} ) |
12 |

1098 | Two sources of equal emf are connected to an external resistance R. The internal resistances of two sources are ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2}left(boldsymbol{R}_{2}>boldsymbol{R}_{1}right) . ) If the potential difference across the source having internal resistance ( R_{2} ) is zero, then; в. ( R=R_{1} R_{2} /left(R-R_{1}right) ) C. ( R=R_{2} timesleft(R_{1}+R_{2}right) /left(R_{2}-R_{1}right) ) D. ( R=R_{2}-R_{1} ) |
12 |

1099 | A square loop of side a lying a perpendicular magnetic field to its plane is changed to a circle. If change occusrs in ( t ) seconds in magnetic field ( B ) tesla, the induced emf is A ( cdot frac{4}{pi} frac{B a^{2}}{t} ) B. ( frac{B a^{2}}{t} ) c. ( frac{B a^{2}}{t}left[frac{4}{pi}-1right] ) D. zero |
12 |

1100 | * Explain the construction and working of an electric generator (AC). Draw a neat diagram and label it. | 12 |

1101 | An electric generator actually acts as: A. source of electric charge B. source of heat energy c. an electromagnet D. a converter of energy |
12 |

1102 | 21. A coil is suspended in a uniform magnetic field, with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating; it is very difficult to stop. But if an aluminium plate is placed near to the coil, it stops. This is due to (a) developement of air current when the plate is placed (b) induction of electrical charge on the plate (c) shielding of magnetic lines of force as aluminium is a paramagnetic material (d) electromagnetic induction in the aluminium plate giving rise to electromagnetic damping (AIEEE 2012 |
12 |

1103 | 10 TUU 29. Two identical cycle wheels (geometrically) have differen number of spokes connected from center to rim. One is having 20 spokes and the other having only 10 (the rim and the spokes are resistanceless). One resistance of value Ris connected between center and rim. The current in R will be (a) double in the first wheel than in the second wheel (b) four times in the first wheel than in the second wheel (c) will be double in the second wheel than that of the first wheel (d) will be equal in both these wheels 1 fredinu D follo |
12 |

1104 | A coil of area ( 80 mathrm{cm}^{2} ) and number of turns 50 is rotating about an axis perpendicular to a magnetic field of 0.05 Tesla at 2000 rotations per minute The maximum value of emf induced in ¡it will be A . ( 200 pi ) volt в. ( frac{10 pi}{3} ) volt c. ( frac{4 pi}{3} ) volt D. ( frac{2}{3} ) volt |
12 |

1105 | A flux of ( 1 m W b ) passes through a strip having an area ( A=0.02 m^{2} . ) The plane of the strip is at an angle of ( 60^{circ} ) to the direction of a uniform field B. The value of B is: A . ( 0.1 T ) B. ( 0.058 T ) c. ( 4.0 m T ) D. None of the above |
12 |

1106 | The maximum emf induced in the coil will be ( A ) ( ^{text {В } cdot} frac{pi^{2} N B_{0}left(a^{2}+a b+b^{2}right)}{T} ) ( c ) ( D ) |
12 |

1107 | A flat coil, ( C ) of ( n ) turn, area ( A ) and resistance ( R ), is placed in a uniform magnetic field of magnitude ( boldsymbol{B} ). The plane of the coil is initially perpendicular to ( B ). The coil is rotated by an angle ( theta ) about a diameter and charge of amount ( Q ) flows through it. The plane of the coil is initially kept parallel to ( B ). The coil is rotated by an angle ( theta ) about the diameter perpendicular to ( B ) and charge of amount ( Q ) flows through it.Choose the correct alternatives This question has multiple correct options A ( cdot theta=90^{circ}, Q=(operatorname{Ban} / R) ) B . ( theta=180^{circ}, Q=(2 B a n / R) ) C ( cdot theta=180^{circ}, Q=0 ) D . ( theta=360^{circ}, Q=0 ) E. answer required |
12 |

1108 | A uniform field of induction ( B ) is changing in magnitude at a constant rate ( d B / d t . ) You are given a mass ( m ) of copper which is to be drawn into a wire of radius ( r ) and formed into a circular loop of radius ( R ). Show that the induced current in the loop does not depend on the size of the wire of the loop. Assuming ( B ) perpendicular the loop |
12 |

1109 | The change in magnetic field lines in a coil is the cause of induced electric current in it. Name the underlying phenomenon. |
12 |

1110 | The conducting rod ( a b ), as shown in figure makes contact with metal rails ( c a ) and ( d b . ) The apparatus is in a uniform magnetic field of ( 0.800 T ), perpendicular to the plane of the figure. If the resistance of the circuit ( a b d c ) is ( 1.50 Omega ) (assumed to be constant), find the force (magnitude and direction) required to keep the rod moving to the right with a constant speed of ( 7.50 m / s . ) You can ignore friction. |
12 |

1111 | Lenz’s law is based on conservation of A. charge B. mass c. energy D. momentum |
12 |

1112 | A closed coil having 100 turns is rotated in a uniform magnetic field ( B=4.0 times ) ( 10^{-4} T ) about a diameter which is perpendicular to the field. The angular velocity of rotation is 300 revolution per minute. The area of the coil is ( 25 mathrm{cm}^{2} ) and its resistance is ( 4.0 Omega . ) Find (a) the average emf developed in half a turn from a position where the coil is perpendicular to the magnetic field, (b)the average emf in full turn and the net charge displaced in part (a). |
12 |

1113 | Assertion(A): The possibility of an electric bulb fusing is higher at the time of switching on and off Reason(R): Inductive effects produce a large current at the time of switch-on and switch-off. A. Both A and R are individually true and R is the correct explanation of A B. Both A and R are individually true but R is not the correct explanation of ( A ) c. A is true but R is false D. Both A and R are false |
12 |

1114 | DD OUT) 16 Two coaxial solenoids are made by winding a thin insulated wire over a pipe of cross-sectional area A = 10 cm’ and length 20 cm. If one of the solenoids has 300 turns and the other 400 turns, their mutual inductance is (Mo = 4 ntx 10-T m/A) (a) 4.78 1 x 10-H (b) 2.4 t x 104 H (c) 2.4 A x 10-H (d) 4.8 x 104 H (AIEEE 2007) |
12 |

1115 | Derive Faradays law of induction from law of conservation of energy. | 12 |

1116 | A copper disc of radius 0.1 m rotated about its centre with 10 revolutions per second in a uniform magnetic field of 0.1 tesla with it’s plane perpendicular to the field. The e.m.f. induced across the radius of disc is: A ( cdot frac{pi}{10} ) volt в. ( frac{2 pi}{10} ) volt c. ( pi times 10^{-2} ) volt D. 2 ( pi times 10^{-2} ) volt |
12 |

1117 | ( frac{sqrt{3}}{frac{1}{4}} ) | 12 |

1118 | The armature of a generator of resistance ( 1 Omega ) is rotated at its rated speed and produces ( 125 V ) without load and ( 115 V ) with full load. The current in the armature coil is ( mathbf{A} cdot 240 A ) в. ( 10 A ) ( c .1 A ) D. ( 2 A ) |
12 |

1119 | For the situation described in figure the magnetic field changes with time ( operatorname{according} ) to ( boldsymbol{B}=left(mathbf{2} . mathbf{0 0} boldsymbol{t}^{3}-mathbf{4 . 0 0} boldsymbol{t}^{2}+right. ) 0.8)( T ) and ( r_{2}=2 R=5.0 mathrm{cm} ) a) Calculate the force on an electron located ( a t P_{2} ) at ( t=2.00 s ) b) What are the magnitude and direction of the electric field at ( P_{1} ) when ( t=3.00 mathrm{s} ) and ( r_{1}=0.02 m ) |
12 |

1120 | Derive the expression for the self inductance of a long solenoid of cross sectional area ( A ) and length ( l ), having ( n ) turns per unit length. |
12 |

1121 | ROV WWW 17. A rectangular loop has a sliding connector PQ of length 1 and resistance R ohm and it is moving with a speed vas shown. The set up is placed in a uniform magnetic field going into the plane of the paper. The three currents 11, 12, and I are (a) I, = – 12 = PI = 2B (b) 11 = 1 = Bk 1 = 2 BRD (©) I, = 12 = 1 = Bly (d) 1, = 12 = BR 1 = BR (AIEEE 2010) |
12 |

1122 | The magnetic needle of a tangent galvanometer is deflected at an angle 30 due to a magnet. The horizontal component of earth’s magnetic field ( 0.34 times 10^{-4} T ) is along the plane of the coil. The magnetic intensity is: A . ( 1.96 times 10^{-4} T ) B . ( 1.96 times 10^{-5} T ) c. ( 1.96 times 10^{4} T ) D. ( 1.96 times 10^{5} T ) |
12 |

1123 | A coil of self-inductance ( L ) is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when : A. frequency of the AC source is decreased B. number of turns in the coil is reduced C . a capacitance of reactance ( X_{C}=X_{L} ) is included in the same circuit D. an iron rod is inserted in the coil |
12 |

1124 | In faraday’s experiment current in not produced in A. the coil is moved and magnetic is stationary B. the magnetic is moved the coil is stationary C. both coil and magnetic are moved in same direction with same speed D. both coil and magnet stationary |
12 |

1125 | what emf ( E ) of the source must be applied to maintain the required current? Consider the total resistance of the circuit to be constant and equal to ( R . ) Disregard the inductance of the circuit. |
12 |

1126 | The magnetic flux linked with a coil at any instant ( t ) is given by the equation ( phi=5 t^{3}-100 t+300 . ) The magnitude of emf induced in the coil after ( 3 s ) is A . ( 10 V ) в. ( 20 V ) ( c .35 V ) D. ( 70 V ) |
12 |

1127 | 10. A rectangular loop with a sliding connector of length 1 = 1.0 m is situated in a uniform magnetic field B – perpendicular to the plane of loop. Resistance of connect is r= 2 12. Two resistance of 6 32 and 3 32 are connected as shown in figure. The external force required to keep the connector moving with a constant velocity v = 2 m/s is 230 (a) 6N (c) 2N (b) 4N (d) IN ca Minolemt |
12 |

1128 | The magnetic flux through a circuit of resistance ‘R’ changes by an amount ( Delta Phi ) at a time ( Delta t . ) Then the total quantity of electric charge ( Q ) that passes any point in the circuit during the time ( Delta t ) is represented by ( ^{mathbf{A}} cdot Q=frac{Delta Phi}{R} ) в. ( Q=frac{Delta Phi}{Delta t} ) c. ( Q=R cdot frac{Delta Phi}{Delta t} ) D. ( Q=1 R cdot frac{Delta Phi}{Delta t} ) |
12 |

1129 | energy is converted into energy by an electric generator. A. mechanical, mechanical B. electrical, electrical c. electrical, mechanical D. mechanical, electrical |
12 |

1130 | A uniform magnetic field is restricted within a region of radius ( r . ) The magnetic field changes with time at a rate ( frac{d vec{B}}{d t} . ) Loop 1 of radius ( R>r ) enclose the region ( r ) and loop 2 of radius ( R ) is outside the region of magnetic field as shown in the figure below. Then the e.m.f. generated is : ( A ) B. Zero in loop 1 and zero in loop 2 c. ( quad frac{d vec{B}}{d t} pi r^{2} ) in loop 1 and ( -frac{d vec{B}}{d t} pi r^{2} ) in loop 2 D. ( -frac{d vec{B}}{d t} pi R^{2} ) in loop 1 and zero in |
12 |

1131 | The magnetic flux linked with a coil varies as ( phi=3 t^{2}+4 t+9 . ) what is the magnitude of the emf at ( t=2 s ? phi ) is in Wh. |
12 |

1132 | (AIEEE 2004 ically about 5 radians per second. 8. A metal conductor of length 1 m rotates vertically one of its ends at an angular velocity 5 radians per If the horizontal component of the earth’s magnetic field 0.2 x 10-4 T, then the emf developed between the two ends of the conductor is (a) 5 uV (b) 50 uV (c) 5 mV (d) 50 mV (AIEEE 2004 |
12 |

1133 | A uniform but time varying magnetic field ( mathrm{B}=boldsymbol{K}_{1} boldsymbol{K}_{2} boldsymbol{t} ) where ( boldsymbol{K}_{1} & boldsymbol{K}_{2} ) are positive constants and t is time (in seconds), is applied perpendicular to the plane of a circular loop of radius a and resistance R.Find the total charge (in coulomb) that will pass through any point of the loop by the time ( mathrm{B} ) becomes zero. [Given a ( =2 mathrm{m}, mathrm{R}=pi Omega, K_{1} ) ( =2 T] ) |
12 |

1134 | toppr ( E ) Q Type your question field at ( t=0 ) and completely emerges out at ( t=T ) sec. The current in the ring varies as A. B. ( c ) D. |
12 |

1135 | Use Lenz’s law to determine the direction of induced current in the situations described by Fig.(a) ( A ) wire of irregular shape turning into a circular shape;(b) A circular loop being deformed into a narrow straight wire. |
12 |

1136 | A rectangular loop is placed near a current carrying straight wire as shown in figure. If the loop is rotated about an axis passing through one of its sides, find the direction of induced current in the loop. |
12 |

1137 | Q Type your question velocity ( v ) out of a region of uniform magnetic field whose magnitude is ( boldsymbol{B} ) The plane of loop and the velocity are both perpendicular to ( vec{B} ). Then the electrical power in the circular loop at the instant when the arc (of circular loop) outside the region of magnetic field subtends an angle ( frac{pi}{3} ) at centre of the loop is ( ^{mathrm{A}} cdot frac{B^{2} a^{2} v^{2}}{R} ) B. ( frac{2 B^{2} a^{2} v^{2}}{R} ) c. ( frac{B^{2} a^{2} v^{2}}{2 R} ) D. None of thes |
12 |

1138 | A conducting rod of mass ( m ) and length is free to move without friction on two parallel long conducting rails, as shown below. There is a resistance ( R ) across the rails. In the entire space around, there is a uniform magnetic field ( boldsymbol{B} ) normal to the plane of the rod and rails. The rod is given an impulsive velocity ( boldsymbol{v}_{0} ) Finally, the initial energy ( frac{1}{2} m v_{0}^{2} ) A. Will be converted fully into heat energy in the resistor B. Will enable rod to continue to move with velocity ( v_{0} ) since the rails are frictionless c. will be converted fully into magnetic energy due to induced current D. Will be converted into the work done against the magnetic field |
12 |

1139 | A rectangular coil is rotated in a uniform magnetic field about an axis passing through its centre and perpendicular to the direction of the field, then the induced voltage in the coil is directly proportional to the: A. Number of turns in the coil B. Area of the coil c. Angular speed of the coil D. All of these |
12 |

1140 | Read the following statements and answer whether the given statement is true or false.
The Lenz’s law is consistent with the law |
12 |

1141 | In an AC generator, a coil with ( N ) turns, all of the same area ( A ) and total resistance ( boldsymbol{R}, ) rotates with frequency in a magnetic field ( B ). The maximum value of emf generated in the coil is: ( mathbf{A} . N . A . B ) в. ( N . A . B . R ) ( ^{mathbf{C}} cdot frac{1}{10} N cdot A cdot B ) D. ( frac{1}{10} N . A . B . R ) |
12 |

1142 | Draw a diagram of AC generator and describe it. Derive an expression for instantaneous value of induced emf | 12 |

1143 | In a uniform magnetic field of induction ( B ) a wire in the form of a semicircle of radius ( r ) rotates about the diameter of the circle with angular frequency ( omega . ) the axis of rotation is perpendicular to the field. If the total resistance of the circuit is ( R ) the mean power generated per period of rotation is A ( cdot frac{B pi r^{2} omega}{2 R} ) B. ( frac{left(B pi r^{2} omegaright)^{2}}{8 R} ) c. ( frac{(B pi r omega)^{2}}{2 R} ) D. ( frac{left(B pi r omega^{2}right)^{2}}{8 R} ) |
12 |

1144 | A rectangular loop of resistance ( mathrm{R} ) and sides I and ( x ) is pulled out of a uniform magnetic field B with a steady velocity v. The necessary force F required for maintaining uniform velocity of withdrawal is A. ( B x l^{2} v / R ) B ( cdot B^{2} l^{2} v / R ) c ( cdot B^{2} l^{2} v^{2} / R ) D. zero |
12 |

1145 | According to which law current ( boldsymbol{I} ) flowing in the rod must vary for the rod to rotate at a constant angular speed. Begin to measure the time from the instant when the rod is in its right-hand horizontal position. Consider the current to be positive when it flows from the axis of rotation toward the ring. | 12 |

1146 | A magnet is moved towards a coil (i) quickly (ii) slowly, then the induced e.m.f. is A. larger in case (i) B. smaller in case (i) c. equal in both the cases D. larger or smaller depending upon the radius of the coil |
12 |

1147 | The number of turns in an air core solenoid of length ( 25 mathrm{cm} ) and radius 4 ( mathrm{cm} ) is ( 100 . ) Its self inductance will be A ( cdot 5 times 10^{-4} H ) в. ( 2.5 times 10^{-4} H ) c. ( 5.4 times 10^{-3} H ) D . ( 2.5 times 10^{-3} mathrm{H} ) |
12 |

1148 | Interpret ( mathrm{K}^{prime}-mathrm{K} ) | 12 |

1149 | op Q Type your question direction. The number of turns is ( n ) and the cross sectional area of the coil is ( A ) When the coil turns through ( 180^{circ} ) about its diameter, the charge flowing through the coil is ( Q ). The total resistance of the circuit is ( R ). What is the magnitude of the magnetic induction? ( ^{A} cdot frac{Q R}{n A} ) в. ( frac{2 Q R}{n A} ) c. ( frac{Q n}{2 R A} ) D. ( frac{Q R}{2 n A} ) |
12 |

1150 | An a.c of ( 50 H z ) and ( 1 A ) peak value flow in the primary coil of a transformer. The mutual inductance between primary and secondary coils is ( 1.5 H . ) Then peak value of induced emf across secondary coil is A. ( 75 pi ) volt B . ( 150 pi ) volt c. 225 volt D. 300volt |
12 |

1151 | Consider a circular coil of wire carrying constant current I, forming a magnetic dipole. The magnetic flux through an infinite plane contains the circular coil and excluding the circular coil area is given by ( mathbf{Phi}_{mathbf{i}} . ) The magnetic flux through the area of the circular coil area is given by ( mathbf{Phi}_{mathbf{0}} ) Which of the following options is correct? ( mathbf{A} cdot Phi_{mathrm{i}}Phi_{0} ) ( mathbf{D} cdot Phi_{mathrm{i}}=-Phi_{0} ) |
12 |

1152 | A step down transformer has 50 turns on secondary and 1000 turns on primary winding. If a transformer is connected to ( 220 V, 1 A ) A.C. source, what is output current of the transformer? A ( cdot frac{1}{20} A ) B. 20 A ( c cdot 100 A ) D. 2 A |
12 |

1153 | What is self inductance? Establish expression for self inductance of a long Solenoid. |
12 |

1154 | How as a scimilicic un raurus ( a, ) is rotating about an axis ( P Q ) with a constant angular velocity ( omega=1 / sqrt{L C} ) with the help of an external agent. ( mathbf{A} ) uniform magnetic field ( B ) exists in space and is directed into the plane of the figure. (circuit part remains at rest) (left part is at rest) This question has multiple correct options A the rms value of current in the circuit is ( frac{pi B a^{2}}{R sqrt{2 L C}} ) B. The rms value of current in the circuit is ( frac{pi B a^{2}}{2 R sqrt{2 L C}} ) C. The maximum energy stored in the capacitor is ( frac{pi^{2} B^{2} a^{4}}{8 R^{2} C} ) D. The maximum power delivered by the external agent is ( frac{pi^{2} B^{2} a^{4}}{4 L C R} ) |
12 |

1155 | A circular loop of radius ( boldsymbol{R} ), carrying current ( I, ) lies in ( x ) -y plane with its center at origin. The total magnetic flux through x-y plane is A. directly proportional to ( I ) B. directly proportional to ( R ) c. inversely proportional to ( R ) D. inversely proportional to ( I ) E. zero |
12 |

1156 | Alternating current is flowing in inductance ( L ) and resistance ( R ). The frequency of source is ( frac{omega}{2 pi} . ) Which of the following statement is correct. A. For low frequency the limiting value of impedance is ( L ) B. For high frequency the limiting value of impedance is ( L omega ) C. For high frequency the limiting value of impedance is ( R ) D. For low frequency the limiting value of impedance is ( L omega ) |
12 |

1157 | The emf induced between ( M ) and ( Q ) if the potential between ( P ) and ( Q ) is ( 100 V ) ( M ) is midpoint of ( boldsymbol{P} ) and ( boldsymbol{Q} ) A . ( 25 V ) в. ( 50 V ) ( c .75 V ) D. ( 100 V ) |
12 |

1158 | If the resistance of the upper half of a rigid loop is twice of that of the lower half, the magnitude of magnetic induction at the centre is equal to: A. zero B. ( frac{mu_{0} I}{4 a} ) c. ( frac{mu_{0} I}{12} ) D. None of these |
12 |

1159 | Draw a neat diagram of ( A C ) dynamo and label the parts. |
12 |

1160 | The potential difference across a ( 150 m H ) inductor as a function of time is shown in figure. Assume that the initial value of the current in the inductor is zero. What is the current when ( t=4.0 m s ? ) A ( cdot 2.67 times 10^{-4} mathrm{A} ) B ( cdot 3.67 times 10^{-2} mathrm{A} ) ( c cdot 6.67 times 10^{-2} mathrm{A} ) D. ( 9.67 times 10^{-4} mathrm{A} ) |
12 |

1161 | In a coil of resistance ( 100 Omega ), a current is induced by changing the magnetic flux through it as shown in the figure. The magnitude of change in flux through the coil is : A. ( 275 mathrm{Wb} ) в. ( 200 mathrm{Wb} ) ( c cdot 225 W b ) D. ( 250 mathrm{Wb} ) |
12 |

1162 | ( A B ) and ( C D ) are smooth, parallel, horizontal rails on which a conductor ( T ) can slide. A cell, E, drives current through the rails and ( T ) This question has multiple correct options |
12 |

1163 | Self inductance of a long solenoid is directly proportional to ( (N ) is no. of turns in solenoid) A . ( N ) B . ( N^{2} ) ( c cdot 1 / N ) D. ( 1 / N^{2} ) |
12 |

1164 | ( Q ) тур When the fan runs at full speed, its speed becomes constant. This is because the torque due to magnetic field inside the fan is balanced by the torque due to air resistance on the blades of the fan and the torque due to friction between the fixed part and the shaft of the fan. The electric power going into the fan is spent (i) in the internal resistance as heat, call it ( P_{1}, ) (ii) in doing work against internal friction and air resistance producing heat, sound, etc., call it ( P_{2} ). When the coil of fan rotates, an emf is also induced in the coil. This opposes the external emf is also induced in the coil. This opposes the external emf applied to send the current to the fan. This emf is called back emf, call it ( e . ) Answer the following questions when the fan is running at full speed.The current flowing into the fan and the value of back emf ( e ) is A. ( 200 A, 5 V ) B . ( 5 A, 200 V ) c. ( 5 A, 195 V ) D. ( 1 A, 0 V ) |
12 |

1165 | A coil of area ( 500 mathrm{cm}^{2} ) having 1000 turns is placed such that the plane of the coil is perpendicular to a magnetic field of magnitude ( 410^{-5} )weber ( / m^{2} ). If it is rotated by 180 degree about an axis passing through one of its diameter in ( 0.1 mathrm{sec}, ) find the average induced emf. A. zero в. ( 30 m V ) ( mathrm{c} .40 mathrm{mV} ) ( mathbf{D} .50 mathrm{mV} ) |
12 |

1166 | Two coils each of self-inductance ( L ) are connected in parallel. It they are separated by a large distance, then what will be the self-inductance of combination? A ( cdot frac{L}{4} ) в. ( frac{L}{2} ) ( c . L ) D. ( 2 L ) |
12 |

1167 | A coil in a simple generator has 200 turns.Now the number of turns in the coil increases to ( 500 . ) What will be its effect: A. current produced will increase B. voltage produced will increase ( c cdot ) both D. none |
12 |

1168 | What is the highest generated power? ( ^{mathbf{A}} cdot P_{max }=frac{v^{2} B^{2} d}{4 rho S} ) B. ( quad P_{max }=frac{v^{2} B^{2} S d}{4 rho} ) ( ^{mathrm{C}} P_{max }=frac{v^{2} B^{2} S d}{rho} ) D ( quad P_{max }=frac{v^{2} B^{2} S d}{2 rho} ) |
12 |

1169 | Derive the expression for the motional emf induced in a conductor moving in a uniform magnetic field. |
12 |

1170 | A magnetic field of ( 2 times 10^{-2} T ) acts at right angles to a coil of area ( 100 mathrm{cm}^{2} ) with 50 turns. The average emf induced in the coil is ( 0.1 V . ) When it is removed from the field in ( t ) second, the value of ( t ) is A . ( 10 s ) B. ( 0.1 s ) c. ( 0.01 s ) D. ( 1 s ) |
12 |

1171 | A current in a 240 turn solenoid varies at ( 0.8 A / s . ) Find emf induced if the length of the solenoid is ( 12 mathrm{cm} ) and radius ( 2 c m ) A ( cdot 6.14 times 10^{-4} V ) в. ( 6.4 times 10^{-3} V ) ( mathrm{c} .3 .07 times 10^{-3} mathrm{V} ) D. ( 3.07 times 10^{-4} V ) |
12 |

1172 | Find the terminal velocity of the connector? |
12 |

1173 | A thick strip of copper is mounted as a compound pendulum about O.If it is made to swing through a uniform magnetic field B normal to the plane of the strip then (neglecting air resistance) it is found that A. strip swings almost freely. B. motion of the strip is heavily damped. c. strip does not oscillate at all but immediately comes to rest in the vertical position D. strip swings almost freely but its temperature decreases |
12 |

1174 | angled isosceles triangle of height ( 10 mathrm{cm} ) is kept such that the ( 90^{circ} ) vertex is very close to an infinitely long conducting wire (see the figure). The wire is electricity insulted from the loop The hypotenuse of the triangle is parallel to the wire. The current in the triangle loop is in counterclockwise direction and increased at a constant rate of ( 10 A s^{-1} . ) Which of the following statement(s) is(are) true? This question has multiple correct options A cdot The magnitude of induced emf in the wire is ( left(frac{mu_{0}}{pi}right) ) volt B. If the loop is rotated at a constant angular speed about the wire, an additional emf of ( left(frac{mu_{0}}{pi}right) ) C. The induced current in the wire is in opposite direction to the current along the hypotenuse D. There is a repulsive force between the wire and the loop |
12 |

1175 | The motion of copper plate is damped when it is allowed to oscillate between the two poles of a magnet. What is the cause of this damping? |
12 |

1176 | Explain seld induction and mutual induction. |
12 |

1177 | toppr Q Type your question ( A ) B ( c ) ( D ) |
12 |

1178 | The coefficients of self induction of two coils are ( L_{1}=8 mathrm{mH} ) and ( L_{2}=2 mathrm{mH} ) respectively. The current rises in the two coils at the same rate. The power given to the two coils at any instant is same. The ratio of induced emf’s in the coils will be : A. ( frac{V_{1}}{V_{2}}=4 ) B. ( frac{V_{1}}{V_{2}}=frac{1}{4} ) c. ( frac{V_{1}}{V_{2}}=frac{1}{2} ) D. ( frac{V_{1}}{V_{2}}=frac{1}{3} ) |
12 |

1179 | A conducting loop in the shape of a right angled isosceles triangle of height ( 10 mathrm{cm} ) is kept such that the ( 90^{circ} ) vertex is very close to an infinitely long conducting wire (see the figure). The wire is electrically insulated from the loop. The hypotenuse of the triangle is parallel to the wire. The current in the triangular loop is in counter clockwise direction and increased at a constant rate of ( 10 A s^{-1} . ) Which of the following statement (s) is (are) true? This question has multiple correct options A. There is a repulsive force between the wire and the loo B. If the loop is rotated at a constant angular speed about the wire, an additional emf of ( left(frac{mu_{0}}{pi}right) ) volt is induced in the wire C . The magnitude of induced emf in the wire is ( left(frac{mu_{0}}{pi}right) ) vo duced current in the wire is in opposite directic to the current along the hypo |
12 |

1180 | Direction of current in the loop at ( t= ) ( frac{pi}{3 omega} ) ( A ). clockwise B. anticlockwise c. no current will flow at that time D. cannot be determined |
12 |

1181 | A current ( l ) is flowing in a straight conductor of length ( L ). The magnetic induction at a point on its axis at a distance ( frac{L}{4} ) from its centre will be A . zero в. ( frac{mu_{0} l}{2 pi L} ) c. ( frac{mu_{0} l}{sqrt{2} L} ) D. ( frac{4 mu_{0} l}{sqrt{5} pi L} ) |
12 |

1182 | An airplane in which the distance between the tips of the wings is 50 meter is flying horizontally with a speed of 360 km/hour over a place where the vertical component of earths magnetic field is ( 2.0 times 10^{-4} ) Testa. The potential difference between the tips of the wings would be:- A . 0.1 B. 1.0 c. ( 0.2 v ) D. ( 0.0 mathrm{v} ) |
12 |

1183 | Assertion Eddy currents in conductors of non-zero resistivity generate heat as well as electromagnetic forces. Reason Current is always associated with heat and electromagnetic forces 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 |

1184 | 100 101 11. A small square loop of wire of side lis placed inside a large square loop of wire of side L (L > I). The loop are coplanar and their centre coincide. The mutual inductance of the i system is proportional to (a) UL (b) BIL (c) L/I (d) L?I1 – |
12 |

1185 | What is self inductance? Name the factors on which self inductance depends. |
12 |

1186 | Assertion(A): An inductor in a D.C. circuit opposes both a steady current and a changing current. Reason(R): Induced emf is generated only when the flux linked with the inductor remains unchanged. A. Both A and R are individually true and R is the correct explanation of A B. Both A and R are individually true but R is not the correct explanation of ( A ) c. A is true but R is false D. Both A and R are false |
12 |

1187 | A square of side L meters lies in the ( x-y ) plane in a region, where the magnetic field given by ( vec{B}=B_{o}(2 hat{i}+3 hat{j}+4 hat{k}) T ) where ( B_{o} ) is constant. The magnitude of flux passing through the square is : B. ( 3 B_{o} L^{2} W b ) ( mathbf{c} cdot 4 B_{o} L^{2} W b ) D. ( sqrt{29} B_{o} L^{2} W b ) |
12 |

1188 | An emf is induced in an aeroplane during its ascent and descent in east- west direction due to A. The horizontal component of the earth’s magnetic field B. The vertical component of the earth’s magnetic field c. Both 1 and 2 D. None of the above |
12 |

1189 | If a current increases from zero to one ampere in 0.1 second in a coil of ( 5 mathrm{mH} ) then the magnitude of the induced e.m.f. will be A . 0.005 volt B. 0.5 volt c. 0.05 volt D. 5 volt |
12 |

1190 | Which of the following units denotes the dimensions ( M L^{2} / Q^{2}, ) where ( Q ) denotes the electric charge? A. Weber (Wb) в. ( W b / mathrm{m}^{2} ) c. Henry ( (H) ) D. H / m ( ^{2} ) |
12 |

1191 | A glass rod of length ( ell ) moves with a velocity ( v ) in a uniform magnetic field ( B ) what will be the emf induced in the rod: A . ( B l v ) в. ( frac{B l}{v} ) c. ( B l ) D. None of these |
12 |

1192 | An inductor with an inductance of ( 3.00 H ) and a resistance of ( 7.00 Omega ) is connected to the terminals of a battery with an emf of ( 12.0 mathrm{V} ) and negligible internal resistance. Find the initial rate of increase of current in the circuit. |
12 |

1193 | A circular coil of mean radius of ( 7 mathrm{cm} ) and having 4000 tums is rotated at the rate of 1800 revolutions per minute in the earth’s magnetic field ( (mathrm{B}=0.5 ) Gauss ), The peak value of emf induced is A . ( 1.158 mathrm{v} ) B. 0. 58 v c. ( 0.29 v ) D. 5.8 |
12 |

1194 | A wheel with 10 metallic spokes each ( 0.5 m ) long is rotated with a speed of 120rev/min in a plane normal to the horizontal component of earth’s magnetic field ( boldsymbol{H}_{boldsymbol{E}} ) at a place.lf ( boldsymbol{H}_{boldsymbol{E}}= ) ( 0.4 G ) at the place, what is the induced emf between the axle and the rim of the wheel? Note that ( 1 G=10^{-4} ) |
12 |

1195 | In A.C generator increasing no. of turns in coil : A. decreases the EMF B. EMF remains same c. increases the EMF D. EMF becomes zero |
12 |

1196 | A field of strength ( frac{mathbf{5} times mathbf{1 0}^{mathbf{4}}}{boldsymbol{pi}} ) ampere turns /meter acts at right angles to a coil of 50 turns of area ( 10^{-2} m^{2} . ) The coil is removed from the field in 0.1 second. Then, the induced e.m.f in the coil is: A . ( 0.1 mathrm{v} ) B. 0.2 ( v ) c. ( 1.96 v ) D. 0.98 |
12 |

1197 | In an AC generator, maximum number of lines of force pass though the coil when the angle between the plane of coil and lines of force is : A ( cdot 0^{circ} ) B. 60 ( c cdot 30 ) D. ( 90^{circ} ) |
12 |

1198 | When the coil and the magnet are both stationary A. there is no deflection in the galvanometer. B. galvanometer deflects c. galvanometer bursts. D. none |
12 |

1199 | Draw a labelled diagram of a simple a.c. generator. |
12 |

1200 | Magnetic flux ( phi ), in weber, in a closed circuit of resistance ( 10 Omega ) varies with time ( t ) in seconds as ( phi=6 t^{2}-5 t+1 ) The magnitude of induced current at ( t=0.25 s ) is : A. ( 0.2 mathrm{A} ) B. 0.6 ( A ) ( c cdot 1.2 A ) D. ( 0.8 mathrm{A} ) |
12 |

1201 | 30. A vertical conducting ring of radius R falls vertically wil a speed Vin a horizontal uniform mag- netic field B which is perpendicular to the plane of the ring. Which of the fol- lowing statements is correct? (a) A and B are at the same potential (b) C and D are at the same potential (c) current flows in clockwise direction (d) current flows in anticlockwise direction |
12 |

1202 | A magnetic field is directed normally downwards through a magnetic frame as shown in the figure. On increasing the magnetic field: begin{tabular}{r|rrrrr} ( 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 ) \ hline end{tabular} [ times times times times times times ] A. plate B will be positively charged B. plate A will be positively charged C. none of the plates will be positively charged D. all of the above |
12 |

1203 | In the following figure the bulb will start lighting suddenly if : A. Key is closed B. Key is opened C. Key is either closed or opened D. Nothing is done |
12 |

1204 | A horizontal telegraph wire ( 0.5 k m ) long running east and west in a part of a circuit whose resistance is ( 2.5 Omega ). The wire falls to ( g=10.0 m / s^{2} ) and ( B= ) ( 2 times 10^{-5} w e b e r / m^{2}, ) then the current induced in the circuit is A. 0.7 amp B. 0.04 amp c. 0.02 amp D. ( 0.01 a m p ) |
12 |

1205 | A charge particle having mass ( mathrm{m} ) and charge ( +boldsymbol{q}, ) given a velocity ( overrightarrow{boldsymbol{V}}_{0}=mathbf{2} overline{boldsymbol{i}}+ ) ( 4 j m / s ) in a region where electric field and magnetic field exists. Magnetic field in the region is ( vec{B}=6 bar{i}-8 bar{j} ) (Tesla). It is observed of charged particle remains constant. Electric field in the region is: A. ( 50 N / C ) в. ( 40 N / C ) c. ( 30 N / C ) D. ( 60 N / C ) |
12 |

1206 | A metal ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The magnet falls with an acceleration: A. Equal to ( g ) B. Less than ( g ) c. Greater than ( g ) ( D . ) none |
12 |

1207 | The magnetic field in a certain region is given by ( vec{B}=(4.0 hat{i}-1.8 hat{k}) times 10^{-3} T ) How much flux passes through a ( 5.0 mathrm{cm}^{2} ) area loop in this region if the loop lies flat on the ( x-y ) plane? A ( cdot 8 times 10^{-5} mathrm{Wb} ) B . ( 3 times 10^{-5} mathrm{Wb} ) c. ( 9 times 10^{-7} W b ) D. ( 3 times 10^{-7} mathrm{Wb} ) |
12 |

1208 | A rectangular frame of wire abcd has dimensions ( 32 mathrm{cm} times 8.0 mathrm{cm} ) and a total resistance of ( 2.0 Omega . ) It is pulled out of a magnetic field ( B=0.020 T ) by applying a force of ( 3.2 times 10^{-5} N ) (figure). It is found that the frame moves with constant speed. Find the emf induced in the loop. |
12 |

1209 | A very small circular loop of radius ( a ) is initially ( (a t t=0) ) coplanar and concentric with a much larger fixed circular loop of radius ( b ). A constant current ( I ) flows in the larger loop. The smaller loop is rotated with a constant angular speed ( omega ) about the common diameter. The emf induced in the smaller loop as a function of time ( t ) is: ( ^{mathbf{A}} cdot frac{pi a^{2} mu_{0} I}{2 b} omega cos (omega t) ) в. ( frac{pi a^{2} mu_{0} I}{2 b} omega sin left(omega^{2} t^{2}right) ) ( ^{text {c. }} frac{pi a^{2} mu_{0} I}{2 b} omega sin (omega t) ) D ( cdot frac{pi a^{2} mu_{0} I}{2 b} omega sin ^{2}(omega t) ) |
12 |

1210 | A disc of radius ( R ) is rolling without sliding on a horizontal surface with a velocity of center of mass ( v ) and angular velocity ( omega ) in a uniform magnetic field ( B ) which is perpendicular to the plane of the disc as shown in figure. ( O ) is the center of the disc and ( P, Q, R ) and ( S ) are the four points on the disc. Which of the following statements is true? This question has multiple correct options A. Due to translation, induced emf across ( P S=B v r ) B. Due to rotation, induced emf across ( Q S=0 ) c. Due to translation, induced emf across ( R O=0 ) D. Due to rotation, induced emf across ( O Q=B v r ) |
12 |

1211 | The current produced in a generator armature is AC because A. the magnetic field reverses at intervals B. The current in the field coils is AC C. the rotation of the armature causes the field through it to reverse D. the commutator feeds current into it in opposite directions every half cycle |
12 |

1212 | A ( 50 ~ m H ) coil carries a current of ( 2 A ) The energy stored in joule is A . ( 0 . ) B. 0.5 c. ( 1 . ) D. 5.0 |
12 |

1213 | A coil of 1200 turns and mean area of ( 500 mathrm{cm}^{2} ) is held perpendicular to a uniform magnetic field of induction ( 4 times 10^{-4} mathrm{T} . ) The resistance of the coil is 20 ohms. When the coil is rotated through ( 180^{0} ) in the magnetic field in 0.1 s, the average electric current (in ( mathrm{mA} ) ) induced is : A ( cdot 12 ) B. 24 ( c . ) 36 D. 48 |
12 |

1214 | A solenoid of self-inductance ( 1.2 H ) is in series with a tangent galvanometer of reduction factor ( 0.9 A ). They are connected to a battery and the tangent galvanometer shows a deflection of ( 53^{circ} ) The energy stored in the magnetic field of the solenoid is: ( left(tan 53^{circ}=4 / 3right) ) begin{tabular}{l} A. 0.8645 \ hline end{tabular} в. ( 0.72 J ) c. ( 0.173 J ) D. ( 1.44 J ) |
12 |

1215 | The magnetic flux linked with a coil, in webers, is given by the equation ( phi= ) ( 8 t^{2}-3 t+5 . ) Then the magnitude of induced emf at 4 sec will be A . 15 v B . ( -61 mathrm{v} ) c. 13 v D. 21 v |
12 |

1216 | The coil is wound on an iron core and looped back on itself so that core has two sets of closely wound coils carrying current in opposite directions. The self inductance is ( A cdot 0 ) B. ( 2 L ) ( mathrm{c} cdot 2 mathrm{L}+mathrm{M} ) D. ( L+2 M ) |
12 |

1217 | A long copper wire contains a current of I ampere. The magnetic flux per metre of the wire for a plane surface inside the wire as shown in figure. ( ^{A} cdot frac{mu_{0}}{2 pi} ) В ( frac{mu_{0}}{4 pi} ) c. ( frac{mu_{0}}{pi} ) D. ( frac{mu_{0}}{6 pi} ) |
12 |

1218 | The length of a wire required to manufacture a solenoid of length ( l ) and self-induction ( L ) is (cross-sectional area is negligible) A ( cdot sqrt{frac{2 pi L l}{mu_{0}}} ) в. ( sqrt{frac{mu_{0} L l}{4 pi}} ) c. ( sqrt{frac{4 pi L l}{mu_{0}}} ) D. ( sqrt{frac{mu_{0} L l}{2 pi}} ) |
12 |

1219 | A copper rod of length ‘I’ rotates at an angular velocity ‘ ( omega^{prime} ) in a uniform magnetic field B as shown in figure. What is the induced emf across its ends? |
12 |

1220 | What is the relationship between an electric current and a magnetic field? | 12 |

1221 | A semicircle loop ( P Q ) of radius ( ^{prime} R^{prime} ) is moved with velocity ( ^{prime} v^{prime} ) in transverse magnetic field as shown in figure. The value of induced emf. at the end of loop is :- |
12 |

1222 | A circular loop of wire is in the same place as an infinitely long wire carrying a constant current i. Four possible motion of the loop are marked by ( mathrm{N}, mathrm{E}, mathrm{W} ) and ( mathrm{S} ) as shown. A clockwise current is induced in the loop when loop is pulled towards ( A ) B. ( c cdot w ) ( D ) |
12 |

1223 | Change in number of magnetic field lines induces A. current in coil B. EMF in the coil c. frequency in coil D. both A and C |
12 |

1224 | A plane electromagnetic wave in a non magnetic dielectric medium is given by ( overline{boldsymbol{E}}=overline{boldsymbol{E}}_{0}left(mathbf{4} times mathbf{1 0}^{-mathbf{7}} boldsymbol{x}-mathbf{5 0} boldsymbol{t}right) ) with distance being in meter and time in seconds. The dielectric constant of the medium is: A . 5.8 B. 2.4 c. 1.6 D. 3.5 |
12 |

1225 | The magnetic flux linked with a coil,in webers,is given by the equations ( phi= ) ( 3 t^{2}+4 t+9 . ) Then the magnitude of induced e. ( mathrm{m} ). ( mathrm{f} ). at ( mathrm{t}=2 ) second will be: A . 2 volt B. 4 volt c. 8 volt D. 16 volt |
12 |

1226 | The phenomenon of producing an emf in a circuit whenever the magnetic flux linked with a coil changes is A. Electro-magnetic induction B. Inducing current c. Inducing voltage D. change in current |
12 |

1227 | A fighter plane of length ( 20 mathrm{m}, ) wing span (distance from tip of one wing to the tip of the other wing) of ( 15 mathrm{m} ) and height ( 5 mathrm{m} ) is flying towards east over Delhi. Its speed is ( 240 m s^{-1} ). The earth’s magnetic field over Delhi is ( 5 times 10^{-5} mathrm{T} ) with the declination angle ( sim 0^{circ} ) and dip of ( theta ) such that ( sin theta=frac{2}{3} . ) If the voltage developed is ( V_{B} ) between the lower and upper side of the plane and ( V_{W} ) between the tips of the wings then ( V_{B} ) and ( V_{W} ) are close to A ( cdot V_{B}=40 m V ; V_{W}=135 mathrm{mV} ) with left side of pilot at higher voltage B . ( V_{B}=45 mathrm{mV} ; V_{W}=120 mathrm{mV} ) with right side of pilot at higher voltage C. ( V_{B}=40 mathrm{mV} ; V_{W}=135 mathrm{mV} ) with right side of pilot at high voltage D. ( V_{B}=45 mathrm{mV} ; V_{W}=120 mathrm{mV} ) with left side of pilot at higher voltage |
12 |

1228 | The circuit diagram shows that resistors ( 2 Omega, 4 Omega ) and ( R Omega ) connected to a battery of e.m.f. 2 V and internal resistance ( 3 Omega ). A main current of 0.25 A flows through the circuit. The p.d. across the internal resistance of the cell is : A . ( 0.75 mathrm{v} ) B. 2 ( c cdot 0.5 v ) 0.11 |
12 |

1229 | The flux of magnetic field through closed conducting loop of resistance 0.4 Whanges with time according to the equation ( phi=0.20 t^{2}+0.40 t+0.60 ) where is time in seconds. Find (i) the induced emf at ( t=2 s . ) (ii) the average induced emf in ( t=0 ) to ( t=5 ) s. (iii) change passed through the loop in ( t=0 ) to ( t=5 s . ) (iv) average current in time interval ( t=0 ) to ( t=5 s ) (v) heat produced in ( t=0 ) to ( t=5 s ) |
12 |

1230 | Describe the principal, construction and working of a single-phase ( A C ) generator | 12 |

1231 | AC generator is also h/a A. convertor B. invertor c. alternator D. none |
12 |

1232 | An aeroplane is moving towards north horizontally with a speed of ( 200 mathrm{m} / mathrm{s} ) at a place where the vertical component of earths magnetic field is ( 0.5 times 10^{-4} ) tesla. Then the induced e.m.f. set up between the tips of the wings of the plane if they are ( 10 m ) apart is: A. 0.1 volt B. 0.01 volt c. 10 volt D. 1 volt |
12 |

1233 | A conducting loop in the shape of a right angled isosceles triangle of height ( 10 mathrm{cm} ) is kept such that the ( 90^{circ} ) vertex is very close to an infinitely long conducting wire (see the figure). The wire is electrically insulated from the loop. The hypotenuse of the triangle is parallel to the wire. The current in the triangular loop is in counter clockwise direction and increased at a constant rate of ( 10 A s^{-1} . ) Which of the following statement (s) is (are) true? This question has multiple correct options A. There is a repulsive force between the wire and the loo B. If the loop is rotated at a constant angular speed about the wire, an additional emf of ( left(frac{mu_{0}}{pi}right) ) volt is induced in the wire C . The magnitude of induced emf in the wire is ( left(frac{mu_{0}}{pi}right) ) vo duced current in the wire is in opposite directic to the current along the hypo |
12 |

1234 | Q Type your question shown in figure are connected at one end to a charged capacitor through a switch ( S, ) which initially open. At the other end, they are connected by a loose wire. The capacitor has charge ( Q ) and mass per unit length of the rod is ( lambda ). The effective resistance of the circuit after closing the switch is ( R ). If the velocity of each rod when the capacitor is discharged after closing the switch is ( boldsymbol{v}=frac{boldsymbol{mu}_{0} boldsymbol{Q}^{2}}{boldsymbol{x} pi boldsymbol{d} boldsymbol{R} boldsymbol{lambda} boldsymbol{l}} . ) Find ( boldsymbol{x} ) (Assume that the displacement of rods during the discharging time is negligible) |
12 |

1235 | Magnetic flux linked with a coil is ( phi= ) ( 5 t^{2}+2 t+3, ) where ( t ) is second and ( phi ) is in weber. At time ( t=1 ) s, the value of induced emf is volt A . 14 B. 1. c. 12 D. 6 |
12 |

1236 | When a rectangular coil is rotated in a uniform magnetic field about an axis passing through its centre and perpendicular to the field, the emf induced in the coil varies: A. Linearly B. Exponentially c. sinusoidally D. None of these |
12 |

1237 | A magnetic field of flux density ( 1.0 mathrm{Wb} ) ( m^{-2} ) acts normal to a 80 tum coil of 0.01 ( m^{2} ) area. The e.m.f. induced in it, if this coil is removed from the field in 0.1 second is : ( A cdot 8 v ) B. ( 4 v ) c. ( 10 v ) D. ( 6 v ) |
12 |

1238 | A wheel with 10 metallic spokes each ( 0.5 mathrm{m} ) long is rotated with a speed of 120 rev/min in a plane normal to the earth’s magnetic field at the place.lf the magnetic of the field is ( 0.4 mathrm{G} ), what is the induced emf between the axle and the rim of the wheel? |
12 |

1239 | Plane of both loops circle and ellipse are held perpendicularly to the uniform magnetic field of strength B, Compare the magnetic flux passing through both loops if ( phi_{c}, ) the magnetic flux through the circular loop and ( phi_{E}, ) the magnetic flux through the elliptical loop given that area of both loops are same. ( mathbf{A} cdot phi_{c}=2.5 phi_{E} ) B ( cdot phi_{c}=sqrt{2.5} ) ( mathbf{c} cdot phi_{c}=phi_{E} ) ( mathbf{D} cdot phi_{E}=sqrt{2.5} phi_{c} ) E ( cdot phi_{E}=2.5 phi_{c} ) |
12 |

1240 | 19. A rod Po is connected to the capacitor plates. The most placed in a magnetic field (B) B directed downward perpendicular to the plane of 3 the paper, If the rod is pulled out of magnetic field with velocity v as shown in figure, (a) Plate M will be positively charged, (b) Plate N will be positively charged, (c) Both plates will be similarly charged. (d) No charge will be collected on plates, |
12 |

1241 | x x ILLUSTRATION 23.2 An angle ZAOB made of a conducting wire moves along its bisector through a magnetic field B as suggested by figure. Find the emf induced between the two free ends if the magnetic field is perpendicular to the plane at the angle. x x x x x x x x x x x x x x x x x x x x x x Көx x x x x x 8 x x x x x x x x x x x xxx x x x x B x x x x x x x x x x x 0 От – х X x x x + x x X x |
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1242 | A coil of radius ( R ) carries current ( I ). Another concentric coil of radius ( r(r< ) ( <R) ) carries current ( i . ) Planes of two coils are mutually perpendicular and both the coil are free to rotate about common diameter. Find the maximum kinetic energy of the smaller coil when both the coils are released. Masses of coils are ( M ) and ( m, ) respectively. |
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1243 | A square-shaped wire loop of mass ( m ) resistance ( boldsymbol{R} ) and side a moving with speed ( v_{0}, ) parallel to the ( x ) -axis, enters a region of uniform magnetic field ( B ) which is perpendicular to the plane of the loop. The speed of the loop changes with distance ( x(x<a) ) in the field, as A ( cdot v_{0}-frac{B^{2} a^{2}}{R m} x ) B. ( _{v_{0}-frac{B^{2} a^{2}}{2 R m} x} ) c. ( _{v_{0}+} frac{B^{2} a}{R m} x ) D. ( v ) |
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1244 | An alternating current generator has an internal resistance ( boldsymbol{R}_{boldsymbol{g}} ) and an internal reactance ( X_{g} . ) It is used to supply power to a passive load consisting of a resistance ( boldsymbol{R}_{g} ) and a reactance ( boldsymbol{X}_{boldsymbol{L}} . ) For maximum power to be delivered from the generator to the load, the value of ( X_{L} ) is equal to A . zero в. ( X_{g} ) c. ( -x_{g} ) D. ( R_{g} ) |
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1245 | ILLUSTRATION 24.5 The potential difference E and current I flowing through the ac circuit is given by E = 5 cos(ot – Tc/6) V and I = 10 sin or A. Find the average power dissipated in the circuit. |
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1246 | 18. A horizontal ring of radius r = 1/2 m is kept in a vertical constant magnetic field 1 T. The ring is collapsed from maximum area to zero area in 1 s. Then the emf induced in the ring is (a) 1V (b) (Tc/4) V (c) (1/2) V (d) TV |
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1247 | Which one of the following statements is true? A. A motor works on the principle of electromagnetic induction B. An electric motor converts mechanical energy into electrical energy C. AC generator has slip rings while DC generator has a commutator D. An electric generator converts electrical energy into mechanical energy |
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1248 | ì iuur 0 ( 10^{-2} m^{2} ) which has inductance ( L= ) 10m ( H ) and negligible resistance is placed in a time-varying magnetic field. Figure shows the variation of B with time for the interval of 4 s. The field is perpendicular to the plane of the loop (given at ( t=0, B=0, I=0) . ) The value of the maximum current induced in the loop is : ( mathbf{A} cdot 0.1 mathrm{mA} ) B. ( 10 mathrm{mA} ) C. ( 100 mathrm{mA} ) D. Data insufficient |
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1249 | Multiple Correct Answers Type The Sl unit of inductance, henry, can be written as This question has multiple correct options A. Weber/ampere B. Volt-second / ampere c. Joule/(ampere) ( ^{2} ) D. Ohm-second |
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1250 | A rectangular loop with a slide wire of length ( l ) is kept in a uniform magnetic field as shown in figure (a). The resistance of slider is ( boldsymbol{R} ). Neglecting self inductance of the loop find the current in the connector during its motion with a velocity ( boldsymbol{v} ) ( (b) ) A ( cdot frac{B l v}{R_{1}+R_{2}+R} ) B. ( frac{B l vleft(R_{1}+R_{2}right)}{Rleft(R_{1}+R_{2}right)} ) c. ( frac{B l vleft(R_{1}+R_{2}right)}{R R_{1}+R R_{2}+R_{1} R_{2}} ) D ( cdot operatorname{Blv}left(frac{1}{R_{1}}+frac{1}{R_{2}}+frac{1}{R_{3}}right) ) |
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1251 | A magnetic field of flux density 10 T acts normal to a coil of 50 turns having 100 em-area. The e.m.f. induced if the coil is removed from magnetic field in ( 0 . ) second is: A. ( 50 v ) B. 60V ( c cdot 80 v ) D. 40v |
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