We provide current electricity practice exercises, instructions, and a learning material that allows learners to study outside of the classroom. We focus on current electricity skills mastery so, below you will get all questions that are also asking in the competition exam beside that classroom.
List of current electricity Questions
| Question No | Questions | Class |
|---|---|---|
| 1 | Potentiometer measures the potential difference more accurately than a voltmeter because: A. it has a wire of high resistance B. it has a wire of low resistance c. it does not draw current from external circuit D. it draws a heavy current from external circuit |
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| 2 | A motor of ( 50 ~ W ) runs for 20 hrs. How many ‘units’ ( ( k W h ) ) of electrical energy are consumed? ( mathbf{A} .5 mathrm{kWh} ) в. ( 2 k W h ) ( c cdot 1 k W h ) D. ( 2.5 mathrm{kWh} ) |
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| 3 | The relaxation time (t) is the: A. Time taken by an electron to drift from one end of a conductor to the other. B. Time taken by an electron to travel unit distance through the conductor. c. The time between two successive collisions of a free electron with the atoms of the metal. D. Time for which a free electron is subjected to the electric field |
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| 4 | Between any two points in a circuit, the sum of all ( ldots ldots . . . . . . . ) is the same through any pathway. A . charge B. current c. potential difference D. resistance |
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| 5 | (i) State Ohm’s law. (ii) A metal wire of resistance ( 6 Omega ) is stretched so that its length is increased to twice its original length. Calculate its new resistance. |
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| 6 | Explain the term ‘drift velocity’ of electrons in a conductor. Hence obtain the expression for the current through a conductor in terms of ‘drift velocity’ |
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| 7 | The resistance of germanium with rise in temperature. A. increases B. decreases c. remains the same D. first increases then decreases |
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| 8 | An electric bulb is rated ( 220 V ) and ( 100 W, ) when it is operated on ( 110 V ) the power consumed will be A . ( 100 mathrm{W} ) в. ( 75 mathrm{W} ) ( mathbf{c} .50 W ) D. ( 25 W ) |
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| 9 | Given ( boldsymbol{R}_{1}=mathbf{5 . 0} pm mathbf{0 . 2} mathbf{Omega} ) and ( boldsymbol{R}_{2}= ) ( 10.0 pm 0.1 Omega . ) What is the total resistance in parallel with possible ( % ) error? |
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| 10 | A bulb uses 5000 J of energy in 10 s calculate its power. A. ( 50 J / ) s B. 500w ( c .5 w ) D. 600 J/s |
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| 11 | Four wires are made from the same metal. Which wire has the lowest resistance? A. Length of wire / ( mathrm{cm}-20 ), Diameter of wire / ( mathrm{mm}-0.20 ) B. Length of wire / ( mathrm{cm}-20 ), Diameter of wire / ( mathrm{mm}-0.40 ) C. Length of wire / ( mathrm{cm}-40 ), Diameter of wire / ( mathrm{mm}-0.20 ) D. Length of wire / ( mathrm{cm}-40 ), Diameter of wire / ( mathrm{mm}-0.40 ) |
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| 12 | A cell of emf ‘E’ and internal resistance is connected across a variable resistor R’. Plot a graph showing variation of terminal voltage ‘V’ of the cell versus the current ‘I’. Using the plot, show how the emf of the cell and its internal resistance can be determined. |
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| 13 | A potentiometer wire of length ( 10 m ) is connected in series with a battery. The e.m.f. of a cell balances against ( 250 mathrm{cm} ) length of wire. If length of potentiometer wire is increased by ( 1 m, ) the new balancing length of wire will be ( mathbf{A} cdot 2.00 m ) B. ( 2.25 m ) c. ( 2.50 m ) D. ( 2.75 m ) |
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| 14 | A group of N cells whose emf varies directly with the internal resistance as per the equation ( boldsymbol{E}_{N}=mathbf{1 . 5 r}_{N} ) are connected as shown in the figure. The current I in the circuit is :- A . 5.1 A B. 0.51 A ( c cdot 1.5 mathrm{A} ) D. 0.15 A |
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| 15 | A block of carbon, ( 1.0 mathrm{cm} ) by ( 2.0 mathrm{cm} ) by ( 5.0 mathrm{cm}, ) has a resistance of 0.015 between its two smaller faces. What is the resistivity of carbon? A ( cdot 1 times 10^{-8} Omega m ) В. ( 2 times 10^{-8} Omega m ) c. ( 4 times 10^{-5} Omega m ) D. ( 6 times 10^{-8} Omega m ) |
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| 16 | A time varying current ( i ) in passed through a resistance ( R ) as shown in figure. The total heat generated in the resistance is: A ( cdot 11 i_{0}^{2} R t_{0} ) B. ( 13 i_{0}^{2} R t_{0} ) ( mathbf{c} cdot 17 i_{0}^{2} R t_{0} ) D. ( 15 i_{0}^{2} R t_{0} ) |
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| 17 | A cell of emf ( 2 mathrm{V} ) delivers current equal to ( 20 % ) of the maximum current, which it can produce through a resistance ( 4 Omega ) Its internal resistance is A . ( 0.1 Omega ) B. 19 ( c cdot 0.5 Omega ) D. 1.5. |
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| 18 | How much resistance should be connected to ( 15 Omega ) resistor shown in the circuit in adjoining figure below so that the points ( mathrm{M} ) and ( mathrm{N} ) are at the same potential |
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| 19 | A battery of e.m.f. ( 3.0 mathrm{V} ) supplies current through a circuit in which the resistance can be changed. A high resistance voltmeter is connected across the battery. When the current is ( 1.5 mathrm{A}, ) the voltmeter reads ( 2.7 mathrm{V} ). The internal resistance of the battery is A . ( 4 Omega ) в. ( 1.2 Omega ) c. ( 0.2 Omega ) D. 2Omega |
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| 20 | Copper metal is a: A. good conductor of electricity B. bad conductor of electricity C . magnetic substance D. bad conductor of heat E. none of these |
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| 21 | A battery of e.m.f. ( 15 mathrm{V} ) and internal resistance ( 2 Omega ) is connected to two resistors of resistance 4 ohm and 6 ohm joined in series. What is the electrical energy spent per minute in 6 ohm resistor? A . 562.5 B. 180 J c. 456.5 J D. 360 J |
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| 22 | 1 ampere is same as ( mathbf{A} cdot 1 C s^{-1} ) B. ( 1 C s ) ( mathbf{c} cdot 1 J C^{-1} ) D. ( 1 V C^{-1} ) |
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| 23 | Reading of the voltmeter is A. ( 2 v ) B. 2.04 c. ( 1.96 mathrm{v} ) D. 1.0 |
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| 24 | connected in a circuit as shown in figure. The galvanometer is kept undeflected always. Here ( A B=l . ) When the switch ( S ) is connected to point ( S_{1} ) ( B P=x_{1} ) and when the switch ( S ) is connected to point ( S_{2}, B P=x_{2} . ) Here the ratio of emf’s of the two batteries, i.e., ( varepsilon_{1} / varepsilon_{2} ) equal/s: ( mathbf{A} cdot x_{1} / x_{2} ) B. ( x_{2} / x_{1} ) c. ( frac{left(l-x_{1}right)}{left(l-x_{2}right)} ) D. ( frac{left(l-x_{2}right)}{left(l-x_{1}right)} ) |
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| 25 | Three resistances of ( 8 Omega, 16 Omega ) and ( 4 Omega ) are joined in parallel. If each resistor is rated ( 0.5 W, ) what is the maximum voltage that may be applied to the combination? A . ( 1 V ) в. ( 1.5 V ) ( c cdot 2 V ) D. 2.5V |
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| 26 | Name two factors on which the internal resistance of a cell depends. This question has multiple correct options A. separation between plates B. emf of cell c. area of plates D. external resistance. |
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| 27 | A wire of resistance ( 4 Omega ) is stretched to twice its original length. In the process of stretching, its area of cross section gets halved. Now, the resistance of the wire is: ( A cdot 8 Omega ) в. 16 Omega c. ( 1 Omega ) D. ( 4 Omega ) |
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| 28 | Material used in heating coils is: A. Nichrome B. Copper c. Silver D. Gold |
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| 29 | Assertion In a simple electric circuit, positive terminal of the battery is a point of lowest potential Reason The electronic current flow in a circuit is from a point of highest potential to a point of lowest potential 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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| 30 | The equivalent resistance between the points 1 and 7 the adjoining circuit (fig) will be ( A cdot frac{7}{1} ) 12 в. ( frac{5}{6} r ) ( c ) D. none of these |
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| 31 | A circuit shown in Fig. has resistances ( R_{1}=20 Omega ) and ( R_{2}=30 Omega . ) At what value of the resistance ( R_{x} ) will the thermal power generated in it be practically independent of small variations of that resistance. The voltage between the points ( A ) and ( B ) is supposed to be constant in this case. |
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| 32 | The indicates the multiplier telling you the power of ten to which the two significant digits in color coding of the resistor must be multiplied (or how many zeros to add) A. 2nd band B. 3rd band c. 4 th band D. last band |
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| 33 | Kirchhoff’s law of meshes is in accordance with law of conservation of: A. charge B. current c. energy D. angular momentum |
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| 34 | Assertion Heater wire must have high resistance than connecting wires and high metallic point. Reason If resistance is high, the electrical conductivity will be less. 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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| 35 | Electromotive force represents A . force B. energy C. energy per unit charge D. current |
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| 36 | Copper contains ( 8.4 times 10^{28} ) free electrons ( / m^{3} . ) A copper wire of crosssectional area ( 7.4 times 10^{-7} m^{2} ) carries a current of 1 A. The electron drift speed is approximately. A ( cdot 10^{-8} mathrm{m} / mathrm{s} ) B. ( 10^{3} mathrm{m} / mathrm{s} ) ( c cdot 1 m / s ) D. ( 10^{-3} mathrm{m} / mathrm{s} ) |
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| 37 | The balancing length for a cell is ( 560 mathrm{cm} ) in a potentiometer experiment. When an external resistance of ( 10 Omega ) is connected in parallel to the cell, the balancing length changes by ( 41 c m ). The internal resistance of the cell in ohms is A . 1.6 B. 1. ( c cdot 12 ) D. 0.8 |
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| 38 | A carbon film resistor has colour code Green Black Violet Gold. The value of the resistor is: A ( .50 M Omega ) в. 500 М ( Omega ) ( mathrm{c} .500 pm 5 % ) М( Omega ) D. ( 500 pm 10 % ) M ( Omega ) |
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| 39 | Electrical power ( P ) is given by the expression ( P=frac{Q times V}{t} . ) time. What does ( Q ) and ( V ) stand for? A. Charge, energy B. Current, voltage c. current, power D. Charge, voltage |
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| 40 | Current ( I_{1} ) in the following circuit is ( A, O, 4 A ) B . -0.4A ( c . ) о.вА D . -0.8A |
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| 41 | Voltmeters ( V_{1} ) and ( V_{2} ) are connected in series across a ( D . C . ) line. ( V_{1} ) reads ( 80 V ) and has a per volt resistance of ( 200 Omega ) ( V_{2} ) has a total resistance of ( 32 k Omega ). The line voltage is ( mathbf{A} cdot 120 V ) в. ( 160 V ) ( mathbf{c} cdot 220 V ) D. ( 240 V ) |
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| 42 | Two lamps one rated ( 60 mathrm{W}, 220 mathrm{V} ) and the other ( 40 mathrm{W}, 220 mathrm{V} ) are connected in parallel to a ( 220 mathrm{V} ) electric supply mains. What is the total current drawn from the electric mains if the voltage of electric supply is ( 220 mathrm{V} ? ) |
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| 43 | For a cell, a graph is plotted between the potential difference ( V ) across the terminals of the cell and the current ( I ) drawn from the cell (see Figure). The emf and the internal resistance of the cell are ( E ) and ( r, ) respectively. Then : A ( . E=2 V, r=0.5 Omega ) B. ( E=2 V, r=0.4 Omega ) c. ( E>2 V, r=0.5 Omega ) D. ( E>2 V, r=0.4 Omega ) |
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| 44 | When no current is passed through a conductor This question has multiple correct options A. the free electrons do not move B. the average speed of a free electron over a large period of time is zero C. the average velocity of a free electron over a large period of time is zero D. the average of the velocities of all the free electrons at an instant is zero |
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| 45 | A charge ( q ) is placed at the centre of the line joining two equal charges ( Q ). The system of the three charges will be in equilibrium if ( q ) is equal to? |
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| 46 | When connected to the ( 220 mathrm{V} ) mains supply, the current in a toaster, a kettle, a lamp and a fan is ( 5.2 mathrm{A}, 9.4 mathrm{A}, 0.5 mathrm{A} ) and 2.6A respectively. Which appliance has the greatest electrical resistance? A. toaster B. kettlein c. lamp D. fan |
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| 47 | A battery is delivering same power to resistance ( R_{1} ) and ( R_{2} . ) Then find the internal resistance of battery : A. ( frac{R_{1}-R_{2}}{2} ) В. ( R_{1}+R_{2} ) c. ( sqrt{R_{1}+R_{2}} ) D. ( sqrt{R_{1}+R_{2} / 2} ) |
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| 48 | Find out the resistance: | 12 |
| 49 | An aluminium wire carrying a current has diameter ( 0.84 mathrm{mm} ). The electric field in the wire is ( 0.49 V / m . ) What is, (a) the current carried by the wire? (b) the potential difference between two points in the wire 12.0 m apart? (c) the resistance of a ( 12.0 mathrm{m} ) length of this wire? Specific resistance of aluminum is ( 2.75 times 10^{8} Omega-m ) |
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| 50 | A metallic wire of resistance ( 20 Omega ) is stretched such that its length becomes three times. The new resistance of the wire will be A ( .6 .67 Omega ) B. ( 60.0 Omega ) c. ( 120 Omega ) D. ( 180 Omega ) |
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| 51 | ( mathbf{1} boldsymbol{A}= ) ( mathbf{A} cdot 10^{2} ) B. ( 10^{3} ) ( mathbf{c} cdot 10^{-3} ) D. ( 10^{-6} ) |
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| 52 | The pd a cross terminals of a cell is found to be 29 volt and 28 volt respectively when it delivers a current of 1 ampere and 2 ampere respectively. The emf and internal resistance of a cell are respectively A. ( 30 mathrm{V}, 2 Omega ) B. 30V,1Omega c. ( 29 v, 1 Omega ) D. ( 28 mathrm{V}, 2 Omega ) |
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| 53 | In a potentiometer experiment for measuring the emf of a cell, the null point is at ( 240 mathrm{cm} ) when we have a ( 500 Omega $ ) resistor in series with the cell and galvanometer. If the series resistance reduced to half, then the null point will be at: A. ( 480 mathrm{cm} ) в. 240 ст ( mathrm{c} .120 mathrm{cm} ) D. ( 60 mathrm{cm} ) |
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| 54 | State Kirchoff’s rules. Use these rules to find the values of current ( boldsymbol{I}_{1}, boldsymbol{I}_{2}, boldsymbol{I}_{3} ) in the circuit diagram given begin{tabular}{|l|l|} hline( I_{1} ) & ( 1 / 2 V ) & ( gamma_{1}=4 Omega ) \ & \ ( vdots ) & 11 \ hline( I_{2} ) & \ ( I_{3} ) & ( 4 V ) & ( gamma_{3}=3 Omega ) \ hline end{tabular} |
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| 55 | The drift velocity of electrons in a conducting wire is of the order of ( 1 m m / s, ) yet the bulb glows very quickly after the switch is put on because A. the random speed of electrons is very high of the order of ( 10^{-6} mathrm{m} / mathrm{s} ) B. the electrons transfer their energy very quickly through collision. c. electric field is set up in the wire very quickly, producing a current through each cross section almost intantaneously D. All the above |
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| 56 | The current i in the circuit (see figure) is : ( A cdot frac{1}{A 5} ) ( B cdot frac{1}{15} A ) ( c cdot frac{1}{10} A ) ( D cdot underline{1} ) |
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| 57 | Three similar cells, each of emf ( 2 V ) and internal resistance ( r ) send the same current through an external resistance of ( 2 Omega, ) when connected in series or in parallel. Then the magnitude of current flowing through the external resistance is : ( mathbf{A} cdot 0.75 A ) в. ( 1 A ) ( c .1 .5 A ) D. zero |
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| 58 | The filament of a bulb takes a current ( 0.1 mathrm{A} ) when potential difference across it is ( 0.2 mathrm{V} ). When the potential difference across it becomes ( 1.0 mathrm{V} ), the current becomes 0.4 A. The resistance of filament in each case will be A. ( 2.0 Omega, 2.5 Omega ) B. ( 2.5 Omega, 2 Omega ) c. ( 1.0 Omega, 2.5 Omega ) D. ( 2.0 Omega, 2 Omega ) |
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| 59 | Copper and silicon is cooled from ( 300 mathrm{K} ) to ( 60 mathrm{K} ), the specific resistance : A. decreases in copper but increase in silicon B. increases in copper but decrease in silicon c. increase in both D. decrease in both |
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| 60 | The graph shown in the figure represents a plot of current versus voltage for given semi-conductor Identify the region. if any, over which the semi-conductor has a negative resistance |
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| 61 | Four similar charges each of magnitude ( Q ) are placed at the four comers of a square of side ‘a’. The intensity of the electric field at the intersection of the diagonal is A. 0 в. ( frac{Q}{4 pi varepsilon_{0} a^{2}} ) c. ( frac{4 Q}{4 pi varepsilon_{0} a^{2}} ) D. ( frac{Q}{8 pi varepsilon_{0} a^{2}} ) |
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| 62 | A physicist works in a laboratory where the magnetic field is 2 T. She wears a silver necklace enclosing an area 100 ( c m^{2} ) of field and having a resistance of ( 0.1 Omega . ) Because of power failure, the field decays to ( 1 T ) in millisecond. The electric charge circulated in the necklace assuming that the magnetic field is perpendicular to area covered by the necklace is ( mathbf{A} cdot 0.01 C ) в. ( 0.001 C ) c. ( 0.1 C ) D. ( 1.0 C ) |
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| 63 | The effective capacitance between the point ( mathrm{P} ) and ( Q ) in the given figure is ( mathbf{A} cdot 4 mu F ) B. ( 16 mu F ) c. ( 26 mu F ) D. ( 10 mu F ) |
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| 64 | A wire has resistance of ( 8 Omega ). If its length is made half by folding, find its resistance after the free ends are connected to each other |
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| 65 | Find the resistance of the voltmeter A. ( 400 Omega ) B. 200 ( Omega ) c. ( 300 Omega ) D. 500 ( Omega ) |
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| 66 | In the primary circuit of potentiometer the rheostat can be varied from 0 to 10Omega. Initially it is at minimum resistance (zero). Find the length ( boldsymbol{A P} ) (in ( mathrm{m} ) ) of the wire such that the galvanometer shows zero deflection. |
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| 67 | The resistance of a bulb filament is ( 100 Omega ) at a temperature of ( 100^{circ} mathrm{C} ). If its temperature coefficient of resistance be 0.005 per ( ^{o} C, ) its resistance will become ( 200 Omega ) at a temperature of : ( mathbf{A} cdot 200^{circ} C ) B. ( 300^{circ} mathrm{C} ) c. ( 400^{circ} mathrm{C} ) D. ( 500^{circ} mathrm{C} ) |
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| 68 | Explain Krichhoff’s laws with examples. | 12 |
| 69 | The power consumed in ( 10 Omega ) resistor in the given circuit is : A. ( 10 W ) В. ( 8 W ) ( c .>10 W ) ( D ) |
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| 70 | Given circuit has ( n ) cells attached to it. All the cells are identical. When one cell is reversed, the current decreases to ( 0.7 A . ) The value of ( n ) is A . 12 B. 16 ( c cdot 20 ) ( D ) |
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| 71 | Two cells when connected in series are balanced on ( 8 m ) on a potentiometer. If the cells are connected with polarities of one of the cell is reversed, then they balance on 2 m. The ratio of emf’s of two cells is A .3: 4 B. 4: 3 ( c .3: 5 ) D. 5: 3 |
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| 72 | The resistors of resistances ( 2 Omega, 4 Omega, 5 Omega ) are connected in parallel. The total resistance of the combination will be : A ( cdot frac{29}{10} Omega ) в. ( frac{19}{20} Omega ) c. ( frac{10}{20} Omega ) D. ( frac{20}{19} Omega ) |
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| 73 | Identify the changes in a circuit on adding a light bulb in parallel to the actual resistance of the circuit. It will: A. decrease the total resistance B. increase the total resistance c. make the voltage lost in each light bulb different D. make the current through each light bulb the same E. not change the total current through the circuit |
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| 74 | For which of the following dependence of drift velocity ( v_{d} ) on electric field E is Ohm’s law obeyed? A ( cdot v_{d} propto E ) B . ( v_{d}= ) constant ( mathbf{c} cdot v_{d} propto sqrt{E} ) D ( cdot v_{d} propto E^{2} ) |
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| 75 | Draw the experimental set-up to verify that ( frac{V}{I} ) is constant for a Conductor |
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| 76 | For making standard resistance, wire of following material is used A. Nichrome B. Copper c. silver D. Manganin |
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| 77 | Consider a thin square sheet of side ( boldsymbol{L} ) and thickness ( t, ) made of a material of resistivity ( rho . ) The resistance between two opposite faces, shown by the shaded areas in the figure is A. directly proportional to L B. directly proportional to t c. independent of D. independent of t |
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| 78 | Deduce the expression for the the equivalent resistance of three resistors connected in Parallel. |
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| 79 | Which of the following has a negative temperature coefficient? A . B. Fe ( c . ) мп D. Agg |
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| 80 | No current flows between two charged bodies when connected if they have same: A. capacity B. charge c. potential D. none of the above |
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| 81 | An immersion heater is rated ( 836 W . ) It should heat ( 1 l ) of water from ( 20^{0} C ) to ( 40^{0} ) ( mathrm{C} ) in about: A. ( 200 s ) B. ( 100 s ) ( mathbf{c} .836 s ) D. ( 418 s ) |
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| 82 | In the circuit shown in figure cells of emf 2,1,3 and ( 1 V ) respectively having resistances ( 2 Omega, 1 Omega, 3 Omega ) and ( 1 Omega ) are their internal resistances respectively. The potential difference between D and B (in volts) A ( cdot frac{5}{13} ) в. ( frac{2}{13} ) c. ( frac{10}{13} ) |
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| 83 | Two wires of Aluminium have same weight and have lengths of ( 10 mathrm{m} ) and 20m. Their resistances are in the ratio. A .1: 2 B . 2: 1 c. 4: 1 D. 1: 4 |
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| 84 | The ratio of resistances between ( A ) and B before and after the switch ( S ) is closed: ( mathbf{A} cdot 9: 8 ) B .7: 8 ( c cdot 2: 3 ) D. 1: 2 |
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| 85 | A battery of e.m.f. ( boldsymbol{E} ) has an internal resistance ‘r’. A variable resistance ( boldsymbol{R} ) is connected to the terminals of the battery. A current ( I ) is drawn from the battery. ( V ) is the terminal P.D. If ( R ) alone is gradually reduced to zero, which of the following best describes ( I ) and ( V ? ) A. I approaches ( E / r, V ) approaches ( E ) B. I approaches infinity, ( V ) approaches ( E ) c. ( I ) approaches zero, Vapproaches ( E ) D. I approaches ( E / r, V ) approaches zero |
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| 86 | Two cells of same emf E but different internal resistances ( r_{1} ) and ( r_{2} ) are connected in series with an external resistance ( R ). The potential drop across the first cell is found to be zero. The external resistance ( boldsymbol{R} ) is A ( cdot r_{1}+r_{2} ) В. ( r_{1}-r_{2} ) c. ( r_{2}-r_{1} ) D. ( r_{1} r_{2} ) |
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| 87 | The point in a Meter bridge is at ( 35.6 mathrm{cm} . ) If the resistances in the gaps are interchanged,the new balance point is: A. ( 64.4 mathrm{cm} ) B. ( 56 mathrm{cm} ) c. 41.2 ст D. ( 56.7 mathrm{cm} ) |
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| 88 | In the given figure, the current in the cell is A . 33 A в. 3.3 А c. 0.33 A D. 3.32 A |
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| 89 | Is it safe for an electrician to carry out electrical repairs outdoors during heavy downpour ? Explain |
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| 90 | The amount of charges that passes any section of the conductors in one second is called: A. current B. power dissipation c. electromotive force D. internal resistance |
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| 91 | Electromotive force of a battery represents ( A cdot ) force B. energy C. electric potential energy per unit charge D. current |
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| 92 | The length of a given cylindrical wire is increased by ( 100 % . ) Due to the consequent decrease in diameter the change in the resistance of the wire will be :- A . 300% B . 200% ( c cdot 100 % ) D. 50% |
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| 93 | A carbon filament has resistance of 120 ( Omega ) at ( 0^{0} C . ) The resistance of a copper filament connected in series with carbon so that the combination has same resistance at all temperatures must be ( alpha ) of carbon ( =-7 times 10^{-4} /^{0} C ; alpha ) of ( operatorname{copper}=4 times 10^{-3} /^{0} C ) A . ( 120 Omega ) B. 21Omega ( c cdot 60 Omega ) D. 210Omega |
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| 94 | For the given potentiometer circuits, potential gradient is ( 0.025 V / m ) and the ammeter reading is 0.1 A. Now, when terminals 1 and 2 are connected balance point is obtained at ( 40 mathrm{cm} ). Also when terminals 1 and 3 are connected balance point in obtained at ( 100 mathrm{cm} ). If ( 3 R=k X, ) then the value of ( k ) will be |
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| 95 | Three identical resistors each of resistance ( R ) are connected to an ideal cell of voltage ( V ) as shown. Total power dissipated in all three resistors is: ( A cdot frac{3 V^{2}}{2 R} ) ( B cdot frac{3 V^{2}}{B} ) c. ( frac{V^{2}}{3 R} ) D. ( frac{2 V^{2}}{3 R} ) |
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| 96 | Three resistors are connected as shown in the diagram. Through the resistor 5 ohm, a current of |
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| 97 | If the length of the wire is doubled, then the specific resistance will be :- ( mathbf{A} cdot ) two times B. (1/2) times c. four times D. same |
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| 98 | If two resistors of resistance ( 30 Omega ) and ( 40 Omega ) are connected in parallel across a battery. The ratio of the potential difference across them is A . 1: 1 B . 2: 1 ( c .3: 4 ) D. 4: 3 |
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| 99 | Fill in the blanks with suitable words Electrica is a Latin word which means |
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| 100 | At what temperature will the resistance of a copper wire become three times its value at ( 0^{0} ) C? [Temperature coefficient of resistance for copper ( =4 times ) ( left.10^{-3} p e r^{0} Cright]: ) ( mathbf{A} cdot 500^{0} C ) B . ( 450^{circ} mathrm{C} ) c. ( 600^{0} C ) D. None of these |
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| 101 | Two cells of emf’s ( 1.25 mathrm{V} ) and ( 0.75 mathrm{V} ) having equal internal resistance are connected in parallel. The effective emf is A . ( 0.75 v ) B. 1.25V c. ( 2.0 v ) D. 1.0v E. ( 0.5 v ) |
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| 102 | Draw the schematic diagram of an electric circuit consisting of a battery of two cells of ( 1.5 mathrm{V} ) each, three resistance of 5 ohm, 10 ohm and 15 ohm respectively and a plug key all connected in series. |
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| 103 | The two cells are connected in series, in a potentiometer experiment, in such a way so as to support each other and to oppose each other. The balancing lengths in two conditions are obtained as ( 150 mathrm{cm} ) and ( 50 mathrm{cm} ) respectively. The ratio of emf’s of two cells will be A . 1: 2 B. 2: c. 1: 4 D. 4: |
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| 104 | When 5 V potential difference is applied across a wire of length ( 0.1 mathrm{m} ), the drift speed of electrons is ( 2.5 times 10^{-4} ) ( mathrm{m} / mathrm{s} . ) If the electron density in the wire is ( 8 times 10^{28} m^{-3}, ) calculate the resistivity of the material of the wire. |
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| 105 | Equivalent resistance of the system and potential difference across the external resistance in the figure. A ( . r, ) в. ( r, E ) ( c cdot o, E ) ‘ ( r, frac{E R}{R+r} ) |
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| 106 | Assertion Statement 1:The current density ( bar{J} ) at any point in ohmic resistor is in direction of electric field ( bar{E} ) at that point. Reason Statement ( 2: A ) point charge when released from rest in a region having only electrostatic field always moves along electric lines of force. 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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| 107 | The resistance of a wire of cross-section ‘a’ and length ‘l’ is R ohm. The resistance of another wire of the same material and of the same length but crosssection ‘4a’ will be ( A cdot 4 R ) в. ( frac{R}{4} ) ( c cdot frac{R}{16} ) D. 16 R |
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| 108 | Three wires of same material are connected in parallel to a source of emf. The length ratio of the wires is 1: 2: 3 and the ratio of their area of cross section is 2: 4: 1 Table 1 Table 2 1 T 6: 6: 1 (p) (a)Resistance ratio : 6: 1 (b) ( begin{array}{ll}text { Current ratio } & text { (q) } 1: 6: 6 \ text { Power ratio } & text { (r) } 1: 1: 6 \ & text { (s) None }end{array} ) (c) ( mathbf{A} cdot 1) ) ( a-r, b-q, c-p ) B. 2) a-p,b-q,c-r c. ( 3) a-r ; b-p, c-p ) D. 4 ) a ( -q, b-p, c-r ) |
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| 109 | Copper has one conduction electron per atom. Its density is ( 8.89 g / m^{3} ) and its atomic mass is ( 63.54 mathrm{g} / mathrm{mol} ). If a copper wire of diameter ( 1.0 mathrm{mm} ) carries a current of 2.0 A. What is the drift speed of the electrons in the wire? A ( cdot 1.9 times 10^{-4} ) В. ( 2.9 times 10^{-4} ) ( mathbf{c} cdot 1.9 times 10^{4} ) D. ( 2.9 times 10^{4} ) |
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| 110 | A battery of emf 2 volt and internal resistance 0.1 ohm is being charged with a current of 5 ampere. The potential difference between the two terminals of the batteries is A ( .2 V ) в. ( 0.5 V ) ( c .1 .5 V ) D. 2.5V |
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| 111 | What happens to the current in the external circuit when a battery ages? A. Remain the same B. Polarize c. Reverse direction D. Increase E. Decrease |
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| 112 | Consider a Wheatstone bridge with resistance and capacitance connected as shown. Find the condition on the resistance and |
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| 113 | When cells are connected in series greater emf is obtained in the circuit. A. True B. False |
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| 114 | If in a Wheatstone bridge the battery and Galvanometer are interchanged, the condition for balance A. is disturbed B. is not disturbed c. depends on the internal resistance of the bridge D. depends on the values of the resistances in the bridge |
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| 115 | ( boldsymbol{I}-boldsymbol{V} ) graph for a metallic wire at two different temperatures, ( boldsymbol{T}_{1} ) and ( boldsymbol{T}_{2} ) is a shown in the figure. Which of the two temperature is lower |
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| 116 | Assertion Bending a wire does not effect electrical resistance Reason Resistance of wire is proportional to resistivity of material 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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| 117 | ( boldsymbol{R}_{1}, boldsymbol{R}_{2}, boldsymbol{R}_{3} ) are different values of ( boldsymbol{R} ) ( mathbf{A}, mathbf{B}, mathbf{C} ) are the null points obtained corresponding to ( boldsymbol{R}_{1}, boldsymbol{R}_{2} ) and ( boldsymbol{R}_{3} ) respectively. For which resistor, the value of ( X ) will be the most accurate and why? ( A cdot R_{1} ) B. ( R_{2} ) ( c cdot R_{3} ) D. All same |
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| 118 | The ( V-I ) graph for a conductor at temperature ( T_{1} ) and ( T_{2} ) are as shown in figure. The term ( left(boldsymbol{T}_{mathbf{2}}-boldsymbol{T}_{mathbf{1}}right) ) is proportional to: ( mathbf{A} cdot cos 2 theta ) B. ( sin 2 theta ) ( c cdot cot 2 theta ) D. ( tan 2 theta ) |
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| 119 | The capacitors ( C_{1}, C_{3}, C_{4}, C_{5} ) shave a capacitance ( 4 mu F ) each and ( C_{2} ) has capacitance ( 10 mu F ). The effective capacitance between ( mathrm{P} ) and ( mathrm{Q} ) will be : ( mathbf{A} cdot 8 mu F ) в. ( 6 mu F ) ( c .4 mu F ) D. ( 2 mu F ) |
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| 120 | A lamp of ( 6 mathrm{V} ) and ( 30 mathrm{W} ) is used in a laboratory but the supply is of ( 120 mathrm{V} ) what will be done to make use of the lamp? (1) A resistance may be used (2) A resistance may be used in series with lamp. (3) The resistance should be of ( 18 Omega ) A. 1,2 and 3 are correct B. 1 and 2 are correct c. 1 and 3 are correct D. 2 and 3 are correct |
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| 121 | When two same conducting rod are kept at different temperature, A. theirs resistivity will be different B. their resistivity will be same c. resistivity doesn’t’ depend on temperature D. none of the above |
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| 122 | For the given circuit diagram; the equivalent resistance across battery is : ( A .5 Omega ) B. ( 10 Omega ) ( c .20 Omega ) D. ( 15 Omega ) |
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| 123 | A piece of copper and another of germanium are cooled from room temperature to ( 77 mathrm{K} ), the resistance of : A. each of them increases B. each of them decreases c. copper decreases and germanium increases D. copper increases and germanium decreases |
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| 124 | The current in a metallic conductor is plotted against voltage at two different temperatures ( T_{1} ) and ( T_{2} . ) Which is correct ( A cdot T_{1}>T_{2} ) В ( cdot T_{1}<T_{2} ) ( c cdot T_{1}=T_{2} ) D. None |
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| 125 | Three resistances are connected to form a ( T ) -shape as shown in the figure. Then the current in the ( 4 mathrm{K} ) resistor is : A. ( 0.93 mathrm{mA} ) B. ( 1.42 mathrm{mA} ) c. ( 2.5 mathrm{mA} ) D. 1.57 m |
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| 126 | A metallic block has no potential difference applied across it, then the mean velocity of free electrons at absolute temperature T is A. Proportional to ( T ) B. Proportional to ( sqrt{T} ) c. zero D. Finite but independent of ( T ) |
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| 127 | A battery of e.m.f. ( 6.0 ~ V ) and negligible internal resistance is connected to a network of resistors and a voltmeter, as shown in Fig. Resistor ( Y ) has a resistance of ( 24 Omega ) and |
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| 128 | Figure shows a uniformly charged hemispherical shell. The direction of electric field at point ( p, ) that is off- centre (but in the plane of the largest circle of the hemisphere), will be along B. pb ( c cdot p c ) D. pd |
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| 129 | When a current ( I ) is set up in a wire of radius ( r, ) the drift velocity is ( v_{d} . ) If the same current is set up through a wire of radius ( 2 r, ) the drift velocity will be A . ( 4 v_{d} ) в. ( 2 v_{d} ) c. ( frac{v_{d}}{2} ) D. ( frac{v_{d}}{4} ) |
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| 130 | A cell can be balanced against ( 110 mathrm{cm} ) and 100 ( mathrm{cm} ) of potentiometer wire, respectively with and without being short circuited through a resistance of 10 . Its internal resistance is – A. 2.0 ohm B. zero c. 1.0 ohm D. 0.5 ohm |
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| 131 | A ( 10 m ) long uniform metallic write having a resistance of ( 20 Omega ) is used as a potentiometer wire. This wire is connected in series with another resistance of ( 480 Omega ) and a battery of emf ( 5 V ) having negligible internal resistance. If an unknown emf e is balanced across ( 6 m ) of the potentiometer wire, calculate: (i) The potential gradient across the potentiometer wire. (ii) The value of the unknown emf e. |
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| 132 | AB ia a potentiate wire of length ( 100 mathrm{cm} ) and is resistance is ( 10 Omega ). It is connected in series with a resistance ( boldsymbol{R}=mathbf{4 0 Omega} ) and a battery of emf ( 2 mathrm{V} ) and negligible internal resistance. If a source of unknown potentiate wire, the value of ( mathrm{E} ) is: ( A cdot 0.8 V ) B. ( 1.6 v ) c. ( 0.06 mathrm{v} ) D. ( 0.16 mathrm{v} ) |
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| 133 | A uniform copper wire carries a current ( boldsymbol{i} ) amperes and has ( boldsymbol{p} ) carriers per metre. The length of the wire is ( l ) metres and its cross-section area is s metre. If the charge on a carrier is ( q ) coulombs, the drift velocity in ( m s^{-1} ) is given by ( mathbf{A} cdot i / l s q ) ( mathbf{B} cdot i / p s q ) ( mathbf{c} cdot p s q / i ) ( mathbf{D} cdot i / p s l q ) |
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| 134 | A table lamp of power 60 W consumed 9 (commercial) units of electricity in the month of April. For how many hours per day, on an average, was the lamp in use? ( A cdot 1 h ) в. ( 3 h ) ( c .5 h ) D. ( 6 h ) |
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| 135 | The resistance of a bulb filament is 100 ( Omega ) at a temperature of ( 100^{0} mathrm{C} ). If its temperature coefficient of resistance be 0.005 per ( ^{0} mathrm{C} ), its resistance will become ( 200 Omega ) at a temperature of : A ( cdot 300^{0} mathrm{C} ) B. ( 400^{circ} mathrm{C} ) ( c cdot 500^{0} c ) D. 200^ |
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| 136 | The equivalent resistance between ( A ) and B is ( A cdot R ) в. ( frac{R}{2} ) ( c .2 R ) D. None of these |
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| 137 | Four cells each of emf ( 1.9 mathrm{V} ) and the internal resistance ( 1 Omega ) are connected to an external resistance of 18 Omega as shown in the figure. Find the terminal potential difference of this combination |
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| 138 | A cell of emf ( ^{prime} E^{prime} ) and internal resistance ( r^{prime} ) draws a current ( ^{prime} I^{prime} . ) Write the relation between terminal voltage ( ^{prime} V^{prime} ) in terms of ( boldsymbol{E}, boldsymbol{I} ) and ( boldsymbol{r} ) |
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| 139 | A galvanometer, together with an unknown resistance in series, is connected across two identical batteries of each ( 1.5 mathrm{V} ). When the batteries are connected in series, the galvanometer records a current of ( 1 A ) and when the batteries are connected in parallel, the current is ( 0.6 A ), then the internal resistance is ( 1 / x^{prime} ) Omega. What is the value of ( x ) ‘? |
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| 140 | Derive the expression to find the unknown resistance in the balanced condition of wheastone bridge. |
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| 141 | The resistance of carbon filament at ( 0^{0} C ) is ( 104 Omega . ) It is connected in series to an iron wire. The temperature coefficient of resistivity of carbon and iron are -0.0003 and +0.0052 per degree Celsius respectively. What must be the resistance of iron wire so that the combined resistance does not change with temperature? A . 15 B. 6 c. 1.5 D. 156 |
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| 142 | Wires ( A ) and ( B ) are made from the same material. Wire A has length 12m and weight 50 g, while wire ( B ) is 18 m long and weighs 40 g. Then the ratio ( left(R_{A} / R_{B}right) ) of their resistances will be : ( A cdot 16 / 45 ) B. 415 ( c cdot 8 / 15 ) D. 419 |
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| 143 | If the voltmeter reads ( 0.21 mathrm{V} ) and the ammeter reads ( 0.1 A ), the resistance of the ammeter is (in ohm) A. 0.0 в. 0.15 ( c cdot 0 . ) D. o. |
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| 144 | A student is asked to connected four cells of e.m.f of ( 1 mathrm{V} ) and internal resistance 0.5 ohm in series with an external resistance of 1 ohm. But one cell is wrongly connected by him with its terminal reversed. the current in the circuit is A ( cdot frac{1}{3} A ) в. ( frac{2}{3} A ) c. ( frac{3}{4} ) D. ( frac{4}{3} ) |
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| 145 | In a circuit two or more cells of the same e.m.f are connected in parallel in order to: A. increase the P.D across a resistance in the circuit B. decrease the P.D across a resistance in the circuit C. facilitate drawing more current from the battery system D. change the e.m.f across the system of batteries |
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| 146 | A cell having EMF E and internal resistance ( r ) is connected to a load ( R ) Find the value of ( R ) such that power dissipated by the cell is maximum |
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| 147 | Ohm’s law is valid for A. gases only B. liquids only C. both liquids and gases D. metallic conductors |
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| 148 | The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are given below – |(amperes) 2 ( V(v text { olts }) ) 1. 6 . 6 3.4 6.7 Plot a graph between ( mathrm{V} ) and ( mathrm{I} ) and calculate the resistance of that resistor. |
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| 149 | Each of the six ideal batteries of emf ( 20 V ) is connected to an external resistance of ( 4 Omega ) as shown in the figure. The current through the resistance is ( mathbf{A} cdot 6 A ) в. ( 3 A ) ( c .4 A ) D. ( 15 A ) |
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| 150 | Kirchhoff’s rules are very useful for analysis of electrical circuits. State Kirchhoff’s junction rules. | 12 |
| 151 | The magnetic flux through a coil perpendicular to its plane and directed into paper is varying according to the relation ( phi=left(2 t^{2}+4 t+6right) m W b ). The emf induced in the loop at ( t=4 s ) is ( mathbf{A} cdot 0.12 V ) в. 2.4V c. ( 0.02 V ) D. ( 1.2 V ) |
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| 152 | If four resistances are connected as shown in the fig. between ( A ) and ( B ), the effective resistance is: A . ( 3 Omega ) B. ( 1 Omega ) c. ( 2.4 Omega ) D. 25 |
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| 153 | Quantity of heat produced by a conductor is directly proportional to in the conductor. A. The time of current flow B. The resistance c. The Square of magnitude of current D. All |
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| 154 | Copper contains ( 8.4 times 10^{28} ) free electrons/ ( m^{3} ). A copper wire of crosssectional area ( 7.4 times 10^{-7} m^{2} ) carries a current of 1 A. The electron drifts speed is approximately: ( mathbf{A} cdot 10^{-8} m / s ) B. ( 10^{-3} mathrm{m} / mathrm{s} ) c. ( 1 m / s ) D. ( 10^{-4} mathrm{m} / mathrm{s} ) |
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| 155 | A battery of ( V ) voltage is connected across the potentiometer wire ( boldsymbol{A} boldsymbol{C} ) of total resistance ( R_{0} ) as shown. Calculate the potential across the resistance ( boldsymbol{R} ) if the sliding contact point ( B ) is exactly at the middle of the potentiometer wire. ( A ) в. ( frac{4 V R_{0}}{2 R_{0}+R} ) c. ( frac{2 V R}{R_{0}+4 R} ) D. ( frac{4 V R_{0}}{R_{0}+2 R} ) |
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| 156 | ( P=frac{V^{2}}{R} ) is applied when A. Current is constant B. Potential difference is constant c. Resistance is constant D. None |
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| 157 | What is a potential meter explain its principal (a)Explain how it can be used to compare the emf of two cells (b)Explain how it can be used to determine the internal resistance of a cells. |
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| 158 | 1) State the law of magnetism. 2) State the law of charges. 3) What happens when a straw is rubbed with a sheet. |
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| 159 | A car bulb connected to a 12 volt battery draw 2 A current when glowing. What is the resistance of the filament of the bulb? A . ( 3 Omega ) в. ( 6 Omega ) ( c .9 Omega ) D. 24 |
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| 160 | A part of circuit with current is shown. The value of ( I ) is : A ( .1 A ) в. ( 2 A ) ( c .4 A ) D. zero |
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| 161 | What is the resistance between ( P ) and Q? ( A cdot frac{3}{4} s ) B. ( frac{4}{3} ) c. ( frac{16}{3} ) D. Infinity |
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| 162 | What is the formula for electric power? A ( cdot P=I^{2} R t ) B . ( P=frac{w}{t} ) c. ( P=V I times t ) D. ( P=v Q ) |
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| 163 | In a Wheatstone bridge if the battery and galvanometer are interchanged then the deflection in galvanometer will: A. Change in previous direction B. Not change c. change in opposite direction D. None of these |
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| 164 | An electric cell does 5 joules of work in carrying 10 -coulomb charge around the closed circuit. The electromotive force of the cell is : A . 2 volt B. 0.5 volt c. 4 volt D. 1 volt |
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| 165 | A resistance of ( R Omega ) draws a current from a potentiometer. The potentiometer has a total resistance ( R_{0} Omega . ) A voltage V is supplied to the potentiometer. The voltage across ( mathrm{R} ) when the sliding contact is in the middle of the potentiometer is: A ( cdot frac{2 V R}{4 R_{0}+R} ) В. ( frac{4 V R}{R_{0}+R} ) ( mathbf{c} cdot frac{V R}{R_{0}+4 R} ) D. ( frac{2 V R}{R_{0}+4 R} ) |
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| 166 | A particular resistance wire has a resistance of 3.0 ohm per metre. The total resistance of three lengths of this wire each ( 1.5 mathrm{m} ) long, joined in parallel will be : A ( .2 .5 Omega ) в. 3 Omega c. ( 4.5 Omega ) D. ( 1.5 Omega ) |
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| 167 | In the circuit shown in figure, the current through A. The ( 3 Omega ) resistor is ( 1.00 A ) B. The ( 3 Omega ) resistor is 0.25 A C. The ( 4 Omega ) resistor is ( 0.50 A ) D. The ( 4 Omega ) resistor is ( 0.25 A ) |
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| 168 | In a potentiometer of wire length ( l ), a cell of emf ( V ) is balanced at a length ( frac{l}{3} ) from the positive of the wire. For another cell of emf ( 1.5 V, ) the balancing length becomes A ( cdot frac{l}{6} ) B. ( frac{l}{2} ) c. ( frac{l}{3} ) D. ( frac{2 l}{3} ) E ( cdot frac{4 l}{3} ) |
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| 169 | In the circuit shown below in Fig. the value of ( x ) if the equivalent resistance between ( A ) and ( B ) is ( 4 Omega ) will be: ( A cdot 2 Omega ) B. ( 1 Omega ) c. ( 1.5 Omega ) D. ( 3 Omega ) |
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| 170 | The electric field ( mathrm{E} ), current density and conductivity ( sigma ) of a conductor are related as A ( . sigma=E / J ) В . ( sigma=J / E ) ( mathrm{c} cdot sigma=J E ) D. ( sigma=1 / E ) |
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| 171 | In the following circuit, the battery ( boldsymbol{E}_{mathbf{1}} ) has an emf of ( 12 V ) and zero internal resistance while the battery ( E ) has emf of 2 volt. If the galvanometer ( G ) reads zero, then the value of the resistance ( boldsymbol{X} ) in ohm is A . 10 в. 100 c. 500 D. 200 |
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| 172 | A uniform wire of resistance ( 100 Omega ) its melted and made in the form of uniform wire, whose length is double that of the original. The resistance of the new wire is A ( .200 sqrt{2} Omega ) B. ( 800 Omega ) c. ( 200 Omega ) D. ( 400 Omega ) |
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| 173 | The diagram shows a resistor connected to a cell of e.m.f. ( 2 V ) How much heat energy is produced in the resistor in six seconds? A ( .2 .5 . ) в. 4.8 . ( c cdot 10 J ) D. ( 60 . ) |
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| 174 | Figure shows a balanced Wheatstone net. Now, it is disturbed by changing ( mathrm{P} ) to ( 11 omega ).Which of the following steps will not bring the bridge to balance again? A. Increasing R by ( 2 omega ) B. Increasing S by ( 20 omega ) C. Increasing Q by ( 10 omega ) D. Making product ( R Q=2200left(omega^{2}right) ) |
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| 175 | 1 ampere current is equivalent to ( mathbf{A} cdot 6.25 times 10^{18} ) electrons ( s^{-1} ) B. ( 2.25 times 10^{18} ) electrons ( s^{-1} ) C ( .6 .25 times 10^{14} ) electrons ( s^{-1} ) D. ( 2.25 times 10^{14} ) electrons ( s^{-1} ) |
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| 176 | The value of capacitance of capacitors shown in above diagram are ( C_{1}= ) ( boldsymbol{C}_{2}=boldsymbol{C}_{3}=boldsymbol{C}_{4}=boldsymbol{8} boldsymbol{mu} mathbf{C} ; boldsymbol{C}_{5}=mathbf{1 0} boldsymbol{mu} boldsymbol{C} ) The equivalent capacitance between and Q is: ( A cdot 8 mu F ) B. ( 24 mu F ) ( c cdot 16 mu F ) D. ( 15 mu F ) |
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| 177 | Find odd man out Plastic, Rubber, Glass, Silver A . Glass B. Rubber c. Silver D. Plastic |
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| 178 | Which is the expression for resistivity of a wire of length ( l ) and cross-section area A? A ( cdot rho=frac{R l}{A} ) B. ( rho=frac{R A}{l} ) ( c cdot rho=frac{A}{R l} ) D. ( rho=frac{R A}{l^{2}} ) |
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| 179 | A cell of E.M.F. E and internal resistance supplies currents for the same time through external resistance ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2} ) respectively. If the heat produced in both cases is the same then the internal resistance is A ( cdot 1 / r=1 / R_{1}+1 / R_{2} ) B. ( r=left(R_{1}+R_{2}right) / 2 ) ( mathbf{c} cdot r=left(R_{1} R_{2}right) ) D. ( r=R_{1}+R_{2} ) |
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| 180 | In the circuit shown in Figure. What must the emf ( epsilon ) of the battery be in order for a current of ( 2.00 A ) to flow through the ( 5.00 V ) battery? Is the polarity of the battery correct as shown? |
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| 181 | 2. In a meter bridge experiment, the null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X <Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X against Y? (a) 50 cm (b) 80 cm (c) 40 cm (d) 70 cm (AIEEE 2004) |
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| 182 | A superconductor has ( T_{C}(0)=100 K ) When a magnetic field of 7.5 Tesla is applied, its ( T_{c} ) decreases to 75 K. For this material one can definitely say that when A ( cdot B=5 ) Tesla, ( T_{c}(B)=80 K ) B. ( B=5 ) Tesla, ( 75 K<T_{c}(B)<100 K ) c. ( B=10 ) Tesla, ( 75 K<T_{c}<100 K ) D. ( B=10 ) Tesla, ( T_{c}=70 K ) |
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| 183 | n identical cells are joined in series with its two cells ( A ) and ( B ) in the loop with reversed polarities. EMF of each shell is ( mathrm{E} ) and internal resistance r. Potential difference across cell ( A ) or ( B ) is: A ( cdot frac{2 E}{n} ) В ( cdot 2 E mid 1-frac{1}{n} ) c. ( frac{4 E}{n} ) D. ( 2 E mid 1-frac{2}{n} ) |
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| 184 | The current in the primary circuit of a potentiometer is ( 0.2 mathrm{A} ). The specific resistance and cross section of the potentiometer wire are ( 4 times 10^{-7} ) ohm metre and ( 8 times 10^{-7} m^{2} ) respectively. The potential gradient will be equal to: A. ( 0.1 mathrm{V} / mathrm{m} ) B. ( 0.2 vee / mathrm{m} ) c. ( 1 mathrm{v} / mathrm{m} ) D. ( 0.5 vee / ) m |
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| 185 | The terminal potential difference of a cell is equal to the emf of the cell when: A. The cell is an open circuitt B. The internal resistance of the cell is zero c. The load resistance ( R ) is much greater than the internal resistance ( r ) D. All are true |
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| 186 | Two wires are as follows. The resistivities, lengths and radii are in the ratio 2: 3,3: 5 and 2: 7 respectively Their resistances are in the ratio of A . 49: 10 B. 7: 2 ( c cdot 2: 4 ) D. 1: 2 |
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| 187 | A point charge of ( q ) mass ( m ) is placed at center of a fix ring of charge ( Q ) and radius ( R ) what is the minimum velocity should be given by ( q ) so they would reach far away from ring. A ( cdot frac{Q q}{5-sqrt{5}} ) в. ( frac{Q q}{sqrt{5}-1} ) c. ( sqrt{frac{Q q}{2 varepsilon varepsilon R m}} ) D. ( frac{2 q}{5-sqrt{5}} ) |
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| 188 | A cell of e.m.f. ( mathrm{E} ) and internal resistance is connected in series with an external resistance nr then the ratio of the terminal potential difference to E.M.F. is A ( cdot 1 / n ) B. ( 1 / n+1 ) ( c cdot n / n+1 ) D. ( n+1 / n ) |
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| 189 | In a meter-bridge, the balancing length from the left end when standard resistance of 1 is in right gap is found to be ( 20 mathrm{cm} ). The value of unknown resistance is A ( .0 .25 Omega ) B. ( 0.5 Omega ) ( c .0 .4 Omega ) D. 4Omega |
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| 190 | A current is divided into two resistors connected in parallel according to Kirchhoff’s law, then the heat produced in the combination is A. zero B. Cannot be predicated c. Minimum D. Maximum |
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| 191 | Two cells ( A ) and ( B ) of emf ( 2 V ) and ( 1.5 vee ) respectively, are connected as shown in figure through an external resistance 10 ( Omega ). the internal resistance of each cell and is ( 5 Omega . ) The potential difference ( boldsymbol{E}_{boldsymbol{A}} ) and ( E_{B} ) across the terminals of the cells A and B respectively are: ( mathbf{A} cdot E_{A}=2.0 V cdot E_{B}=1.5 V ) B ( . E_{A}=2.125 V, E_{B}=1.375 V ) ( mathbf{c} cdot E_{A}=1.875 V, E_{B}=1.625 V ) D ( . E_{A}=1.875 V, E_{B}=1.375 V ) |
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| 192 | Calculate the total power of 2 fans, if each of them draws a current of ( 5 A ) at a p.d of ( 200 V ) A . ( 2000 omega ) в. ( 1000 V ) ( c .250 omega ) D. 2 |
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| 193 | Four resistors are connected as shown in figure. A ( 6 V ) battery of negligible resistance is connected across terminal ( boldsymbol{A C} ). The potential difference ( operatorname{across} ) terminals ( B ) and ( D ) will be : A . ( 0 V ) в. ( 1.5 V ) ( c .2 V ) D. ( 3 V ) |
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| 194 | How many electrons constitute a current of one microampere? ( mathbf{A} cdot 6.25 times 10^{6} ) B. ( 6.25 times 10^{12} ) ( mathbf{C} cdot 6.25 times 10^{9} ) D. ( 6.25 times 10^{15} ) |
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| 195 | The resistance ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2} ) are joined in parallel and a current is passed so that the amount of heat liberated is ( boldsymbol{H}_{1} ) and ( H_{2} ) respectively. The ratio ( frac{H_{1}}{H_{2}} ) has the value A ( cdot frac{R_{2}}{R_{1}} ) в. ( frac{R_{1}}{R_{2}} ) c. ( frac{R_{1}^{2}}{R_{2}^{2}} ) D. ( frac{R_{2}^{2}}{R_{1}^{2}} ) |
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| 196 | Assertion: The resistance of a milliammeter is greater than that of ammeter Reason: Shunt resistance in case of |
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| 197 | Assertion When current through a bulb decreases by ( 0.5 %, ) the glow of bulb decreases by ( 1 % ) Reason Glow (Power) which is directly proportional to square of current. 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 incorrect |
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| 198 | Statement-1: When two conducting wires of different resistivity having same cross section area are joined in series, the electric field in them would be equal when they carry current Statement-2: When wires are in series |
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| 199 | The force between two electrons when placedair is equal to 0.5 times the weight of an electrons find the distance between two electrons (masselectron ( left.=mathbf{9 . 1} times mathbf{1 0}^{-mathbf{3 1}} mathbf{k g}right) ) A . 7.2 m B. 72cm c. 72 m D. 720m |
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| 200 | Figure below shows a portion of an electric circuit with the currents in ampere and their directions. The magnitude and direction of the current in the portion ( boldsymbol{P} boldsymbol{Q} ) is: ( A cdot 0 A ) B. ( 3 A ) from ( P ) to ( Q ) ( c .4 A ) from ( Q ) to ( P ) D. ( 6 A ) from ( Q ) to ( P ) |
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| 201 | Define the following: (a) 1 volt ( P D ) (b) Electric power |
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| 202 | What is the reason for using Tungsten as a filament in electric bulb? | 12 |
| 203 | Dimension of temperature coefficient ( alpha ) is |
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| 204 | Draw the ( V-I ) characteristies of an LED. state two advantages of LED lamps over conventional incandescent lamps. |
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| 205 | Value of Current i in the following circuit is :- A . 13 A B. 12 A ( c cdot 9 A ) D. None of these |
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| 206 | The electric field intensity ( E, ) current density ( J ) and specific resistance ( k ) are related to each other through the relation ( A cdot E=frac{J}{k} ) в. ( E=J k ) c. ( _{E}=frac{k}{J} ) D. ( k=J E ) |
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| 207 | When a current of ( 0.5 A ) is passed through two resistors in series, the potential difference between the ends of the series arrangement is ( 12.5 % . ) On connecting them in parallel and passing a current of ( 1.5 A ), the potential difference across them is ( 6 V ). The two resistances, in ohms, are ( A cdot 5,20 ) B. 5, 15 c. 5,10 D. 15,20 |
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| 208 | The equivalent resistance between the points ( x ) and ( y ) of the circuit. If each resistance is 25 ohm is ( A cdot 25 Omega ) B. 1000 ( c .50 Omega ) D. 12.5Omega |
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| 209 | n identical cells, each of emf ( varepsilon ) and internal resistance ( r, ) are joined in series to form a closed circuit. One cell ( A ) is joined with reversed polarity. The potential difference across each cell, except ( A ), is A ( cdot frac{2 varepsilon}{n} ) в. ( frac{n-1}{n} ) c. ( frac{n-2}{n} ) D. ( frac{2 n}{n-2} ) |
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| 210 | In the circuit shown in figure, ( boldsymbol{E}_{1}= ) ( mathbf{3} boldsymbol{V}, boldsymbol{E}_{2}=mathbf{2} boldsymbol{V}, boldsymbol{E}_{3}=mathbf{1} boldsymbol{V} ) and ( boldsymbol{r}_{mathbf{1}}=boldsymbol{r}_{mathbf{2}}= ) ( r_{3}=1 o h m ) (a) Find the potential difference between the points ( A ) and ( B ) and the currents through each branch. (b) If ( r_{2} ) is short circuited and the point ( A ) is connected to point ( B ) through a resistance ( R, ) find the currents through ( boldsymbol{E}_{1}, boldsymbol{E}_{2}, boldsymbol{E}_{3} ) and the resistor ( boldsymbol{R} ) |
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| 211 | ( mathbf{A} ) ( 4 Omega(text { or } 4 text { ohm }) ) wire and ( a 2 Omega ) (or 2 ohm)wire are connected in parallel. ( mathbf{A} ) current of ( 3 A ) passes through the wires. How much current passes through the 2 ( Omega(text { or } 2 text { ohm }) ) wire? ( A cdot 2 A ) B. 4A ( c cdot 6 A ) D. 8A |
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| 212 | Statement 1: The drift speed of electrons in metals is small (in the order of a few ( m m / s) ) and the charge of an electron is also very small ( left(1.6 times 10^{-19} Cright), ) yet we can obtain a large current in a metal. Statement 2: At room temperature, the thermal speed of electrons is very high (about ( 10^{7} ) times the drift speed) A. Statement 1 is True, Statement 2 is True; Statement 2 is a correct explanation for Statement 1 B. Statement 1 is True, Statement 2 is True; Statement 2 is not a correct explanation for statement c. Statement 1 is True; Statement 2 is False D. Statement 1 is False; Statement 2 is True |
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| 213 | ( N ) cells, each of emf ( E ) and internal resistance ( r, ) are connected in a closed ring so that the positive terminal of each cell is joined to the negaive terminal of the next cell as shown in the adjoining diagram. Any two points of this ring are connected through an external resistance ( R ). Find the current ( operatorname{in} R ) |
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| 214 | Two charges each q nC. are placed at two vertices of an equilaterial triangle of side ( 1 mathrm{m} ). The filed at the other vertex is A ( cdot sqrt{2} q ) B. ( 9 sqrt{3} q ) c. ( frac{sqrt{3} q}{10} ) D. ( frac{9 q}{sqrt{3}} ) |
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| 215 | Assertion: The drift velocity of electrons in a metallic wire will decrease, if the temperature of the wire is increased. Reason: On increasing temperature, conductivity of metallic wire decreases. A. Both (A) and (R) are true and (R) is the correct explanation of B. Both (A) and (R) are true but (R) is not the correct explanation of A c. (A) is true but (R) is false D. (A) is false but (R) is true |
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| 216 | A coil made of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is kept close to the wire ? outside opposite |
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| 217 | Find out the current flowing through resistor ( boldsymbol{R}_{1} ) |
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| 218 | Calculate the power used in the ( 2 Omega ) resistor in each of the following circuits: (i) a ( 6 V ) battery in series with ( 1 Omega ) and ( 2 Omega ) resistors, and (ii) a ( 4 V ) battery in parallel with ( 12 Omega ) and ( 2 Omega ) resistors. |
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| 219 | The resistance of a conductor at ( 20^{circ} mathrm{C} ) is 3.15 ohm and at ( 100^{circ} mathrm{C} ) is 3.75 ohm. Determine the temperature co-efficient of resistance of the conductor. What will be the resistance of the conductor at 0 ( ^{o} C ? ) |
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| 220 | The current flowing in the primary circuit of potentiometer is ( 2 A ) and the resistance of its wire is ( 0.2 Omega / m . ) If a one ohm standard coil gets balanced at ( 250 mathrm{cm} ) length of the wire, then the current flowing in the coil will be A . ( 0.1 mathrm{A} ) B. 1A c. ( 1.5 mathrm{A} ) D. 0.05A |
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| 221 | A source of constant potential difference is connected across a conductor having irregular cross section as shown,then A. Electric field intensity at ( P ) is greater than that at ( Q ) B. rate of electrons crossing per unit area of cross section at ( P ) is less than that at ( Q ) c. the rate of generation of heat per unit length at ( P ) is greater than at ( Q ) D. mean kinetic energy of free electrons at ( P ) is greater than that at ( Q ) |
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| 222 | A wire has resistance of ( 12 Omega ). It is cut into two parts and both halve are connected in parallel. The new resistance is A . ( 3 Omega ) в. ( 1.5 Omega ) c. ( 12 Omega ) D. ( 6 Omega ) |
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| 223 | A current of ( I ) ampere flows through a resistance ( R ) when connected across a cell of emf ( E ) and internal resistance ( 1 Omega ) When ( R ) is increased by ( 50 % ), the current through the circuit is ( 0.8 A . ) The value of ( boldsymbol{R} ) is : A . ( 1 Omega ) B. ( 1.5 Omega ) ( c .2 Omega ) D. 4Omega |
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| 224 | Define temperature coefficient of resistance. |
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| 225 | The minimum resistance that can be obtained by connecting 5 resistance of ( frac{1}{4} Omega ) each is A ( cdot frac{4}{5} Omega ) в. ( frac{4}{Omega} ) ( c .20 Omega ) D. ( 0.05 Omega ) |
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| 226 | A metallic wire has a resistance of ( 3.0 Omega ) at ( 0^{circ} mathrm{C} ) and ( 4.8 Omega ) at ( 150^{circ} mathrm{C} ). Find the temperature coefficient of resistance of its material |
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| 227 | Ohm’s law is : A. ( V I ) B . ( I^{2} R ) ( c . I R ) D. ( R^{2} I ) |
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| 228 | Find the potential at the centre of arrangement having 6 charged particles of ( Q=5 mu C ) each arranged in the form of a hexagon of side length 0.1 ( mathrm{m} ) |
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| 229 | The power dissipated in the circuit shown in the figure is 30 watts. The value of R is A . ( 20 Omega ) В. ( 5 Omega ) ( c .10 Omega ) D. ( 30 Omega ) |
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| 230 | f power dissipated in the ( 9 Omega ) resistor in the circuit shown is 36 Watt, the potential difference across the ( 2 Omega ) resistor is : A. 2 volt 3. 4 volt ( c .8 ) volt D. 10 volt |
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| 231 | The effective capacitance between ( mathrm{P} ) and Q of the figure below is : ( C_{1}=C_{3}=C_{4}=C_{5}=10 mu F ) ( C_{2}=100 mu F ) A ( .10 mu F ) B. ( 40 mu F ) ( c .5 mu F ) D. ( 20 mu F ) |
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| 232 | All resistance are connected in the series. The current is flowing through circuit is ( 2 A ) and battery is of 20 Volts. What is the power dissipated through one of the ( 4 Omega ) : ( A cdot 4 w ) B. 8 w ( c cdot 16 w ) D. 32 ( w ) E. 36 |
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| 233 | Determine the current drawn from 12 supply with internal resist ( 0.5 Omega ) by infinite network. Each resistor has ( 1 Omega ) resistance ( A cdot 3 A ) 3. 2.7A ( c .3 .7 A ) D. 4.2 A |
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| 234 | The relation between potential difference (V) and current (I) was discovered by : A. Newton B. Ampere ( c . ) onm D. volt |
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| 235 | With the usual notations, check if the following equation ( S_{t}=u+frac{1}{2} a(2 t-1) ) is dimensionally correct or not. |
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| 236 | A carbon resistance with color band is ( 200 Omega . ) If red band is replaced by green band then the new resistance is: ( mathbf{A} cdot 500 Omega ) в. 300Omega c. ( 400 Omega ) D. ( 100 Omega ) |
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| 237 | Assertion Potentiometer is used only to compare potential differences. Reason The potentiometer draws current from the voltage source being measured. 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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| 238 | Let ( f=50 mathrm{Hz}, ) and ( mathrm{C}=100 mu mathrm{F} ) in an ( mathrm{AC} ) circuit containing a capacitor only. If the peak value of the current in the circuit is ( 1.57 mathrm{A} ) at ( mathrm{t}=0 . ) The expression for the instantaneous voltage across the capacitor will be: A ( . E=50 sin (100 pi t-pi / 2) ) В. ( E=100 sin (50 pi t) ) c. ( E=50 sin pi t ) D. ( E=50 sin (100 pi t+pi / 2) ) |
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| 239 | Assertion When a battery is short-circuited, the terminal voltage is zero. Reason In the situation of a short-circuit, the current is zero A. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion B. Both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct. |
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| 240 | Assertion In a Meter Bridge experiment, null point for unknown resistance is measured. Now, the unknown resistance is put inside an enclosure maintained at a higher temperature. The null point can be obtained at the same point as before by decreasing the value of the standard resistance. and Reason Resistance of a metal increases with increase in temperature. 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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| 241 | State the two Kirchhoff’s rules used in electric networks. How are there rules justified? |
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| 242 | Blue,green,yellow and yellow is the color band on the resistor,find its resistance? ( mathbf{A} cdotleft(75 times 10^{4}right) Omega pm 5 % ) B . ( left(65 times 10^{4}right) Omega pm 5 % ) C ( cdotleft(52 times 10^{4}right) Omega pm 5 % ) D. ( left(65 times 10^{4}right) Omega pm 10 % ) |
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| 243 | A metallic conductor of irregular cross- section is as shown in the figure. A constant potential difference is applied across the ends (1) and ( (2) . ) Then (1) A. the current at the cross-section ( P ) equal the current at the cross-section ( Q ) B. the electric field intensity at ( P ) is less than that of ( Q ) C. the rate of heat generated per unit time at ( Q ) is greater than that at ( P ) D. the number of electrons crossing per unit area of cross-section at ( P ) is less than that at ( Q ) |
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| 244 | The unit of e.m.f. of a cell is: A. dyne B. volt c. ampere D. joule |
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| 245 | A bulb of ( 100 mathrm{W}-200 mathrm{V} ) is connected to a ( 160 mathrm{V} ) supply. Find the power consumed. A. ( 25 mathrm{w} ) B. 64 W ( c cdot 45 w ) D. 20 W |
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| 246 | The equivelent resistance between ( A ) and ( B ) is ( ^{A} cdot frac{288}{56} Omega ) В. ( 12 Omega ) ( c cdot 8 ) ( D ) |
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| 247 | Which of the following statements are wrong w.r.t the specific resistance of wire? This question has multiple correct options A. It varies with its length B. It varies with its cross-section c. It varies with its mass D. It varies with nature of material |
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| 248 | A series-parallel combination of battery consisting of a large number ( N=300 ) of identical cells, each with an internal resistance ( r=0.3 Omega, ) is loaded with an external resistance ( boldsymbol{R}=mathbf{1 0} boldsymbol{Omega} ). then, the number ( n ) of parallel group consisting of an equal number of cells connected in series at which the external resistance generates highest thermal power is A. 3 B. 4 ( c .5 ) D. none of the above |
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| 249 | Eight identical cells each of potential and internal resistance r are connected in series to form a closed circuit. An ideal voltmeter connected across 2 cells will read :- A . 13 E B. zero ( c cdot 2 E ) D. 10 E |
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| 250 | An electron is moving near to a conducting loop then the induced current in the loop is- A . clockwise B. anticlockwise c. first anticlockwise and then clockwise D. no current |
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| 251 | Describe Kelvins method to determine the resistance of galvanometer by using meter bridge. |
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| 252 | An electric heater of power 3 kW is used for one minute.Find the energy supply by the heater. | 12 |
| 253 | Three identical bulbs are connected as shown in figure. When switch ( S ) is closed, the power consumed in bulb ( B ) is ( P . ) What will be the power consumed by the same bulb when switch ( S ) is opened? ( ^{A} cdot frac{9 P}{4} ) в. ( frac{16 P}{9} ) c. ( frac{9 P}{16} ) D. ( frac{4 P}{9} ) |
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| 254 | A wire of resistance ( 4 Omega ) is stretched to double its original length. The resistance of the stretched wire would be A . ( 2 Omega ) в. ( 4 Omega ) c. ( 8 Omega ) D. ( 16 Omega ) |
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| 255 | (a) Define potential gradient. (b) Write Kirchhoff’s junction rule. In the given diagram write the value of current ( boldsymbol{I} ) |
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| 256 | The resistance of an object depends on its : A. shape B. material of which it is composed ( c . ) size D. all of the above |
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| 257 | If the length and area of cross-section of a conductor are doubled, then its resistance will be A. unchanged B. halvedd c. doubled D. quadrupled |
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| 258 | Null point with ( 1 V ) cell comes out to be ( 55 mathrm{cm} ) and with ( R=10 Omega ) it is ( 50 mathrm{cm} ) What is the internal resistance of the cell? A . ( 0.5 Omega ) В. ( 0.4 Omega ) ( c .1 Omega ) D. ( 0.2 Omega ) |
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| 259 | Define the term ‘drift velocity’ of charge carriers in a conductor and write its relationship with the current flowing through it. |
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| 260 | A potentiometer wire of length ( 1.0 mathrm{m} ) has a resistance of ( 15 Omega ). It is connected to a ( 5 V ) battery in series with a resistance of 5 Omega. Determine the emf of the primary cell which gives a balance point at 60 ( mathrm{cm} ) |
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| 261 | Two square metal plates ( A ) and ( B ) are of the same thickness and material. The side of ( B ) is twice that of ( A ). If the resistances of ( A ) and ( B ) are denoted by ( boldsymbol{R}_{A} ) and ( boldsymbol{R}_{B}, ) Then ( left(frac{boldsymbol{R}_{boldsymbol{A}}}{boldsymbol{R}_{boldsymbol{B}}}right) ) is ( A cdot frac{1}{2} ) B. 2 ( c .1 ) ( D ) |
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| 262 | In the experimental set up of metre bridge shown in the figure, the null point is obtained at a distance of ( 40 mathrm{cm} ) from A. If a ( 10 Omega ) resistor is connected in series with ( R_{1}, ) the null point shifts by 10cm. The resistance that should be connected in parallel with ( left(boldsymbol{R}_{1}+mathbf{1 0}right) boldsymbol{Omega} ) such that the null point shifts back to its initial position is? A. ( 40 Omega ) в. ( 60 Omega ) ( c .20 Omega ) D. ( 30 Omega ) |
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| 263 | An electric alpole consists or small charged objects ( A ) and ( B ) of charges ( -q ) and ( +q ) and masses ( m ) and ( 4 m ) respectively. They are connected by a light non -conducting rod of length ( L ) This system is hinged at ( A ) so that it can rotate in vertical plane. A uniform electric field of intensity ( boldsymbol{E} ) is applied vertically downward. The rod is released from horizontal position as shown in figure. The angular velocity of the rod when the rod becomes vertical is. A ( cdot sqrt{frac{4 m g+q E}{2 m l}} ) B. ( sqrt{frac{6 m g+q E}{2 m l}} ) c. ( sqrt{frac{8 m g+q E}{6 m l}} ) D. ( sqrt{frac{2 m g+q E}{2 m l}} ) |
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| 264 | The resistivity of a semiconductor A. Increases as the temperature increases B. Decreases as the temperature increases C. Remains constant even when temperature varies D. None of the above |
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| 265 | If the switch at point ( P ) is opened (shown in the figure) choose the correct option A. the current in ( R_{1} ) would not change B. the potential difference between point ( X ) and the ground would increas c. the current provided by the battery would increase D. the emf produced by the battery (assumed to have internal resistance) would change |
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| 266 | State any two possible sources of errors in meter bridge experiment. | 12 |
| 267 | By increasing the temperature, the specific resistance of a conductor and a semiconductor A. decreases for both B. increases for both c. increases, decreases D. decreases, increases |
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| 268 | Consider the cylindrical element as shown in the figure. Current flowing the through element is ( I ) and resistivity of material of the cylinder is ( rho . ) Choose the correct option out the following A. Power loss in first half is four times the power loss in second half B. Voltage drop in first half is twice of voltage drop in second half c. Current density in both halves are equal D. Electric field in both halves is equal |
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| 269 | The thermo-emf of a copper-constant couple is ( 40 mu V ) per degree. The smallest temperature difference that can be detected with this couple and galvanometer of ( 100 Omega ) resistance capable of measuring the minimum current of ( 1 mu A ) is A ( cdot 2.5^{circ} mathrm{C} ) B. ( 2^{circ} C ) ( mathbf{c} cdot 1.5^{circ} mathrm{C} ) D. ( 1^{circ} mathrm{C} ) |
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| 270 | How can the current rating of a cell be increased? A. by increasing friction B. by increasing voltage c. by increasing electrostatic D. cant be increased |
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| 271 | A ( 30 V, 90 W ) lamp is to be operated on a ( 120 V D C ) line. For proper glow, a resistor of ….. should be connected in series with the lamp A . 10 B. 20 c. 30 D. 40 |
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| 272 | n the circuit shown in the figure, the ammeter reading is: ( A cdot 0.8 A ) B. 1.2 A ( c cdot 2 A ) D. ( 0.4 mathrm{A} ) |
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| 273 | The product of resistivity and conductivity of a conductor is constant. Explain it. |
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| 274 | The temperature coefficient of resistance of platinum is ( boldsymbol{alpha}=mathbf{3 . 9 2} times ) ( 10^{-1} K^{-1} ) at ( 20^{circ} C . ) Find the temperature at which the increase in the resistance of platinum wire is ( 10 % ) of its value at ( 20^{circ} C ) A ( .40 .5^{circ} mathrm{C} ) в. ( 45.5^{circ} mathrm{C} ) c. ( 48.5^{circ} mathrm{C} ) D. ( 43.5^{circ} mathrm{C} ) |
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| 275 | When we pay for our electricity bill, we are paying for the: A. charge used. B. current used c. power used. D. energy used |
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| 276 | The equivalent resistance of network of three ( 2 Omega ) resistors can not be A . 0.67 B. 2Omega ( c .3 Omega ) D. ( 6 Omega ) |
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| 277 | Six identical resistors are connected as shown in the figure. The equivalent resistance will be: A. Maximum between P and R B. Maximum between Q and R c. Maximum between P and Q D. All are equal |
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| 278 | Figure shows a piece of semiconductor pure one) ( mathrm{S} ) in series with a variable resistors ( mathrm{R} ) and a source of constant voltage ( V . S ) is heated and the current is kept constant by adjustment of R. Which of the following factors will decrease during the precess? 1. The drift velocity of the conduction electrons in S. 2. The DC resistors of ( S ) 3. The number of conduction electrons in S. A. Only 1 B. 1 and 2 c. ( 1,2, ) and 3 D. only |
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| 279 | In a metre bridge, the gaps are closed by two resistances ( mathrm{P} ) and ( mathrm{Q} ) and the balance point is obtained at ( 40 mathrm{cm} ) When ( Q ) is shunted by a resistance of 10 ( Omega, ) the balance point shifts to ( 50 mathrm{cm}, ) The values of ( P ) and ( Q ) arc A ( cdot frac{10}{3} Omega, 5 Omega ) B. ( 20 Omega, ) 30Omega c. ( 10 Omega, ) 15Omega D. ( 5 Omega, frac{15}{2} Omega ) |
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| 280 | An electric bulb consumes ( 7.2 k J ) of electrical energy in 2min. What is the power of the electric bulb? |
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| 281 | A 50 V d.c power supply is used to charge a battery of eight lead accumulators, each of emf ( 2 mathrm{V} ) and internal resistance ( 1 / 8 Omega ). The charging current also runs a motor connected in series with the battery. The resistance of the motor is ( 5 Omega ) and the steady current supply is 4 A. The mechanical power stored in the motor is A. ( 80 mathrm{w} ) B. 40 ( w ) ( c cdot 64 w ) D. 30 w |
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| 282 | What is a free electron? A. Any electron that is not attached to an ion, atom, or molecule and is free to move under the influence of an applied electric or magnetic field B. Any electron that is attached to an ion, atom, or molecule and is free to move under the influence of an applied electric or magnetic field C. Any neutron that is not attached to an ion, atom, or molecule and is free to move under the influence of an applied electric or magnetic field D. None |
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| 283 | Rate of dissipation of Joule’s heat in resistance per unit volume is (symbols have usual meaning) A ( cdot sigma E ) в. ( sigma J ) ( c . J E ) D. None |
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| 284 | In the figure, resistivities of two conductors of same material are ( rho_{1} Omega ) ( m ) and ( rho_{2} Omega-m ) respectively. Write the value of ratio of ( rho_{1} ) and ( rho_{2} ) |
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| 285 | A free electron in an electric field A. remains stationary B. moves from the higher potential to the lower potential C. moves from the lower potential to the higher potential D. None |
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| 286 | The resistance ( R ) of a conductor varies with temperature as shown in the given figure. If the relation between ( R ) and ( t ) is given as, ( boldsymbol{R}_{t}=boldsymbol{R}_{0}left(1+boldsymbol{alpha}+boldsymbol{beta} boldsymbol{t}^{2}right), ) then A. ( alpha ) and ( beta ) are negative B. ( alpha ) is positive but ( beta ) is negative ( c cdot alpha ) and ( beta ) are positive D. ( alpha ) is negative but ( beta ) is positive |
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| 287 | In the circuit diagram shown all the capacitors are in ( mu F . ) The equivalent capacitance between points ( A ) and ( B ) is ( (operatorname{in} mu F) ) A ( cdot frac{14}{5} ) B. 7.5 ( c cdot frac{3}{7} ) D. none of these |
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| 288 | Four charges ( +boldsymbol{Q},-boldsymbol{Q},+boldsymbol{Q},-boldsymbol{Q} ) are placed at the corners of a square taken order. At the centre of the square A. ( E=0, V=0 ) B. ( E=0, V neq 0 ) c. ( E neq 0, V=0 ) D. ( E neq 0, V neq 0 ) |
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| 289 | If a rod has resistance ( 4 Omega ) and if rod is turned as half circle, then the resistance along diameter is ( mathbf{A} cdot 1.56 Omega ) B . ( 2.44 Omega ) c. ( 4 Omega ) D. 2Omega |
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| 290 | The potentiometer is more appropriate for measuring potential difference than a voltmeter because A. the resistance of voltmeter is high B. the sensitivity of a potentiometer is higher than that of voltmeter C. the resistance of potentiometer wire is very low D. the potentiometer does not draw any current from the unknown source of emf |
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| 291 | A boy has two spare light bulbs in his drawer. One is marked ( 240 mathrm{V} ) and ( 100 mathrm{W} ) and the other is marked ( 240 mathrm{V} ) and ( 60 mathrm{W} ) He tries to decide which bulb should be used and why?? A. The 60 W light bulb has more resistance and therefore burns more brightly B. The 60W light bulb has less resistance and therefore burns less brightly c. The 100 w bulb has more resistance and therefore burns more brightly D. The 100 W bulb has less resistance and therefore burns less brightly |
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| 292 | An unknown resistance ( R_{1} ) is connected in series with a resistance of 10 ohm. This combination is connected to one gap of a metre bridge, while other gap is connected to another resistance ( boldsymbol{R}_{2} ) The balance point is at ( 50 mathrm{cm} . ) Now, when the 10 ohm resistance is removed, the balance point shifts to ( 40 mathrm{cm} . ) Then, the value of ( boldsymbol{R}_{1} ) is A. ( 60 Omega ) B. 40Omega c. ( 20 Omega ) D. ( 10 Omega ) |
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| 293 | The potential difference in open circuit for a cell is ( 2.2 mathrm{V} ). When a ( 4 Omega ) resistor is connected between its two electrodes the potential difference becomes ( 2 mathrm{V} ) The internal resistance of the cell will be A . ( 1 Omega ) B. ( 0.2 Omega ) ( c .2 .5 Omega ) D. ( 0.4 Omega ) |
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| 294 | The resultant resistance between ( A ) and B is, given the galvanometer is ideal with resistance 0 A . ( 4 Omega ) B. ( 2 Omega ) ( c .1 Omega ) D. ( 10 Omega ) |
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| 295 | The resistivity of a wire depends on its A. length B. area of cross-section c. material D. all of the above three factors |
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| 296 | An experiment to verify ohm’s law, a conductor of resistance ( R ) is taken During the experiment, temperature of the conductor increases with the flow of current. Resistance of the conductor will A. Remains same B. Decrease c. Increase D. First increases then decreases |
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| 297 | A wire has a resistance of 10 ohm. Its resistance if it is stretched by one-tenth of its original length is: A . ( 12.1 Omega ) B. ( 7.9 Omega ) ( c cdot 11 Omega ) D. ( 9 Omega ) |
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| 298 | If temperature is decreased, then relaxation time of electrons in metals will ( A ). increase B. decrrease C. fluctuate D. remains constant |
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| 299 | Resistance of conductor is doubled keeping the potential difference across it constant. The rate of generation of heat will: A. become one fourth B. be halved c. be doubled D. become four times |
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| 300 | The wattage of an electric heater which draws 5 A current when connected to a ( 220 mathrm{V} ) supply is |
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| 301 | Two resistances 6 and 12 ohms are connected in parallel to a battery of 10 volts. The current in amperes in 12 ohm resistor is A . ( 5 / 6 ) B. 6/5 ( c cdot 4 / 3 ) D. 3/4 |
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| 302 | What is the current of ( I_{2} ? ) | 12 |
| 303 | toppr Q Type your question. from point A through point G in the graphs directly below. Which of the graphs shows the voltage from point ( A ) to point ( G ? ) ( A cdot A ) B. B ( c cdot c ) ( D cdot D ) ( E . ) |
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| 304 | toppr Q Type your question_ move in the direction of current and return to P. The potential ( V ) at every point of the conductor is plotted against the distance covered (x). Which of the following best represents the resulting Curve? ( mathbf{A} ) ( B ) ( mathbf{C} ) ( D ) |
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| 305 | A resistance is shown in the figure. Its value and tolerance are given respectively by: ( mathbf{A} cdot 27 K Omega, 20 % ) B ( .270 K Omega, 5 % ) ( mathbf{c} .270 K Omega, 10 % ) D. ( 27 mathrm{K} Omega, 10 % ) |
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| 306 | The ( I-V ) characteristics of a metal wire at two different temperatures ( left(T_{1}right. ) and ( T_{2} ) ) are given in the adjoining figure. Here, we can conclude that: ( A cdot T_{1}>T_{2} ) в. ( T_{1}<T_{2} ) ( c cdot T_{1}=T_{2} ) D ( cdot T_{1}=2 T_{2} ) |
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| 307 | The emf of a cell is ( varepsilon ) and its internal resistance is ( r . ) Its terminals are connected to a resistance ( R ) The potential difference between the terminals is ( 1.6 V ) for ( R=4 Omega, ) and ( 1.8 mathrm{V} ) for ( boldsymbol{R}=mathbf{9} boldsymbol{Omega} . ) Then ( mathbf{A} cdot varepsilon=1 V, r=1 Omega ) B. ( varepsilon=2 V, r=1 Omega ) ( mathbf{c} cdot varepsilon=2 V, r=2 Omega ) D. ( varepsilon=2.5 V, r=0.5 Omega ) |
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| 308 | Two resistors, ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2}, ) are identical but the potential difference across ( boldsymbol{R}_{1} ) is half the potential difference across ( R_{2} . ) What is the ratio of the current in ( R_{1} ) to the current in ( R_{2} ? ) A ( cdot frac{1}{4} ) B. ( frac{1}{2} ) c. D. 2 E . 4 |
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| 309 | Match the following: Table – 1 (a) Minimum current will flow through (b) Maximum current will flow through (c) Maximum power will be generated across (d) Minimum power will be generated across ( mathbf{A} cdot a-p ; b-p ; c-q ; d-r ) B ( . a-r ; b-r ; c-p ; d-s ) ( mathbf{c} cdot a-q ; b-p ; c-r ; d-q ) D. ( a-s ; b-s ; c-r ; d-q ) |
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| 310 | If the resistance of a circuit is halved and the potential difference is kept constant, then the current will become A. 4 times B. 8 times c. double D. half |
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| 311 | Time taken by a 836 Wheater to heat one litre of water from ( 10^{circ} mathrm{C} ) to ( 40^{circ} mathrm{C} ) is: A. 50 s B. 100 s ( c cdot 150 s ) D. 200 |
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| 312 | What is the current through the resistor ( 6 Omega ) in the circuit shown in figure. A . ( 10 / 3 ) A B. ( 5 / 2 ) A ( c cdot 5 / 3 A ) ( D cdot 1 / 4 A ) |
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| 313 | When the resistivity of all pure metals increases, then the temperature will : A. decrease B. increase c. remain constant D. first decrease and then increase |
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| 314 | Three resistors of ( 10 Omega, 15 Omega ) and ( 20 Omega ) are connected in series in a circuit. If the potential drop across the ( 15 Omega ) resistor is ( 3 V ), find the current in the circuit, potential drop across ( 10 Omega ) and the net emf of the source used in the circuit. (Draw the circuit diagram) |
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| 315 | Electric heaters used for cooking have the filament or the heating coil on a plate made up of clay because A. Clay is a bad conductor of heat B. Clay is a bad conductor of electricity c. Both ( A & B ) D. None of these |
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| 316 | A rectangular metal block has dimensions ( 3 c m times 1 c m times 1 c m . ) The ratio of the resistance measured between the two opposite rectangular faces to that measured between the two square forces of the block is: A . 1: 3 B. 1: 9 c. 3: 1 D. 9: 1 |
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| 317 | ( 1 W h(text { Watt hour }) ) is equal to A. ( 36 times 10^{5} J ) B. ( 36 times 10^{4} J ) c. ( 3600 J ) D. ( 3600 J s^{-1} ) |
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| 318 | An electrical cable of copper has just one wire of radius ( 9 mathrm{mm} ). Its resistance is ( 5 Omega .6 ) different well-insulated copper wires each of radius ( 3 mathrm{mm} ) replace this single copper wire of the cable. The total resistance of the cable will now be equal to A . ( 7.5 Omega ) B. ( 45 Omega ) c. ( 90 Omega ) D. 270Omega |
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| 319 | A steady current flows in a metallic conductor of non-uniform cross-section. Which of the following quantities is constant along the conductor? A . Drift speedd B. current c. currently density D. None of these |
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| 320 | If a resistance ( R ) is melted and recasted to half of its length, then the new resistance of the wire will be A ( cdot frac{R}{2} ) в. ( 2 R ) c. ( R ) D. ( frac{R}{4} ) |
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| 321 | ( mathbf{5 0} boldsymbol{V} ) battery is supplying current of ( mathbf{1 0} ) amp when connected to a resistor. If the efficiency of battery at this current is 25 %. Then internal resistance of battery is:- A . ( 2.5 Omega ) B. ( 3.75 Omega ) c. ( 1.25 Omega ) D. ( 5 Omega ) |
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| 322 | When a battery connected across a resistor of ( 16 Omega, ) voltage across the resistor is ( 12 mathrm{V} ). When the same battery is connected across a resistor of ( 10 Omega ) voltage across it is 11 V. The internal resistance of the battery (in ohm) is : A ( cdot frac{10}{7} ) B. ( frac{20}{7} ) c. ( frac{25}{7} ) D. ( frac{30}{7} ) |
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| 323 | n the circuit shown below emf of each batter y is 5V; and has an internal resistance of ( 1.0 Omega . ) The current in the circuit ( left(I_{0}right) ) and the reading in an ideal voltmeter (V) are A ( cdot I_{0}=1 A, V=0 ) В . ( I_{0}=5 A, V=0 ) c. ( I_{0}=1 A, V=1 ) D . ( I_{0}=5 A . V=1 ) |
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| 324 | The electric current flowing through a conductor is directly proportional to the across the two ends of the conductor. A. conductance B. capacitance c. inductance D. potential difference |
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| 325 | Obtain balancing condition of Wheatstone’s bridge Kirchoff’s rules electrical circuit. |
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| 326 | Calculate the equivalent resistance between the points ( A ) and ( B ) in the given circuit in ohms. A. 6 в. ( c cdot 2 ) ( D ) |
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| 327 | Two point charges ( q_{1} ) and ( q_{2} ) are placed as shown. Resultant electric field origin is along -y-axis, ( left(frac{boldsymbol{q}_{1}}{boldsymbol{q}_{2}}right) ) equals to: A ( cdot frac{1}{sqrt{2}} ) B. ( frac{1}{2 sqrt{2}} ) ( c cdot sqrt{2} ) ( D ) |
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| 328 | The unit of an electrical parameter whose formula is ( left[M^{1} L^{2} T^{-3} A^{-2}right] ) is: A. ohm B. ampere c. volt D. newton |
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| 329 | Two wires made of same material have Iengths in the ratio 1: 2 and their volumes in the same ratio. The ratio of their resistances is: A . 4: 1 B . 2: 1 c. 1: 2 D. 1: 4 |
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| 330 | Find the currents ( I_{1} ) and ( I_{2} ) for the circuit shown in given figure. A ( cdot I_{1}=-6 A ) and ( I_{2}=9 A ) B . ( I_{1}=6 A ) and ( I_{2}=9 A ) ( mathbf{c} cdot I_{1}=-6 A ) and ( I_{2}=-9 A ) ( mathrm{D} cdot I_{1}=-9 A ) and ( I_{2}=6 A ) |
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| 331 | Six resistors each of ( 10 Omega ) are connected as shown. Find the equivalent resistance in ohms between points ( X ) and ( Y ) |
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| 332 | The drift velocity of the electron in a copper wire of length ( 2 mathrm{m} ) under the application of a potential difference of ( 200 mathrm{V} ) is ( 0.5 mathrm{ms}^{-1} ).Their mobility is (in ( left.m^{-2} V^{-1} s^{-1}right) ) ( mathbf{A} cdot 5 times 10^{-3} ) B. ( 2.5 times 10^{-2} ) c. ( 5 times 10^{2} ) D. ( 10^{-3} ) |
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| 333 | If Ohm’s law is presumed to be valid, then drift velocity ( V_{d} ) and electric field ( E ) are related as A ( cdot v_{d} propto E^{2} ) B ( cdot v_{d} propto sqrt{E} ) c. ( v_{d} propto E ) D. ( v_{d} propto E_{0} ) |
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| 334 | Potentiometer measures potential more accurately because A. it measures potential in open circuitt B. it uses sensitive galvanometer for null deflection c. it uses high resistance potentiometer wire. D. it measures potential in closed circuit |
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| 335 | From the observation of Ohm’s law ( 1 rightarrow ) V graph is drawn here. From that which points are concluded? |
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| 336 | The induced current produced in a closed coil is always in nature. A. strength B. alternating c. less D. primary |
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| 337 | AB is a wire of potentiometer with the increase in the value of resistance ( mathrm{R} ), the shift in the balance point J will be. A. Towards B B. Towards A c. Remains constant D. First towards B then back towards |
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| 338 | Find ( boldsymbol{R} ) | 12 |
| 339 | Which of the following options, which describe the dependence of drift velocity ( v_{d} ) on electric field ( E, ) obeys Ohm’s law? A ( cdot v_{d} propto E ) В ( cdot v_{d} propto E^{2} ) ( mathbf{c} cdot v_{d} propto sqrt{E} ) D. ( v_{d}= ) constant |
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| 340 | A metal block has dimension ( 10 mathrm{cm} times ) ( 5 c m times 2 c m ).the ratio of maximum to minimum resistance that can be obtained from it is ( mathbf{A} cdot 25: 1 ) B. 1: 25 ( mathbf{c} cdot 10: 3 ) D. 3: 10 |
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| 341 | An electric circuit contains an operating heating element and a lit lamp. Which statement best explains why the lamp remains lit when the heating element is removed from the circuit? A. The lamp and heating element were connected in parallel B. The lamp has less resistance than the heating element C. The lamp has more resistance than the heating element D. The lamp and heating element were connected in series |
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| 342 | A negatively charged rod is brought close to two metal spheres which are in contact with each other, and the spheres are separated in the presence of the rod. Then A. The sphere close to the rod acquires a negative charge and the other sphere acquires a positive charge B. The sphere close to the rod acquires a positive charge and the other sphere acquires a negative charge c. Both the spheres will acquire positive charge D. Both the spheres will acquire negative charge |
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| 343 | Potentiometer wire of length ( 1 mathrm{m} ) is connected in series with ( 490 Omega ) resistance and ( 2 mathrm{V} ) battery. If ( 0.2 mathrm{mV} / mathrm{cm} ) is the potential gradient, then resistance of the potentiometer wire is? A . ( 4.9 Omega ) B. ( 7.9 Omega ) ( c .5 .9 Omega ) D. ( 6.9 Omega ) |
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| 344 | If ( E=16 ) volts, ( r=4 Omega ) and distance of balance point ( P ) from end ( A ) is ( 90 mathrm{cm} ) then the value of ( X ) is A . ( 3 Omega ) B. ( 6 Omega ) ( c .9 Omega ) D. ( 12 Omega ) |
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| 345 | The ratio of the drifty velocity ( v_{d} ) and r.m.s. velocity of electrons is ( mathbf{A} cdot 10^{-10} ) B . ( 10^{-5} ) ( mathbf{c} cdot 10^{-3} ) D. ( 10^{-6} ) |
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| 346 | Induced current is produced in a coil, only when its ends are A. not closed B. closed ( c cdot operatorname{both} A & B ) D. None of the above |
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| 347 | Which is represented by the electric current? A. Charge per unit volume B. Charge per unit time c. charge per unit area D. Both A.and B |
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| 348 | Assertion When a wire is stretched to two times its length keeping the diameter same, its resistance becomes 4 times Reason Resistance is directly proportional to length of wire 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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| 349 | Brown, Red and Orange coloured bands on a Carbon resistor are followed by silver band. The value of resistor is ( mathbf{A} cdot 320 Omega pm 5 % ) B . ( 12 k Omega pm 5 % ) c. ( 320 Omega pm 10 % ) D. ( 12 k Omega pm 10 % ) |
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| 350 | When n number identical cell of emf ( mathrm{E} ) and internal resistance is connected in series, the net internal resistance of the system will be A ( cdot frac{n E r}{1+E} ) B ( cdot n^{2} r ) ( c cdot n r ) D. ( n / r ) |
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| 351 | In Wheatstone’s bridge the values of resistors ( mathrm{P} ) and ( mathrm{Q} ) are respectively 3 and x. If ( 4 Omega ) and ( 2 Omega ) are the values of resistors ( mathrm{R} ) and ( mathrm{S} ) respectively, then ( times ) is ( A ) B. 1.5 ( c cdot 2.5 ) ( D cdot 2 ) |
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| 352 | Electricians wear rubber gloves because: A. it is soft B. it is water proof c. it is an insulator D. it is inexpensive |
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| 353 | A ( 5.0 mathrm{A} ) current is setup in an external circuit by a ( 6.0 mathrm{V} ) storage battery for 6.0 min. The chemical energy of the battery is reduced by В. ( 1.08 times 10^{-4} ) 」 c. ( 1.8 times 10^{4} ) j D. ( 1.8 times 10^{-4} mathrm{J} ) |
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| 354 | A wire of length ( L ) and 3 identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised at ( triangle T ) in time ( t . N ) number of similar cells is now connected in series with a wire of the same material and cross-section but of length ( 2 L ). The temperature of the wire is raised by the same amount ( triangle boldsymbol{T} ) in the same time ( t ). The value of ( boldsymbol{N} ) is: ( A ) B. 6 ( c cdot 8 ) ( D ) |
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| 355 | In figure the voltmeter and ammeter shown are ideal. Then voltmeter and ammeter readings, respectively, are: A . ( 32.978 vee, 3 mathrm{A} ) B. 3 V, 0.236 A c. ( 120 vee, 4.198 ) A D. ( 120 vee, 3 mathrm{A} ) |
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| 356 | Consider a conductor of variable cross section in which current is flowing from cross section 1 to 2 . Then This question has multiple correct options A. current passing through both the cross sections is the same B. current through 1 is less than that through 2 c. drift velocity of electrons at 1 is less than that at 2 . D. drift velocity is same at both the cross sections |
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| 357 | The voltages across the two resistors are given by ohm’s law as: ( mathbf{A} cdot V=I R ) в. ( V=I+R ) ( c cdot V=frac{I}{R} ) D. ( V=I+frac{1}{R} ) |
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| 358 | A letter ( A ) is constructed of a uniform wire of resistance ( 1 Omega / c m . ) The sides of the letter are ( 20 mathrm{cm} ) and the cross piece in the middle is ( 10 mathrm{cm} ) long.The resistance between the ends of the legs will be: A . ( 32.4 Omega ) B. ( 28.7 Omega ) c. ( 26.7 Omega ) D. ( 24.7 Omega ) |
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| 359 | Relation between current in a conductor and time is shown in Figure. If the resistance of the conductor is ( R ), then the total heat dissipated across resistance ( boldsymbol{R} ) is : A ( cdot frac{i_{0}^{2} R t_{0}}{2} ) B. ( frac{i_{0}^{2} R t_{0}}{4} ) c. ( frac{i_{0}^{2} R t_{0}}{3} ) D ( cdot i^{2}_{0} R t_{0} ) |
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| 360 | Which of the following devices has a source of emf inside it? A. Voltmeter B. Ammeter c. ohm-meter D. Rectifier |
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| 361 | Two wires each of radius of cross section ( r ) but of different materials are connected together end to end (i.e., in series). If the densities of charge carriers in the two wires are in the ratio ( 2: 3, ) the drift velocity of electrons in the two wires will be in the ratio of A .2: 3 B. 3: 2 c. 4: 9 D. 9: 4 |
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| 362 | The figure shows a source (a battery) with an emf ( E ) of ( 12 V ) with an internal resistance ( r ) of ( 2 Omega ) and an external resistance of ( 4 Omega ) is added to complete the circuit. What are the voltmeter and ammeter readings? |
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| 363 | For a heater rated at ( 4.4 mathrm{kW} ; 220 mathrm{V} ) Calculate the current drawn by the heater. A . 40 A B. 20A ( c cdot 12.6 A ) D. ô |
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| 364 | Which of the following statements is false? A. Kirchhoff’s second law represents energy conservation. B. Wheatstone bridge is the most sensitive when all the four resistances are of the same order of magnitude. C. In a balanced Wheatstone bridge if the cell and the galvanometer are exchanged, the null point is disturbed. D. A rheostat can be used as a potential divider. |
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| 365 | Assertion IF a resistor is connected to a battery, the current increases when the temperature increases. Reason For resistors, resistance increases with increase in temperature. A . Assertion is incorrect and Reason is correct B. Both Assertion and Reason are correct but Reason is the correct explanation for Assertion c. Both Assertion and Reason are correct but Reason is not the correct explanation for assertion D. Assertion is correct and Reason is incorrect |
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| 366 | In the figure shown below the maximum possible unknown resistance ( (X) ) that can be measured by the post office box ( operatorname{are} X_{max } ) is given by ( R times 10^{5} Omega ) then ( mathrm{R} ) is (given that in this experiment we can take out only one plug from arm ( A B ) and only one plug from arm BC but from arm AD we can take out many plugs) |
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| 367 | The battery of a trunk has an emf of ( 24 mathrm{V} ) If the internal resistance of the battery is ( 0.8 Omega . ) What is the maximum current that can be drawn from the battery? A . 30 A B. 32 A c. 33 A D. 34A |
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| 368 | The rate of flow of an electric charge is known as: A. Electric potential B. Electric conductance c. Electric current D. None of these |
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| 369 | A charge is moving across a junction, then. A. Momentum will be conserved B. Momentum will not be conserved C. At some places momentum will be conserved and at some other places momentum will not be conserved D. None of these |
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| 370 | Why is the Wheatstone bridge better than the other methods of measuring resistances? A. It does not involve Ohm’s law B. It is based on Kirchoff’s law c. It has four resistor arms D. It is a null method |
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| 371 | In the fig. the potentiometer wire ( A B ) of length ( L & ) resistance ( 9 r ) is joined to the cell ( D ) of e.m.f. ( varepsilon ) and internal resistance ( r . ) The cell ( C s ) e.m.f. is ( varepsilon / 2 ) and its internal resistance is ( 2 r . ) The galvanometer ( G ) will show no deflection then find length ( A J: ) |
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| 372 | On comparing the emf’s ( E_{1} ) and ( boldsymbol{E}_{2}left(boldsymbol{E}_{1}>boldsymbol{E}_{2}right) ) of two cells by a potentiometer, the balancing lengths come out to be ( l_{1} ) and ( l_{2} ) respectively, then A ( cdot l_{1}l_{2} ) D. none of the above |
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| 373 | What potential difference is needed between the hands for a lethal shock current? ( A cdot 100 V ) B. 10 ( v ) c. ( 120 v ) D. 150 V |
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| 374 | 100 J of heat is produced each second in a ( 4 Omega ) resistor. Find the potential difference across the resistor. |
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| 375 | 4. In the experiment, the curve between Ax and AW is shown as dotted line (1). If we use an another sx wire of same material, but with double length and double radius, which of the curve is expected? (a) 1 (b) 2 (c) 3 (d) 4 AW |
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| 376 | What is the expression for the electrical power spent in flow of current through a conductor in terms of resistance and potential difference? A. ( V^{2} / R ) в. ( V / R^{2} ) c. ( V R ) D ( cdot V^{2} R ) |
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| 377 | In a closed circuit drawing current from cell, the emf of a cell is always A. Less than potential difference B. More than potential difference c. Half of the potential difference D. Double of the potential difference |
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| 378 | A wire has a nonuniform cross sectional area as shown in the figure. A steady current i flows through it. Which one of the following statements is correct? A. Drift speed of the electrons is constant B. Drift speed of decreases on moving from A to B C. Drift speed of increases on moving from A to B D. Drift speed varies randomly |
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| 379 | Ine v-I grapn ror a conauctor at temperature ( T_{1} ) and ( T_{2} ) are as shown in the fig. The term ( left(T_{2}-T_{1}right) ) is proportional to A ( cdot frac{sin 2 theta}{sin ^{2} theta} ) B. ( frac{cot 2 theta}{sin ^{2} theta} ) c. ( frac{cos 2 theta}{sin 2 theta} ) D. ( frac{tan 2 theta}{sin ^{2} theta} ) |
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| 380 | The tables show the resistance values for three different resistors and the currents through each resistor. What is the ranking of the power dissipated by each resistor, greatest first? ( begin{array}{lc}text { Current 1 } & mathbf{2 I} \ text { Resistance 1 } & R \ text { Current 2 } & I \ text { Resistance 2 } & 2 R \ text { Current 3 } & I \ text { Resistance 3 } & 4 Rend{array} ) A ( .3,2, ) and 1 tie ( mathbf{B} cdot 3,2,1 ) ( c ) 1,2,3 D. 1 and 3 tie, 2 E . All tie |
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| 381 | A secondary cell after long use has an emf of ( 1.9 V ) and a large internal resistance of ( 380 Omega ). What maximum current can be drawn from the cell? Could the cell drive the starting motor of a car? ( mathbf{A} cdot 5 m A, ) yes B. ( <5 m A ), Yes ( mathbf{c} .5 m A, ) No ( mathbf{D} cdot<5 m A, ) No |
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| 382 | The free electron gas theory explains conduction in A. metals only B. semiconductors only c. insulators only D. all of these |
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| 383 | Find the current through the ( 10 Omega ) resistor shown in figure: ( mathbf{A} cdot 0.5 A ) B. ( 1 A ) ( c cdot 2 A ) D. ( 5 A ) |
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| 384 | In the circuit shown in the figure, the heat produced in the ( 5 Omega ) resistor due to a current flowing in it, is 10 calories per second. The heat produced in the ( 4 Omega ) resistor is? A ( cdot 1 ) cal ( s^{-} ) B . 2 cal ( s^{-1} ) ( c cdot 3 ) cal ( s^{-1} ) D. 4 cal ( s^{-} ) |
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| 385 | Assertion The temperature coefficient of resistance is always positive Reason On increasing the temperature the resistance of metals and alloys increase 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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| 386 | Calculate the cost of using four 500 W air-conditioners for eight hours each day for a 30 day month. The unit cost of electrical energy is Rs. 1.50 per ( mathrm{kWh} ) |
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| 387 | If the figure shows a part of an electric circuit, then the current ( I ) is A . ( 1 A ) в. ( 3 A ) ( c .2 A ) D. 4.4 |
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| 388 | Calculate the force per unit length a long sraight wire carring of 4.0 A due to a parallel wire carrying current of 6.0 a. This distance between the wire is 3.0 ( mathrm{cm} ) |
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| 389 | Calculate the steady current through the ( 2 Omega ) resistor in the circuit shown in the figure. |
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| 390 | Which physical quantity cannot be determined with the help of potentiometer? ( A ) B. ( c cdot L ) D. R |
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| 391 | In the following circuit diagram the value of resistance ( X ) for the potential difference between ( mathrm{B} ) and ( mathrm{D} ) is zero : ( A .4 ) ohm B. 6 ohm ( c .8 ) ohm D. 9 ohm |
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| 392 | The resistance of a metal increases with the increase of temperature due to A. Number of electrons B. Velocity of electrons c. Scattering of electrons with core ions D. Thermal motion of core ions |
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| 393 | A potentiometer wire is ( 100 mathrm{cm} ) long and a constant potential difference is maintained across it. Two cells are connected in series first to support one another and then in opposite direction. The balance points are obtained at 50 ( mathrm{cm} ) and ( 10 mathrm{cm} ) from the positive end of the wire in the two cases. The ratio of emf’s is: A . 5: 1 в. 5: 4 ( c .3: 4 ) D. 3: 2 |
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| 394 | The effective resistance between points P and Q of the electrical circuit shown in the figure is A ( cdot frac{2 R r}{R+r} ) B. ( frac{8 R(R+r)}{3 R+r} ) ( c cdot 2 r+4 R ) D. ( frac{5 R}{2}+2 ) |
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| 395 | Heat produced in a wire of resistance ( boldsymbol{R} ) due to current flowing at constant potential difference is proportional to A ( cdot frac{1}{R^{2}} ) в. ( frac{1}{R} ) ( c . R ) D. ( R^{2} ) |
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| 396 | How will the reading in the ammeter ( mathbf{A} ) of figure be affected if another identical bulb ( Q ) is connected in parallel to ( P ) as shown. The voltage in the mains is maintained at a constant value A. the reading will be reduced to one-half. B. the reading will not be affected. C. the reading will be double of the previous one D. the reading will be increased fourfold. |
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| 397 | When the electric resistance are connected in parallel, which one of the following quantities is not affected? A. Potential difference B. Resistance c. Electric current D. Capacity |
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| 398 | Figure given below shows uniformly positively charged, thin rod of length ( L ) and four points ( A, B, C ) and ( D ) at the same distance ( d ) from the rod, with position as marked. If ( V_{A}, V_{B}, V_{C} ) and ( V_{D} ) are their respective potentials then. A ( cdot V_{B}>V_{A}>V_{C}>V_{D} ) в. ( V_{B}>V_{A}>V_{C}=V_{D} ) ( mathbf{c} cdot V_{A}=V_{B}>V_{C}=V_{D} ) D. ( V_{D}>V_{B}>V_{A}>V_{C} ) |
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| 399 | A voltmeter of a very high resistance is joined in the circuit as shown in figure. The voltage shown by this voltmeter will be ( A cdot 5 V ) B. ( 6 V ) c. ( 2.5 V ) D. ( 3 V ) |
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| 400 | In the figure, the potentiometer wire ( boldsymbol{A} boldsymbol{B} ) of length ( L ) and resistnace ( 9 r ) is joined to the cell ( D ) of e.m.f and internal resistance ( r . ) The cell ( C^{prime} ) s emf is ( varepsilon / 2 ) and its internal resistance is ( 2 r ) The galvanometer ( G ) will show no deflection when the length ( A J ) is A. ( 4 L / 9 ) B. ( 5 L / 9 ) c. ( 7 L / 18 ) D. ( 11 L / 18 ) |
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| 401 | An electrical appliance is rated ( mathbf{1 5 0 0} W, mathbf{2 5 0} V . ) This appliance is connected to ( 250 V ) mains. Calculate the current drawn. A . ( 5 A ) в. ( 10 A ) ( c cdot 6 A ) D. 2A$ |
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| 402 | A piece of copper and a piece of germanium are cooled from room temperature to ( 80 K . ) Then, which one of the following is correct? A. Resistance of each will increase B. Resistance of each will decrease c. Resistance of copper will decrease while that of germanium will increase D. Resistance of copper will increase while that of germanium will decrease |
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| 403 | In the arrangement shown in figure when the switch ( S_{2} ) is open, the galvanometer shows no deflection for ( l=L / 2 . ) When the switch ( S_{2} ) is closed, the galvanometer shows no deflection for ( l=5 L / 12 . ) The internal resistance ( (r) ) of ( 6 mathrm{V} ) cell, and the emf ( E ) of the other battery are respectively ( A cdot 3 Omega, 8 V ) B. ( 2 Omega, 12 V ) c. ( 2 Omega, 24 V ) D. ( 3 Omega, 12 V ) |
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| 404 | The figure shows three circuits I, II and III which are connected to a ( 3 V ) battery. If the powers dissipated by the configurations ( boldsymbol{I}, boldsymbol{I} boldsymbol{I} ) and ( boldsymbol{I} boldsymbol{I} boldsymbol{I} ) are ( boldsymbol{P}_{1}, boldsymbol{P}_{2} ) and ( P_{3} ) respectively, then : ( mathbf{A} cdot P_{1}>P_{3}>P_{2} ) В ( cdot P_{2}>P_{1}>P_{3} ) ( mathbf{c} cdot P_{1}>P_{2}>P_{3} ) ( mathbf{D} cdot P_{3}>P_{2}>P_{1} ) |
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| 405 | What is fractional change in the resistance of a filament of ( boldsymbol{alpha}=mathbf{1 0} times ) ( 10^{-4} /^{circ} mathrm{C}, ) when temperature changes from ( 25^{circ} mathrm{C} ) to ( 40^{circ} mathrm{C} ? ) |
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| 406 | The resistance of a metallic conductor increases with temperature due to: A. change in carrier density B. change in dimension of the conductor C. increase in the number of collisions among the carriers D. increase in the rate of collisions between the carriers and the vibrating atoms of the conductor. |
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| 407 | Two cells of emf ( 1.5 v ) and ( 2.0 v ) have internal resistances ( 0.2 Omega ) and ( 0.3 Omega ) respectively are connected in parallel. Calculate the emf and internal resistance of the equivalent cell? |
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| 408 | A length of ( 150 mathrm{cm} ) of a potentiometer wire is required to balance the emf of a cell. When a ( 5 Omega ) resistor is connected across the terminals of the cell, the length required for balance is ( 125 mathrm{cm} ) The internal resistance of the cell is A . 1 ohm B. 1.1 ohm c. 1.2 ohm D. 1.3 ohm |
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| 409 | For a given voltage ( V ), if resistance is changed from ( R ) to ( left(frac{R}{n}right), ) power consumed changes from ( P ) to: ( A cdot n P ) B. ( frac{p}{n} ) ( c cdot n^{2} p ) D. ( frac{P}{n^{2}} ) |
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| 410 | The resistance of a heating element is ( 99 Omega ) at room temperature. What is the temperature of the element if the resistance is found to be ( 116 Omega ? ) (Temperature coefficient of the material of the resistor is ( 1.7 times 10^{-4} o C^{-1} ) ). A ( cdot 9999^{circ} mathrm{C} ) B . ( 1005.3^{circ} mathrm{C} ) ( mathbf{c} cdot 1020.2^{circ} mathrm{C} ) D. ( 1037.1^{circ} mathrm{C} ) |
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| 411 | A student carries out an experiment and plots the ( V ) -I graph of three samples of nichrome wire with resistances ( mathrm{R} 1, ) R2 and ( mathrm{R} 3 ) respectively (Figure.12.5). Which of the following is true? ( mathbf{A} cdot R_{1}=R_{2}=R_{3} ) B ( cdot R_{1}>R_{2}>R_{3} ) ( mathbf{c} cdot R_{3}>R_{2}>R_{1} ) ( mathbf{D} cdot R_{2}>R_{3}>R_{1} ) |
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| 412 | Match the Column I with Column II. Column I (Physical quantity) Column II (Dimensional formula) (Dimensio formula) (A) Premittivity of free space ( (p) ) ( left[M^{0} L^{0} T^{-1}right] ) (В) ( left[M L^{3} T^{-3} A^{-2}right] ) (C) ( begin{array}{ll}text { Radiant flux } & text { (q) } \ text { Resistivity } & text { (r) } \ text { Hubble } & text { (s) } \ text { constant } & text { (s) }end{array} ) ( left[mathrm{M} mathrm{L}^{2} mathrm{T}^{-3}right] ) A (D) (s) ( quadleft[M^{-1} L^{-3} T^{4} A^{2}right] ) ( A cdot A-p, B-q, C-r, D-s ) B. ( A-q, B-p, C-s, D-r ) C. ( A-s, B-r, C-q, D-p ) ( D cdot A-r, B-s, C-q, D-p ) |
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| 413 | When current ( i ) is flowing through a conductor, the drift velocity is ( v ). If the value of current through the conductor and its area of cross-section is doubled, then new drift velocity will be A . ( 4 v ) в. ( frac{v}{2} ) c. ( frac{v}{4} ) D. ( v ) |
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| 414 | When a battery connected across a resistor of ( 15 Omega, ) voltage across the resistor in ( 12 V . ) When the same battery is connected across a resistor of ( 10 Omega ) voltage across it is ( 11 mathrm{V} ). The internal resistance of the battery (in ohm) is A. ( frac{10}{7} ) в. ( frac{20}{7} ) ( c cdot frac{2}{7} ) D. ( frac{30}{7} ) |
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| 415 | A ( 10 mathrm{V} ) battery with internal resistance 1 ( Omega ) and a ( 15 V ) battery with internal resistance ( 0.6 Omega ) are connected in parallel to a voltmeter. The reading in the voltmeter will be close to ( A, 11.9 mathrm{V} ) в. 13.1 c. ( 24.5 mathrm{v} ) D. ( 12.5 mathrm{v} ) |
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| 416 | A resistance of ( 2 Omega ) is connected across one gap of a metre bridge (the length of the wire is ( 100 mathrm{cm} ) ) and an unknown resistance greater than ( 2 Omega ) is connected across the other gap. When these resistances are interchanged, the balance point shifts by ( 20 mathrm{cm} ) Neglecting any corrections, the unknown resistance is: A . ( 4 Omega ) в. 3 ( Omega ) ( c cdot 5 Omega ) D. ( 6 Omega ) |
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| 417 | Which color band in the color coding of a resistor has the multiplier ( 10^{-1} ) ? A. Silver B. Gold c. Yellow D. orange |
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| 418 | Fill in the blank: To increase the effective resistance in a circuit the resistors are connected in |
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| 419 | Match list – I with List – II List – List – II |
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| 420 | If a cell of constant E.M.F. produces the same amount of the heat during the same time in two independent resistors ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2}, ) when they are separately connected across the terminals of the cell, one after the another, the internal resistance of the cell is ( sqrt{x R_{1} R_{2}} ). Find ( x ) |
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| 421 | In the circuit shown, the galvanometer shows zero current.The value of resistance R is : ( 4.1 Omega ) В. ( 10 Omega ) ( c cdot 4 Omega ) D. ( 9 Omega ) |
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| 422 | Below is a chart describing the parameters of 5 metal wires: begin{tabular}{lll} Wire & Length ( (boldsymbol{m}) ) & Diameter ( (boldsymbol{m m}) ) \ 1 & 1 & 0.5 \ 2 & 1 & 1 \ 4 & 2 & 0.5 \ 5 & 2 & 1 \ hline 6 & 2 & 2 \ hline end{tabular} Assuming all of the wires are made from the same material, rank these wires from highest to lowest resistance. A. 4,5,6,1,3,2 B. 3,2,1,6,5,4 C. 4,1,5,2,6,3 D. 1,4,2,5,3,6 E. 4,5,6,1,2,3 |
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| 423 | A material B’ has twice the specific resistance of ( mathbf{A}^{prime} . ) A circular wire made of B’ has twice the diameter of a wire made of ( mathbf{A}^{prime} . ) Then for the two wires to have the same resistance, the ratio ( boldsymbol{P}_{mathrm{A}} / boldsymbol{P}_{mathrm{B}} ) of their respective lengths must be ( A cdot 2 ) B. 1 ( c cdot frac{1}{2} ) D. |
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| 424 | In Figure circuit section, ( A B ) absorbs energy at a rate of 50W when a current ( =1.0 mathrm{A} ) passes through it in the indicated direction. What is the potential difference between ( A ) and ( B ) ? A ( .10 V ) в. ( 50 V ) ( c cdot 20 V ) D. 30V |
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| 425 | If doubling the voltage across a resistor doubles the current through the resistor then A. the resistor value decreased. B. the resistor value increased c. the resistor value did not change. D. it is impossible to determine the change in the resisto value |
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| 426 | The resistance of the given carbon resistor is ( left(2.4 times 10^{6} pmright) 5 % Omega . ) What is the sequence of colours on the strips provided on resistor? |
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| 427 | Give reasons for the following. Stationary coil and stationary magnet can not produce induced electric current |
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| 428 | The drift velocity of an electron is doubled if the applied electric field across the conductor is A. three times B. doubled c. half D. four times |
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| 429 | Two electric bulbs have ratings respectively of ( 25 W, 220 V ) and ( 100 W, 220 V ). If the bulbs are connected in series with a supply of ( 440 V, ) which bulb will fuse? ( mathbf{A} cdot 25 W ) bulb B. ( 100 W ) bulb c. Both of these D. None of these |
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| 430 | Masses of three wires of the same metal are in the ratio 1: 2: 3 and their lengths in the ratio ( 3: 2: 1 . ) Electrical resistances of these wires will be in the ratio A. 1: 2: 3 B. 3: 2: 1 c. 1: 6: 27 D. 27: 6: 1 |
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| 431 | If the temperature of a conductor is increased, its resistance will A. not increase B. increase. c. decrease. D. change according to the whether |
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| 432 | At what moment when the potentiometer is balanced A. Current flows only in the primary circuit. B. Current flows only in the secondary circuit c. current flows in both primary and secondary circuits. D. current doesnot flow in any circuit |
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| 433 | In comparing e.m.f.s of 2 cells with the help of potentiometer, at the balance point, the current flowing through the wire is taken from: A. 1 ) Any one of these cells B. 2) both of these cells c. 3 ) Battery in the main circuit D. 4 ) From an unknown source |
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| 434 | For a heater rated at ( 4 k W ; 220 V ) Calculate the resistance of the heater element. A . ( 20 Omega ) B . ( 21.6 Omega ) c. ( 200 Omega ) D. ( 12.2 Omega ) |
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| 435 | Each resistor shown is 9 ohms. When hooked to a 6 -volt battery, which combination would produce 2 watts of power? ( A ) B. ( c ) D. |
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| 436 | The number of electrons in the outermost orbit of carbon atom is ( A cdot 3 ) B. 4 ( c cdot 6 ) ( D ) |
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| 437 | A wire had a resistance of ( 12 Omega ). It is bent in the form ofa circle.The effective resistance between two points on any diameter is A . ( 3 Omega ) B. ( 6 Omega ) ( c .12 Omega ) D. ( 24 Omega ) |
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| 438 | Assertion In a meter bridge experiment null point for an unknown resistance is put inside an enclosure maintained at a higher temperature. The null point can be obtained at the same point as before by decreasing the value of the standard resistance. Reason Resistance of metal increases with increase in temperature. 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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| 439 | Three equal resistors connected in series across a source of e.m.f. dissipate 10 watts of power. What will be the power dissipated in watts if the same resistors are connected in paralle across the same source of e.m.f.? A. ( 10 W ) в. ( 30 W ) c. ( 90 W ) D. ( frac{10}{3} W ) |
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| 440 | is a property that resists the flow of electrons in a conductor. A. Capacitance B. Inductance c. Resistance D. None of above |
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| 441 | For the circuit shown in Figure, the equivalent resistance between ( boldsymbol{A} ) and ( boldsymbol{C} ) is ( A cdot frac{12}{11} ) B. ( frac{13}{11} ) ( c cdot frac{14}{11} r ) ( D cdot frac{15}{11} ) |
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| 442 | A source of constant potential difference is connected across a conductor having irregular cross- section as shown in figure. Then :- A. Electric field intensity at ( P ) is greater than at ( Q ). B. Rate of electric current crossing per unit area of cross section at ( P ) is less than that at ( Q ) C. The rate of generation of heat per unit length at ( P ) is greater than that at ( Q ). D. Mean kinetic energy of free electron at ( P ) is greater than that at ( Q ) |
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| 443 | toppr Q Type your quess of potential difference across it is 3 ( c ) D |
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| 444 | When a potential difference ( boldsymbol{V} ) is applied across a conductor at a temperature ( boldsymbol{T}, ) the drift velocity of electrons is proportional to ( mathbf{A} cdot sqrt{V} ) в. ( V ) c. ( sqrt{T} ) D. ( T ) |
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| 445 | The potentiometer wire of length has ( 100 mathrm{cm} ) has a resistance of ( 10 Omega ).It is connected in series with a resistance of ( 5 Omega ) and an acceleration of emf ( 3 V ) having magnitude resistance. A source A source of ( 1.2 mathrm{V} ) is balanced against ength I’ Of the potential wire. Find the value of L. |
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| 446 | In the circuit shown in figure. Current through ( R_{2} ) is zero if ( R_{4}=2 Omega ) and ( boldsymbol{R}_{3}=mathbf{4} boldsymbol{Omega} ) In this case: A . current through ( R_{3} ) is ( 2 A ) B. current through ( R_{4} ) is 3 A ( c . ) both (1) and (2) are correct D. both (1) and (2) are wrong |
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| 447 | The current ( I ) and voltage ( V ) graphs for a given metallic wire at two different temperatures ( T_{1} ) and ( T_{2} ) are shown in the figure. It is concluded that : A ( cdot T_{1}>T_{2} ) В. ( T_{1}<T_{2} ) ( mathbf{c} cdot T_{1}=T_{2} ) D. ( T_{1}=2 T_{2} ) |
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| 448 | What conclusion can you draw from the following observations on a resistor made of alloy manganin? ( begin{array}{llll}begin{array}{l}text { Current } \ text { A }end{array} & begin{array}{l}text { Voltage } \ text { V }end{array} & begin{array}{l}text { Current } \ text { A }end{array} & begin{array}{l}text { Voltage } \ text { v }end{array} \ begin{array}{l}text { 0.2 } \ text { 0.4 }end{array} & begin{array}{l}text { 3.94 } \ text { 7.87 }end{array} & begin{array}{l}text { 3.0 } \ text { 4.0 }end{array} & begin{array}{l}text { 59.2 } \ text { 78.8 }end{array} \ begin{array}{l}text { 0.6 } \ text { 0.8 }end{array} & begin{array}{l}text { 11.8 } \ text { 15.7 }end{array} & begin{array}{l}text { 5.0 } \ text { 1.0 }end{array} & begin{array}{l}text { 6.0 } \ text { 19.7 }end{array} & begin{array}{l}text { 98.6 } \ text { 7.0 }end{array} & begin{array}{l}text { 118.5 } \ text { 138.2 }end{array} \ begin{array}{ll}text { 2.0 } & text { 39.4 } & text { 8.0 } & text { 158.0 }end{array}end{array} ) |
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| 449 | If the color code of the carbon resistance is Red, Orange yellow, Gold. Find the value of resistance. |
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| 450 | The value of the resistance ( R ) in figure is adjusted such that power dissipated in the ( 2 Omega ) resistor is maximum. Under this condition This question has multiple correct options A ( . R=0 ) в. ( R=8 Omega ) c. power dissipated in the ( 2 Omega ) resistor is ( 72 ~ W ) D. power dissipated in the ( 2 Omega ) resistor is ( 8 W ) |
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| 451 | The masses of three copper wires are in the ratio 1: 2: 3 and their lengths are in the ratio ( 3: 2: 1 . ) The ratio of their resistance is: A. 27: 6: 1 B. 9: 3: 1 ( mathrm{c} cdot 6: 3: 2 ) D. 1: 2: 3 |
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| 452 | The length of a potentiometer wire is 10m. The distance between the null points on its wire corresponding to two cells comes out to be ( 60 mathrm{cm} ). If the difference of emf’s of the cells is 0.4 volt then the potential gradient on potentiometer wire will be ( A cdot 0.67 mathrm{V} / mathrm{m} ) B. ( 0.5 vee / ) m c. ( 2.5 mathrm{V} / mathrm{m} ) D. ov ( / mathrm{m} ) |
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| 453 | When the current in a wire is ( 1 A ), the drift velocity is ( 1.2 times 10^{-4} mathrm{ms}^{-1} . ) The drift velocity when current becomes 5 A is A ( cdot 1.2 times 10^{-4} mathrm{ms}^{-1} ) В. ( 3.6 times 10^{-4} mathrm{ms}^{-1} ) ( mathbf{c} cdot 6 times 10^{-4} m s^{-1} ) D. ( 4.8 times 10^{-4} mathrm{ms}^{-1} ) |
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| 454 | As the temperature of a conductor increases, its resistivity and conductivity change. The ratio of resistivity to conductivity A. increases B. decreases c. remains constant D. may increase or decrease depending on the actual temperature |
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| 455 | An ionization chamber with parallel conducting plates as anode and cathode, has ( 5 times 10^{7} ) electrons and the same number of singly charged positive ions per ( c m^{3} . ) The electrons are moving towards the anode with velocity ( 0.4 mathrm{m} / mathrm{s} ) The current density from anode to cathode is ( 4 mu A / m^{2} . ) The velocity of positive ions moving towards cathode is A. ( 0.4 m s^{-1} ) B. zero c. ( 1.6 m s^{-1} ) D. ( 0.1 m s^{-1} ) |
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| 456 | There are two wires, ( A ) and ( B ), made of same material. Both the wires have the same length. It is observed that the resistance of wire ( A ) is four times the resistance of wire ( mathrm{B} ), then find the ratio of their cross sectional areas. A . 4: 1 B. 1: 4 c. 1: 2 D. 2: 1 |
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| 457 | Three resistance ( P, Q, R ) each of ( 2 Omega ) and an unknown resistance S form the four arms of a Wheatstone’s bridge circuit. When a resistance of ( 6 Omega ) is connected in parallel to ( mathrm{S} ) the bridge gets balanced What is the value of S? A . ( 2 Omega ) B. 3Omega ( c cdot 6 Omega ) D. 1Omega |
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| 458 | Match the following: Column II gives the order of resistivity for materials in column I |
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| 459 | Which color band in the resistor is having highest tolerance? A . Violet B. Green c. Blue D. None of the above |
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| 460 | The number of 160 ohms resistors to be connected in parallel to produce 5 A current on a ( 100 mathrm{V} ) line is: ( A cdot 2 ) B. 4 ( c cdot 8 ) D. 10 |
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| 461 | In the circuit shown in the figure, the heat produced in the ( 5 Omega ) resistor due to the current flowing through it is ( mathbf{1 0} ) cal ( s^{-1} ) The heat generated in the ( 4 Omega ) resistor is A ( cdot 1 ) cal ( s^{-1} ) B. 2 cal ( s^{-1} ) c. 3 cal ( s^{-1} ) D. 4 cal ( s^{-} ) |
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| 462 | In a torch there are two cells each of 1.45 volt and ( 0.15 Omega . ) Each cell gives a current to filament of a lamp of ( 1.5 Omega ) then the value of current in ampere is :- A. 16.11 B. 1.611 c. 0.1611 D. 2.6 |
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| 463 | The resistance of a conductor is: A. Inversely proportional to the length B. Directly proportional to the square of the radius C. Inversely proportional to the square of the radius D. Directly proportional to the square root of the length |
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| 464 | A current passes through an ohmic conductor of nonuniform cross section. Which is the following quantities are independent of the cross-section? This question has multiple correct options A. The charge crossing in a given time interval B. Drift speed c. Current density D. Free-electron density |
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| 465 | Rate at which electric work is done is called as ? A. electric power B. electric energy c. electric force D. voltage. |
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| 466 | Assertion A steady current is flowing in a conductor hence there is an electric field within the conductor and Reason In case of steady current, there can be no accumulation of charges, so no electric field can be established. 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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| 467 | Drift velocity ( v_{a} ) varies with the intensity of elastic filed as per the relation: A ( cdot v_{a} ) is directly proportionate to B. ( v_{a} ) is inversely proportionate to E ( mathbf{c} cdot v_{a} ) is constant D. ( v_{a} ) is directly proportional to ( E^{2} ) |
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| 468 | In the circuit shown in figure, ammeter and voltmeter are ideal. If ( boldsymbol{E}=mathbf{4} boldsymbol{V}, boldsymbol{R}= ) ( 9 Omega ) and ( r=1 Omega, ) then readings of ammeter and voltmeter are This question has multiple correct options A ( cdot A_{m}=1 A ) B . ( A_{m}=2 A ) c. ( V_{m}=3 V ) D. ( V_{m}=4 V ) |
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| 469 | Two ( 2 Omega ) resistances are connected in parallel in circuit ( X ) and in series in circuit Y. The batteries in the two circuits are identical and have zero internal resistance. Assume that the energy transferred to resistor A in circuit ( X ) within a certain time is ( W ). The energy transferred to resistor ( mathrm{B} ) in circuit ( Y ) in the same time will be: A ( cdot frac{1}{4} w ) B. ( frac{1}{2} w ) c. ( 2 w ) D. ( 4 mathrm{w} ) |
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| 470 | Which graph represents the total heat developed from time ( t=0 ) by a resistor carrying a steady current? ( (mathbf{A}) ) ( (mathbf{D}) ) |
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| 471 | toppr Q Type your question_ across the resistor wire AB. A standard cell which maintains a constant emf of ( 1.02 mathrm{V} ) (for very moderate currents up to a few mA) gives a balance point at ( 67.3 mathrm{cm} ) length of the wire. To ensure very low currents drawn from the standard cell, a very high resistance of 600 ( mathrm{k} Omega ) is put in series with it, which is shorted close to the balance point. The standard cell is then replaced by a cell of unknown emf and the balance point found similarly, turns out to be at ( 82.3 mathrm{cm} ) length of the wire.(a) What is the value ( varepsilon ?(b) ) What purpose does the high resistance of 600 k ( Omega ) have?(c) Is the balance point affected by this high resistance? (d) Is the balance point affected by the internal resistance of the driver cell? (e) Would the method work in the above situation if the driver cell of the potentiometer had an emf of ( 1.0 mathrm{V} ) instead of 2.0 V?(f) Would the circuit work well for determining an extremely small emf, say of the order of a few mV (such as the typical emf of a thermocouple)? If not, how will you modify the circuit? |
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| 472 | In the method using the transformers, assume that the ratio of the number of turns in the primary to that in the secondary in the step-up transformers is ( 1: 10 . ) If the power to the consumers has to be supplied at ( 200 V, ) the ratio of the number of turns in primary to that in the secondary in the step-down transformer is B. 150: 1 c. 100: 1 D. 50: 1 |
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| 473 | Figure shows a meter bridge (which is nothing but a practical Wheatstone bridge), consisting of two resistors ( X ) and Y together in parallel with a meter long constantan wire of uniform cross section. Which the help of a movable contact ( mathrm{D} ), one can change the ratio of resistance of the two segments of the wire until a sensitive galvanometer ( G ) connected across B and D shows no deflection. The null point is found to be a distance of ( 33.7 mathrm{cm} . ) The resistor Y is shunted by a resistance of ( 12 omega, ) and the null point is found to shift by a distance of ( 18.2 mathrm{cm} . ) Determine the approximate resistance of ( X ) and ( Y ) in ohm. |
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| 474 | Write Kirchhoff’s first rule (law of junction). Drawing a circuit diagram of Wheatstone bridge, derive condition for zero deflection in the bridge. |
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| 475 | The sides of rectangle block are 23 and ( 4 mathrm{cm} ) The ratio of the maximum to minimum resistance between its parallel force is. |
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| 476 | Infinite charges are lying at ( boldsymbol{x}= ) ( 1,2,4,8 dots ) meter on ( X ) -axis and the value of each charge is ( Q . ) The value of intensity of electric field at point ( boldsymbol{x}=mathbf{0} ) due to these charges will be respectively ( mathbf{A} cdot 12 times 10^{8} Q N / C ) в. zero c. ( 69 times 10^{9} Q N / C ) D. ( 4 times 10^{9} Q N / C ) |
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| 477 | In Fig. voltmeter is not ideal. If the voltmeter is removed from ( boldsymbol{R}_{1} ) and then put across ( R_{2}, ) what will be the effect on current I? Given ( boldsymbol{R}_{1}>boldsymbol{R}_{2} ) This question has multiple correct options A . decreases B. remains same ( c ). increases D. it would have been same if voltmeters were idea |
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| 478 | The effective equivalent resistance between A and B in the figure, is? A ( cdot frac{3}{2} ) B. ( frac{2}{3} ) R c. ( frac{2}{5} ) R D. 2 R |
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| 479 | Find the value of ( R ) so that no deflection is noticed in the galvanometer when the switch ( S ) is closed or open A . ( 4 Omega ) B. ( 8 Omega ) ( c cdot 6 Omega ) D. None of these |
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| 480 | In a metre bridge, the balancing point obtained at ( 40 mathrm{cm} . ) If a resistance equa that in the left gap is shunted across it the new balancing point. ( A cdot 20 mathrm{cm} ) B. 25 cm c. ( 30 mathrm{cm} ) D. 15 ( mathrm{cm} ) |
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| 481 | The diameter of a copper wire is ( 2 mathrm{mm} ) a steady current of 6.25 A is generated by ( 8.5 times 10^{28} / m^{3} ) electrons flowing through it. Calculate drift velocity of conduction electrons. |
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| 482 | For a given cell, its terminal voltage depends on and A. external resistance, internal resistance B. internal resistance only c. external resistance only D. none of these |
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| 483 | Mention two limitations of Ohm’s law. | 12 |
| 484 | What is the ratio of heat generation in ( mathrm{R} ) and ( 2 R ) in same time in. |
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| 485 | Which of the following is true for carbon resistors? A. Resistance value does not get changed by change in temperature B. Current carrying capacity and hence power wattage are limited to about 50 watts c. It has low-temperature coefficient value. D. stability and reliability are very good. |
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| 486 | At ( 100^{circ} mathrm{C}, ) resistance of a conducting coil is ( 4.2 Omega . ) If the temperature coefficient of resistance is ( 0.004^{circ} mathrm{C} ) what will be the resistance of ( 0^{circ} mathrm{C} ) ? (in ohm ( A cdot 3 ) B. 5 ( c cdot 4 ) D. 3.5 |
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| 487 | An electric motor operating on ( 50 V ) D.C. supply draws a current of ( 10 A ). If the efficiency of the motor is ( 40 % ), then the resistance of the winding of the motor is: A. ( 1.5 Omega ) B. 3Omega c. ( 4.5 Omega ) D. ( 6 Omega ) |
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| 488 | Which of the following statements is/are incorrect for a meter bridge, which is used to compare two resistances? A. If its wire is replaced by another wire having same length, made of same material but having twice the cross sectional area, the accuracy increases. B. If its wire is replaced by another wire of different material, having same cross sectional area but of twice the length, accuracy increases. C. If its wire is replaced by another wire of same material, having half the cross sectional radius and half the length, accuracy decreases but sensitivity increases D. Metre bridge works on the principle of Wheat-stone bridge |
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| 489 | Two cells of emf ( E_{1} ) and ( E_{2}left(E_{1},>E_{2}right) ) are connected as shown in figure. When a potentiometer is connected between ( mathbf{A} ) and ( mathrm{B} ), the balancing length of the potentiometer wire is ( 300 mathrm{cm} ). When the same potentiometer is connected between ( A ) and ( C, ) the balancing length is ( 100 mathrm{cm} . ) The ratio of ( E_{1} ) and ( E_{2} ) is ( A cdot 3: 2 ) B. 4: 3 ( c cdot 5: 4 ) D. 2: 1 |
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| 490 | A ( 60 mathrm{HP} ) car is moving with a uniform velocity of ( 54 mathrm{km} / mathrm{hr} ). Find the forward force exerted by its engine. | 12 |
| 491 | A counter consists of a cylindrical cathode of radius ( 1 c m ) and an anode wire of radius ( 0.01 c m ) which is placed along the axis of the cathode. A voltage of ( 2.3 k V ) is applied between the cathode and anode. The electric field on the anode surface must be: A ( cdot 2.3 times 10^{5} V m^{-1} ) B. ( 5 times 10^{6} V m^{-1} ) ( mathbf{c} cdot 4.6 times 10^{5} mathrm{Vm}^{-1} ) D. ( 2.5 times 10^{6} mathrm{Vm}^{-1} ) |
12 |
| 492 | A square aluminium rod is ( 1 mathrm{m} ) long and ( 5 mathrm{mm} ) on edge. What must be the radius of another aluminium rod whose length is ( 1 mathrm{m} ) and which has the same resistance as the previous rod? A. ( 5.0 mathrm{mm} ) B. 4.2 mm ( c .2 .8 mathrm{mm} ) D. ( 1.4 mathrm{mm} ) |
12 |
| 493 | In the meter bridge shown, the resistance ( X ) has a negative temperature coefficient of resistance. Neglecting the variation in other resistors, when current is passed for some time, in the circuit balance point should shift towards: ( A cdot A ) в. ( B ) ( c . ) First ( A ) then ( B ) D. It will remain at |
12 |
| 494 | Three copper wires of lengths and cross sectional areas are ( (l, A)left(2 l, frac{A}{2}right) ) and ( left(frac{l}{2}, 2 Aright) . ) Resistance is minimum in A ( cdot ) wire of cross-sectional area ( frac{A}{2} ) B. wire of cross-sectional area ( A ) c. wire of cross-sectional area ( 2 A ) D. same in all the three cases |
12 |
| 495 | A metal wire of resistance ( 3 Omega ) is elongated to make a uniform wire of double its previous length. This new wire is now bent and the ends joined to make a circle. If two points on this circle make an angle ( 60^{circ} ) at the centre, the equivalent resistance between these two points will be? A ( cdot frac{12}{5} Omega ) в. ( frac{5}{3} Omega ) c. ( frac{5}{2} Omega ) D. ( frac{7}{2} Omega ) |
12 |
| 496 | In a potentiometer experiment, it is found that no current passes through the galvanometer when the terminals of the cell are connected across ( 52 mathrm{cm} ) of the potentiometer wire. If the cell is shunted by a resistance of ( 5 Omega, ) a balance is found when the cell is connected across ( 40 mathrm{cm} ) of the wire. Find the internal resistance of the cell. A . ( 1.5 Omega ) B . 2Omega ( c .2 .5 Omega ) D. 12 |
12 |
| 497 | Which physical quantity is measured in ( k W ) A. electric energy B. voltage c. charge D. electric power |
12 |
| 498 | In the circuit shown in the fig the heat produced in resistance ( R_{1} ) can be measured by A. connecting both voltmeter and an ammeter in parallel to ( R_{1} ) B. connecting ammeter in series with ( R_{1} ) and voltmeter in parallel to both ( R_{1} ) and ( R_{2} ) C. connecting ammeter in parallel to ( R_{1} ) and voltmeter in series with ( R_{1} ) D. connecting voltmeter in parallel to ( R_{1} ) and ammeter in series with ( R_{1} ) |
12 |
| 499 | In case of the circuit arrangement shown below, the equivalent resistance between ( A ) and ( B ) is: A. ( 10 Omega ) 3. ( 2.5 Omega ) ( c cdot frac{50}{3} s ) Done of the above |
12 |
| 500 | In the figure shown below, the maximum possible unknown resistance ( (X), ) that can be measured by the post office box are ( X_{max } ) is fiven by ( R times 10^{5} Omega, ) then ( R ) is (given that in this experiment, we can take out only one plug from arm ( A B ) and only one plug from arm BC, but from arm AD we can take out many plugs): ( A ) B. ( c ) E. none of thes |
12 |
| 501 | In a meter bridge experiment, the null point is obtained at ( 20 mathrm{cm} ) from one end of the wire when resistance ( boldsymbol{X} ) is balanced against another resistance ( Y ) If ( X<Y ), then where will the new position of the null point be from the same end, if one decides to balance a resistance of ( 4 X ) against ( Y ? ) ( mathbf{A} cdot 40 mathrm{cm} ) в. ( 80 mathrm{cm} ) ( c .50 mathrm{cm} ) D. ( 70 mathrm{cm} ) |
12 |
| 502 | Copper wire of length ( 3 m ) and the area of cross section ( 1.7 times 10^{-6} m^{2} ) has a resistance of ( 3 times 10^{-2} m^{2} ) ohms. Calculate the resistivity of copper? |
12 |
| 503 | The balancing point in a meter bridge is ( 44 mathrm{cm} . ) If the resistances in the are gaps are inchanged the new balance point is A. ( 44 mathrm{cm} ) B. 56 ( mathrm{cm} ) c. ( 50 mathrm{cm} ) D. 22 ( mathrm{cm} ) |
12 |
| 504 | A bulbs is connected to a battery of p.d. ( 4 mathrm{V} ) and internal resistance ( 2.5 Omega . A ) stedy current of ( 0.5 mathrm{A} ) (i) the total energy supplied by the battery in 10 minutes, (ii) the resistance of the bulb,and (iii) the energy displated in the bulb in 10 minutes |
12 |
| 505 | Can we measure a resistance of the order of ( 0.160 Omega ) using a Wheatstone’s bridge? Support your answer with reasoning? |
12 |
| 506 | The current in the given circuit is A. 0.3 amp B. 0.4 amp ( mathbf{c} cdot 0.1 mathrm{amp} ) D. 0.2 amp |
12 |
| 507 | If a wire of resistance ( R ) is stretched to double of its length keeping the diameter same, then new resistance will be: A. ( R / 2 ) в. ( 2 R ) ( c .4 R ) D. ( 16 R ) |
12 |
| 508 | Two rods ( A ) and ( B ) made up of same metal have same length. The ratio of their resistances is ( 1: 2 . ) If these rods are immeresed in water then loss in weight will be :- ( A . ) more in ( A ) B. more in B c. same is A and B D. in the ratio 1: 2 |
12 |
| 509 | A cylindrical bar magnet is kept along the axis of a circular coil. If the magnet is rotated about its axis, then – A. a current will be induced in the coil B. no current will be induced in the coil c. only emf will be induced in the coil D. an emf and current both will be induced in the coil |
12 |
| 510 | The current ( I_{1}(text { in } A) ) flowing through ( 1 Omega ) resistor in the above circuit is : A . 0.25 B. 0.2 ( c .0 .5 ) D. 0.4 |
12 |
| 511 | The ratio of the concentration of electrons to that of holes in a semiconductor is ( frac{7}{4}, ) then what is the ratio of their drift velocities: A ( cdot frac{5}{8} ) B. ( frac{4}{5} ) ( c cdot frac{5}{4} ) ( D cdot frac{4}{7} ) |
12 |
| 512 | Three equal resistors connected across a source of e.m.f. together dissipate 10 watt of power. What will be the power dissipated in watts if the same resistors are connected in parallel across the same source of e.m.f? A . 10 в. ( frac{10}{3} ) ( c . ) 30 D. 90 |
12 |
| 513 | The potential differnce ( left(boldsymbol{V}_{boldsymbol{A}}-boldsymbol{V}_{boldsymbol{B}}right) ) between the points ( A ) and ( B ) in the given figure is A ( .9 V ) B. ( 6 V ) ( c .3 V ) D. ( 4 V ) |
12 |
| 514 | State whether given statement is True or False Glass is a good insulator. A. True B. False |
12 |
| 515 | A current of ( 300 mathrm{mA} ) is made to flow through a ( 6 k Omega ) resistor. What is the potential difference across the resistor? A . ( 1800 v ) B. 50v c. ( 0.02 v ) D. 500v |
12 |
| 516 | Copper and Carbon wires are connected in series and the combined resistor is kept at ( 0^{circ} mathrm{C} ). Assuming the combined resistance does not vary with temperature, the ratio of the resistances of Carbon and Copper wires at ( 0^{circ} C ) is: (Temperature coefficients of resistivity of Copper and Carbon respectively are ( left.4 times 10^{-3} /^{circ} C text { and }-0.5 times 10^{-3} /^{circ} Cright) ) ( A ) в. 6 ( c cdot 2 ) ( D ) |
12 |
| 517 | A straight conductor of uniform cross- section carries a current, ( I ). If ( ^{prime} s^{prime} ) is the specific charge of an electron, the momentum of all the free electrons per unit length of the conductor, due to their drift velocity only, is A . Is в. ( sqrt{frac{I}{s}} ) c. ( frac{1}{s} ) ( left(frac{I}{s}right)^{2} ) |
12 |
| 518 | The resistance of ( 2 Omega ) is connected across one gap of a meter-bridge (length of the wire is ( 100 mathrm{cm} ) ) and an unknown resistance greater than ( 2 Omega ) is connected across the other gap. When the resistance are interchanged, the balance point shifts by 20cm. Neglecting any corrections, the unknown resistance is: ( (text { in } Omega) ) |
12 |
| 519 | Which of the following statement is correct? A. Liquids obey partially the Ohm’s law B. Liquids fully obeys the Ohm’s law C. Liquid do not obeys the Ohm’s law D. None of the above |
12 |
| 520 | A charge q of mass m starting from rest is allowed to move between two points having a potential difference of V volts. What is the final velocity of the charge? | 12 |
| 521 | In Wheatstone’s bridge, three resistors ( P, Q, R ) are connected in three arms in order and ( 4^{t h} ) arm ( mathrm{S} ) is formed by two resistors ( s_{1} ) and ( s_{2} ) connected in parallel. The condition for bridge to be balanced is: ( frac{P}{Q}= ) A ( cdot frac{Rleft(s_{1}+s_{2}right)}{s_{1} s_{2}} ) В. ( frac{s_{1} s_{2}}{Rleft(s_{1}+s_{2}right)} ) c. ( frac{R s_{1} s_{2}}{left(s_{1}+s_{2}right)} ) D. ( frac{left(s_{1}+s_{2}right)}{R s_{1} s_{2}} ) |
12 |
| 522 | A wire when connected to ( 220 mathrm{V} ) mains supply has power dissipation ( P_{1} . ) Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is ( P_{2} ). Then ( P_{2}: P_{1} ) is ( A ) B. 4 ( c cdot 2 ) D. 3 |
12 |
| 523 | f ( i=0.25 ) amp. in the fig the value of ( R ) is :- ( A cdot 48 Omega ) в. ( 12 Omega ) c. ( 120 Omega ) D. ( 42 Omega ) |
12 |
| 524 | A material ( B ) has twice the specific resistance of ( A . ) A circular wire made of ( B ) has twice the diameter of a wire made of ( A ). Then for the two wires to have the same resistance, the ratio ( l_{B} / ) ( l_{A} ) of their respective lengths must be: ( A ) B. 1/2 ( c cdot 1 / 4 ) D. |
12 |
| 525 | ( mathbf{A} ) ( 2.0 V ) potentiometer used for the determination of internal resistance of a ( 1.5 V ) cell. The balance point of the cell in open circuit is ( 76 mathrm{cm} ). When a resistor of ( 9.5 Omega ) is used in the external circuit of the cell, the balance point shifts to ( 57 mathrm{cm} ) length of the potentiometer wire. Determine the internal resistance of the cell A ( .1 .7 Omega ) В. ( 2.5 Omega ) c. ( 1.5 Omega ) D. ( 0.5 Omega ) |
12 |
| 526 | Explain briefly the coil and magnet experiment to demonstrate electromagnetic induction. | 12 |
| 527 | A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be: A. doubled. B. four times c. one-fourth D. halved |
12 |
| 528 | A current of 2 A passing through conductor produces 80 J of heat in 10 seconds. The resistance of the conductor is – A . ( 0.5 Omega ) B. 2Omega ( c .4 Omega ) D. 20Omega |
12 |
| 529 | A battery of ( 10 mathrm{V} ) and internal resistance ( 0.5 Omega ) is connected across a variable resistance R. The value of ( R ) for which the power delivered in its maximum state, is equal to :- A ( .0 .5 Omega ) в. ( 1 Omega ) c. ( 1.5 Omega ) D. ( 2.0 Omega ) |
12 |
| 530 | Assertion In a meter bridge experiment, a high resistance is always connected in series with a galvanometer. Reason As resistance increases, current through the circuit increases. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
12 |
| 531 | A steady current i passes through a linear conductor of uniform cross- section. Any given segment of the conductor has A. a net negative charge B. a net positive charge c. a zero net charge of any kind D. a net charge proportional to the volume of the segment |
12 |
| 532 | A table lamp of power 60 W consumed 9 (commerical) units of electricity in the month of April. For how many hours per day, on an average, was the lamp in use? ( A cdot 1 h ) B. 3h ( c cdot 5 h ) ( D cdot 6 h ) |
12 |
| 533 | Of the two bulbs in a house, one glows brighter than the other. Which of the two has a large resistance? A. The bright bulb B. The dim bulb c. Both have the same resistance D. The brightness does not depend upon the resistance |
12 |
| 534 | Open circuit voltage of a source is 7.86 V and its short circuit current is 9.25 A. Find the current when an external resistance of ( 2.4 Omega ) is connected A . ( 1.4 mathrm{A} ) B. 1.82A c. 2.01A D. 2.4A |
12 |
| 535 | The internal resistance of a cell of emf ( 1.5 V, ) if it can deliver a maximum current of ( 3 A ) is A . ( 0.5 Omega ) B. 4.5Omega ( c .2 Omega ) D. 1Omega |
12 |
| 536 | Find ( C_{A B} ) if each capacitor is ( C ) in the figure shown : A. 3C B. 2C ( c cdot c ) D. ( c / 2 ) |
12 |
| 537 | Find the emfs ( varepsilon_{1} ) and ( varepsilon_{2} ) in the circuit in Figure. Also find the potential difference of point ( b ) relative to point ( a ) |
12 |
| 538 | ( mathbf{1 0 mu A s}= ) coulombs. A ( cdot 10^{-4} ) -4 B. ( 10^{-5} ) ( mathrm{c} cdot 10^{-3} ) D. ( 10^{-6} ) |
12 |
| 539 | When ( n ) number identical cell of emf ( E ) and internal resistance, ( r ) is connected in parallel, the net internal resistance of the system will be ( A ) B . ( n r ) c. ( r / n ) D. ( n / r ) |
12 |
| 540 | 5. If emf of battery is 100 V, then what was the resistance of Rheostat adjusted at reading (2)? (i = 2 A, V = 20 V). 4A 10 20 30 40 (a) 10Ω (c) 30 Ω (b) 20 Ω (d) 40 Ω |
12 |
| 541 | The balancing length for a cell is ( 560 mathrm{cm} ) in a potentiometer experiment. When an external resistance of ( 10 Omega ) is connected in parallel to the cell, the balancing length changes by ( 60 mathrm{cm} ). If the internal resistance of the cell is ( frac{N}{10} Omega, ) where ( N ) is an integer then value of ( mathrm{N} ) is |
12 |
| 542 | Let ( C ) be the capacitance of a capacitor discharging through a resistor R.Suppose ( t ) is the time taken for the energy stored in the capacitor to be reduced to half its initial value and t2 is the time taken for the charge to reduce to one fourth its initial value.Then the ratio t1/t2 will be |
12 |
| 543 | Two metallic spheres of radii ( 2 mathrm{cm} ) and ( 6 mathrm{cm} ) are given charges ( 3 times 10^{-2} mathrm{C} ) and ( 7 times 10^{-2} C, ) respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is A ( cdot 7.5 times 10^{-2} C ) В. ( 4 times 10^{-2} mathrm{C} ) c. ( 3.5 times 10^{-2} C ) D. ( 2 times 10^{-2} C ) |
12 |
| 544 | State whether the following statement is True or False The Sl unit of charge is coulomb. |
12 |
| 545 | Find ( rho ) using ( a=frac{-n}{T} ) ( mathbf{A} cdot rho propto T^{n} ) B ( cdot rho propto T^{n-1} ) c. ( rho propto T^{-n} ) D. ( rho propto frac{n}{T} ) |
12 |
| 546 | Different materials have A. different resistivityyyy B. same resistivity c. O resistivity D. none of the above |
12 |
| 547 | Assertion Kirchhoff’s junction rule can be applied to a junction of several lines or a point in a line. Reason When steady current is flowing, there is no accumulation of charges at any junction or at any point in a line. 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 |
| 548 | If a copper wire is stretched to make its radius decrease by ( 0.1 % ), the percentage changes in its resistance is approximately A . ( -0.4 % ) B. ( +0.8 % ) c. ( +0.4 % ) D. ( +0.2 % ) |
12 |
| 549 | A 10 V battery of negligible internal resistance is connected across a ( 200 mathrm{V} ) battery and a resistance of ( 38 omega ) as shown in the figure. Find the value of the current in circuit. |
12 |
| 550 | For a certain load, the true power is ( 150 W ) and the reactive power is ( 125 W ) The apparent power is A. ( 19.52 W ) В. ( 195.2 W ) ( mathrm{c} cdot 275 mathrm{W} ) D. 25W |
12 |
| 551 | ( 1 mathrm{mA}=_{-}-_{-}—^{mathrm{A}} ) ( mathbf{A} cdot 10^{3} A ) B. ( 10^{-3} A ) ( c cdot 10^{6} A ) D. ( 10^{-6} A ) |
12 |
| 552 | Each of the resistors shown in Figure has resistance ( R ). Find the equivalent resistance between ( A ) and ( B ) ( ^{A} cdot frac{7 R}{4} ) в. ( frac{5 R}{4} ) c. ( frac{9 R}{4} ) D. ( frac{11}{4} ) |
12 |
| 553 | Which of the following sets has different dimensions? A. Pressure, Young’s modulus, stress B. Emf, potential difference, electric potential c. Heat, work done, energy D. Dipole moment, electric flux, electric field |
12 |
| 554 | Match the following: ( begin{array}{ll}text { List- I } & text { List – II } \ text { a) Resistivity } & text { e) volt } \ text { b) Conductivity } & text { f) siemen } \ text { c) emf } & text { g) ohm-metre } \ text { d) conductance } & text { h) mho / metre }end{array} ) ( A cdot a-e, b-f, c-g, d-h ) B. ( a-f, b-e, c-g, d-h ) ( c cdot a-g, b-h, c-e, d-f ) ( D cdot a-h, b-g, c-e, d-f ) |
12 |
| 555 | The three resistance of equal value are arranged in the different combinations shown below. Arrange them in increasing order of power dissipation. A. ( ||<|<| V<1 ) B. ( |<|<mid V<1 ) c. ( |<| V<|mid<| ) D. ( |<|mid<|<1 V ) |
12 |
| 556 | The number of free electrons in 1 c.c. of Copper is A. ( 8.4 times 10^{22} ) B. ( 5.8 times 10^{22} ) ( mathbf{c} cdot 10^{15} ) D. ( 10^{20} ) |
12 |
| 557 | In a metallic conductor, electric current is thought to be due to the movement of A . ions B. amperes c. electrons D. protons |
12 |
| 558 | Three equal resistors connected in series across a source of e.m.f dissipate 10 watts of power. What will be the power dissipated in watts if the same resistors are connected in parallel across the same source of e.m.f? A. ( 10 mathrm{w} ) B. 30 W c. ( 90 mathrm{w} ) D. ( frac{10}{3} W ) |
12 |
| 559 | A wire of resistance ( 20 Omega ) is covered with ice and a voltage of ( 210 mathrm{V} ) is applied across the wire, then rate of melting the ice is A. ( 0.85 mathrm{g} / mathrm{s} ) B. 1.92 ( g / ) s c. ( 6.56 mathrm{g} / mathrm{s} ) D. All of these |
12 |
| 560 | Two cells of emf ( 4 V ) and ( 2 V ) and internal resistance ( 2 Omega ) and ( 1 Omega ) respectively are connected in parallel so as to send the current in the same direction through an external resistance of ( 10 Omega ). Find the potential difference across ( 10 Omega ) resistor. |
12 |
| 561 | A steady current passes through a wire of non-uniform cross-section. The quantities which depend on the Area of cross-section are: A. Free electron density B. Resistivity C. Drift velocity D. Charge crossing in a given time interval |
12 |
| 562 | The number of turns in th coil of an ( a c ) generator is 5000 and the area of the coil is ( 0.25 m^{2} . ) The coil is rotated at the rate of 100 cycles/s in a magnetic field of ( 0.2 T . ) The peak value of emf generated is nearly: A. ( 786 k V ) ( V ) в. ( 440 mathrm{kV} ) c. ( 220 k V ) D. ( 157.1 k V ) |
12 |
| 563 | In a potentiometer experiment, the balancing length of a cell is ( 560 mathrm{cm} ) When an external resistance of ( 10 Omega ) is connected in parallel to the cell, the balancing length changes by ( 60 mathrm{cm} . ) The internal resistance of a cell is A . ( 1.4 Omega ) в. ( 1.6 Omega ) c. ( 0.12 Omega ) D. ( 1.2 Omega ) |
12 |
| 564 | An electric tea kettle has two electric heating coils. When one of the coil is switched on the tea begins to boil in 6 minutes. When the other is switched on the boiling begins in 8 minutes If both the coils are now arranged in series and switched on, boiling starts in A . ( 24 / 7 ) minutes B. 12 minutes c. 14 minutes D. 4 minutes |
12 |
| 565 | A galvanometer is an instrument capable to measure A. small voltage B. small current ( c ). both (a) and (b) D. none of these |
12 |
| 566 | If e.m.f of cell is ( boldsymbol{E} ) with internal resistance ( r ) and external resistance is ( boldsymbol{R}, ) then terminal voltage will be : A ( cdot frac{E r}{R+r} ) в. ( frac{E R}{R+r} ) c. ( E ) D. ( frac{E r R}{R+r} ) |
12 |
| 567 | Assertion Voltmeter is much better than a potentiometer for measuring emf of cell Reason A potentiometer draws no current while measuring emf of a cell. |
12 |
| 568 | The e.m.f. of a cell is ( _{–}-_{-}- ) the voltage across its terminals when no current flows. Fill in the blank. A. more than B. less than c. equal to D. none of these |
12 |
| 569 | Assertion Ohm’s law is not valid if current depends on voltage non-linearly. Reason Ohm’s law is a fundamental law of nature. 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 |
| 570 | Nichrome and copper wire of same length and same radius are connected in series. Current ( I ) is passed through them. Which wire gets heated up more? Justify your answer. |
12 |
| 571 | Steady current flows in a metallic conductor of non-uniform cross-section. Which of the following quantities is a constant along the conductor? A. Current B. Current density c. Electric field D. Drift speed |
12 |
| 572 | A galvanometer (coil resistance ( 99 Omega) ) is converted into a ammeter using a shunt of ( 1 Omega ) and connected as shown in the figure ( ( i ) ). The ammeter reads ( 3 A ) The same galvanometer is converted into a voltmeter by connecting a resistance of ( 101 Omega ) in series. This voltmeter is connected as shown in figure ( ( i i ) ). Its reading is found to be ( 4 / 5 ) of the full scale reading. Find the internal resistance ( r ) of the cell (in ohms) |
12 |
| 573 | There are a large number of cells available, each marked ( (6 V, 0.5 Omega) ) to be used to supply current to a device of resistance ( 0.75 Omega, ) requiring ( 24 A ) current. How should the cells be arranged, so that power is transmitted to the load using minimum number of cells? A. Six rows, each containing four cells B. Four rows, each containing six cells c. Four rows, each containing four cells D. Six rows, each containing Six cells |
12 |
| 574 | The resistance of wire is 5 ohm at ( 50 C ) and 6 ohm at 100 C. The resistance of the wire at ( 0 mathrm{C} ) willbe A. 2 ohm B. 1 ohm c. 4 ohm D. 3 ohm |
12 |
| 575 | toppr 5 Q Type your question- gate and from the door of the house. Select the correct possible circuit(s) required. ( A ) в. ( c ) ( D ) |
12 |
| 576 | (a) Why are the connections between the resistors in a meter bridge made of thick copper strips? (b) Why is it generally preferred to obtain the balance point in the middle of the meter bridge wire? (c) Which material is used for the meter bridge wire and why? OR A resistance of ( mathrm{R} Omega ) draws current from a potentiometer as shown in the figure. The potentiometer has a total resistance ( R_{0} Omega . ) A voltage ( V ) is supplied to the potentiometer. Derive an expression for the voltage across ( mathrm{R} ) when the sliding contact is in the middle of the potentiometer. |
12 |
| 577 | Find equivalent resistance between ( mathbf{X} ) and ( Y ) ( A ) B. R/L ( c cdot 2 R ) 5. 5 |
12 |
| 578 | Appliances based on heating effect of current work on A. only A.c. B. only D.C. c. both A.c. and D.c. D. none of these |
12 |
| 579 | The circuit given below is for the operation of an industrial fan. The resistance of the fan is 3 ohm. The regulator provided with the fan is a fixed resistor and a variable resistor in parallel. Under what value of the variable resistance given, power transferred to the fans will be maximum? The power source of the fan is a dc source with internal resistance of 6ohm A . ( 3 Omega ) B. ( c cdot alpha ) D. 6.9 |
12 |
| 580 | A carbon resistor of ( (47 pm 4.7) k Omega ) is to be marked with rings of different colours for its identification. The colour code sequence will be: A. Yellow-Green-Violet-Gold B. Violet-Yellow-Orange-Silver c. Green-orange-violet-Gold D. Yellow-violet-orange-silver |
12 |
| 581 | Four bulbs marked ( 40 W, 250 V ) are connected in series with ( 250 V ) mains, the total power consumed is A. ( 10 W ) в. ( 40 W ) c. ( 320 W ) D. ( 160 W ) |
12 |
| 582 | A cell of emf ( 1.5 % ) and internal resistance ( 0.5 Omega ) is connected to a conductor whose ( V-I ) graph is an shown in the figure. Then, the terminal voltage of the cell is ( mathbf{A} cdot 0.75 V ) в. ( 1.0 V ) c. ( 1.25 V ) D. ( 1.5 V ) |
12 |
| 583 | Find the potential gradient along AB A ( cdot 0.1 mathrm{Vcm}^{-1} ) B. ( 0.03 mathrm{Vcm}^{-1} ) c. ( 0.04 mathrm{Vcm}^{-1} ) D. ( 0.02 mathrm{vcm}^{-1} ) |
12 |
| 584 | The resistivity of a potentiometer wire is ( rho ) and the area of cross section of the wire is ( A . ) If the current flowing in the circuit is ( I ), then potential gradient will be A. ( I A ) в. ( I A / rho ) c. ( I rho / A ) D. IA |
12 |
| 585 | toppr ( t ) Q Type your question supply ( ): ) ( A ) B. ( c ) ( D ) |
12 |
| 586 | The resistance of a coi is ( 4.2 Omega ) at ( 100^{circ} mathrm{C} ) and the temperature coefficient of resistance of its material is ( 0.004 /^{circ} mathrm{C} . ) Its resistance at ( 0^{circ} mathrm{C} ) A . ( 6.5 Omega ) B. 3Omega ( c .5 Omega ) D. 4Omega |
12 |
| 587 | A cell sends a current through a resistance ( R ) for time ( t ; ) next the same cell sends current through another resistance ( r ) for the heat is developed in both the resistance, then the internal resistance of the cell is: A. ( (R+r) / 2 ) в. ( (R-r) / 2 ) c. ( sqrt{R r} ) D. ( sqrt{R r} / 2 ) |
12 |
| 588 | The cell has an emf of ( 2 V ) and the internal resistance of this cell is ( 0.1 Omega ), i is connected to a resistance of ( 3.9 Omega ), the voltage across the cell will be ( mathbf{A} cdot 0.5 V ) в. ( 1.9 V ) c. ( 1.95 V ) D. ( 72 ~ V ) |
12 |
| 589 | If six identical cells each having an emf of ( 6 V ) are connected in parallel, the emf of the combination is A . ( 1 v ) B. 36V ( c cdot 1 / 6 v ) D. ( 6 v ) |
12 |
| 590 | A cell of constant ( e m f ) first connected of a resistance ( R_{1} ) and then connected to a resistance ( boldsymbol{R}_{2} ). If power delivered in both cases is same then the internal resistance of the cell is: A ( cdot sqrt{R_{1} R_{2}} ) в. ( sqrt{frac{R_{1}}{R_{2}}} ) c. ( frac{R_{1}-R_{2}}{2} ) D. ( frac{R_{1}+R_{2}}{2} ) |
12 |
| 591 | Does the value of resistance of a conductor depend upon the potential difference applied across it or current passes through it? |
12 |
| 592 | A graph is plotted between the potential difference (applied across the ends of a conductor) and the current (following through the conductor). The graph is a straight line A. having intercepts on both axes B. having an intercept on the X-axis c. having an intercept on the Y-axis D. none of these |
12 |
| 593 | A substance that prevents electric current from passing through it is called A. a conductor B. an insulator c. a semiconductor D. a superconductor |
12 |
| 594 | A voltmeter of resistance ( 998 Omega ) is connected across a cell of emf ( 2 mathrm{V} ) and internal resistance 2Omega. The potential difference across the voltmeter is? ( mathbf{A} cdot 1.99 mathrm{v} ) B. 3.5v c. ( 5 v ) D. ( 6 v ) |
12 |
| 595 | A current ( i ) passes through a wire of length ( L, ) radius ( R ) and resistively ( rho . ) The rate of heat generated is A ( cdot frac{i rho L}{pi r^{2}} ) В. ( i^{2}left(frac{L rho}{pi r^{2}}right) ) ( ^{mathbf{c}} cdotleft(frac{i^{2} rho L}{r}right) ) D. none of these |
12 |
| 596 | The value of current ( i ) in the given circuit is: A. zero B. 5 Amp. c. 7 Amp D. 11 Amp |
12 |
| 597 | Average value of current or voltage over a half cycle can be zero also. This depends on the time interval (of course T/2) over which average value is to be found.Why? |
12 |
| 598 | An electric bulb of ( 15 mathrm{V} ) is connected to a battery of ( 15 mathrm{V} ) which has negligible resistance. If the resistance offered by the bulb is ( 5 Omega ) the power of the bulb is ( ldots ) W. A . 225 B. 75 ( c .30 ) D. 45 |
12 |
| 599 | A potentiometer wire ( 10 mathrm{m} ) long has a resistance of ( 40 Omega . ) It is connected in series with a resistance box and a ( 2 mathrm{V} ) storage cell. If the potential gradient along the wire is ( 0.1 mathrm{mV} / mathrm{cm}, ) the resistance in the box is ( A cdot 760 Omega ) B. 260Omega c. ( 1060 Omega ) D. ( 960 Omega ) |
12 |
| 600 | Two identical loops ( A ) and ( B ) lying in the same plane carry equal currents. Four points ( P, Q, R ) and ( S ) are in the plane of the loops. Choose the correct statement A. The field at P must be out of the plane of the paper B. The field at ( Q ) must be into the plane of the paper c. the field at ( R ) must be out of the plane of the paper D. The field at ( s ) must be out of the plane of the paper |
12 |
| 601 | In a metre bridge experiment null point is obtained at ( 40 mathrm{cm} ) form one end of the wire when resistance ( X ) is balanced against another resistance Y. If ( mathrm{X}<mathrm{Y} ) then the new position of the null point from the same end, if one decides to balance a resistance of ( 3 mathrm{X} ) against ( mathrm{Y} ) will be close to ( mathbf{A} cdot 80 mathrm{cm} ) B. ( 75 mathrm{cm} ) ( c cdot 67 mathrm{cm} ) D. ( 50 mathrm{cm} ) |
12 |
| 602 | A wire is cut into three equal parts and then connected in parallel with the same source. How will it (i) resistance and resistivity gets affected? (ii) How would the total current and the current through the parts change? |
12 |
| 603 | An electrical device operate at 12 A current and ( 120 mathrm{V} ) D.C. If it is connected with ( 250 mathrm{V} ) and ( 30 mathrm{Hz} ) AC. then power consumption: A. 625 w B. 1250 W ( c . ) 6250 ( w ) D. zero |
12 |
| 604 | The reading of ammeter is ( x ) amperes and that of voltmeter is 20 volts shown in the figure. Then ( x ) is: ( A cdot 4 ) ( B ) ( c cdot 8 ) ( D ) |
12 |
| 605 | Match the entries in column A with appropriate ones from column B. |
12 |
| 606 | Current flow takes place across a conductor only when a p.d in maintained across its two ends. A. True B. False |
12 |
| 607 | A battery of internal resistance ( 4 Omega ) is connected tot he network of resistance as shown. In order to give the maximum power to the network, the value of ( operatorname{Rin} Omega ) should be: ( A cdot frac{4}{9} ) ( B cdot frac{8}{9} ) ( c cdot 2 ) ( D cdot 18 ) |
12 |
| 608 | The terminal voltage of a cell in open circuit condition is A. Less than its emf B. More than its emf c. Equal to its emf. D. Depends on its internal resistance. |
12 |
| 609 | Resistance of a metal wire of length 1 m is ( 104 Omega ) at ( 20 C . ) If the diameter of the wire is 0.15 mm, find the resistivity of the metal at that temperature. |
12 |
| 610 | A conductor wire, having ( 10^{29} ) free electrons per ( m^{3} ) carries a current of ( 20 A . ) If the cross-section of the wire is ( 1 m m^{2}, ) then the drift velocity of electrons will be of the order of: A ( cdot 10^{-5} m s^{-1} ) B. ( 10^{-3} mathrm{ms}^{-1} ) c. ( 10^{-4} m s^{-1} ) D. ( 10 m s^{-1} ) |
12 |
| 611 | Define mobility of a charge carrier What is its relation with relaxation time? |
12 |
| 612 | How does the resistance of a wire vary with its cross sectional area. |
12 |
| 613 | When is the Wheatstone’s bridge said to be most sensitive? | 12 |
| 614 | can be used to verify Ohm’s law :- ( A ) B. ( c ) ( D ) |
12 |
| 615 | In the absence of an electric field, the mean velocity of free electrons in a conductor at absolute temperature ( (boldsymbol{T}) ) is A . zero B. independent of ( T ) c. proportional to ( T ) D. proportional to ( T^{2} ) |
12 |
| 616 | A student while performing an experiment was surprised to find that when two identical cells are either connected in series or in parallel across a ( 2 Omega ) resistor, the same current passes through the resistor. What is the internal resistance of each cell? A . ( 2 Omega ) B. ( 4 Omega ) ( c cdot 1 Omega ) D. 3Omega |
12 |
| 617 | Find the voltage ( V_{a b} ) in the circuit shown in figure. ( A cdot+3 V ) ( B .-3 v ) ( c cdot+6 v ) ( 0 .-6 ) |
12 |
| 618 | Four wires of the same diameter are connected, in turn, between two points maintained at a constant potential difference. Their resistivity’s and lengths are; ( rho ) and ( L(text { wire } 1), 1.2 rho ) and 1.2L (wire 2), ( 0.9 rho ) and 0.9L (wire 3) and ( rho ) and ( 1.5 mathrm{L} ) (wire 4 ). Rank the wires according to the rates at which energy is dissipated as heat, greatest first. A ( .4>3>1>2 ) в. ( 4>2>1>3 ) c. ( 1>2>3>4 ) D. ( 3>1>2>4 ) |
12 |
| 619 | If the wire in the experiment to determine the resistivity of a material using metre bridge is replaced by copper or hollow wire the balance point i.e. null point shifts A. to right B. to left c. at same point D. None of these |
12 |
| 620 | Draw the circuit diagram of a meter bridge to explain how it is based on Wheatstone bridge. |
12 |
| 621 | n a circuit given below calculate the potential difference between points ( B ) and ( D ). Also find the potential difference across the terminals of ( G ) and ( boldsymbol{H} ) |
12 |
| 622 | Two cells, having emfs of ( 10 V ) and ( 8 V ) respectively, are connected in series with a resistance of ( 24 Omega ) in the external circuit. If the internal resistances of each of these cells in ohm are ( 200 % ) of the value of their emf’s respectively, find the terminal potential difference ( operatorname{across} 8 V ) battery. A ( .0 .3 A, 3.2 V ) B. ( 0.5 A, 3.2 V ) c. ( 0.3 A, 1.2 V ) D. ( 0.5 A, 2.2 V ) |
12 |
| 623 | Ashokbhai goes to an electric shop to buy an electric bulb to obtain light in a small room of his home. Which of the following statement is scientifically correct A. Give bulb of ( 60 mathrm{V} ) B. Give bulb of ( 60 mathrm{J} / mathrm{s} ) c. Give bulb of ( 60 A ) D. Give bulb of ( 60 mathrm{W} ) |
12 |
| 624 | The diameter of a copper wire is ( 2 mathrm{mm} ) a steady current of 6.25 A is generated by ( 8.5 times 10^{28} / m^{2} ) electron flowing through it. Calculate the drift velocity of conduction electrons. |
12 |
| 625 | Explore and answer: Does pure water conduct electricity? If not, what can we do to make it conduct? |
12 |
| 626 | Assertion: A current flows in a conductor only when there is an electric field within the conductor. Reason : The drift velocity of electron in presence of electric field decreases. |
12 |
| 627 | Which device is used to measure the potential difference between two points of a conductor in the laboratory? A. Voltameter B. Ammeter c. Potentiometer D. Galvanometer |
12 |
| 628 | Which of the following quantities do not change when a resistor connected to a battery is heated due to the current? A. Drift speed B. Resistivity c. Resistance D. Number of free electrons |
12 |
| 629 | The device used to detect and measure electric charges is |
12 |
| 630 | Find the equivalent resistance in between ( A ) and ( B ) for the circuit shown in the figure. A . ( 30 Omega ) B. ( 5 Omega ) c. ( 10 Omega ) D. 20Omega |
12 |
| 631 | Consider the potentimeter circuit arranged as in figure. The potentometer wire is ( 600 mathrm{cm} ) long. (a) At what distance from the point ( boldsymbol{A} ) should the jockey touch the wire to get zero deflection in the galvanometer? (b) If the jockey touches the wire at a distance of ( 560 mathrm{cm} ) from ( mathrm{A} ), what will be the current in the galvanometer? |
12 |
| 632 | Assertion Ohm’s law is applicable for all conducting elements Reason Ohm’s law is a fundamental 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 |
| 633 | (a) Why are the connections between the resistor in a meter bridge made of thick copper strips? (b) Why is it generally preferred to obtain the balance point in the middle of the meter bride wire? (c) Which material is used for the meter bridge wire and why? |
12 |
| 634 | connected across a ( 4 m ) long uniform wire having resistance ( 4 Omega / m . ) The cells of small emfs ( epsilon_{1}=2 V ) and ( epsilon_{2}=4 V ) having internal resistance ( 2 Omega ) and ( 6 Omega ) respectively, are connected as shown in the figure. If galvanometer shows no deflection at the point ( N, ) the distance of point ( N ) from the point ( A ) is equal to ( A cdot underline{1}_{-} ) ( B cdot 1 ) ( -n ) c. ( 25 mathrm{cm} ) D. 50 |
12 |
| 635 | Four bulbs marked ( 40 W, 250 V ) are connected in series with ( 250 V ) mains, the total power consumed is A. ( 10 W ) в. ( 40 W ) c. ( 320 W ) D. ( 160 W ) |
12 |
| 636 | Space between two concentric conducting spheres of radii a and ( b(b>a) ) is filled with a medium of resistivity ( rho . ) The resistance between the two spheres will be : A ( cdot frac{rho}{4 pi}left(frac{1}{a}-frac{1}{b}right) ) в. ( frac{rho}{2 pi}left(frac{1}{a}-frac{1}{b}right) ) c. ( frac{rho}{2 pi}left(frac{1}{a}+frac{1}{b}right) ) D. ( frac{rho}{4 pi}left(frac{1}{a}+frac{1}{b}right) ) |
12 |
| 637 | Two resistors of resistances ( 2 Omega ) and ( 6 Omega ) are connected in parallel. This combination is then connected to a battery of emf ( 2 mathrm{V} ) and internal resistance ( 0.5 Omega . ) What is the current flowing through the battery? A. 4 A в. ( frac{4}{3} A ) c. ( frac{4}{17} A ) D. 1A |
12 |
| 638 | Two batteries of emf ( boldsymbol{E}_{1} ) and ( boldsymbol{E}_{2}left(boldsymbol{E}_{2}>right. ) ( E_{1} ) ) and internal resistance ( r_{1} ) and ( r_{2} ) respectively are connected in parallel as shown in figure |
12 |
| 639 | The Figure represents a part of a closed circuit. The p.d. In volts between the points ( A ) and ( B ) i.e. ( V_{A}-V_{B} ) is |
12 |
| 640 | You are given a resistance wire of length ( 100 mathrm{cm} ) and a battery of negligible internal resistance. In which of the following cases is the largest amount of heat generated? A. When the wire is divided in two parts and both the parts are connected to the battery in parallel B. When the wire is connected to the battery directly c. when the wire is divided in to four parts and all the fou parts are connected in parallel to the battery D. When only half of the wire is connected to the battery |
12 |
| 641 | A ( 10 V ) cell of negligible internal resistance is connected in parallel across a battery of emf ( 200 mathrm{V} ) and internal resistance ( 38 Omega ) as shown in the figure. Find the value of current in the circuit. |
12 |
| 642 | Potential gradient along AB is ( mathbf{A} cdot 1 / 5 mathrm{Vm}^{-1} ) B. 2/5 Vm ( ^{-1} ) c. ( 3 / 5 mathrm{Vm}^{-1} ) D. ( 4 / 5 mathrm{Vm}^{-1} ) |
12 |
| 643 | Find the value of currents ( l_{1}, l_{2} ) and ( l_{3} ) | 12 |
| 644 | Find the potential at the centre of arrangement having 6 charged particles of ( Q=5 mu C ) each arranged in the form of a hexagon of side length 0.1 ( mathrm{m} ) |
12 |
| 645 | Two cells ( A ) and ( B ) of e.m.f ( 2 V ) and ( 1.5 V ) respectively, are connected as shown in figure through an external resistance 10Omega. The internal resistance of each cell is 5Omega. The potential difference ( V_{A} ) and ( V_{B} ) across the terminals of the cells ( A ) and B respectively are. A ( cdot V_{A}=2.0 V, V_{B}=1.5 mathrm{V} ) B . ( V_{A}=2.12 V, V_{B}=1.375 V ) C ( . V_{A}=1.875 V, V_{B}=1.625 V ) D. ( V_{A}=1.875 V, V_{B}=1.375 V ) |
12 |
| 646 | Assertion The electric bulbs glows immediately when switch is on. Reason The drift velocity of electrons in a metallic wire is very high. 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 |
| 647 | A negligibly small current is passed through a wire of length ( 15 mathrm{m} ) and uniform cross-section ( 6.0 times 10^{-7} m^{2} ) and its resistance is measured to be 5.0Omega. What is the resistivity of the material at the temperature of the experiment? |
12 |
| 648 | The value of e is A . ( 1.36 mathrm{v} ) B. 2.63 c. ( 1.83 mathrm{v} ) D. none |
12 |
| 649 | If a copper wire is stretched to make it ( 0.1 % ) longer, the percentage increases in resistance will be A . 0.2% B. 2% c. 1% D. 0.1% |
12 |
| 650 | A potentiometer wire of length ( L ) and a resistance ( r ) are connected in series with a battery of e.m.f. ( boldsymbol{E}_{0} ) and ( mathbf{a} ) resistance ( r_{1} . ) An unknown e.m.f. ( boldsymbol{E} ) is balanced at a length ( l ) of the potentiometer wire. The e.m.f. ( boldsymbol{E} ) will be given by: A ( cdot frac{L E_{0} r}{left(r+r_{1}right) l} ) в. ( frac{L E_{0} r}{l r_{1}} ) ( mathbf{c} cdot frac{E_{0} r}{left(r+r_{1}right)} cdot frac{l}{L} ) D. ( frac{E_{0} l}{L} ) |
12 |
| 651 | Five cells of emf ( 1.5 mathrm{V} ) and internal resistance 0.2 ohm are connected in series. The maximum current that can be delivered is A . 7.5A B. 1.5A ( c cdot 4 A ) D. 2A |
12 |
| 652 | What is the colour code of a corbon resistor having a resistance of ( 470 Omega ) and a tolerance of 5%? |
12 |
| 653 | The lengths of two wires made of the same material are in the ratio ( 2: 1 . ) If the masses of the two wires are in the ratio ( 1: 8, ) find the ratio of their resistances ( mathbf{A} cdot 1: 16 ) B. 32: 1 ( mathbf{c} cdot 16: 1 ) D. 1: 32 |
12 |
| 654 | In order to increase the resistance of a given wire of uniform cross-section to four times its value, a fraction of its length is stretched uniformly till the full length of the wire becomes ( frac{3}{2} ) times the original length.What is the value of this fraction? ( A cdot frac{1}{4} ) B. ( frac{1}{8} ) ( c cdot frac{1}{16} ) D. ( frac{1}{6} ) |
12 |
| 655 | In the given figure, when galvanometer shows no deflection, the current (in ampere flowing through ( 5 Omega ) resistance will be A . ( 1.7 A ) В. ( 0.6 A ) ( c .0 .9 A ) D. ( 1.2 A ) |
12 |
| 656 | A battery and a variable resistor are in series with a small fan. A switch is closed, and the fan runs. When the variable resistor is moved slightly to the left, the fan slows down a little. When the variable resistor is moved slightly to the right, the fan speeds up a little. If the variable resistor in the circuit is set all the way to the right, what happens in the circuit? I. The fan runs faster II. The voltage decreases. III. The current increases. A . I only B. Il only c. I and III only D. I I and III only E . I, II, and III |
12 |
| 657 | Consider a neutral conducting sphere. A positive point charge is placed outside the sphere. The net charge on the sphere is then, A. negative and distribute uniformly over the surface of the sphere B. negative and appears only at the sphere closest to the point charge c. negative and distribute non-uniformly over the entire surface of the sphere D. zero |
12 |
| 658 | Which of the following is the correct one ( ? ) A. The resistivity of an alloy is equal that of pure metals. B. The resistivity of an alloy is lower than that of pure metals c. The resistivity of an alloy is higher than that of pure metals D. None of above |
12 |
| 659 | ( = )
( L_{k} ) |
12 |
| 660 | The diagrams show different resistor arrangements. Which arrangement has the smallest |
12 |
| 661 | Consider the following statements A and ( mathrm{B} ) and identify the correct answer A: Thermistors can have only -ve temperature coefficient of resistors. B : Thermistors with -ve temperature coefficients of resistance are used as resistance thermometers to measure low temperature of the order of ( 10 mathrm{K} ) A. 1 both ( A ) and ( B ) are true B. 2) both A and B are false c. 3 ) A is true and ( B ) is false D. 4 ) A is false, but ( B ) is true |
12 |
| 662 | A cell of emf ( E ) volts with no internal resistance is connected to a wire of uneven cross-sectional area. The wire has three sections of equal length. The radius of the middle section is ( a ) and the other are ( 2 a ). The ratio of the potential difference across the middle section to any other section is A .2: 1 B . 4: 1 c. 1: 2 D. 1: 4 |
12 |
| 663 | Define e.m.f. of a cell. How can you compare the emf of two cells using potentiometer? | 12 |
| 664 | In a meter bridge with a standard resistance of ( 5 Omega ) in the left gap, the ratio of balancing lengths on the meter bridge wire is ( 2: 3 . ) The unknown resistance is A . ( 3.3 Omega ) B. ( 7.5 Omega ) c. ( 10 Omega ) D. 15Omega |
12 |
| 665 | You are given three bulbs ( 25 mathrm{W}, 40 mathrm{W} ) and ( 60 mathrm{W} ). Which of them has the lowest resistance? A. 25 watt bulb B. 40 watt bulb c. 60 watt bulb D. Insufficient data |
12 |
| 666 | The dry cell of E.M.F ( 12 V ), is connected in series to a ( 3 Omega ) and a ( 6 Omega ) resistor Calculate the total power supplied by the dry cell. ( mathbf{A} .9 W ) B. ( 72 mathrm{W} ) c. ( 16 W ) D. ( 2 W ) |
12 |
| 667 | Each of Kirchoff’s two laws presumes that some quantity is conserved. Which row states Kirchhoff’s first law This question has multiple correct options |
12 |
| 668 | In the circuit shown in Figure the heat produced in resistance R1 can be measured by A. connecting both voltmeter and an ammeter in parallel to R1 B. both voltmeter in series with ( mathrm{R} 1 ) and voltmeter in parallel to both R1 and R2 C. connecting ammeter in parallel to R1 and voltmeter in series with R1 D. connecting voltmeter in parallel to R1 and ammeter in series with R1 |
12 |
| 669 | A domestic electric circuit has a fuse of 5 A. What is the maximum number of ( mathbf{1 0 0} W(mathbf{2 2 0} V) ) bulbs that can be safely used in the circuit? |
12 |
| 670 | The arm PQ can revolve with uniform speed continuously about P round the circular uniform potentiometer track XYZ. The voltage between RS will vary with respect to time: A. sinusoidally B. Linearly c. Rectangularly D. Like saw tooth |
12 |
| 671 | The length and area of cross -section of a conductor are doubled, then its resistance is A. halved B. unchanged c. doubled D. quadrupled |
12 |
| 672 | How will you compare the e.m.f of two cells using a potentiometer? | 12 |
| 673 | Resistivity is A. an extensive property B. intensive property C . elastic property D. none of the above |
12 |
| 674 | It takes 16 min to boil some water in an electric kettle. Due to some defect it becomes necessary to remove ( 10 % ) turns of the heating coil of the kettle. After repairs, how much time will it take to boil the same mass of water? A. 17.7 min B. 14.4 min c. 20.9 min D. 13.7 min |
12 |
| 675 | What is the power gain? | 12 |
| 676 | In the metre bridge experiment of resistances, the known and unknown resistances are inter-changed. The error so removed is: A. end correction B. index error c. due to temperature effect D. random error |
12 |
| 677 | Primary circuit of potentio meter is as shown in the diagram find potentia gradient. |
12 |
| 678 | Two cells of emfs ( E_{1} ) and ( E_{2} ) are connected in series. Their internal resistances are ( r_{1} ) and ( r_{2} ) respectively. Compute the equivalent emf and equivalent internal resistance. |
12 |
| 679 | What is the equivalent resistance of the system about ( A ) and ( C ? ) ( A ) ( B . r ) 2 ( c cdot 3 r ) 2 D. ( 2 r ) |
12 |
| 680 | Find the ratio of the power developed in segment AE to that in segment HM. ( A ) B. 2 ( c cdot 3 ) ( D cdot 4 ) |
12 |
| 681 | In a meter bridge experiment ( S ) is a standard resistance. ( boldsymbol{R} ) is a resistance wire. It is found that balancing length is ( l=25 mathrm{cm} . ) If ( R ) is replaced by a wire of half length and half diameter that of ( boldsymbol{R} ) of same material, then the balancing distance ( left.l^{prime} text { (in } c mright) ) will now be |
12 |
| 682 | The practical unit of resistance is ( Omega ) and ( 1 Omega ) is equal to: A ( cdot 10^{18}_{e m u} ) В. ( 10^{9} )ети ( mathbf{c} cdot 10^{15} e m u ) D. none of these |
12 |
| 683 | Name and define unit for electric current |
12 |
| 684 | In this circuit, when certain current flows, the heat produced in ( 5 Omega ) is ( 4.05 J ) in a time ( t . ) The heat produced in ( 2 Omega ) coil in the same time interval is A . 5.76 в. 1.44 ( c .2 .88 ) D. 2.02 |
12 |
| 685 | Consider the following two statements: (A) Kirchhoff’s Junction Law follows from conservation of charge. (B) Kirchhoff’s Loop Law follows from conservative nature of electric field A. Both A and B are correct B. A is correct but B is wrong c. A is correct but A is wrong D. Both A and B are wrongg |
12 |
| 686 | Power dissipated in the circuit shown in the figure 30 watt. The value of R is A . ( 5 Omega ) B. ( 15 Omega ) ( c cdot 10 Omega ) D. 20 ( Omega ) |
12 |
| 687 | Consider the following two statements: 1) Kirchoff’s junction law follows from the conservation of charge 2) Kirchoff’s loop law follows from the conservation of energy. Which of the following is correct? A. both 1 and 2 are wrong B. 1 is correct and 2 is wrong C. 1 is wrong and 2 is correct D. both 1 and 2 are correct |
12 |
| 688 | Measure of the opposition to the flow the free electron is known as A. current B. Resistance c. conductance D. Capacitance |
12 |
| 689 | Which are good insulators? This question has multiple correct options A. wood B. copper c. human body D. glass |
12 |
| 690 | Variation of resistance of the conductor with temperature is as shown The temperature co-efficient ( (alpha) ) of the |
12 |
| 691 | 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. What is the p.d. across the ( R Omega ) and ( 2 Omega ) resistor? A. ( 0.25 vee, 0.5 mathrm{V} ) B. 0.25 V, 0.25 V ( c cdot 2 v, 1 v ) D. ( 0.5 vee, 0.25 ) |
12 |
| 692 | Resistance of a metallic conductor depends on A. Its length B. Its area of cross section c. Temperature D. All the above |
12 |
| 693 | A cell, an ammeter and a voltmeter are all connected in series. The ammeter reads a current I and the voltmeter a potential difference V. If a torch bulb is connected across the voltmeter, then. A. Both I and v will increase B. Both I and V will decrease c. I will increase but ( V ) will decrease D. I will decrease but V will increase |
12 |
| 694 | The resistance of a hot tungsten filament is about 10 times the cold resistance. What will be the resistance of ( 100 W, 200 V ) lamp when not in use? A . ( 20 Omega ) B. ( 40 Omega ) c. ( 200 Omega ) D. ( 400 Omega ) |
12 |
| 695 | What is the resultant resistance of the given circuit ? A . ( 20 Omega ) B. ( 8 Omega ) ( mathbf{c} .7 .2 Omega ) D. ( 12 Omega ) |
12 |
| 696 | A straight conductor of uniform cross- section carried a current I. Let s=specific charge of an electron. The momentum of all the free electrons per unit length of the conductor, due to their drift velocities only, is A . Is B. ( 1 / s ) c. ( sqrt{I / s} ) D. ( (I / s)^{2} ) |
12 |
| 697 | Derive the condition of balance for Wheatstone bridge. |
12 |
| 698 | Rate at which electric work is done is A. Potential difference B. Energy c. Power D. All |
12 |
| 699 | ( mathbf{A} ) ( 24 V ) battery having internal resistor of ( X Omega ) is connected to a ( 4 Omega ) resistor, causing a current of ( 5 A ). Find out the value of ( boldsymbol{X} ) ? ( mathbf{A} cdot 0 W ) B. ( 0.8 W ) c. ( 0.4 W ) D. ( 1.6 W ) E . ( 1.2 W ) |
12 |
| 700 | The value of the current ( boldsymbol{I}_{1}, boldsymbol{I}_{2} ) and ( boldsymbol{I}_{3} ) flowing through the circuit given below is? A ( cdot I_{1}=-3 A, I_{2}=2 A, I_{3}=-1 A ) B . ( I_{1}=2 A, I_{2}=-3 A, I_{3}=-1 A ) C ( . I_{1}=3 A, I_{2}=-1 A, I_{3}=-2 A ) D ( cdot I_{1}=1 A, I_{2}=-3 A, I_{3}=-2 A ) E ( cdot I_{1}=2 A, I_{2}=-1 A, I_{3}=-3 A ) |
12 |
| 701 | Assertion When the radius of a copper wire is doubled, its specific resistance is increased. Reason Specific resistance is independent of cross-section of material used. 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 |
| 702 | The resistance of one ohm is very approximately equal to that of a column of mercury ( 1.06 m ) long and of uniform cross-section of one hundredth of ( 1 mathrm{cm}^{2} ). Find the resistivity of mercury. A ( cdot 6.4 times 10^{-7} Omega m ) В . ( 7.4 times 10^{-7} Omega m ) c. ( 9.4 times 10^{-7} Omega m ) D. ( 2.4 times 10^{-7} Omega m ) |
12 |
| 703 | If a copper ring is moved towards the north pole of a bar magnet, then: A. the ring will not be affected B. the ring will become warm c. an alternating current will flow in the ring D. the ring will be positively charged |
12 |
| 704 | The figure below shows a variable resistor in a dimmer switch. How would you turn the switch to make the lights: ( (a) ) brighter, and (b) dimmer? Explain. |
12 |
| 705 | Calculate the amount to heat produced per second when a bulb of ( 50 mathrm{W}, 200 mathrm{V} ) glows assuming that only ( 20 % ) of the electric energy is converted into light. A. 20 B. 400 ( c . ) 50 D. 200 |
12 |
| 706 | Show how you would connect 3 resistors each of resistance 6 ohm, so that the combination has a resistance of (i) 9 ohm (ii) 4 ohm |
12 |
| 707 | Keeping the length of the conductor constant, if the radius of the conductor is doubled, then its resistance becomes A. Double B. Quadrupled c. Half D. Four times less |
12 |
| 708 | The graph between potential difference and current for a conductor is a straight line passing through the origin. Which law is illustrated by such a graph? A. Law ofcombination of resistances B. Henry’s law c. ohm’slaw D. Joule’s law ofheating |
12 |
| 709 | ( n ) identical cells each of electromotive force ( e ) and internal resistance ( r ) are connected in series of this combination The current through ( V ) is: A ( cdot frac{2 e}{n} ) в. ( frac{n e}{n R+r} ) c. ( frac{e}{R+n r} ) D. ( frac{n e}{R+r} ) |
12 |
| 710 | The equivalent capacitance between points ( X ) and ( Y ) in figure shown is : ( A ) В. ( 4 mu F ) c. ( frac{18}{5} mu F ) D. none of these |
12 |
| 711 | Two metallic wires ( A ) and ( B ) of equal dimensions but made of different materials, having resistivities ( rho ) and ( 2 rho ) temperature coefficients of resistivities ( 2 alpha ) and ( alpha ) are connected in series. The temperature coefficient of resistance of the composite wire equals: ( ^{mathrm{A}} rho_{e q}=frac{3}{2} rho ) в. ( quad alpha_{e q}=frac{3}{2} ) ( c cdot rho_{e q}=3 rho ) D. ( _{alpha_{e q}}=frac{4}{3} alpha ) |
12 |
| 712 | If ( i_{1}=3 sin omega t ) and ( i_{2}=4 cos omega t, ) then ( i_{3} ) is – ( mathbf{A} cdot 5 sin left(omega t+53^{circ}right) ) B. ( 5 sin left(omega t+37^{circ}right) ) ( mathbf{c} cdot 5 sin left(omega t+45^{circ}right) ) ( mathbf{D} cdot 5 cos left(omega t+53^{circ}right) ) |
12 |
| 713 | The current that passes through 20 ohm resistance when it is connected in parallel with a 30 ohm resistance and this set is connected to a battery of ( 2 mathrm{V} ) is A . ( 0.2 A ) B. ( 0.3 mathrm{A} ) c. ( 0.1 mathrm{A} ) D. 0.016A |
12 |
| 714 | In the Bohr’s model of hydrogen atom, the electron moves around the nucleus in a circular orbit of-radius ( 5 times 10^{-11} ) meters. If its time period is ( 1.5 times 10^{-16} ) sec, then current associated with the electron motion is A. zero B. ( 1.6 times 10^{-19} A ) c. 0.17 А D. ( 1.07 times 10^{-3} A ) |
12 |
| 715 | In the circuit shown the resistance ( R ) has a value that depends on the current. Specifically, R is 20 ohms when I is zero and the increase in resistance in ohms is numerically equal to one half of the current in amperes. What is the value of current I in circuit? A. 8.33 amp B. 10 amp c. 12.5 amp D. 18.5 amp |
12 |
| 716 | If 2.2 kilowatt power is being transmitted at ( 44 mathrm{KV} ) on a ( 20 Omega ) line, then power loss will be: A. 0.1 watt B. 1.4 watt c. 100 watt D. 0.05 watt |
12 |
| 717 | A wire of uniform cross-section has a resistance of ( R ). If it is drawn to three times the length, but the volume remains constant, what will be its resistance? ( mathbf{A} cdot 3 R Omega ) B. ( 5 R Omega ) ( mathbf{c} .7 R Omega ) D. ( 9 R Omega ) |
12 |
| 718 | Two cells of emf ( boldsymbol{E}_{1} ) and ( boldsymbol{E}_{2}left(boldsymbol{E}_{1}>boldsymbol{E}_{2}right) ) are connected shown in figure. When a potentiometer is connected between ( mathbf{A} ) and ( mathrm{B} ), the balancing length of the potentiometer wire is ( 300 mathrm{cm} . ) On connecting the same potentiometer between ( A ) and ( C, ) the balancing length is ( 100 mathrm{cm} . ) The ratio ( E_{1} / E_{2} ) is A . 3: 1 B. 1: 3 ( c cdot 2: 3 ) D. 3: 2 |
12 |
| 719 | A ( 500 W ) heating unit is designed to operate on a ( 115 mathrm{V} ) line. If line voltage drops to ( 110 V ) line, the percentage drop in heat output will be: A. ( 7.6 % ) B. ( 8.5 % ) c. ( 8.1 % ) D. 10.2 % |
12 |
| 720 | In a Wheatstone bridge, three resistances ( P, Q ) and ( R ) are connected in the three arms and the fourth arm is formed by two resistances ( S_{1} ) and ( S_{2} ) connected in parallel. The condition for the bridge to be balanced will be A ( cdot frac{P}{Q}=frac{Rleft(S_{1}+S_{2}right)}{2 S_{1} S_{2}} ) в. ( frac{P}{Q}=frac{R}{S_{1}+S_{2}} ) c. ( frac{P}{Q}=frac{2 R}{S_{1}+S_{2}} ) D. ( frac{P}{Q}=frac{Rleft(S_{1}+S_{2}right)}{S_{1} S_{2}} ) |
12 |
| 721 | What is the relation between resistance ( mathrm{R} ) and resistivity ( rho ) of a wire ( ? ) A ( cdot R=frac{rho A}{l} ) в. ( R=frac{rho l}{A} ) c. ( R=frac{A}{rho l} ) D. ( _{R}=frac{l}{rho A} ) |
12 |
| 722 | In a meter bridge experiment, the ratio of the left gap resistance to right gap resistance is ( 2: 3, ) the balance point from left is? ( mathbf{A} cdot 60 mathrm{cm} ) B. ( 50 mathrm{cm} ) c. ( 40 mathrm{cm} ) D. ( 20 mathrm{cm} ) |
12 |
| 723 | A non-zero current passes through the galvanometer F shown in the circuit when the key ‘K’ is closed and its value does not change when the key is opened. Then which of the following statement(s) is/are true? This question has multiple correct options A. The galvanometer resistance is infinite B. The current through the galvanometer is ( 40 mathrm{mA} ) c. After the key is closed, the current through ( 200 Omega ) resistor is same as the current through the ( 300 Omega ) resistor D. The galvanometer resistance is ( 150 Omega ) |
12 |
| 724 | The figure is a part of a closed circuit Find the currents ( i_{1}, i_{2} ) and ( i_{3} ) |
12 |
| 725 | Ohm’s law can be applied to A. ohmic devices B. non-ohmic devices ( c . ) both (a) and (b) D. none |
12 |
| 726 | The dimensions of a rectangular parallelepiped are ( 1 mathrm{cm} times 1 mathrm{cm} times ) ( 100 mathrm{cm} . ) If its specific resistance is ( 3 x ) ( 10^{-7} Omega m ) then the resistance between its rectangular faces will be A ( cdot 3 times 10^{-9} Omega ) В. ( 3 times 10^{-7} Omega ) c. ( 3 times 10^{-5} Omega ) D. ( 3 times 10^{-3} Omega ) |
12 |
| 727 | A resistance of ( 2 Omega ) is connected across one gap of a metre-bridge (the length of the wire is ( 100 mathrm{cm} ) ) and an unknown resistance, greater than ( 2 Omega ), is connected across the other gap. When these resistance are interchanged, the balance point shifts by ( 20 mathrm{cm} ) Neglecting any corrections, the unknown resistance is A. ( 3 Omega ) в. ( 4 Omega ) ( c cdot 5 Omega ) D. ( 6 Omega ) |
12 |
| 728 | The resistance of a wire at room temperature ( 30^{circ} mathrm{C} ) is found to be ( 10 Omega ) Now to increase the resistance by ( 10 % ) the temperature of the wire must be: [The temperature coefficient of resistance of the material of the wire is ( left.0.002 text { per }^{circ} Cright] ) A ( cdot 36^{circ} mathrm{C} ) в. ( 83^{circ} ) С ( mathbf{c} cdot 63^{circ} C ) D. ( 33^{circ} mathrm{C} ) |
12 |
| 729 | A potentiometer wire of length 10 m and resistance ( 30 Omega ) is connected in series with a battery of emf ( 2.5 V ) internal resistance ( 5 Omega ), and an external resistance ( boldsymbol{R} ). If the fall of potential along the potentiometer wire is ( mathbf{5 0} mu V boldsymbol{m} boldsymbol{m}^{-1}, ) then the value of ( boldsymbol{R} ) is found to be ( 23 n Omega ). What is ( n ? ) |
12 |
| 730 | What is the power produced by an appliance marked “240 V, 2 A”? A. ( 8.3 mathrm{mw} ) B. 60 ( w ) c. ( 120 mathrm{w} ) D. ( 480 mathrm{w} ) |
12 |
| 731 | The electrical resistance of pure platinum increases linearly with increasing temperature over a small range of temperature. This property is used in a Platinum resistance thermometer. The relation between ( boldsymbol{R}_{boldsymbol{theta}} ) (Resistance at ( theta ) K) and ( R_{0} ) (Resistance ( left.operatorname{at} theta_{0} Kright) ) is given by ( R_{theta}=R_{0}[1+alpha(theta- ) ( left.left.boldsymbol{theta}_{0}right)right], ) where ( boldsymbol{alpha}= ) temperature coefficient of resistance. Now, if a Platinum resistance thermometer reads ( 0^{circ} mathrm{C} ) when its resistance is ( 80 Omega ) and ( 100^{circ} mathrm{C} ) when its resistance is ( 90 Omega ), find the temperature at which its resistance is ( 86 Omega ) |
12 |
| 732 | Assertion If we bend an insulated conducting wire, the resistance of the wire increases. Reason The drift velocity of electrons in bent wire decreases. 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 |
| 733 | A copper wire carries a current of density Assuming that one free electrone corresponding to each copper atom,evalute the distance which will be covered by an electrone during its displacement along the wire |
12 |
| 734 | Two resistors of resistances ( boldsymbol{R}_{1}= ) ( 100 pm 3 o h m ) and ( R_{1}=200 pm 4 o h m ) are connected (a) in series, (b) in parallel. Find the equivalent resistance of the (a) series combination, (b) parellel combination. Use for ( (a) ) the relation ( boldsymbol{R}=boldsymbol{R}_{1}+boldsymbol{R}_{2} ) and for ( (boldsymbol{b}) ) ( frac{1}{R^{prime}}=frac{1}{R_{1}}+frac{1}{R_{2}} ) and ( frac{triangle R^{prime}}{R^{prime 2}}=frac{triangle R_{1}}{R_{1}^{2}}+ ) ( frac{triangle boldsymbol{R}_{2}}{boldsymbol{R}_{2}^{2}} ) |
12 |
| 735 | The resistance of the platinum wire of a platinum resistance thermometer at the ice point is ( 5 Omega ) and at steam point is ( 5.39 Omega . ) When the thermometer is inserted in a hot bath, the resistance of the platinum wire is ( 5.795 Omega . ) Calculate the temperature of the bath. |
12 |
| 736 | Two resistors equal resisitances are joined in series and a current is passed through the combination. Neglect any variation in resistance as the temperature changes. In a given time interval This question has multiple correct options A. equal amounts of thermal energy must be produced in the resistors B. unequal amount of thermal energy may be produced c. the temperature must rise equally in the resistors D. the temperature may rise equally in the resistors |
12 |
| 737 | To balance the bridge in the circuit, the values of ( mathrm{R} ) is ( A cdot 8 Omega ) B. ( 4 Omega ) ( c cdot 20 Omega ) D. ( 12 Omega ) |
12 |
| 738 | In a metre bridge, the balancing length from the left end (standard resistance of one ohm is in the right gap) is found to be ( 20 mathrm{cm} ). The value of the unknown resistance is A . ( 4 Omega ) B. ( 0.5 Omega ) c. ( 0.4 Omega ) D. ( 0.25 Omega ) |
12 |
| 739 | There are 5 tube-lights each of ( 40 W ) in a house. These are used on an average for 5 hrs / day. In addition, there is an immersion heater of ( 1500 W ) used on an average for 1 h ( / ) day. The number of units of electricity that are consumed in a month of 30 days is: A. 25 units B. 50 units c. 75 units D. 100 units |
12 |
| 740 | ( boldsymbol{n} ) identical cells, each of internal resistance ( (r) ) are first connected in parallel and then connected in series ( operatorname{across} ) a resistance ( (boldsymbol{R}) . ) If the current through ( R ) is same in both the cases then: A. ( R=r / 2 ) в. ( r=R / 2 ) c. ( R=r ) ( mathbf{D} cdot r=0 ) |
12 |
| 741 | The length of a potentiometer wire is ( 1200 mathrm{cm} ) and it carries a current of ( 60 m A . ) For cell of emf ( 5 V ) and internal resistance of ( 20 Omega ), the null point on it is found to be at ( 1000 mathrm{cm} . ) The resistance of whole wire is: A . ( 60 Omega ) в. ( 100 Omega ) ( c .80 Omega ) D. ( 120 Omega ) |
12 |
| 742 | An electric current is the rate of flow of electric charges and it is measured in Ampere. A. True B. False |
12 |
| 743 | According to Ohm’s law the graph of potential difference and current is A. Straight line passing through origin B. Curved c. Line having an intercept on ( x ) -axis D. Circular |
12 |
| 744 | The resistance between ( A ) and ( B ) in the given figure will be(in ohm): A. 20 B. 30 c. 90 D. more than 10 but less than 20 |
12 |
| 745 | The potential difference across the ends of a resistor is ( _{-}-_{-}-_{-}-_{-}- ) to the current through it A. directly proportional B. inversely proportional c. square proportional D. none of these |
12 |
| 746 | Assertion : Current is passed through a metallic wire, heating it red. When cold water is poured on half of it, the rest becomes more hot. Reason: Resistance decreases due to |
12 |
| 747 | An electric toaster draws ( 8 A ) current in a ( 220 V ) circuit. It is used for ( 2 h r . ) What is the cost of operating the toaster if the ( operatorname{cost} ) of electrical energy is Rs. ( 4.5 / k W h ? ) A. ( R s .9 .50 ) B. Rs. 25.50 c. ( R s .14 .84 ) D. Rs. 15.84 |
12 |
| 748 | State Ampere’s circuital law. | 12 |
| 749 | When a resistor of ( 11 Omega ) is connected in series with a electric cell. The current following in it is ( 0.5 A . ) Instead when a resistor of ( 5 Omega ) is connected to the same electric cell in series, the current increases by ( 0.4 A . ) The internal resistance of the cell is A. ( 1.5 Omega ) B. 2Omega ( c .2 .5 Omega ) D. 3.5Omega |
12 |
| 750 | Mobility of free electrons in a conductor ¡s: A. directly proportional to electron density B. directly proportional to relaxation time C. inversely proportional to electron density D. inversely proportional to relaxation time |
12 |
| 751 | Two cells of same emf are connected in series. Their internal resistances are ( r_{1} ) and ( r_{2} ) respectively and ( r_{1}>r_{2} . ) When this combination is connected to an external resistance ( R ) then the potential difference between the terminals of first cell becomes zero. In this condition the value of R will bw A ( cdot frac{r_{1}-r_{2}}{2} ) B. ( frac{r_{1}+r_{2}}{2} ) c. ( r_{1}-r_{2} ) D. ( r_{1}+r_{2} ) |
12 |
| 752 | Two conductors ( A ) and ( B ) of the same length and diameter are connected across the same battery. The resistivity of ( A ) is twice that of ( B ). If ( P_{A} ) and ( P_{B} ) be the powers dissipated ( operatorname{across} A ) and ( B, ) respectively, then A ( cdot P_{A}=P_{B} ) В. ( P_{A}>P_{B} ) c. ( P_{A}<P_{B} ) D. ( P_{A}=P_{B}=1 ) |
12 |
| 753 | A wire ( 50 mathrm{cm} ) long and ( 1 mathrm{mm}^{2} ) in cross section carries a current of 4 A when connected to a 2 V battery. The resistivity of the wire is A. ( 2 times 10^{-7} Omega m ) В. ( 5 times 10^{-7} Omega m ) c. ( 4 times 10^{-6} Omega m ) D. ( 1 times 10^{-6} Omega m ) |
12 |
| 754 | There is a current of 40 amperes in a wire of ( 10^{-16} m^{2} ) area of cross-section. If the number of free electrons per ( m^{3} ) is ( 10^{29}, ) then the drift velocity will be: A ( cdot 1.25 times 10^{3} mathrm{m} / mathrm{s} ) в. ( 2.50 times 10^{3} ) т/ ( s ) c. ( 2.0 times 10^{6} mathrm{m} / mathrm{s} ) D. ( 25 times 10^{6} mathrm{m} / mathrm{s} ) |
12 |
| 755 | One ampere equals A ( cdot 10^{6} mu A ) В ( cdot 10^{-6} mu A ) ( mathbf{c} cdot 10^{-3} mu A ) D. 10 A |
12 |
| 756 | The graph represent a current-voltage behaviour of a water-voltameter. spot the correct explanation. A. Dissociation takes place at ( E_{1} ) and it obeys Ohm’s law thereafter. B. Ohm’s law is not valid for low voltages C. Ohm’s law is obyed but only for potential difference larger than back emf. D. Electrolyte does not obey Ohm’s law. |
12 |
| 757 | A metal wire of resistivity ( 64 times 10^{-6} Omega ) and length ( 198 mathrm{cm} ) has a resistance of 7 Omega. Calculate its radius. |
12 |
| 758 | In the given in each the current in each resistance is: A. ( 0 A ) B. ( 1 A ) c. ( 0.25 A ) D. ( 0.5 A ) |
12 |
| 759 | A cell drives a current through a circuit The e.m.f. of the cell is equal to the work done in moving unit charge: This question has multiple correct options A. from the positive to negative plate of the cell B. from the positive plate back to the positive plate C. from the negative plate back to the negative plate D. from any point in the circuit back to the same point |
12 |
| 760 | Resistance of a platinum resistance thermom-eter is 2 ohm at ( 20^{circ} mathrm{C}, 4 ) ohm at ( 100^{circ} C ) and 2.2 ohm at some temperature. this temperature-is A ( cdot 20^{circ} mathrm{C} ) B. 30 ( mathbf{c} cdot 40^{circ} mathrm{C} ) D. ( 28^{circ} mathrm{C} ) |
12 |
| 761 | Three ( 60 mathrm{W} ), 120 ( mathrm{V} ) light bulbs are connected across a ( 120 mathrm{V} ) power line as shown in Fig. Find the voltage across each bulb. |
12 |
| 762 | Suppose a current carrying wire has a cross-sectional area that gradually become smaller along the wire has the shape of a very long cone as shown in figure.Then: This question has multiple correct options A. electric current is different in different portions of wire B. electric current is same everywhere. C. drift speed of electrons at point ( A ) is lesser than that of at point B. D. drift speed of electrons at point ( A ) is same as that of at point B. |
12 |
| 763 | An energy source will supply a constant current into the load if its internal resistance is A. zero B. nonzero but less than the resistance of the loadd c. equal to the resistance of the loadd D. very large as compared to the load resistance |
12 |
| 764 | You have three resistors of values ( 2 Omega, 3 Omega, ) and ( 5 Omega . ) If they are in parallel then the total resistance is : ( mathbf{A} cdot 0.97 Omega ) в. ( 2 Omega ) ( c .10 Omega ) D. 3. |
12 |
| 765 | The graph of two conductors of same materials connected in series justify (i) which one has more resistance (ii)Which one will produce more heat? |
12 |
| 766 | The circuit shown in Figure contains three resistors ( boldsymbol{R}_{1}=mathbf{1 0 0} boldsymbol{Omega}, boldsymbol{R}_{2}=mathbf{5 0} boldsymbol{Omega} ) and ( R_{3}=20 Omega ) and cells of emfs ( E_{1}= ) ( 2 V ) and ( E_{2} . ) The ammeter indicates a current of 50 mA. Determine the currents in the resistors and the emf of the second cell. The internal resistance of the ammeter and of the cells should be neglected |
12 |
| 767 | A cell of negligible resistance and emf 2 volt is connected to a series combination of 2,3 and 5 ohm. The potential difference in volts between the terminals of 3 -ohm resistance will be: A. ( 0.6 v o l t ) B. ( frac{2}{3} ) volt c. ( 3 v o l t s ) D. ( 6 v o l t s ) |
12 |
| 768 | ( fleft(x_{A}=2 V ) calculate current flowing right. through the circuit and calculate ( V_{B} ) and ( V_{C} ? ) |
12 |
| 769 | The temperature co-efficient of resistance of a wire is ( 0.0012 /^{circ} mathrm{C} ). Its resistance is ( 1 Omega ) at ( 300 K . ) At what temperature, its resistance will be ( 2 Omega ? ) A . ( 1133 K ) B. ( 854 K ) c. ( 1217 K ) D. ( 1154 K ) |
12 |
| 770 | Assertion Drift velocity of electrons is independent of time. Reason Electrons are accelerated in the presence of electric field. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |
| 771 | 36 identical cell each having emf 1.5 volt and internal resistance ( 0.5 Omega ) are connected in series with an external resistance of ( 12 Omega ). If 6 cells are wrongly connected then current through the circuit will be A ( cdot 1.2 mathrm{A} ) B. 1 A ( c cdot 2 A ) D. 4 A |
12 |
| 772 | The North pole of a magnet is brought near a negatively charged conductor. A. Force acting on the pole will be zero B. Force acting on the pole will be maximum. c. Force acting on the pole will be minimum. D. none |
12 |
| 773 | Four conductors of resistance 4,3,9 and 6 ohm are connected in ( A B, B C, C D ) and DA arms of a Wheatstone bridge. The bridge can be balanced by connecting. A. ( 1) 6 ) ohm in series with 3 ohm conductor B. 2) 4 ohm in parallel with 6 ohm conductor c. 3 ) 3 ohm in series with 3 ohm conductor D. 4 ) 5 ohm in series with 6 ohm conductor |
12 |
| 774 | With the help of a neatly drawn and labelled diagram, obtain balancing condition of a Wheatstone bridge. |
12 |
| 775 | Two electric charges ( 12 mu C ) and ( -6 mu ) electric field intensity at zero potentia and outside the region between them A ( cdot 1.25 times 10^{6} N / C ) В. ( 3.75 times 10^{5} N / C ) c. ( 4.5 times 10^{6} N / C ) D. ( 6.75 times 10^{5} N+C ) |
12 |
| 776 | What is the power produced by an appliance marked ” ( 240 V, 2 A ? ) A. ( 8.3 m W ) в. ( 60 W ) c. ( 120 W ) D. ( 480 W ) |
12 |
| 777 | Which of the following is not true for wire wound resistor? A. It has a lower order of stability and reliability. B. It has high power rating with a low tolerance value. C. Easy to make wire wound resistor of value 0.01 Ohm. D. It is not suitable for high-frequency circuits. |
12 |
| 778 | The temperature coefficient of a wire is ( 0.00125^{0} C^{-1} . ) At ( 300 mathrm{K} ) its resistance is one ohm.The resistance of the wire will be ( 2 Omega ) at ( mathbf{A} cdot ) 1154 ( mathbf{K} ) B. ( 1100 mathrm{k} ) ( c cdot 1400 k ) D. 1127 K |
12 |
| 779 | Why can one ignore quantisation of electric charge when dealing with macroscopic i.e., large scale charges? | 12 |
| 780 | The slope of current (I) versus voltage (V) is called: A . resistance B. resistivity c. conductivity D. conductance |
12 |
| 781 | No two equipotential surface intersect each other ?why? | 12 |
| 782 | Electric current is due to flow of charge carriers in the conductors. Which of the following is/are correct? This question has multiple correct options A. The drift speed of charge carriers is a very small fraction of the mean thermal agitation speed of the same charge carriers B. The number of charge carriers per unit volume is always the same as the number of atoms of the conductor per unit volume C. The drift velocity is proportional to the electric field applied ordinarily D. In an intrinsic semiconductor, the charge carriers are either electrons only or holes only; both of them may not participate in conduction |
12 |
| 783 | An ideal cell having a steady emf of 2 volts is connected across the potentiometer wire of length ( 10 m ). The potentiometer wire is of magnesium and having resistance of ( 11.5 Omega / m . ) An another cell gives a null point at ( 6.9 m ). If a resistance of ( 5 Omega ) is put in series with potentiometer wire, the new position of the null point is given as ( frac{x}{10} m . ) Find ( x ) |
12 |
| 784 | Two resistances ( R_{1} ) and ( R_{2} ) are made of different materials. The temperature coefficient of the material of ( boldsymbol{R}_{1} ) is ( boldsymbol{alpha} ) and that of material of ( boldsymbol{R}_{2} ) is ( -boldsymbol{beta} ). The material of ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2} ) will not change with temperature if ( frac{boldsymbol{R}_{1}}{boldsymbol{R}_{2}} ) equal to ( mathbf{A} cdot frac{alpha}{beta} ) В. ( frac{alpha+beta}{alpha-beta} ) c. ( frac{alpha^{2}+beta^{2}}{2 alpha beta} ) D. ( frac{beta}{alpha} ) |
12 |
| 785 | Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area ( 1.0 times 10^{-7} m^{2} ) carrying a current of 1.5 A. Assume the density of conduction electrons to be ( 9 times 10^{28} m^{-3} ) |
12 |
| 786 | The wire loop PQRSP formed by joining two semi-circular wires of radii ( boldsymbol{R}_{1} ) and ( R_{2} ) carries a current I as shown. The magnitude of the magnetic induction at the centre ( C ) is A ( cdot frac{mu_{0} I}{4} frac{R_{2}-R_{1}}{R_{2}} ) В ( cdot frac{mu_{0} I}{4} frac{R_{2}-R_{1}}{R_{1}} ) C ( cdot frac{mu_{0} I}{4} frac{R_{2}-R_{1}}{R_{2} R_{1}} ) D. None of these |
12 |
| 787 | A long wire carrying a current ( i ) is bent to form a plane angle ( alpha ). Find the magnetic field ( B ) at point on the bisector of this angle situated at a distance ( x ) from the vertex |
12 |
| 788 | In the circuit shown here, ( boldsymbol{E}_{mathbf{1}}=boldsymbol{E}_{2}= ) ( boldsymbol{E}_{3}=2 boldsymbol{V} ) and ( boldsymbol{R}_{1}=boldsymbol{R}_{2}=boldsymbol{4} ) ohms. The current flowing between points ( A ) and ( B ) through battery ( boldsymbol{E}_{2} ) is :- A . zero B. 2 amp from A to B c. 2 amp from ( B ) to ( A ) D. none of the above |
12 |
| 789 | A battery of ( boldsymbol{E} boldsymbol{M} boldsymbol{F} ) 3 ( boldsymbol{v} ) and internal resistance ( r ) connected in series with the resistor ( 55 Omega ) through can ammeter of resistance ( 1 Omega ) it reads ( 50 m A ) Calculate ( r ) |
12 |
| 790 | The resistances of the four arms ( P, Q, R ) and ( sin ) a Wheatstone’s bridge are 10 ohm, 30 ohm, 30 ohm and 90 ohm, respectively. The e.m.f. and internal resistance of the cell are 7 volt and 5 ohm respectively. If the galvanometer resistance is 50 ohm, the current drawn from the cell will be A . ( 1.0 mathrm{A} ) B. 0.2 A ( c cdot 0.1 mathrm{A} ) D. 2.0 A |
12 |
| 791 | For electrolytes, Ohm’s Law may be written as: A ( cdot frac{V}{I}=R ) B. ( frac{V+V_{b a c k}}{I}=R ) c. ( frac{V-V_{b a c k}}{I}=R ) D. ( frac{V_{b a c k-V}}{I}=R ) |
12 |
| 792 | Assertion The wire of a potentiometer should be of uniform area of cross section. Reason It satisfies the requirement of the principle of the potentiometer. 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 |
| 793 | The resistance of all the wire between any two adjacent dots is ( R ). The equivalent resistance between ( A ) and ( B ) as shown is A . ( 7 R / 13 ) B. ( 7 R / 6 ) c. ( 14 R / 8 ) D. ( 15 R / 7 ) |
12 |
| 794 | According to kircholf’s second law: | 12 |
| 795 | If ( 400 Omega ) of resistance is made by adding four ( 100 Omega ) resistance of tolerance ( 5 % ) then the tolerance of the combination is? A . ( 15 % ) B. 20% c. ( 5 % ) D. ( 10 % ) |
12 |
| 796 | Twelve identical resistors of ( 6 Omega ) each are connected to form a cube as shown above. The effective resistance across the solid diagonal, AG is : ( A .5 Omega ) B. ( 4.5 Omega ) ( c .3 .5 Omega ) ( mathbf{D} cdot 1.5 Omega ) |
12 |
| 797 | ( boldsymbol{V}-boldsymbol{I} ) graph for two wires ( boldsymbol{A} ) and ( boldsymbol{B} ) are shown in the figure. If the both wires are of same length and same thickness, which of the two is made of a material of high resistivity? Given justification for your answer. |
12 |
| 798 | A nichrome wire ( 1 mathrm{m} ) long and ( 1 mathrm{mm}^{2} ) in crosssectional area draws 4 ampere at 2 volt. The resistivity of nichrome is A ( cdot 1 times 10^{-7} n m ) В. ( 2 times 10^{-7} n m ) c. ( 4 times 10^{-7} n m ) D. ( 5 times 10^{-7} n m ) |
12 |
| 799 | An inductor of 2 henry and a resistance of 10 ohms are connected in series with a battery of 5 volts. The initial rate of change of current is: A. 0.5 amp/sec B. 2.0 amp/sec c. 2.5 amp/sec D. 0.25 amp / sec |
12 |
| 800 | The reading of poteniometer if ( 4 V ) battery is used instead of ( e ), is A ( .88 .3 mathrm{cm} ) в. ( 47.3 mathrm{cm} ) ( mathrm{c} .95 mathrm{cm} ) D. cannot be calculated |
12 |
| 801 | A simple circuit consisting of three resistors is shown above. ( boldsymbol{R}_{1} ) has the same resistance of ( boldsymbol{R}_{2} ) and ( boldsymbol{R}_{2} ) has twice the resistance of ( boldsymbol{R}_{3} ). If the switch remains closed, determine the ratio of heat dissipated of ( boldsymbol{R}_{1} ) to ( boldsymbol{R}_{2} ) ( mathbf{A} cdot 1: 9 ) B. 1: 3 c. 1: D. 3: E. 9: 1 |
12 |
| 802 | toppr ( L ) Q туре your question potentiometer and measures the corresponding current in the circuit. The table of data and the resistance vs. current graph created by the student is shown below. Based on the experimental data collected by the student, determine the emf of the battery. B. 0.5 c. 1.0 D. 2.0 E. 3.0 |
12 |
| 803 | ( A 1^{circ} C ) rise in temperature is observed in a conductor by passing a certain current. If the current is doubled, then the rise in temperature is approximately ( mathbf{A} cdot 2.5^{circ} mathrm{C} ) B . ( 4^{circ} mathrm{C} ) ( mathrm{c} cdot 2^{circ} mathrm{C} ) D. ( 1^{circ} mathrm{C} ) |
12 |
| 804 | Electrical power ( P ) is given by expression : ( boldsymbol{V} times boldsymbol{x} . ) What is ( boldsymbol{x} ) ? A. Charge B. current c. Resistance D. None of these |
12 |
| 805 | Consider a long conductor, the middle of which is earthed. If the potential difference across the two ends of the conductor is ( 220 mathrm{V} ), then what is the potential at the ends and the middle point? A. ( 220 V ) all over the conductor B. ( 110 V ) and ( -110 V ) at ends and ( 0 V ) at the mid point C. ( 0 V ) at ends and ( 220 V ) at midpoint D. ( -220 mathrm{V} ) all over the conductor |
12 |
| 806 | In the 5 band color resistor,which color bands are considered as significant digits? A. First band only B. First three bands c. First two bands D. Last band |
12 |
| 807 | ( cdotleft[begin{array}{l}1 \ 1end{array}right]_{1}^{1}, quad ) ( a_{-1 / 1}^{11}[1]_{1} ) ( therefore sum_{i=1}^{infty} z_{k} ) |
12 |
| 808 | The mass of a wire of resistance 20 ohm is 50 gram. The resistance of the same wire of mass 10 gram is A . ( 4 Omega ) B. 5Omega ( c cdot 100 Omega ) D. 80Omega |
12 |
| 809 | In an experiment of Wheatstone bridge, if the positions of cells and galvanometer are interchanged, then the balance points will A. change B. remain unchanged c. depend on the internal resistance of the cell and resistance of the galvanometer D. none of these |
12 |
| 810 | Two wires of resistance ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2} ) at ( 0^{circ} C ) have temperature coefficient of resistance ( alpha_{1} ) and ( alpha_{2}, ) respectively. These are joined in series. The effective temperature coefficient of resistance is :- A ( cdot frac{alpha_{1}+alpha_{2}}{2} ) в. ( sqrt{alpha_{1} alpha_{2}} ) c. ( frac{alpha_{1} R_{1}+alpha_{2} R_{2}}{R_{1}+R_{2}} ) D. ( frac{sqrt{R_{2} R_{1} alpha_{1} alpha_{2}}}{sqrt{R_{1}^{2}+R_{2}^{2}}} ) |
12 |
| 811 | An electric iron is connected to a ( 200 V ) mains supply and draws a current of ( 4.0 A ) What is the power rating of the iron? ( mathbf{A} cdot 800 W ) в. ( 50 W ) c. ( 106 W ) D. ( 112 W ) |
12 |
| 812 | Which resistor is difficult to make of having a value less than about 2 Ohms? A. Iron Resistor B. Carbon Resistor c. Wire wound Resistor D. Both b and c |
12 |
| 813 | Q Type your question- and of fixed emf, the resistor ( boldsymbol{R}_{1} ) has fixed resistance and the resistance of resistor ( boldsymbol{R}_{2} ) can be varied (but ( boldsymbol{R}_{2} ) is always nonzero). Then the electric power delivered to the resistor of resistance ( R_{1} ) is independent of the value of resistance ( boldsymbol{R}_{2} ) Reason f potential difference across a fixed resistance is unchanged, the power delivered to the resistor remains constant. 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 |
| 814 | State whether true or false: Good conductors have excess of free electrons. A. True B. False |
12 |
| 815 | A student connects four cells, each of internal resistance ( frac{1}{4} Omega, ) in series. One of the cells is incorrectly connected because its terminals are reversed. The value of external resistance is ( 1 Omega . ) If the emf of each cell is 1.5 volt then current in the circuit will be A ( cdot frac{4}{3} A ) B. 0 c. ( frac{3}{4} ) D. ( 1.5 A ) |
12 |
| 816 | How many electrons flow through a wire, when 1 A current passes for a millisecond? |
12 |
| 817 | What is mean by drift velocity? current of 0.5 ampere flows in a wire of radius ( 0.5 m m . ) If the number of free electrons in the wire be ( 4 times 10^{28} ) per ( m^{3} ) calculate their drift velocity. |
12 |
| 818 | Six equal capacitors each of capacitance ( C ) are connected as shown in the figure. The equivalent capacitance between points ( A ) and ( B ) is : A ( .1 .5 mathrm{c} ) ( B ) ( c cdot 2 c ) D. ( 0.5 mathrm{c} ) |
12 |
| 819 | Two long straight cylindrical conductors with resistivities ( rho_{1} ) and ( rho_{2} ) respectively are joined together as shown in figure. If current I flows through the conductors, the magnitude of the total free charge at the interface of the two conductors is A . zero в. ( frac{left(rho_{1}-rho_{2}right) I varepsilon_{0}}{2} ) ( mathbf{c} cdot varepsilon_{0} Ileft|rho_{1}-rhoright| ) ( mathbf{D} cdot varepsilon_{0} Ileft|rho_{1}+rhoright| ) |
12 |
| 820 | Two resistors are connected a) in series b) in parallel. The equivalent resistance in two cases are 9 ohm and 2 ohm respectively. Then the resistance of the component resistors are. A. 2 ohm and 7 ohm B. 3 ohm and 6 ohm c. 3 ohm and 9 ohm D. 5 ohm and 4 ohm |
12 |
| 821 | Five conducting parallel plates having area ( A ) and separation between them ( d ) are placed as shown in the figure. Plate number 2 and 4 are connected with wire and between ( A ) and ( B, ) a cell of emf ( E ) is connected. Find the charge flown through the cell. |
12 |
| 822 | ( 1 m A= ) ( mathbf{A} cdot 1000 A ) B. ( 10^{-3} A ) ( mathbf{c} cdot 1 C s^{-1} ) D. None |
12 |
| 823 | The equivalent resistance between ( A ) and B is: A ( frac{8 R}{5} ) в. ( frac{5 R}{8} ) ( c cdot frac{3 R}{8} ) D. ( frac{7 R}{8} ) |
12 |
| 824 | In the circuit shown, the value of currents ( I_{1}, I_{2} ) and ( I_{3} ) are ‘ 3 A, ( frac{-3}{2} A, frac{9}{2} ), 3. ( frac{9}{2} A, 3 ) A, ( frac{-3}{2} ) A c. ( 5 A, 4 A,-3 ) f ( 7 A, frac{5}{4} A, frac{9}{2} A ) |
12 |
| 825 | The expression of electric power ( (boldsymbol{P})= ) A ( cdot I R^{2} ) в. ( V I ) c. ( I R ) D. ( V R^{2} ) |
12 |
| 826 | If a wire is stretched to make its length three times, its resistance will become A. Three times B. One-third c. Nine times D. One-ninth |
12 |
| 827 | In the shown arrangement of the experiment of the meter bridge if ( boldsymbol{A C} ) corresponding to null deflection of galvanometer is ( x, ) what would be its value if the radius of the wire ( A B ) is doubled? ( A ) B. ( x / 4 ) ( c cdot 4 x ) D. ( 2 x ) |
12 |
| 828 | For the circuit shown, with ( boldsymbol{R}_{1}= ) ( mathbf{1 . 0 Omega}, boldsymbol{R}_{mathbf{2}}=mathbf{2 . 0 Omega}, boldsymbol{E}_{mathbf{1}}=mathbf{2} boldsymbol{V} ) and ( boldsymbol{E}_{mathbf{2}}= ) ( E_{3}=4 V, ) the potential difference between the points ( ^{prime} a^{prime} ) and ( ^{prime} b^{prime} ) is approximately (in ( V ) ) ( A cdot 2.7 ) в. 3.3 ( c .2 . ) 3.3 .3 |
12 |
| 829 | Three ( 100 W, 150 V ) lamps are connected across ( 150 V ) line.Find voltage across each and power disseminate in 3 bulbs. |
12 |
| 830 | In general, the resistance to electric current of a material; in particular, the degree to which a material resists the flow of electricity is called A. conductivity B. resistivity c. conductance D. none of the above |
12 |
| 831 | Which pair is not correct for the instrument used in the laboratory and their uses from the following? Instrument uses To measure the electric ( begin{array}{ll}text { (A) } & text { Voltmeter }end{array} quad ) potential difference To measure the electric (B) ( quad ) Ammeter ( quad ) current To detect the presence (C) Galvanometer of current To supply the electric (D) ( quad ) Resistor ( quad ) energy to circuit ( A cdot A ) B. B ( c cdot c ) ( D cdot D ) |
12 |
| 832 | When two unknown resistances are placed in the gaps of meterbridge, the null point is found to be ( 40 mathrm{cm} ) from one end of the bridge wire. When one of the resistances is shunted with a 10 ohm coil, the null point is ( 25 mathrm{cm} ) from the same end. The value of each of the unknown resistances is ( mathbf{A} cdot 15 Omega, 10 Omega ) в. ( 10 Omega, 15 Omega ) ( mathbf{c} cdot 20 Omega, 30 Omega ) D. ( 30 Omega, 20 Omega ) |
12 |
| 833 | The power of the heater is ( 1000 W ) at ( 1000^{circ} mathrm{C} . ) What will be its power at ( 4000^{circ} mathrm{C} ? ) Given, temperature coefficient of resistance of heater-wire is ( 1.4 times ) ( 10^{-40} C^{-1} ) A ( .1 .42 times 10^{3} W ) в. ( 1.3 times 10^{3} mathrm{W} ) c. ( 9.68 times 10^{3} W ) D . ( 1.08 times 10^{3} W ) |
12 |
| 834 | Define mobility. Give its unit. | 12 |
| 835 | The product of resistivity and conductivity of a cylindrical conductor depends on A. Temperature B. Material c. Area of cross-section D. None of the above |
12 |
| 836 | What should be the characteristic of fuse wire? A. High melting point, high specific resistance B. Low melting point, low specific resistance C. High melting point, low specific resistance D. Low melting point, high specific resistance |
12 |
| 837 | Draw. Wheatstone’s bridge circuit and write the condition for its balance. | 12 |
| 838 | The length of potentiometer wire is ( 10 mathrm{m} ) and is connected in series with an accumulator. The e.m.f. of a cell balances against ( 250 mathrm{cm} ) length of wire. If the length of potentiometer wire is increased by ( 1 mathrm{m} ), calculate the new balancing length of wire. |
12 |
| 839 | Electromotive force of a cell is basically ( mathbf{a} ) ( A cdot ) force B. power c. work D. current capacity |
12 |
| 840 | A potentiometer wire of length ( 1 m ) has a resistance of ( 10 Omega ). It is connected to a ( 6 V ) battery in series with a resistance of 5. Determine the emf of the primary cell which gives a balance point at ( 40 mathrm{cm} ) |
12 |
| 841 | If the switch at point ( P ) is opened (shown in the figure) choose the correct option A. the current in ( R_{1} ) would not change B. the potential difference between point ( X ) and the ground would increas c. the current provided by the battery would increase D. the emf produced by the battery (assumed to have internal resistance) would change |
12 |
| 842 | The quantity of charge flowing per unit time is called A . capacitance. B. charge density. c. current D. potential difference |
12 |
| 843 | If the current through a resistor in a circuit increases by ( 3 %, ) the power dissipated by the resistor A. Increases approximately by 3%. B. Increases approximately by 6%. c. Increases approximately by ( 9 % ) D. Decreases approximately by 3% |
12 |
| 844 | A uniform wire of resistance ( 1 Omega m^{-1} ) is bent into a circle of radius 1 m. The same wire is connected across a diameter ( A B ) as shown in the figure. The effective resistance between ( A ) and ( boldsymbol{B} ) is: ( A ) B. ( frac{2 pi}{pi+2} Omega ) c. ( frac{pi+4}{2 pi} Omega ) D. ( frac{2 pi}{pi+4} Omega ) |
12 |
| 845 | The relation, between current density and drift velocity ( v_{d} ) is? A ( . j=n e v_{d} ) B. ( j=frac{n e}{v_{d}} ) C. ( j=frac{v_{d} e}{n} ) D. ( j=n e v_{d}^{2} ) |
12 |
| 846 | An electric iron is connected to the 230 V mains supply. A current of 8 A flows through the iron. How much energy is transferred to the heater each second? A . ( 1640 J ) B. 1840J c. ( 1750 J ) D. 980J |
12 |
| 847 | Effective capacitance between ( A ) and ( B ) in the figure shown is (all capacitances ( operatorname{are} operatorname{in} mu boldsymbol{F}) ) ( ^{A} cdot frac{3}{14} mu F ) в. ( frac{14}{3} mu F ) ( c cdot 21 mu F ) D. ( 23 mu F ) |
12 |
| 848 | An accumulator of emf 2 Volt and negligible internal resistance is connected across a uniform wire of length ( 10 mathrm{m} ) and resistance ( 30 Omega ). The appropriate terminals of a cell of emf ( 1.5 V o l t ) and internal resistance ( 1 Omega ) is connected to one end of the wire, and the other terminal of the cell is connected through a sensitive galvanometer to a slider on the wire. If the balancing change when the cell of 1.5 volt is shunted with a resistance of ( 5 Omega ) is ( frac{x}{4} m . ) Find ( x ) |
12 |
| 849 | Find the relation between drift velocity and relaxation time of charge carriers in a conductor. A conductor of length ( boldsymbol{L} ) is connected to a d.c. The source of emf ( E^{prime} . ) If the length of the conductor is tripled by stretching it, keeping ( ^{prime} boldsymbol{E}^{prime} ) constant, explain how its drift velocity would be affected. |
12 |
| 850 | In the circuit shown, the current in the 1 ( Omega ) resistor is ( mathbf{A} cdot 1.3 A, ) from ( P ) to ( Q ) B. ( 0 A ) c. ( 0.13 A ), from ( Q ) to ( P ) ( 0.13 A, ) from ( P ) to ( Q ) |
12 |
| 851 | The belt of an electrostatic generator is ( 50 mathrm{cm} ) wide and travels at ( 30 mathrm{cm} / mathrm{sec} ) The belt carries into the sphere at a rate corresponding to ( 10^{-4} ) ampere. What is the surface density of charge on the belt. A ( cdot 6.7 times 10^{-5} mathrm{Am}^{-2} ) В. ( 6.7 times 10^{-4} mathrm{Am}^{-2} ) c. ( 6.7 times 10^{-7} mathrm{Am}^{-2} ) D. ( 6.7 times 10^{-8} mathrm{Am}^{-2} ) |
12 |
| 852 | In a parallel circuit of bulbs, A. same current exists in all the bulbs B. voltage across each bulb remains the same C. failure of any bulb leads to a break in the circuit D. all the above |
12 |
| 853 | By increasing the temperature, the specific resistance of a conductor and a semiconductor. A. Increasing for both B. Decreases for both c. Increases, decreases D. Decreases, increases |
12 |
| 854 | e.m.f. is measured in A. Joules B. ( frac{text { Joules }}{text { coulomb }} ) c. Joule-coulombs D. coulomb |
12 |
| 855 | Write Kirchhoff’s first rule. A battery of ( mathbf{1 0} boldsymbol{V} ) and negligible internal resistance is connected to the diagonally opposite corners of a cubical network consisting of 12 resistors each of resistance ( 2 Omega ) Determine the equivalent resistance of the network. |
12 |
| 856 | In a balanced wheat stone bridge, current in the galvanometer is zero. It remains zero when ( [1] . ) battery emf is increased ( [2] . ) all resistances are increased by 10 ohms ( [3] . ) all resistances are made five times ( [4] . ) the battery and the galvanometer are interchanged A . only [1] is correct B. [1],[2] and [3] are correct c. [1],[3] and [4] are correct D. [1] and [3] are correct |
12 |
| 857 | For driving current of ( 2 A ) for 6 minute in a circuit. ( 1000 J ) of work is to be done. The e.m.f. of the source in the circuit is A . ( 1.38 V ) в. ( 1.68 V ) c. ( 2.03 V ) D. 3.10V |
12 |
| 858 | in a meter bridge, the balance point is found to be ( 40 mathrm{cm} ) from one end (say end A). if a resistance of ( 10 Omega ) is connected in series with ( R, ) a balance point is obtained ( 60 mathrm{cm} ) from end A. What are the values of ( R ) and ( S(S ) is other resistance in series with ( boldsymbol{R} ) )? |
12 |
| 859 | If current in a source of e.m.f. is in the direction of e.m.f., the energy of the source A. Increase B. Decrease c. Remains constant D. zero |
12 |
| 860 | The total current supplied to the circuit by the battery is ( mathbf{A} cdot 1 mathbf{A} ) B. 2 A ( c cdot 4 A ) ( D cdot 6 A ) |
12 |
| 861 | Kirchoff’s junction law is equivalent to A. Conservation of energy B. conservation of charge c. conservation of electric potential D. Conservation of electric flux |
12 |
| 862 | A cell of emf ( E ) is connected across a resistance ( R ). The potential difference across the terminals of the cell is ( V ) What is the internal resistance of the cell? A ( cdot E-frac{V}{R} ) в. ( frac{E-V}{V} ) c. ( frac{E-V}{R} times V ) D. ( frac{E-V}{V} times R ) |
12 |
| 863 | In the circuit shown in the figure the heat produced in the 5 ohm resistor due to the current flowing through it is 10 calories per second. The heat generated in the 4 ohm resistor is A. 1 calorie ( / )per B. 2 calorie/sec c. 3 calorie ( / )per D. 4 calorie / per |
12 |
| 864 | Figure below shows a portion of an electric circuit with the currents in amperes and their directions. The magnitude and direction of the current in the portion ( P Q ) is ( mathbf{A} cdot 0 A ) B. ( 3 A ) from ( P ) to ( Q ) c. ( 4 A ) from ( Q ) to ( P ) D. ( 6 A ) from ( Q ) to ( P ) |
12 |
| 865 | The electrical energy in kilowatt hours consumed in operating ten ( 50 ~ W ) bulbs for 10 hrs/day in a month of 30 days is A. 1500 B. 15000 c. 15 D. 150 |
12 |
| 866 | Three equal resistors are connected as shown in figure. the maximum power consumed by each resistor is 18 W. Then the maximum power consumed by the combination is : A. ( 18 W ) в. ( 27 W ) ( c .36 W ) D. ( 54 W ) |
12 |
| 867 | A battery of 20 cells (each having e.m.f. 1.8 volt and internal resistance 0.1 ohm is charged by 220 volts and the charging current is 15 A. The resistance to be put in the circuit is A . 10.27 ohms B. 12.27 ohms c. 8.62 ohms D. 16.24 ohms |
12 |
| 868 | In the circuit shown in the figure, ammeter and voltmeter are ideal. If ( E=4 V ) and ( R=15 Omega ) and ( r=1 Omega, ) then the reading of the ammeter is A ( cdot frac{1}{3} A ) ( B cdot frac{2}{3} A ) ( c cdot 1 A ) D. ( frac{1}{4} A ) |
12 |
| 869 | A battery of emf ( 15 mathrm{V} ) and internal resistance of ( 4 Omega ) is connected to a resistor. If the current in the circuit is 2 A and the circuit is closed. Resistance of the resistor and terminal voltage of the battery will be. A ( .2 .5 Omega, 6 vee ) B. ( 3.5 Omega, 6 v ) c. ( 2.5 Omega, 7 v ) D. ( 3.5 Omega, 7 vee ) |
12 |
| 870 | A heater coil operates at ( 1200 v ) when connected to a ( 240 W ) supply.The resistivity and area of across section of the coil are : A ( cdot A=frac{rho l}{7000} ) в. ( A=frac{rho l}{8000} ) c. ( _{A}=frac{rho l}{6000} ) D. ( _{A}=frac{rho l}{600} ) |
12 |
| 871 | In the adjoining diagram ( boldsymbol{R}_{1}= ) ( mathbf{1 0 Omega}, boldsymbol{R}_{2}=mathbf{2 0 Omega}, boldsymbol{R}_{3}=mathbf{4 0 Omega}, boldsymbol{R}_{4}=mathbf{8 0 Omega} ) and ( V_{A}=5 V, V_{B}=10 V, V_{C}= ) ( 20 V, V_{D}=15 V . ) The current in the resistance ( boldsymbol{R}_{1} ) will be A. 0.4 A towards 0 B. 0.4 A away from 0 ( c . ) 0.6 A towards 0 D. 0.6 A away from 0 |
12 |
| 872 | Which of the following does not belong to the group formed by the others? A. Iron B. Tin c. Glass D. stee |
12 |
| 873 | Two resistances of ( 400 Omega ) and ( 800 Omega ) are connected in series with a 6 volt battery of negligible internal resistance. A voltmeter of resistance ( 10,000 Omega ) is used to measure the potential difference across ( 400 Omega ). The error in the measurement of the potential difference in volts approximately is : A . 0.01 B. 0.02 ( c .0 .03 ) D. 0.05 |
12 |
| 874 | Two wires of the same material and length have radii in the ratio of 2: 3 Compare their resistance. |
12 |
| 875 | A wire of resistance ( 40 Omega ) is bent into a square. Then consider the following statements: a) resistance between opposite corners is ( 20 Omega ) b) resistance between adjucent corners is ( 7.5 Omega ) c) resistance between mid points of opposite sides is ( 10 Omega ) d) resistance between mid points of adjacent sides is ( 15 Omega ) A. a and dare correct B. b and d are correct C. ( b ) and ( c ) are correct D. a and b are correct |
12 |
| 876 | A resistance col of ( 60 Omega ) is immersed in ( 42 mathrm{kg} ) of water. What is the rise in temperature of water per minute if a steady current of ( 7 mathrm{A} ) is made to flow through the coli? A ( cdot 10.10^{circ} mathrm{C} ) B. 9.51 ( ^{circ} mathrm{C} ) ( mathbf{c} cdot 1.0^{circ} mathrm{C} ) D. ( 0.5^{circ} mathrm{C} ) |
12 |
| 877 | Which of the two meters, voltmeter or potentiometer, is preferred to measure the emf of a battery? Why? |
12 |
| 878 | Assertion Drift velocity of electrons is independent of time. Reason Electrons are accelerated in the presence of electric field. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
12 |
| 879 | A battery having an emf of 12 Volt and an internal resistance of ( 2 Omega ) is connected to another battery having an emf of 18 Volt and an internal resistance of ( 2 Omega ) in such a way that they are opposing each other and the circuit is closed. Calculate the following. 1. Current flowing in the circuit. 2. Electrical power in the two batteries. 3.Terminal voltage of the two batteries. 4. Electric power consumed in the batteries. |
12 |
| 880 | Our body can conduct electric current. A. True B. False |
12 |
| 881 | In the circuit shown, the heat produced in ( 5 Omega ) resistor is 10 calorie/sec. The heat produced/sec in ( 4 Omega ) resistor will be : A . 1 cal B . 2 cal ( c .3 ) cal D. 4 cal |
12 |
| 882 | ( boldsymbol{P}=boldsymbol{I}^{n} times boldsymbol{R}(text { where } mathrm{P}=text { Power, } mathrm{R}= ) Resistane, I= Current) The value of ( n ) A . B. – c. 1 D. |
12 |
| 883 | An electrical appliance is rated at 1000 KVA, 220V. If the appliance is operated for 2 hours, calculate the energy consumed by the appliance in: (i) kWh. (ii) joule. |
12 |
| 884 | The magnitude of electric field at different points along the length of the rod is given by A ( cdot frac{V_{o}}{L^{2}}(L-X) ) B. ( frac{V_{o}}{(L+X)} ) c. ( frac{V_{o}}{L} ) D. ( frac{V_{o}}{2 L} ) |
12 |
| 885 | When a resistance of 2 ohms is connected across the terminals of a cell,the current is 0.5 A. When the resistance is increased to 5 ohms,the current becomes 0.25 A. The e.m.f. of the cell is :- A . 1.0 B. 1.5 c. ( 2.0 v ) D. 2.5 |
12 |
| 886 | In the circuit shown here, the cell is ideal with emf of 2 volt. Then This question has multiple correct options A. no current flows in the galvanometer B. a current of ( 0.2 A ) flows through galvanometer c. potential difference across ( C_{1} ) is ( 1.2 V ) D. potential difference across ( C_{2} ) is ( 1.0 % ). |
12 |
| 887 | A material that lets electricity to pass through it is called a/an- A. Electrical appliances B. Electrical conductor c. Electrical insulator D. None of these |
12 |
| 888 | If the length of the filament of a heater is reduced by ( 25 % ), the power of the heater will A. increase by about ( 25 % ) B. increase by about ( 33 % ) c. decrease by about ( 25 % ) D. decrease by about ( 33 % ) |
12 |
| 889 | The wire used in the arrangement shown in the figure has a resistance of ( r Omega ) per metre. The equivalent resistance between points ( A ) and ( B ) is: ( ^{A} cdotleft(frac{6}{11}right)^{r} ) в. ( frac{2 pi r}{(pi+1)} ) c. ( frac{6 pi r}{(16+3 pi)} ) D. ( frac{3 pi r}{(10+3 pi)} ) |
12 |
| 890 | Calculate the current through the circuit and the potential difference across the diode shown in figure. The drift current for the diode is ( 20 mu A ) |
12 |
| 891 | For a heater rated at ( 4 k W ; 220 V ) Calculate the resistance of the heater element. A . ( 20 Omega ) B . ( 21.6 Omega ) c. ( 200 Omega ) D. ( 12.2 Omega ) |
12 |
| 892 | A solid spherical non-conductor of radius ( 5 mathrm{cm} ) has the potential of ( 50 mathrm{V} ) at its outer surface. The potential at its center is A .100 B. 75 v c. zero D. 50 v |
12 |
| 893 | At room temperature, ( 27^{circ} mathrm{C} ), the resistance of a heating element is 100 ( Omega ). What is the temperature(in ( ^{circ} C ) ) of the element if the resistance is found to be ( 117 Omega ) ? Given that the temperature coefficient of the material of the resistor is ( 1.70 times 10^{-4} C^{-1} ) |
12 |
| 894 | The device used to generate large amount of electricity is A . electric cell B. storage battery c. solar cell D. electric generator |
12 |
| 895 | In which of the following cells, the potential difference between the terminals of a cell exceeds its emf. (a) (b) (No current) ( (mathbf{d}) ) ( (c) ) ( A ) B. ( b ) ( c ) D. ( d ) |
12 |
| 896 | Sl unit of resistance is volt. A. True B. False |
12 |
| 897 | Sl unit of electric power is | 12 |
| 898 | Draw a labeled diagram of the experiment explaining Ohm’s law. | 12 |
| 899 | Draw a circuit diagram of an electric circuit containing a cell, a key, an ammeter, a resistor of ( 4 Omega ) in series with a combination of two resistors ( (8 Omega ) each ) in parallel and a voltmeter across parallel combination. Each of them dissipate maximum energy and canwithstand a maximum power of ( 16 W ) without melting. Find the maximum current that can flow through the three resistors. |
12 |
| 900 | A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor is /are A. current, electric current and drift velocity B. drift speed only c. current and drift speed only D. current only |
12 |
| 901 | A cell of emf ( boldsymbol{E} ) Volt with no internal resistance is connected to a wire whose cross section changes. The wire has three sections of equal length. The middle section has a radius ( a ), whereas the radius of the outer two sections is 2a. The ratio of the potential difference across section ( A B ) to the potential difference across section ( C A ) is : ( A ) B. 4 ( c cdot frac{1}{2} ) D. |
12 |
| 902 | In the given circuit diagram calculate the current ( I_{2} ) through the resistor of ( mathbf{1 0 Omega} ) |
12 |
| 903 | A silicon piece and a silver piece are connected in series and a potential difference is applied between their free ends. The potential difference applied on them are ( V_{1} ) and ( V_{2} ) respectively They are then cooled to ( 200 K . ) Now A ( cdot V_{1} ) increases and ( V_{2} ) decreases B. Both increase c. Both decrease D. ( V_{1} ) decreases and ( V_{2} ) increases |
12 |
| 904 | Draw labelled graphs to show how electrical resistance varies with temperature for: (a) A piece of carbon. |
12 |
| 905 | Which of the following quantities do not change when a resistor connected to a battery is heated due to the current? A . Resistance B. Resistivity c. Drift velocity D. Free electron density |
12 |
| 906 | A metallic conductor at ( 10^{circ} mathrm{C} ) connected in the left gap of Meter Bridge gives balancing length ( 40 mathrm{cm} . ) When the conductor is at ( 60^{circ} mathrm{C} ), the balance point shifts by ( 5 mathrm{cm} . ) The temperature coefficient of resistance of the material of the wire A . (1 / 210) / ( ^{circ} mathrm{C} ) B. (1 / 220) / ( ^{circ} mathrm{C} ) ( c cdot(1 / 200) /^{prime} c ) D. (1 / 201) / ( ^{circ} mathrm{C} ) |
12 |
| 907 | The analogous term to voltage. A. True B. False |
12 |
| 908 | Resistance of a wire at ( 20^{circ} C ) is ( 20 Omega ) and at ( 500^{circ} mathrm{C} ) is ( 60 Omega . ) At what temperature its resistance is ( 25 Omega ) ( mathbf{A} cdot 160^{circ} C ) B. ( 250^{circ} mathrm{C} ) ( mathbf{c} cdot 100^{circ} mathrm{C} ) D. ( 80^{circ} mathrm{C} ) |
12 |
| 909 | In the electric network shown in the figure, use Kirchhoff’s rules to calculate the power consumed by the resistance ( R=4 Omega ) |
12 |
| 910 | The number of electric lines of force that radiate outwards from ( 8.85 mu mathrm{C} ) of charges in a vacuum is: A ( cdot 10^{-6} ) – ( ^{-6}-10 ) B. ( 10^{-12} ) ( c cdot 10^{12} ) D. ( 10^{circ} ) |
12 |
| 911 | When two unknown resistors are connected in series with a battery, ( 225 W ) power is delivered to the combination with a total current ( 5 A ). For the same total current ( 50 W ) is delivered when the resistors are connected in parallel. Find the ratio of the two resistances ( A cdot 2 ) B. 5 ( c cdot 4 ) D. 10 |
12 |
| 912 | What is the alternative term used for metre bridge? |
12 |
| 913 | Which of the above is incosistent for the given meter bridge: ( begin{array}{lll}text { 1. } & 1000 Omega & text { 60 cm } \ text { 2. } & 100 Omega & text { 13 cm } \ text { 3. } & 10 Omega & 1.5 mathrm{cm} \ text { 4. } & 1 Omega & 1 mathrm{cm}end{array} ) ( A ) B. ( c ) ( D ) |
12 |
| 914 | Wires ( A ) and ( B ) have resistivities ( rho_{A} ) and ( boldsymbol{rho}_{B},left(rho_{B}=2 rho_{A}right) ) and have lengths ( l_{A} ) and ( l_{B} . ) If the diameter of the wire ( B ) is twice that of ( A ) and the two wires have same resistance, then ( frac{l_{B}}{l_{A}} ) is: ( A cdot 2 ) B. c. ( 1 / 2 ) D. ( 1 / 4 ) |
12 |
| 915 | A current ( I ) flows through a uniform wire of diameter ( d ) when the mean electron drift velocity is ( v . ) The same current will flow through a wire of diameter ( frac{d}{2} ) made of the same material if the mean drift velocity of the electron is A. ( frac{v}{4} ) в. ( frac{v}{2} ) ( c cdot 2 v ) D. ( 4 v ) |
12 |
| 916 | resistances are connected as shown in the figure. Initially resistance ( boldsymbol{P}=4 Omega ) and the neutral point ( N ) is at ( 60 c m ) from ( A . ) Now an unknown resistance ( boldsymbol{R} ) is connected in series to ( boldsymbol{P} ) and the new position of the neutral point is at ( 80 c m ) from ( A ). The value of unknown resistance ( boldsymbol{R} ) is : ( mathbf{A} cdot 6 Omega ) B. ( 7 Omega ) c. ( frac{33}{5} Omega ) D. ( frac{20}{3} Omega ) |
12 |
| 917 | Figure shows a potentiometer circuit for comparison of two resistances. The balance point with a standard resistor ( R=10.0 Omega ) is found to be ( 58.3 mathrm{cm}, ) while that with the unknown resistance ( X ) is ( 68.5 mathrm{cm} . ) Determine the value of ( mathrm{X} ). What might you do if you failed to find a balance point with the given cell of emf ( epsilon ? ) |
12 |
| 918 | As the temperature of a conductor increases, its resistivity and conductivity change. The ratio of resistivity to conductivity A. increases B. decreases c. remains constant D. may increase or decrease depending on the actual temperature |
12 |
| 919 | A steady current flow in a metallic conductor of non-uniform cross-section. The quantity/quantities remaining constant along the whole length of the conductor is/are: A. current, electric field and drift speedd B. drift speed only c. current and drift speed D. current only |
12 |
| 920 | If each capacitors has capacitance ( c ) in the given figure, then find ( C_{A B} ) ( A ) в. ( C / 2 ) ( 3 C / 2 ) 2. none of the abov |
12 |
| 921 | Assertion If the length of the conductor is doubled, the drift velocity will become half of the original value (keeping potential difference unchanged). Reason At constant potential difference, drift velocity is inversely proportional to the length of the conductor. 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 |
| 922 | Write the colour code for ( 4.7 ~ K Omega pm ) ( 10 % ) |
12 |
| 923 | Find the potentials of points ( A ) and ( B: ) A ( cdot V_{A}=+10 V ; V_{B}=0 V ) B . ( V_{A}=+7.5 V ; V_{B}=-2.5 V ) c. ( V_{A}=+2.5 V ; V_{B}=-7.5 V ) D. ( V_{A}=+0 V ; V_{B}=-10 V ) |
12 |
| 924 | A cell develops the same power across two resistance ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2} ) seprarately.The internal resistance of the cell is : A ( cdot R_{1}+R_{2} ) в. ( frac{R_{1}+R_{2}}{2} ) c. ( sqrt{R_{1} R_{2}} ) D. ( frac{sqrt{R_{1} R_{2}}}{2} ) |
12 |
| 925 | Two resistances are connected in two configurations- series or parallel. Which represents the parallel combination? ( A, A ) B. A and B both ( c . ) D. none of these |
12 |
| 926 | If the total electrical power consumed when they are both connected to this emf source in parallel is ( boldsymbol{X} boldsymbol{P}_{1}+boldsymbol{Y} boldsymbol{P}_{2} ) Find out the value of ( X+Y ) ? |
12 |
| 927 | The four wires from a larger circuit intersect at junction A a shown. What is the magnitude and direction of the current between points ( A ) and ( B ? ) A. 2 A from ( A ) to ( B ) B. 2 A from ( B ) to ( A ) C. 3 A from A to B D. 3 A from B to A |
12 |
| 928 | Three identical batteries each emf 4 V and zero of negligible internal resistance are connected as shown in figure below. The potential difference between the poilints ( A ) and ( Gleft(V_{A}-V_{G}right) ) A . 4 v B . ( -4 V ) ( c cdot 8 v ) ( mathbf{D} cdot-8 V ) |
12 |
| 929 | For the coil shown in the figure what must be done to induce a clockwise current? A. Either move the north pole of a magnet down into the coil, or move the south pole of the magnet up out of the coil B. Either move the south pole of a magnet down into the coil, or move the north pole of the magnet up out of the coil C. Move either pole of the magnet down into the coil D. Move either pole of the magnet up into the coil |
12 |
| 930 | What is the total resistance and current in the circuit? A. ( 2.5 Omega, 0.4 A ) B. ( 2 Omega, 1.6 A ) c. ( 2.5 Omega, 1.6 A ) D. ( 6 Omega, 1.6 A ) |
12 |
| 931 | In an electric iron heat produced is same, whether it is connected across an A.C. source or across 50 constant voltage. R.M.S, value of the A.C. voltage applied is A . ( 50 V ) B. Zero c. ( 50 sqrt{2} V ) D. ( frac{50}{sqrt{2}} V ) |
12 |
| 932 | An electric refrigerator rated ( 600 W ) operates 8 hours / day. What is the cost of the energy to operate it for 30 days at Rs.4.00 per k Wh? |
12 |
| 933 | Unit of electric power may also be expressed as: A. volt ampere B. kilowatt hour c. watt second D. joule secono |
12 |
| 934 | An electric bulb is designed to draw power ( P_{0} ) at voltage ( V_{0} . ) If the voltage is ( v, ) it draws a power ( P, ) then ( ^{A} cdot P=left(frac{V}{V_{0}}right) P_{0} ) в. ( P=left(frac{V_{0}}{V}right) P_{0} ) ( ^{mathrm{c}} P=left(frac{V_{0}}{V}right)^{2} P_{0} ) ( P=left(frac{V}{V_{0}}right)^{2} P_{0} ) |
12 |
| 935 | Wheatstones’s bridge cannot be used for measurement of very resistances. A . high B. low c. low(or) high D. zero |
12 |
| 936 | ( A, B, C ) and ( D ) are four coils of wires of 2,2 2 and 3 ohm resistances respectively and are arranged to form a Wheatstone bridge.The resistance which the coil ‘D’ must be shunted in order that the bridge may be balanced is: A . ( 4 Omega ) B. 6. ( c .3 Omega ) D. ( 8 Omega ) |
12 |
| 937 | A rectangular carbon block has dimensions ( 1.0 mathrm{cm} times 1.0 mathrm{cm} times 50 mathrm{cm} ) Resistance are measured first across two square ends and then across two rectangular ends, respectively. If resistivity carbon is ( 3.5 times 10^{-5} Omega m ) then value of measured resistances respectively are ( mathbf{A} cdot 17.5 times 10^{-2} Omega, 7 times 10^{-5} Omega ) B . ( 7 times 10^{-5} Omega, 7.5 times 10^{-2} Omega ) C. ( 17.5 times 10^{-4} Omega, 7 times 10^{-7} Omega ) D. ( 7.5 Omega, 7 times 10^{-2} Omega ) |
12 |
| 938 | Statement-1: The resistivity of a semiconductor decreases with increases of temperature Statement-2: In a conducting solid, the rate of collision between free electrons and ions increases with the increase of temperature A. Statement-1 is true and Statement-2 is correct explanation for Statement- B. Statement-1 is true and Statement-2 is NOT the correct explanation for Statement- c. Statement- 1 is true, Statement- 2 is false D. Statement-1 is false, Statement-2 is true |
12 |
| 939 | Find the equivalent resistance between ( A ) and ( E ) (The resistance of each resistor is ( R ).) ( A cdot frac{7}{12} F ) 3. ( frac{7}{13} ) f ( c cdot frac{7}{15} ) D. ( frac{8}{13} R ) |
12 |
| 940 | An electric bulb of resistance ( 480 Omega ) is connected to ( 220 V . ) Find electric energy consumed in ( 10 s ) A . ( 1000 J ) в. ( 9600 J ) c. 1008.35 D. ( 1118.7 J ) |
12 |
| 941 | Two resistances are connected in two gaps of a metre bridge. The balance point is ( 20 mathrm{cm} ) from the zero end. ( A ) resistance of ( 15 Omega ) is connected in series with the smaller of the two. The null point shifts to ( 40 mathrm{cm} . ) The value of the smaller resistance in ohms is. A . 3 B. 6 c. 9 D. 12 |
12 |
| 942 | In the circuits shown below the ammeter ( A ) reads ( 4 a m p ) and the voltmeter ( V ) reads 20 volts. The value of the resistance ( boldsymbol{R} ) is A. Slightly more than 5 ohms B. Slightly less than 5 ohms c. Exactly 5 ohms D. None of the above |
12 |
| 943 | Electricity is a form of A. Force B. Energy c. Tension D. Shock |
12 |
| 944 | A uniform but time varying magnetic field is present in a circular region of radius R. The magnetic field is perpendicular and into the plane of the loop and the magnetic of field is increasing at a constant rate ( alpha . ) There is a straight conducting rod of length ( 2 mathrm{R} ) placed as shown in figure. The magnitude of induced emf across the rod is This question has multiple correct options ( mathbf{A} cdot 60^{circ} ) B. ( 90^{circ} ) ( c cdot 30^{circ} ) D. ( 20^{circ} ) |
12 |
| 945 | A wire has a diameter of ( 0.2 m m ) and a length of ( 50 mathrm{cm} . ) The specific resistance of it’s material is ( 40 times 10^{-6} ) ohmcm. The current through it, when a potential difference of ( 2 V ) is applied across it, is ( mathbf{A} cdot 3 cdot 14 A ) B . ( 31.4 A ) c. ( 0.314 A ) D. ( 0.0314 A ) |
12 |
| 946 | The resistivity of a wire varies with A . length B. cross-section c. mass D. material |
12 |
| 947 | The potential difference across a ( 6 Omega ) resistor is ( 12 V . ) The current flowing in the resistor will be A ( .4 A ) B. 2A ( c cdot 0.5 A ) D. 1A |
12 |
| 948 | Metals have A. Zero resistivity B. High resistivity C . Low resistivity D. Infinite resistivity |
12 |
| 949 | A cell of e.m.f ( 3 V ) and internal resistance ( 4 Omega ) is connected to two resistance ( 10 Omega ) and ( 24 Omega ) joined in parallel. Find the current through each resistance using kirchhoff’s laws. |
12 |
| 950 | is the electrical energy produced or consumed per unit time. |
12 |
| 951 | The colour code of a resistor is brown, black and brown. Then the value of resistance is A . ( 10 Omega ) в. ( 100 m Omega ) c. ( 0.1 k Omega ) D. ( 100+5 % ) |
12 |
| 952 | In a Wheatstones’s bridge, three resistances ( P, Q ) and ( R ) are connected in the three arms and the fourth arm is informed by two resistances ( S_{1} ) and ( S_{2} ) connected in parallel. The condition for the bridge to be balanced will be ( ^{mathrm{A}} cdot frac{P}{Q}=frac{2 R}{S_{1}+S_{2}} ) B. ( frac{P}{Q}=frac{Rleft(S_{1}+S_{2}right)}{S_{1} S_{2}} ) c. ( frac{P}{bar{Q}}=frac{Rleft(S_{1}+S_{2}right)}{2 S_{1} S_{2}} ) D. ( frac{P}{Q}=frac{R}{S_{1}+S_{2}} ) |
12 |
| 953 | Sensitivity of potentiometer can be increased by A. increasing the e.m.f. of the cell. B. increasing the length of the potentiometer. c. decreasing the length of the potentiometer wire. D. none of these. |
12 |
| 954 | Which of the following represents Ohm’s Law? A. ( 1=Q . ) B. I = V.R ( c cdot 1=frac{R}{V} ) ( D cdot 1=frac{V}{R} ) |
12 |
| 955 | Three unequal resistance are connected in parallel. Two of these resistances are in the ratio ( 1: 2 . ) The equivalent resistance of these three connected in parallel is ( 1 Omega . ) What is the highest resistance value among these three resistances if no resistance is fractional? A . ( 10 Omega ) B. ( 8 Omega ) ( c .15 Omega ) D. ( 6 Omega ) |
12 |
| 956 | A uniform electric field ( overrightarrow{boldsymbol{E}} ) exists between 2 plates, a charged particle enters the space between the plates and perpendicular to ( vec{E} ). The path of the particle between the plates is a: A. straight line B. hyperbola c. parabola D. circle |
12 |
| 957 | Match the following | 12 |
| 958 | In the pictured circuit, If the reading of voltmeter 1 is ( 3.0 V ) the reading of ammeter 2 is ( 20 A ) and the reading of voltmeter 3 is ( 5.0 ~ V, ) what is the terminal voltage of the battery? ( mathbf{A} cdot 8.0 V ) B. ( 3.0 V ) c. ( 5.0 V ) D. ( 10.0 V ) E. Not enough is given to answer this questio |
12 |
| 959 | Four identical cells of emf ( boldsymbol{E} ) and internal resistance ( r ) are to be connected in series. Suppose if one of the cell is connected wrongly, the equivalent emf and effective internal resistance of the combination is ( mathbf{A} cdot 4 E ) and ( 4 r ) B. ( 4 E ) and ( 2 r ) ( mathbf{c} cdot 2 E ) and ( 4 r ) D. ( 2 E ) and ( 2 r ) |
12 |
| 960 | Two cells of equal emf and of internal resistances ( r_{1} ) and ( r_{2}left(r_{1}>r_{2}right) ) are connected in series. On connecting this combination to an external resistance ( mathrm{R}, ) it is observed that the potential difference across the first cell becomes zero. The value of R will be. ( mathbf{A} cdot r_{1}+r_{2} ) В. ( r_{1}-r_{2} ) c. ( frac{r_{1}+r_{2}}{2} ) D. ( frac{r_{1}-r_{2}}{2} ) |
12 |
| 961 | (a) In a metre bridge [Fig.], the balance point is found to be at ( 39.5 mathrm{cm} ) from the end ( A, ) when the resistor ( Y ) is of ( 12.5 Omega ) Determine the resistance of X. Why are the connections between resistors in a Wheat stone or meter bridge made of thick copper strips?(b) Determine the balance point of the bridge above if ( mathbf{X} ) and ( Y ) are interchanged.(c) What happens if the galvanometer and cell are interchanged at the balance point of the bridge? Would the galvanometer show any current? |
12 |
| 962 | In the circuit shown in figure, the ( 5 Omega ) resistance develops 20.00 cal/s due to the current flowing through it. The heat developed in ( 2 Omega ) resistance (in cal/s) is A. 23.8 B. 14.2 ( c cdot 11.9 ) D. 7. |
12 |
| 963 | A potentiometer is connected between and B and the balance point is obtained at ( 203.6 mathrm{cm} . ) When the end of the potentiometer connected to B is shifted to ( C, ) then the balance point is obtained at ( 24.6 mathrm{cm} . ) If now the potentiometer be connected between ( mathrm{B} ) and ( mathrm{C} ), the balance point will be at: A. ( 179.0 mathrm{cm} ) В. ( 197.2 mathrm{cm} ) c. ( 212.0 mathrm{cm} ) D. ( 228.0 mathrm{cm} ) |
12 |
| 964 | The infinity resistance plug in a postoffice box has A. an airgap only. B. a resistance coil of infinite resistance. c. largest resistance available in box. D. resistance of the coil 5000 ( Omega ) |
12 |
| 965 | The circuit below shows three identical resistors labeled ( 1,2, ) and ( 3 . ) The reading on the ammeter is 12.0 A. How much current flows in each resistors? A. 4.0 A в. 12.0 А c. 36.0 А D. we cannot determine the current values without knowing the resistor va E. we cannot determine the current values without knowing the batter |
12 |
| 966 | In an experiment of verification of Ohm’s law, following observations are obtained: Potential difference 0.5 ( begin{array}{lll}text { 1.0 } & text { 1.5 } & text { 2.0 }end{array} ) ( v ) (in volt’) Current in 0.2 ( 0.4 quad 0.6 ) ampere From observation table the resistance in circuit is A. ( 2.5 Omega ) в. ( 2 Omega ) ( c .5 Omega ) D. ( 3 Omega ) |
12 |
| 967 | A cell can be balanced against ( 110 mathrm{cm} ) and ( 100 mathrm{cm} ) of potentiometer wire respectively, with and without being short-circuited through a resistance of 10Omega. Its internal resistance is : A . ( 1.0 Omega ) B. ( 0.5 Omega ) c. ( 2.0 Omega ) D. zero |
12 |
| 968 | A cell of emf ( E ) and internal resistance ( r ) is connected across a resistance ( r ). The potential difference between the terminals of the cell must be A. ( E ) B. ( E / 2 ) c. ( E / 4 ) D. ( 3 E / 2 ) |
12 |
| 969 | A resistor of resistance ( R ) is connected to an ideal battery. If the value of ( boldsymbol{R} ) is decreased, the power dissipated in the resistor will A. Increase B. Decrease c. Remains unchanged D. None of these |
12 |
| 970 | Two point charges each of ( 1 C ) separated by 1 m distance experience a force of ( 5.6 times 10^{9} N ) in vacuum. How much force is experienced by them if they are immersed in water., keeping the distance of separation between them same? ( boldsymbol{K}=mathbf{8 0} ) for water. |
12 |
| 971 | By increasing the temperature the resistance of a conductor A. increases B. decreases c. remains constant D. initially increases then decreases |
12 |
| 972 | A battery of e.m.f. ( 3.0 mathrm{V} ) supplies current through a circuit in which the resistance can be changed. A high resistance voltmeter is connected across the battery. When the current is ( 1.5 mathrm{A}, ) the voltmeter reads ( 2.7 mathrm{V} ). The internal resistance of the battery is A . ( 4 Omega ) в. ( 1.2 Omega ) c. ( 0.2 Omega ) D. 2Omega |
12 |
| 973 | A cell balances against a length of ( 200 mathrm{cm} ) on a potentiometer wire, when it is shunted by a resistance of 8Omega. The balancing length reduces by ( 40 mathrm{cm} ) when it is shunted by a resistance of ( 4 Omega ) Calculate the balancing length when the cell is in open circuit. Also calculate the internal resistance of the cell. |
12 |
| 974 | Two cells of emf’s approximately ( 5 V ) and 10V are to be accurately compared using a potentiometer of length ( 400 mathrm{cm} ) A. The battery that runs the potentiometer should have voltage of ( 8 mathrm{V} ) B. The battery of potentiometer can have a voltage of ( 15 mathrm{V} ) and ( R ) adjusted so that the potential drop across the wire slightly exceeds ( 10 mathrm{V} ) C. The first portion of ( 50 mathrm{cm} ) of wire itself should have a potential drop of ( 10 mathrm{v} ) D. Potentiometer is usually used for comparing resistances and not voltages |
12 |
| 975 | Write Ohm’s law. Write name of devices ( X ) and ( Y ) in the given circuit related to Ohm’s Law. |
12 |
| 976 | The specific resistance of a rod of copper as compared to that of thin wire of copper is A. more B. less c. same D. depends upon the length and area of wire |
12 |
| 977 | A voltmeter of reading up to ( 1000 m V ) is calibrated by a potentiometer. An emf of ( 1.08 V ) is balanced across ( 5.4 m ) length of the wire. When voltmeter reading is ( 0.9 V, ) the balancing length is ( 4.55 m ) The error in the voltmeter reading is: A. -0.01mV B. 0.5 mv c. ( 0.25 mathrm{mv} ) D. No error |
12 |
| 978 | A wire of radius r and another wire of radius ( 2 r, ) both of same material and length are connected in series to each other. The combination is connected across a battery. The ratio of the heats produced in the two wires will be A . 4.00 B . 2.00 c. 0.50 D. 0.25 |
12 |
| 979 | For a metallic wire, the ratio of voltage to corresponding current is? A. Independent of temperature B. Increases with rise in temperature C. Increases or decreases with rise in temperature depending upon the metal D. Decreases with rise in temperature |
12 |
| 980 | If current ( boldsymbol{I}_{1}=mathbf{3} boldsymbol{A} sin omega boldsymbol{t} ) and ( boldsymbol{I}_{2}=boldsymbol{4} boldsymbol{A} ) ( cos omega t, ) then ( I_{3} ) is : A .5 Asin ( left(omega t+53^{circ}right) ) B. 5 Asin ( left(omega t+37^{circ}right) ) c. 5 Asin ( left(omega t+45^{circ}right) ) D. 5 Asin ( left(omega t+30^{0}right) ) |
12 |
| 981 | Which of the following are the properties of fuse wire? A. Made of alloy of tin B. Has a low melting point c. connected in series with main supply D. All of the above |
12 |
| 982 | Space between two concentric spheres of radii ( r_{1} ) and ( r_{2}, ) such that ( r_{1}<r_{2}, ) is filled with a material of resistivity ( rho ) Find the resistance between inner and outer surface of the material. A ( cdot frac{r_{1}}{r_{2}} frac{rho}{2} ) В. ( frac{r_{2}-r_{1}}{r_{r} r_{2}} frac{rho}{4 pi} ) c. ( frac{r_{1} r_{2}}{r_{2}-r_{1}} frac{rho}{4 pi} ) D. None of these |
12 |
| 983 | The resistances in left and right gap of a meter bridge are ( 20 Omega ) and ( 30 Omega ) respectively. When the resistance in the left gap is reduced to half its value, the balance point shifts by A. ( 15 mathrm{cm} ) to the right B. ( 15 mathrm{cm} ) to the left c. ( 20 mathrm{cm} ) to the right D. ( 20 mathrm{cm} ) to the left |
12 |
| 984 | Describe briefly with the help of a circuit diagram, how a potentiometer is used to determine the internal resistance of cell. |
12 |
| 985 | In the figure ( A B ) is a wire of length 100 ( mathrm{cm} ) whose resistance is ( 5 Omega ). If galvanometer reads zero, the current flowing in the wire AB is A . ( 0.1 mathrm{A} ) B. 0.5 ( c cdot 1 A ) D. ( 1.4 A ) |
12 |
| 986 | adjacent circuit. With the resistors ( P=50 Omega ) and ( Q=100 Omega, ) the null point is obtained at ( C ) where ( A C=33 mathrm{cm} ) When the resistors are interchanged, the null point is found at ( C ) with ( A C= ) ( 67 mathrm{cm} . ) The systematic error in this experiment seems to be due to non- coincidence of ( A ) and ( B ) with 0 cm mark and ( 100 mathrm{cm} ) mark respectively. If these and errors are equivalent to ( ^{prime} a^{prime} c m ) and ( b^{prime} c m ) respectively, then they are. A. 0 and 1 B. 1 and 0 c. 0.33 and 0.33 D. 1 and 1 |
12 |
| 987 | Resistance of a conductor of length ‘x’ is r’. If its area of cross-section is ‘a’, What is its resistivity? What is its unit? |
12 |
| 988 | ( mathbf{A} ) ( 2 Omega ) resistor is connected in series with ( R Omega ) resistor. This combination is connected across a cell. When the potential difference across ( 2 Omega ) resistor is balanced on potentiometer wire, null point is obtained at length of 300cm. When the same procedure is repeated for ( R Omega ) resistor, null point is obtained at length ( 350 mathrm{cm}, ) value of ( mathrm{R} ) is: A. 5 в. 3.33 c. 4.6 D. 2.83 |
12 |
| 989 | What does the slope of V-I graph for a conductor represent? A. Capacitance B. Power c. Inductance D. Resistance |
12 |
| 990 | At temperature ( 0 K, ) the germanium behaves as a/an A. conductor B. insulator c. super-conductor D. ferromagnetic |
12 |
| 991 | Four wires made of same material have different lengths and radii. The wire having more resistance in the following is A ( .1=100 mathrm{cm} mathrm{r}=1 mathrm{mm} ) B. ( 1=50 mathrm{cm} mathrm{r}=2 mathrm{mm} ) c. ( 1=100 mathrm{cm} mathrm{r}=1 / 2 mathrm{mm} ) D. ( 1=50 mathrm{cm} mathrm{r}=1 / 2 mathrm{mm} ) |
12 |
| 992 | A conductor carries a current of ( 50 mu A ) If the area of cross-section of the conductor is ( 50 mathrm{mm}^{2} ), then value of the current density in ( A m^{-2} ) is A . 0.5 B. ( c cdot 10^{-3} ) D. ( 10^{-6} ) |
12 |
| 993 | ( mathbf{A} ) ( 5 V ) battery of negligible internal resistance is connected across a ( 200 V ) battery and a resistance of ( 39 Omega ) as shown in the figure. Find the value of the current |
12 |
| 994 | A cell of emf 5 V can supply a total energy of ( 9000 mathrm{J}, ) then the total charge that can be obtained from the cell would be A . 180 B. 18000 c. 1800 D. 18 |
12 |
| 995 | It is desired to make a long cylindrical conductor whose temperature coefficient of resistivity at ( 20^{circ} C ) will be close to zero. If such a conductor is made by assembling alternate disks of iron and carbon, Find the ratio of the thickness of a carbon disk to that an iron disk. (For carbon, ( boldsymbol{rho}=mathbf{3 5 0 0} times ) ( 10^{-8} Omega m ) and ( alpha=-0.50 times 10^{-3}^{circ} C^{-1} ) for iron, ( rho=9.68 times 10^{-8} Omega ) and ( alpha= ) ( left.mathbf{6 . 5} times mathbf{1 0}^{-mathbf{3} circ} mathbf{C}^{-mathbf{1}}right) ) A . 0.36 B. 0.036 ( c .1 . ) D . 2.0 |
12 |
| 996 | A cell of emf ( e_{1} ) in the secondary circuit gives null deflection for ( 1.5 mathrm{m} ) length of potentiometer of wire length ( 10 mathrm{m} ). If another cell of emf ( e_{2} ) is connected in series with ( e_{1} ) then null deflection was obtained for ( 2.5 mathrm{m} ) length. Then ( mathrm{e}_{1}: mathrm{e}_{2} ) is: A . 3: 5 B. 5: 3 ( c cdot 3: 2 ) D. 2: 3 |
12 |
| 997 | Obtain an expression for e.m.f. induced in a coil rotating with uniform angular velocity in a uniform magnetic field. Show graphically the variation of e.m.f. with time ( (t) ) Resistance of a potentiometer wire is ( 0.1 Omega / c m . ) A cell of e.m.f. ( 1.5 V ) is balanced at ( 300 mathrm{cm} ) on this |
12 |
| 998 | In figure given below, find the value of resistance ( X ) for which points ( A ) and ( B ) are at the same potential: |
12 |
| 999 | In the circuit shown below This question has multiple correct options A. Current flowing in the circuit is ( 200 mathrm{mA} ) B. Power supplied by the battery is 2 watt c. Current from ( X ) to ( Y ) is zero D. Potential difference across ( 10 Omega ) is equal to zer |
12 |
| 1000 | Two bar magnets are placed on a piece of cork which floats on water. The magnets are so placed that their axis are mutually perpendicular. Then the cork A. rotates B. moves a side c. oscillates D. neither rotates nor oscillates |
12 |
| 1001 | Two resistors of ( 2 Omega ) and ( 4 Omega ) are connected in parallel. Two more resistors ( 3 Omega ) and ( 6 Omega ) are also connected in parallel. These two combinations are in series with a battery of emf ( 5 V ) and internal resistance ( 0.7 Omega . ) Calculate the current through ( 6 Omega ) resistor. |
12 |
| 1002 | A silver wire has temperature coefficient of resistivity ( 4 times 10^{-3} /^{circ} C ) and its resistance at ( 20^{circ} mathrm{C} ) is ( 10 Omega ) Neglecting any change in dimensions due to the change in temperature, its resistance at ( 40^{circ} mathrm{C} ) is? A . ( 0.8 Omega ) в. ( 1.8 Omega ) ( c .9 .2 Omega ) D. ( 10.8 Omega ) E . ( 11.6 Omega ) |
12 |
| 1003 | Shown in the figure below is a meter- bridge set up with null deflection in the galvanometer The value of the unknown resistor ( boldsymbol{R} ) is |
12 |
| 1004 | The resistance of wire is ( 20 Omega ). The wire is stretched to three time its length. Then the resistance will now be ( mathbf{A} cdot 6.67 Omega ) B. ( 60 Omega ) c. ( 120 Omega ) D. ( 180 Omega ) |
12 |
| 1005 | The effective resistance between the points ( X ) and ( Y ) in the given circuit is ( A cdot 8 / 3 Omega ) B. ( 8 Omega ) ( c .4 Omega ) D. ( 2 Omega ) |
12 |
| 1006 | The drift speed of the conduction electrons is: A. ( 2.5 mathrm{cm} / mathrm{s} ) B. ( 5 mathrm{cm} / mathrm{s} ) c. ( 7.5 mathrm{cm} / mathrm{s} ) D. ( 15 mathrm{cm} / mathrm{s} ) |
12 |
| 1007 | What is the current in the circuit shown (Figure) ( mathbf{A} cdot 1.5 A ) B. ( 0,5 A ) ( mathbf{c} .2 .5 A ) D. None of these |
12 |
| 1008 | At what temperature would the resistance of a copper conductor be double its resistance at ( 0^{circ} mathrm{C} ? ) Given ( alpha ) for copper is ( 3.9 times 10^{-3}^{circ} C^{-1} ) A ( cdot 256.4^{circ} mathrm{C} ) в. ( 512.8^{circ} mathrm{C} ) ( c cdot 100^{circ} mathrm{C} ) D. 256.4k |
12 |
| 1009 | toppr Q Type your question wires have same length, but thickness of wire ( mathrm{B} ) is twice that of wire ( mathrm{A} ). The conducting wires connecting ( A ) and ( B ) to the ideal cell are resistance less. The dependence of electric potential on position along the length of two wires is given in option. ( A ) B. ( c ) D. ( E ) |
12 |
| 1010 | A part of an electric circuit is shown in the figure below : Using Kirchhoff’s 2nd law, find the current ( I ) flowing through the ( 4 Omega ) resistor |
12 |
| 1011 | The specific resistance of a metal wire is ( 64 times 10^{-6} Omega times c m ., ) the length is 198 ( mathrm{cm} ) and the resistance is ( 7 Omega ). The radius of wire is :- A. ( 2.4 mathrm{cm} ) B. 0.24 cm c. ( 0.024 mathrm{cm} ) D. ( 24 mathrm{cm} ) |
12 |
| 1012 | While studying the dependence of potential difference (V) across a resistor on the current (I) Passing through it, in order to determine the resistance of the resistor, a student took 5 readings for different values of current and plotted a graph between and I. He got a straight line graph passing through the origin. What does the straight line signify? Write the method of determining resistance of the resistor using this graph. |
12 |
| 1013 | Three equal resistors connected in series across a source of e.m.f together dissipate 10W power. The power dissipated if the same resistors are connected in parallel across the same source of emf is A ( . ) 1) ( 10 w ) B. 2) 30w ( c cdot 3) ) 90w D. 4 cow |
12 |
| 1014 | If a resistance ( 5 Omega ) is connected in the left gap of a meter bridge and ( 15 Omega ) in the other gap then position of balancing point is ( A cdot 10 mathrm{cm} ) B. 20 cm c. ( 25 mathrm{cm} ) D. 75 cm |
12 |
| 1015 | A battery of emf ( 10 mathrm{v} ) and internal resistance of 0.5 ohms is connected across ( A ) variable resistance R.The maximum value of ( mathrm{R} ) is given by: A . ( 0.5 Omega ) B. ( 1.00 Omega ) c. ( 2.0 Omega ) D. ( 0.25 Omega ) |
12 |
| 1016 | A conductor of non uniform cross section is connected across a potentia difference ( V ) as shown in the figure, Choose the correct option regarding the |
12 |
| 1017 | A wire of resistance ( 20 Omega ) is bent to form a closed square. What is the resistance across a diagonal of the square. |
12 |
| 1018 | Four cells, each of emf ( E ) and internal resistance ( r, ) are connected in series across an external resistance ( boldsymbol{R} ). By mistake one of the cells is connected in reverse. Then the current in the external circuit is: A ( cdot frac{2 E}{4 r+R} ) в. ( frac{3 E}{4 r+R} ) c. ( frac{3 E}{3 r+R} ) D. ( frac{2 E}{3 r+R} ) |
12 |
| 1019 | Equivalent resistance between point ( mathbf{A} ) and ( mathrm{B} ) in the combination of resistance shown is ( mathbf{A} cdot 7 / 5 Omega ) B . ( 13 / 5 Omega ) c. ( 9 / 8 Omega ) D. ( 7 / 13 Omega ) |
12 |
| 1020 | A copper wire of ( 3 m m^{2} ) cross sectional area carries a current of 5 ampere. The magnitude of the drifty velocity for the electrons in the wire, (Assume copper to be monovalent, ( M_{C u}=63.5 k g / k ) mol and density of copper ( =mathbf{8 9 2 0} mathbf{k g} / mathbf{m}^{mathbf{3}} ) ). A. ( 0.24 mathrm{m} / mathrm{s} ) В. ( 0.12 mathrm{m} / mathrm{s} ) c. ( 2.4 mathrm{m} / mathrm{s} ) D. ( 0.06 mathrm{m} / mathrm{s} ) |
12 |
| 1021 | Two 220 volt, 100 watt bulbs are connected first in series and then in parallel. Each time the combination is connected to a 220 volt a.c.supply line. The power drawn by the combination in each case respectively will be A. 50 watt, 100 watt B. 100 watt, 50 watt c. 200 watt, ( , 150 ) watt D. 50 watt, 200 watt |
12 |
| 1022 | The temperature coefficient of resistance of conductor varies as ( boldsymbol{alpha}(boldsymbol{T})=boldsymbol{3} boldsymbol{T}^{2}+boldsymbol{2} boldsymbol{T} . ) If ( boldsymbol{R}_{0} ) is resistance at ( T=0 ) and ( R ) is resistance at ( T, ) then A ( . R=R_{0}(6 T+2) ) B . ( R=2 R_{0}(3+2 T) ) C ( . R=R_{0}left(1+T^{2}+T^{3}right) ) D. ( R=R_{0}left(1-T+T^{2}+T^{3}right) ) |
12 |
| 1023 | Define the term dielectric constant. Give its S.l.unit. |
12 |
| 1024 | The definition of resistance given by ( R=frac{V}{I} ) holds good for: A. conductors only B. Metals only c. Non-ohmic devices only D. All conducting devices, whetheror not they obey onm’s law |
12 |
| 1025 | The value of unknown resistance ( boldsymbol{X} ) will be A ( .402 .49 Omega ) 3. 403 . ( c cdot 404 Omega ) D. 210Omega |
12 |
| 1026 | State Kirchoff’s law for an electrical network. Using these laws deduce the condition for balance in a wheatstone bridge. Three resistors ( 2 Omega, 4 Omega ) and ( 5 Omega ) are combined in parallel. What is the total resistance of the combination? |
12 |
| 1027 | Veena’s car radio will run from a ( 12 vee ) car battery that produces a current of 0.20 A even when the car engine is turned off The car battery will not longer operate when it has lost ( 1.2 times 10^{6} J ) of energy. If Veena gets out of the car, leaving the radio on by mistake, how long will it take for the car battery to go completely dead, i.e., lose all energy? |
12 |
| 1028 | toppr Q Type your question OB are resistanceless and rotating with constant angular velocity ( omega ) in the same plane as that ring, about hinge point ‘0 and the separation between 0 and ( mathrm{C} ) (centre of ring) is’ ( 2 ell ) as shown in the figure. Find the current in the rod ‘OA’ when the both rod becomes tangent to the ring. A. Zero B. [ frac{B a V}{R} e frac{-3 t}{2 C R} ] ( c ) [ frac{B a V}{R} e frac{3 t}{2 C R} ] D. [ frac{B a V}{R} e frac{-4 t}{2 C R} ] E. None of the above |
12 |
| 1029 | In the circuit shown in figure heat developed across ( 2 Omega, 4 Omega ) and ( 3 Omega ) resistances are in the ratio of A .2: 4: 3 в. 8: 4: 12 ( c cdot 4: 8: 27 ) D. 8: 4: 27 |
12 |
| 1030 | Match the Column I with Column II. Column Column A nn II ( mathrm{O} mathrm{h}_{mathrm{m}} ) ( mathrm{i}_{mathrm{S}} ) ( mathrm{applin}_{mathrm{d}} ) Whe the the (A) ( (p) ) metals applicable to The (B) Ohm’s law is not applicable to ( (q) ) grr reer greater resistivity (C) alloys have ( quad ) (r) ( quad ) diodes, electrolytes, semiconductors ( A cdot A-r, B-q, C-p ) B. ( A-p, B-r, C-q ) C. ( A-r, B-p, C-q ) D. A-q, B-r, C-p |
12 |
| 1031 | Which of the two switches ( S_{1} ) and ( S_{2} ) shown in figure will produce short- circuiting? ( A cdot S_{1} ) B. ( S_{2} ) c. Both ( S_{1} ) and ( S_{2} ) D. Neither ( S_{1} ) nor ( S_{2} ) |
12 |
| 1032 | Brown,black and gold is the color band on the resistor,find its resistance? A ( cdot 10 times 10^{-2} Omega ) B. 1Omega c. ( 100 Omega ) D. ( 10 times 10^{0} Omega ) |
12 |
| 1033 | In a potentiometer experiment the balancing with a cell is at length 240 ( mathrm{cm} . ) On shunting the cell with a resistance of ( 2 Omega ) the balancing length becomes ( 120 mathrm{cm} . ) The internal resistance of the cell is? A . ( 1 Omega ) в. ( 0.5 Omega ) ( c .4 Omega ) D. ( 2 Omega ) |
12 |
| 1034 | A coil made of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is held stationary inside the coil? outside opposite |
12 |
| 1035 | A steady current is set up in a metallic wire of nonuniform cross-section How is the rate of flow of electrons (R) related the area of cross-section |
12 |
| 1036 | Assertion (A) :When the radius of a copper wire is doubled, its specific resistance increases Reason (R) :Specific resistance is independent of cross-section of material used A. Both A & R are true and R is the correct explanation of ( A ) B. Both A & R are true and R is not a correct explanation of c. A is true but R is false D. A is false but R is true |
12 |
| 1037 | The resistance across ( mathrm{M} ) and ( mathrm{N} ) in the given figure where each resistor shown if of ( r Omega ) is: ( A cdot frac{r}{2} ) B. ( frac{r}{3} ) ( c cdot 6 r ) D. 2r |
12 |
| 1038 | In a potentiometer experiment of a cell of emf ( 1.25 mathrm{V} ) gives balancing length of ( 30 mathrm{cm} . ) If the cell is replaced by another cell, balancing length is found to be 40 cm. What is the emf of second cell? ( mathbf{A} cdot simeq 1.57 V ) ( mathbf{B} cdot simeq 1.67 V ) ( mathbf{c} . simeq 1.47 V ) ( mathbf{D} cdot simeq 1.37 V ) |
12 |
| 1039 | A cell supplies a current of ( 0.9 mathrm{A} ) through a ( 2 Omega ) resistor and a current of ( 0.3 mathrm{A} ) through a ( 7 Omega ) resistor. The internal resistance of the cell is :- A . ( 1.0 Omega ) в. ( 0.5 Omega ) c. ( 2.0 Omega ) D. ( 1.2 Omega ) |
12 |
| 1040 | State the working principle of potentiometer explain with the help of circuit diagram. How the emf of two primary cells are compared by using the potentiometer | 12 |
| 1041 | Find the net capacitance between ( A ) and B in Fig: ( mathbf{A} cdot 5 / 2 mu F ) B . ( 2 / 5 mu F ) ( mathbf{c} cdot 9 / 22 mu F ) D. ( 22 / 9 mu F ) |
12 |
| 1042 | The insulator of electricity is : A. copper B. silk c. human body D. acidulated water |
12 |
| 1043 | Assertion Total current entering a circuit is equal to leaving the circuit by Kirchhoff’s law. Reason It is based on conservation of energy. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion. B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion. C. Assertion is correct but Reason is incorrect. D. Both Assertion and Reason are incorrect. |
12 |
| 1044 | Assertion A potentiometer having 10 wires is more accurate than the potentiometer having 1 wire Reason Potential gradient of 10 -wire potentiometer is much less 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 |
| 1045 | The resistance of the wire in the platinum resistance thermometer at ice point is ( 5 Omega ) and at steam point is 5.25 ( Omega ). When the thermometer is inserted in an unknown hot bath its resistance is found to be ( 5.5 Omega ). The temperature of the hot bath is? A ( cdot 100^{circ} mathrm{C} ) B . ( 200^{circ} mathrm{C} ) c. ( 300^{circ} mathrm{C} ) D. ( 350^{circ} mathrm{C} ) |
12 |
| 1046 | A conductor has a non-uniform section as shown in the figure. A steady current is flowing through it. Then the drift speed of the electrons: A. varies unpredictably B. increases from P to Q c. decreases from P to Q D. is constant throughout the wire |
12 |
| 1047 | Aluminium ( left(boldsymbol{alpha}=mathbf{4} times mathbf{1 0}^{-mathbf{3}} boldsymbol{K}^{-1}right) ) resistance of ( 60 Omega ) and carbon ( left(alpha=0.5 times 10^{-3} K^{-1}right) ) resistance ( 40 Omega ) are connected in parallel. The combination is heated. The effective resistance is A. Greater than ( 24 Omega ) B. Less than ( 24 Omega ) c. Greater than ( 40 Omega ) D. Greater than ( 100 Omega ) |
12 |
| 1048 | A rheostat is used in an electrical circuit A. to change the resistance of the circuit. B. to change the potential difference. c. to change the emf D. to change the current through a particular instrument |
12 |
| 1049 | Two wires of the same material but of different diameters carry the same current I. If the ratio of their diameters is ( 2: 1, ) then the corresponding ratio of their mean drift velocities will be ( A cdot 4: ) B. 1: 1 ( c cdot 1: 2 ) ( D cdot 1: 4 ) |
12 |
| 1050 | Appropriate material to be used in the construction of resistance boxes out of the following is A. copper B. iron c. manganin D. aluminium |
12 |
| 1051 | You are given n identical wires, each of resistance R When these are connected in parallel, the equivalent resistance is X. When these will be connected in series, then the equivalent resistance will be A ( cdot X / n^{2} ) в. ( n^{2} X ) ( c cdot x / n ) D. nx |
12 |
| 1052 | For a metallic wire, the ratio ( frac{V}{i} ) (where, ( mathbf{V}= ) applied potential difference and ( mathbf{i}= ) current flowing A. is independent of temperature B. increases as the temperature rises C. decreases as the temperature rises D. increases or decreases as temperature rises depending upon the metal. |
12 |
| 1053 | Which of the following methods does not help to minimize the error due to contact resistance in Wheatstone’s meter bridge experiment: A. The wire used must be uniform B. The wire used must be non-uniform c. Null point is obtained near the middle of the wire D. Interchange the positions of unknown resistance (X) and known resistance(R) |
12 |
| 1054 | Assertion: Material used in the construction of a standard resistance is constantan or manganin Reason : Temperature coefficients of constantan and Magnanin are very small A. Both (A) and (R) are true and (R) is the correct explanation of (A) B. Both (A) and (R) are true but (R) is not the correct explanation of ( (A) ) c. (A) is true but (R) is false D. (A) is false but (R) is true |
12 |
| 1055 | Four 2 ohm resistors are connected together along the edges of a square. A 10V battery of negligible internal resistance is connected across a pair of the diagonally opposite corners of the square. The power dissipated in the circuit is A. ( 100 mathrm{w} ) B. 50w ( c .25 w ) D. 20w |
12 |
| 1056 | A potentiometer has a driving cell of negligible internal resistance. The balancing length of a Daniel cell is ( 5 mathrm{m} ) If the driving cell had internal resistance, the balancing length of the same Daniel cell would have been A. More B. Less c. same D. Cannot be said from the data |
12 |
| 1057 | A metal wire of circular cross-section has a resistance ( boldsymbol{R}_{1} ). The wire is now stretched without breaking so that its length is doubled and density is assumed to remain same. If the resistance of the wire now becomes ( boldsymbol{R}_{2} ) then ( R_{2}: R_{1} ) is: A .1: B. 1: 2 ( c cdot 4: ) D. 1: 4 |
12 |
| 1058 | esistance is connected across a uniform wire of length ( 1 m ). The positive terminal of another battery of e.m.f. ( 4 V ) and internal resistance ( 1 Omega ) is joined to the point ( A ) as shown in the figure. The ammeter shows zero deflection when the jockey touches the wire at the point ( C ) The length AC is equal to ( A cdot 2 / 3 m ) ( 3.1 / 3 mathrm{m} ) ( c cdot 3 / 5 m ) 12 |
12 |
| 1059 | The current through the ( 8 Omega ) resistor is ( A cdot 4 A ) B. 2 A c. zero D. 2.5 A |
12 |
| 1060 | A meter bridge is set-up as shown, to determine an unknown resistance. ( boldsymbol{X} ) using a standard 10 ohm resistor. The galvanometer shows null point when tapping key is a ( 52 mathrm{cm} ) mark. The end- corrections are ( 1 mathrm{cm} ) and ( 2 mathrm{cm} ) respectively for the ends ( A ) and ( B ). The determined value of ( X ) is: ( mathbf{A} cdot 10.2 mathrm{ohm} ) B. 10.6 ohm c. 10.8 ohm D. 11.1 ohm |
12 |
| 1061 | A heater is designed to operate with a power of ( 1000 W ) on a line of ( 100 V ). It is connected in combination with resistance of ( 10 Omega ) and a resistance ( R ) to line of ( 100 mathrm{V} ). The value of ( mathrm{R} ) so the entire circuit operates with a power of ( mathbf{6 2 5} boldsymbol{W} ) is ( A cdot 5 Omega ) В. ( 10 Omega ) ( c .15 Omega ) D. 20Omega |
12 |
| 1062 | An ideal battery of ( 4 V ) and resistance ( R ) are connected in series in the primary circuit of a potentiometer of length ( 1 boldsymbol{m} ) and resistance ( 5 Omega . ) The value of ( R, ) to given a potential difference of ( 5 m V ) ( operatorname{across} 10 c m ) of potentiometer wire is: ( mathbf{A} cdot 490 Omega ) в. ( 480 Omega ) c. ( 395 Omega ) D. ( 495 Omega ) |
12 |
| 1063 | Find the value of ( n ) for carbon A . 0.15 в. 0.3 ( c .0 .9 ) D. 0.6 |
12 |
| 1064 | The value of ( I ) in the figure shown below is A . ( 19 A ) в. ( 21 A ) ( c .8 A ) ( D cdot 4 A ) |
12 |
| 1065 | A 50 V d.c power supply is used to charge a battery of eight lead accumulators, each of emf ( 2 mathrm{V} ) and internal resistance ( 1 / 8 Omega ). The charging current also runs a motor connected in series with the battery. The resistance of the motor is ( 5 Omega ) and the steady current supply is 4 A. The chemical power stored in the battery is ( A cdot 64 mathrm{W} ) B. 96 ( w ) ( c cdot 16 w ) D. 50 w |
12 |
| 1066 | The potential difference between the terminals of an electric heater is ( 220 mathrm{V} ) and the current is 5A. What is the resistance of the heater? A . 22 B. 11 ( c cdot 44 ) D. 1100 |
12 |
| 1067 | Match Column ( I ) with Column ( I I: ) | 12 |
| 1068 | The resistance ( R ) of a conductor varies with the temperature as shown in the figure. If it is written as ( boldsymbol{R}_{1}=boldsymbol{R}_{0}(mathbf{1}+ ) ( left.boldsymbol{alpha} boldsymbol{t}+boldsymbol{beta} boldsymbol{t}^{2}right) ) A ( cdot alpha ) and ( beta ) are both negative B. ( alpha ) is positive and ( beta ) is negative c. ( alpha ) and ( beta ) are both positive D. ( alpha ) is negative and ( beta ) positive |
12 |
| 1069 | Which of the following is true for electrical energy? ( mathbf{A} cdot E=P times t ) в. ( quad E=frac{P}{t} ) c. ( _{E}=frac{V^{2}}{R t} ) D. None of these |
12 |
| 1070 | Which part of the curve shown in fig represents the postitive resistane? This question has multiple correct options ( mathbf{A} cdot A B ) B. ( B C ) ( mathbf{c} cdot C D ) ( mathbf{D} cdot D E ) |
12 |
| 1071 | A wire has resistance of 3.1 at ( 30 C ) and resistance 4.5 at ( 100^{circ} C . ) The temperature coefficient of resistance of the wire is B. ( 0.0024^{circ} mathrm{C}^{-1} ) c. ( 0.0032^{circ} mathrm{C}^{-1} ) D. ( 0.0064^{circ} mathrm{C}^{-1} ) |
12 |
| 1072 | It is observed in a potentiometer experiment that no current passes through the galvanometer across when the terminals of a cell are connected across a certain length of the potentiometer wire. On shuting the cell by a ( 2 Omega ) resistance, the balancing length is reduced to half. The internal resistance of the cell is :- A . ( 4 Omega ) B. 2Omega c. ( 1 Omega ) D. 8Omega |
12 |
| 1073 | In the circuit shown, the readings of ammeter and voltmeter are ( 4 A ) and ( 20 V ) respectively. The meters are non ideal, then ( boldsymbol{R} ) is: ( A cdot 5 Omega ) B. greater than ( 5 Omega ) C. Less than ( 5 Omega ) D. between ( 4 Omega ) and ( 5 Omega ) |
12 |
| 1074 | Each capacitors has capacitance ( C ) in Fig. Find ( boldsymbol{C}_{boldsymbol{A} boldsymbol{B}} ) ( A ) B. 2 ( c cdot c / 2 ) D. 3C/2 |
12 |
| 1075 | State Ohm’s law. Suggest an experiment to verify it and explain the procedure. |
12 |
| 1076 | Assertion The kinetic energy of electrons in a metallic wire will increase, if the temperature of the wire is increased Reason On increasing temperature, conductivity of metallic wire decreases 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 |
| 1077 | Which of the follwing does not belong to the group formed by the others? A. Iron B. Tin c. Glass D. stee |
12 |
| 1078 | A single battery is connected to three resistances as shown in Figure. This question has multiple correct options A. The current through 7 ( Omega ) resistance is 4 A B. The current through ( 3 Omega ) resistance is 4 A c. The current through ( 6 Omega ) resistance is 2 A D. The current through ( 7 Omega ) resistance is 0 |
12 |
| 1079 | Ten identical batteries each of emf 2 V are connected in series to a ( 8 Omega ) resistor. If the current in the circuit is 2 A, then the internal resistance of each battery is A . ( 0.2 Omega ) В. ( 0.3 Omega ) ( c .0 .4 Omega ) D. ( 0.5 Omega ) E . ( 1 Omega ) |
12 |
| 1080 | The difference between the electrostatic potential of the positive end the negative end of an electric cell is the of the cell. |
12 |
| 1081 | In the given circuit, the value of current is A . 12 ampere B. 11 ampere c. 0.5 ampere D. zero |
12 |
| 1082 | Figure (a) and figure (b) both are showing the variation of resistivity ( (rho) ) with temperature (T) for some materials. Identify the type of these materials. A. Conductor and semiconductor B. Conductor and Insulator c. Insulator and semiconductor D. Both are conductors |
12 |
| 1083 | This graph is for A. Ohmic conductor B. Non-ohmic conductor C . Electrolytes D. Diodes |
12 |
| 1084 | Draw the diagram of induction coil and label the following: a. Primary coil b. Make and break arrangement. |
12 |
| 1085 | A battery of emf ( 10 mathrm{V} ) and internal resistance ( 3 mathrm{W} ) is connected to a resistor. If the current in the circuit is ( 0.5 mathrm{A}, ) what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed? |
12 |
| 1086 | Choose the correct option A. rubber rod becomes positive and fur becomes negative B. both rod becomes positive C. rubber rod becomes negative and fur becomes positive D. both becomes neutral |
12 |
| 1087 | When there is an electric current through a conducting wire along its length then an electric field must exist A. inside the wire but normal to it B. inside the wire but parallel to it it c. outside the wire but normal to it D. outside the wire but parallel to it |
12 |
| 1088 | Four concentric spherical shell is ( A, B, C ) AND ( D ) has radius ( a, 2 a, 3 a ) and ( 4 a ) shell ( B ) and ( D ) has charge ( +q ) and ( -q ) The shell ( ^{prime} C^{prime} ) is earthed. Find ( V_{A}-V_{C} ) A ( cdot frac{k q}{2 a} ) в. ( frac{k q}{3 a} ) ( c cdot frac{k q}{4 a} ) D. ( frac{k q}{6 a} ) |
12 |
| 1089 | The Kirchhoff’s first ( operatorname{law}left(sum i=0right) ) and second law ( left(sum i R=sum Eright), ) where the symbols have their usual meanings, are respectively based on A. conservation of charge, conservation of energy B. Conservation of charge, conservation of momentum c. conservation of energy, conservation of charge D. conservation of momentum, conservation of charge |
12 |
| 1090 | The charge flowing through a resistor ( boldsymbol{R} ) varies with time ( t ) as ( Q=3 t-6 t^{2} . ) The heat produced in ( boldsymbol{R} ) till the current in it becomes zero is A ( cdot frac{3 R}{4} ) в. ( frac{3 R}{2} ) c. ( frac{4 R}{2} ) D. ( frac{9 R}{2} ) |
12 |
| 1091 | ( boldsymbol{L} ) If length of potentiometer wire is ( frac{-}{2} ) and resistance is ( x ) then value of unknown emf ( boldsymbol{E} ) is: A ( cdot frac{2 E_{0} x ell}{r_{1}+x} ) B. ( frac{2 E_{0} x ell}{2 r_{1}+x} ) c. ( frac{4 E_{0} x ell}{2 r_{1}+x} ) D. ( frac{4 E_{0} x ell}{r_{1}+x} ) |
12 |
| 1092 | In the given circuit resistors ( A ) and ( B ) made of same metal are of the same length but A is thicker than B which of the two ammeters will show a higher reading? Justify your answer |
12 |
| 1093 | Find the emf and internal resistance of the equivalent cell between ( A ) and ( B ). put [ begin{array}{l} varepsilon_{1}=3 mathrm{V}, r_{1}=2 Omega varepsilon_{2}=2 V, r_{2}=1 Omega \ varepsilon_{3}=6 V, r_{3}=1 Omega end{array} ] |
12 |
| 1094 | The potentiometer wire 10 m long and 20 ohm resistance is connected to a 3 volt emf battery and a 10 ohm resistance. The value of potential gradient in volt( / boldsymbol{m} ) of the wire will be A . 1.0 B. 0.2 c. ( 0 . ) D. 0.02 |
12 |
| 1095 | Primary circuit of potentiometer is as shown in the diagram. Find potential drop across the wire AB. |
12 |
| 1096 | Write the principle on which the working of a metre bridge is based. In an experiment on meter bridge, student obtains the balance point at the point ( J ) such that ( A J=40 c m ), as shown in figure. The values of ( boldsymbol{R} ) and ( boldsymbol{X} ) are both doubled and then interchanged. Find the new position of the balance point. If the galvanometer and battery are also interchanged how will the position of balance point be affected |
12 |
| 1097 | A current is induced in a coil by electromagnetic induction. A. Only when coil moves in the magnetic field B. Only when a magnetic is moved into a coil C. Only when the coil and magnet move with respect to each other D. None of the above |
12 |
| 1098 | In the circuit shown in fig., all wires have equal resistance ( mathrm{R}(=5 Omega) ). The equivalent resistance between ( A ) and ( B ) : A ( cdot 10 / 7 Omega ) B. 15/4 ( Omega ) ( c .7 Omega ) D. 3 ( Omega ) |
12 |
| 1099 | ( frac{=}{frac{i}{L}} ) | 12 |
| 1100 | Find the terminal voltage across ( boldsymbol{E}_{1} ) and ( boldsymbol{E}_{2} ) in fig : A. ( 3.6 V, 7.8 V ) B. ( 2.4 V, 7.8 V ) c. ( 3.6 V, 10 V ) D. ( 2.4 V, 10.2 V ) |
12 |
| 1101 | The resultant of two resistances connected in parallel is 2 oh ( m ) and when connected in series, the resultant becomes 9 oh ( m ). The values of the resistance are: A. 7 ohm, 2 ohm B. 11ohm, 7ohm c. 4.5 and 8 ohm D. 3ohm, 6ohm |
12 |
| 1102 | Which of the following statements is/are correct for potentiometer circuit? A. Sensitivity doesn’t depend on the length of the potentiometer wire. B. Sensitivity is inversely proportional to potential difference applied across the potentiometer wire. C. Accuracy of potentiometer can be increased, only by increasing length of the wire. D. Range is independent of potential difference applied across the potentiometer wire. |
12 |
| 1103 | Each resistance shown in figure is ( 2 Omega ) The equivalent resistance between ( boldsymbol{A} ) and ( B ) is ( A cdot 2 S ) в. 4 ? ( c cdot 85 ) 0.1 |
12 |
| 1104 | The fixed resistance is called A. rheostat B. resistor ( c cdot k e y ) D. switch |
12 |
| 1105 | If the resistance of a conductor is ( 5 Omega ) at ( 50^{circ} mathrm{C} & 7 Omega ) at ( 100^{circ} mathrm{C}, ) then mean temperature coefficient of resistance (of material) is A ( cdot 0.013 /^{circ} mathrm{C} ) B. 0.004/ ( ^{circ} mathrm{C} ) c. ( 0.006 /^{circ} mathrm{C} ) D. ( 0.008 /^{circ} mathrm{C} ) |
12 |
| 1106 | ( sum_{k=1}^{k} ) | 12 |
| 1107 | The internal resistance of a primary cell is 4 Omega. It generates a current of ( 0.2 mathrm{A} ) in an external resistance of ( 21 Omega ). The rate of chemical energy consumed in providing the current is A ( cdot 0.42 mathrm{J} mathrm{s}^{-} 1 ) B. 0.84 J ( s^{-1} ) c. ( 1 J s^{-1} ) D. 5 J ( s^{-1} ) |
12 |
| 1108 | On increasing the resistance in a circuit, the current in it : A. decreases B. increases c. remains unchanged D. nothing can be said |
12 |
| 1109 | What do you understand by the internal resistance of a cell? The potential difference of a cell becomes ( 1.8 mathrm{V} ) when ( 0.5 A ) current is drown and when ( 1.0 A ) current is drawn, it becomes ( 1.6 mathrm{V} ). Find the internal resistance of the cell and its e.m.f. |
12 |
| 1110 | A bulb of ( 22 Omega ) is producing light when connected to ( 220 mathrm{V} ) supply. What is the electric power of the bulb. A. 2200 watt B. 1000 watt c. 22 watt D. 2 watt |
12 |
| 1111 | Twelve cells, each having an e.m.f of ( mathrm{E} ) volt are connected in series and are kept in a closed box. Some of these cells are wrongly connected with positive and negative terminals reversed. This 12 cell battery is connected in series with an ammeter, an external resistance ( mathrm{R} ) ohms and a two-cell battery (two cells of the same type used earlier, connected perfectly in series). The current in the circuit when the 12 -cell battery and 2 cell battery aid each other is ( 3 A ) and is 2A when they oppose each other. Then the number of cells in 12-cells battery that are connected wrongly is: A . 14 B. 3 ( c cdot 2 ) D. |
12 |
| 1112 | A current I is passing through a wire having two sections ( mathrm{P} ) and ( mathrm{Q} ) of uniform diameters d and ( d / 2 ) respectively if the mean drift velocity of electrons in section ( mathrm{P} ) and ( mathrm{Q} ) is denoted by and respectively then. |
12 |
| 1113 | What are the factors on which resistance of a conductor depends? |
12 |
| 1114 | Two wires of equal length, one of aluminium and the other of copper have the same resistance. Which of the two wires is lighter? Hence explain why aluminium wires are preferred for overhead power cables. ( left(rho_{A I}=2.63 timesright. ) ( 10^{-8} Omega m, rho_{C u}=1.72 times 10^{-8} Omega m ) Relative density of ( A I=2.7, ) of ( C u=8.9 . ) |
12 |
| 1115 | The resistance of the series comb of two resistance is S. When they are joined in parallel the total resistance is P. If ( mathrm{S}=mathrm{nP} ) then the minimum possible value of ( n ) is: ( A cdot 4 ) B. 3 ( c cdot 2 ) ( D ) |
12 |
| 1116 | Find power dissipated in ( 4 Omega ) resistor: ( A cdot 12 w ) B. 16 ( w ) ( c cdot 4 w ) ( 0.6 mathrm{w} ) |
12 |
| 1117 | What is the current in branch ( A B ) of the circuit shown? A . ( 1.5 A ) в. ( 2 A ) c. ( 1.33 A ) D |
12 |
| 1118 | In a potentiometer arrangement, a cell of emf ( 1.25 mathrm{V} ) gives a balance point at ( 35.0 mathrm{cm} ) length of the wire. If the cell is replaced by another cell and the balance point shifts to ( 63.0 mathrm{cm}, ) what is the emf of the second cell? |
12 |
| 1119 | Figure shows three circular arcs, each of radius ( mathrm{R} ) and total charge as indicated. The net electric potential at the centre of curvature is? A ( cdot frac{Q}{2 pi varepsilon_{R}} ) B・ ( frac{Q}{3 pi varepsilon_{R}} ) c. ( frac{2 Q}{pi_{c e R} R_{R}} ) D. ( frac{Q}{pi varepsilon R} ) |
12 |
| 1120 | Every atom makes one free electron in copper. If 1.1 ampere current is flowing in the wire of copper having ( 1 mathrm{mm} ) diameter, then the drift velocity (approx) will be (density of copper ( =9 times ) ( 10^{3} k g / m^{3} ) and atomic weight of copper ( =mathbf{6 3}) ) A. ( 0.1 m m / s ) B. ( 0.2 mathrm{mm} / mathrm{s} ) ( mathbf{c} cdot 0.3 m m / s ) D. ( 0.2 c m / s ) |
12 |
| 1121 | Q Type your question aissipatea is nignest? (Neglect the internal resistance of the power supply) ( A ) B. ( c ) ( D ) |
12 |
| 1122 | In the circuit shown in fig., the potential difference between the points ( C ) and ( D ) is balanced against ( 40 mathrm{cm} ) length of potentiometer wire of total length 100 ( mathrm{cm} . ) In order to balance the potential difference between the points D and ( E ) the jockey should be pressed on potentiometer wire at a distance of A . ( 16 mathrm{cm} ) B. 32 ( mathrm{cm} ) ( c .56 mathrm{cm} ) D. ( 80 mathrm{cm} ) |
12 |
| 1123 | Current passing through a coil of resistance R decreases uniformly as shown in the figure. If total amount of charge q is passing through the coil during a time interval ( t_{0} ) then what will be the total amount of heat generated through it? A ( cdot frac{3}{4} frac{q^{2} R}{t_{0}} ) в. ( frac{4}{3} frac{q^{2} R}{t_{0}} ) c. ( frac{q^{2}}{t_{R}} ) D. ( frac{q^{2} R^{2}}{t^{2}} ) |
12 |
| 1124 | Electric current arises from the flow of charged particles. Now This question has multiple correct options A. In metals it is dominant due to flow of electrons B. In semiconductors it is jointly due to flow of holes and electrons C. In electrolytes it is due to flow of negative ions only D. In discharge tubes containing gases at low pressure it is due to flow of positive ions only |
12 |
| 1125 | Resistance ( R, 2 R, 3 R ldots N R ) if, ( N R ldots ) are connected in parallel. Their resultant resistance will be A. B. R/2 ( c cdot 0 ) D. ( infty ) |
12 |
| 1126 | Calculate total resistance, total current and p.d across ( 7 Omega ) resistor |
12 |
| 1127 | 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 |
12 |
| 1128 | Four resistances of each 20 ohm are connected to form a square ( boldsymbol{A}, boldsymbol{B}, boldsymbol{C}, boldsymbol{D} ) The resultant resistance between the corners ( A C ) and the resistance between ( A B ) are: A ( .40 Omega, 15 Omega ) B. ( 15 Omega, 40 Omega ) c. ( 15 Omega, 20 Omega ) D. ( 20 Omega, 15 Omega ) |
12 |
| 1129 | A common device which can supply small electric current continuously for a sufficient time |
12 |
| 1130 | The resistance between ( A ) and ( B ) is A ( cdot frac{288}{56} Omega ) В. ( 12 Omega ) ( c cdot frac{8}{3} Omega ) D. ( frac{9}{4} Omega ) |
12 |
| 1131 | n the circuit shown in the figure, the ammeter reading is: ( A cdot 0.8 A ) B. 1.2 A ( c cdot 2 A ) D. ( 0.4 mathrm{A} ) |
12 |
| 1132 | The resistance can be increased by : A. decreasing the area B. decreasing the length c. either (A) or (B) D. none of these |
12 |
| 1133 | Name the principle on which metre bridge is based. | 12 |
| 1134 | If a copper wire is stretched to make it ( 0.1 % ) longer, the ( % ) change in the resistance is A . 0.3% B. 0.2% c. 0.1% D . 0.02% |
12 |
| 1135 | When a current of ( 2 mathrm{A} ) flows in a battery from negative to positive terminal, the potential difference across it is 12 V. If a current of 3 A flowing in the opposite direction produces a potential difference of ( 15 V ), the emf of the battery is? A . ( 54 v ) B. ( 13.2 mathrm{V} ) c. ( 65 v ) D. ( 50 v ) |
12 |
| 1136 | Calculate the electric current in the circuit shown. A ( .1 .5 A ) в. ( 0.5 A ) ( c .2 .5 A ) 0.2 |
12 |
| 1137 | toppr Q Type your question the following: 4 B. ( c ) ( D ) |
12 |
| 1138 | Find out the total current flowing in the circuit as shown in above figure? ( A cdot 4 A ) B. 3A c. ( 2 A ) D. ( frac{4}{3} ) ( E ) |
12 |
| 1139 | Resistance of a electric heater is ( 20 Omega ) and it draws a current of 2A. Calculate its power. A. 0 (zero) ( w ) B. 20w c. ( 40 mathrm{w} ) D. 80w |
12 |
| 1140 | Each of the resistance in the network shown in figure is equal to R. The resistance between the terminals ( A ) and B is ( A cdot R ) B. 5R ( c . ) 3R ( D cdot 6 r ) |
12 |
| 1141 | The internal resistance of a primary cell is 4 ohm. It generates a current of 0.2 ampere in an external resistance of 2 ohm. The rate at which chemical energy is consumed in providing the current is A ( .0 .42 mathrm{J} / mathrm{s} ) B. 0.24 J/ ( c cdot 5 J / s ) ( D cdot 1 J / s ) |
12 |
| 1142 | Stopping Potential is: | 12 |
| 1143 | A steady current is set up in a metallic wire of non-uniform cross section. Then the drift velocity is related to the area of ( operatorname{cross} operatorname{section}(A) ) as: A. ( V_{d} propto A^{-1} ) B. ( V_{d} propto A ) ( mathbf{C} cdot V_{d} propto A^{2} ) D. ( V_{d} ) is independent of ( A ) |
12 |
| 1144 | The following table gives the current ( i ) through two devices for several values of potential difference ( V ) of Device 1 Device ( 2(text { SI Units }) ) ( begin{array}{llll}text { Device } & text { Device } & text { Device } & text { Device } \ 1 & 1 & 2 & 2 \ V & I & V & I \ 2 & 4.5 & 2 & 1.5 \ 3 & 6.75 & 3 & 2.2 \ 4 & 9 & 4 & 2.8end{array} ) A. Device 1 is ohmic, device 2 is non ohmic B. Device 1 is non ohmic, device 2 is ohmic c. Both are non ohmic. D. Both are ohmic |
12 |
| 1145 | State Kirchhoff’s laws of electrical circuits with the help of suitable circuit diagram. Write formula of zero deflection of Wheatstone bridge. |
12 |
| 1146 | In which direction does current flow in an electric circuit ? Also, write the SI unit of electric current. |
12 |
| 1147 | A circuit is shown below.lf ( A ) is an ideal ammeter, B an ideal Battery of voltae ( V ) and ( C ) an ideal voltmeter, what will be reading of the ( frac{text { eading of } boldsymbol{A}}{text { reading }} ) ? ( A ) в. 2 R ( c cdot frac{R}{2} ) ( D ) |
12 |
| 1148 | quantıties for the pictured circult. What is the current flowing through the resistor ( 3 ? ) Battery Terminal Voltage ( quad 16.0 mathrm{v} ) Voltmeter 1 Reading Ammeter 1 Reading Ammeter 2 Reading ( 7.0 mathrm{A} ) ( A cdot 8.0 A ) B. 13.0 A ( c cdot 7.0 A ) D. 16.0 A E. 6.0 |
12 |
| 1149 | For a cell terminal potential difference is ( 2.2 mathrm{V} ) when circuit is open and reduces to ( 1.8 mathrm{V} ) when cell is connected to a resistance of ( boldsymbol{R}=mathbf{5} Omega ) then determine internal resistance of cell is :- A ( cdot frac{10}{9} Omega ) в. ( frac{9}{10} Omega ) c. ( frac{11}{9} Omega ) D. ( frac{5}{9} Omega ) |
12 |
| 1150 | A storage battery has e.m.f. 15 volt and internal resistance 0.05 ohm. Its terminal voltage when it is delivering 10 ampere is: A. 30 volt B. 1.00 volt c. 14.5 volt D. 15.5 volt |
12 |
| 1151 | The resistance of a wire of length 100 ( mathrm{cm} ) and ( 7 times 10^{-3} mathrm{cm} ) radius is 6 ohm. Its specific resistance is ( mathbf{A} cdot 924 times 10^{-8} Omega c m ) В. ( 92.4 times 10^{-8} Omega c m ) c. ( 900 times 10^{-8} Omega c m ) D. ( 224 times 10^{-8} Omega c m ) |
12 |
| 1152 | Three identical bulbs are connected in parallel with a battery. The current drawn from the battery is ( 6 A ). If one of the bulbs gets fused, what will be the total current drawn from the battery? ( mathbf{A} cdot 6 A ) в. ( 2 A ) ( c .4 A ) D. ( 8 A ) |
12 |
| 1153 | Which of the following best describe the current? A. the rate of flow of charged particles through a conducting medium B. only present when there is no voltage C. the flow of a conductor through charged particles D. faster than the speed of light E. the random movement of electrons from atom to atom |
12 |
| 1154 | A copper wire of resistance ( R ) is cut in to ten parts of equal length. Two pieces each are joined in series and then five such combinations are joined in parallel. The new combination will have a resistance A. ( R ) в. ( frac{R}{4} ) c. ( frac{R}{5} ) D. ( frac{R}{25} ) |
12 |
| 1155 | The figure shows a meter bridge with null deflection in the galvanometer. The value of unknown resistance R is? ( mathbf{A} cdot 158 Omega ) B . ( 151.67 Omega ) c. ( 128.65 Omega ) D. ( 130 Omega ) |
12 |
| 1156 | S.I. unit of electric current is: A. ampere B. volt c. farad D. coulomb |
12 |
| 1157 | A current flows in a wire of circular cross section with the free electrons travelling with drift velocity ( bar{V} ). If an equal current flows in a wire of same material and twice the radius, the new drift velocity is: ( mathbf{A} cdot bar{V} ) B. ( frac{vec{v}}{2} ) c. ( frac{vec{v}}{4} ) D. 2 ( bar{V} ) |
12 |
| 1158 | A wire of resistance ( 10.0 Omega ) is stretched and increases its length by ( 20 % ). Its resistance then would be: ( neglect any change in volume or resistivity A . ( 10.0 Omega ) B. ( 12.0 Omega ) c. ( 14.4 Omega ) D. ( 10.2 Omega ) |
12 |
| 1159 | toppr Q Type your question salvaluilicio ” 2 and a variable voltage source V. The correct circuit to carry out the experiment is ( A ) B. ( c ) ( D ) |
12 |
| 1160 | At a constant voltage the heat developed in a uniform wire varies inversely as the length of the wire used. |
12 |
| 1161 | For ohmic conductor the drift velocity ( boldsymbol{v}_{boldsymbol{d}} ) and the electric field applied across it are related as : ( mathbf{A} cdot v_{d} propto sqrt{E} ) B ( cdot v_{d} propto E^{2} ) c. ( v_{d} propto E ) D. ( v_{d} propto frac{1}{E} ) |
12 |
| 1162 | Specific resistance of all metals is mostly affected by A. volume B. pressure c. temperature D. magnetic field |
12 |
| 1163 | State Ohm’s Law using a suitable experiment,explain the terms involved and draw its graphical representation. | 12 |
| 1164 | Derive the relation between the resistances of the arms of a Wheatstone bridge in its balance condition. Write its two applications. |
12 |
| 1165 | Find the radius of the wire of length ( 25 m ) needed to prepare a coil of resistence ( 25 Omega ) (Resistivity of material of wire is ( left.3.142 times 10^{-7} Omega mright) ) |
12 |
| 1166 | Carbon resistors are of two types: A. composition type resistor and film type resistor B. rheostat and film type resistor C. rheostat and variable resistor D. composition type resistor and rheostat |
12 |
| 1167 | An infinite non-conducting sheet of charge has a surface charge density of ( 10^{-7} C / m^{2} . ) The separation between two equipotential surfaces near the sheet whose potential difference by ( 5 V ) is A ( .0 .88 mathrm{cm} ) В. ( 08.8 m m ) c. ( 0.88 m ) D. ( 5 times 10^{-7} m ) |
12 |
| 1168 | The emf of the battery in a thermocouple is doubled. The rate of heat generation at one of the junctions will A. remains unchanged B. becomes half c. becomes double D. becomes four times |
12 |
| 1169 | Which of the following theories could not explain completely the behaviour of conductors, insulators, and semiconductors. A. energy band theory B. free electron theory c. valence electron theory D. None |
12 |
| 1170 | Find the current flows through a copper wire of length ( 0.2 mathrm{m}, ) area of crosssection ( 1 m m^{2}, ) when connected to a battery of ( 4 mathrm{V} ). Given that electron mobility is ( 4.5 times 10^{-6} m^{2} s^{-1} ) and charge on an electron is ( 1.6 times 10^{-19} C ) The number density of electron in copper wire is ( 8.5 times 10^{2} 8 m^{3} ) |
12 |
| 1171 | Current ( ^{prime} i^{prime} ) coming from the battery and ammeter reading are A ( cdot frac{3}{8} A, frac{1}{8} A ) в. ( frac{1}{8} A, frac{1}{8} A ) c. ( 2 A, frac{2}{3} ) ‘ ( 2 A, frac{1}{8} ) |
12 |
| 1172 | What is the non linear ( V-I ) relation in a pn Junction in forward bias? A. ( I=I_{s} e^{V / V_{T}} ) В . ( I=I_{s}left(e^{V / V_{T}}-1right) ) C ( . I=I_{s}left(1-e^{V / V_{T}}right) ) ( D ) |
12 |
| 1173 | A galvanometer (coil resistance ( 99 Omega) ) is converted into a ammeter using a shunt of ( 1 Omega ) and connected as shown in the figure ( ( i ) ). The ammeter reads ( 3 A ) The same galvanometer is converted into a voltmeter by connecting a resistance of ( 101 Omega ) in series. This voltmeter is connected as shown in figure ( ( i i ) ). Its reading is found to be ( 4 / 5 ) of the full scale reading. Find the internal resistance ( r ) of the cell (in ohms) |
12 |
| 1174 | A current ( i ) is flowing through the wire of diameter ( d ) having drift velocity of electrons ( v_{d} ) in it. What will be new drift velocity when diameter of wire is made ( frac{boldsymbol{d}}{boldsymbol{4}} ) ( mathbf{A} cdot 4 V_{d} ) в. ( frac{V_{d}}{4} ) ( mathbf{c} cdot 16 V_{d} ) D. ( frac{V_{d}}{16} ) |
12 |
| 1175 | mass m carrying charge ( q . ) The bead freely move on the smooth fixed ring placed on a smooth horizontal plane. In the same plane a charge ( +Q ) has also been fixed as shown. The potential at the point ( boldsymbol{P} ) due to ( +boldsymbol{Q} ) is ( boldsymbol{V} ). The velocity with which the bead should projected from the point ( P ) so that is can complete a circle should be greater than A ( cdot sqrt{frac{6 q V}{m}} ) B. ( 4 sqrt{frac{q V}{m}} ) c. ( sqrt{frac{3 q V}{m}} ) D. ( sqrt{frac{7 q V}{2 m}} ) |
12 |
| 1176 | What is the S.I. unit of electrical power? A. watts B. joules c. volts D. ampere |
12 |
| 1177 | A resistance of ( 2 Omega ) is connected across one gap of a metrebridge ( the length of the wire is ( 100 mathrm{cm} ) ) and an unknown resistance, greater than ( 2 Omega, ) is connected across the other gap. When these resistance’s are interchanged, the balance point shifts by ( 20 mathrm{cm} ) Neglecting any corrections, the unknown resistance is: A . ( 3 Omega ) B. ( 4 Omega ) ( c .5 Omega ) D. ( 6 Omega ) |
12 |
| 1178 | Copper and Germanium are cooled from room temperature to ( 100 K . ) Then the resistance of A. Germanium decreases, Copper increases B. Germanium decreases, Copper decreases c. Germanium increases, Copper decreases D. Germanium increases, Copper increases |
12 |
| 1179 | ( n^{prime} ) cells, each of emf ( ^{prime} e^{prime} ) and internal resistance ‘ ( r^{prime} ) are joined in series to form a row.’ ( m^{prime} ) such rows are connected in parallel to form a battery of ( boldsymbol{N}=boldsymbol{m} boldsymbol{n} ) cells. This battery is connected to an external resistance ( ^{prime} boldsymbol{R}^{prime} ) What is the emf of this battery and how much is its internal resistance? |
12 |
| 1180 | Six resistors of each 2 ohm are connected as shown in the figure. The resultant resistance between ( A ) and ( B ) is. ( mathbf{A} cdot 4 Omega ) B. ( 2 Omega ) ( c cdot 1 Omega ) D. ( 10 Omega ) |
12 |
| 1181 | What is called the rate of doing work in an electric circuit? A. Power B. Energy c. current D. voltage |
12 |
| 1182 | Kirchhoff’s law of junction, ( sum I=0 ), is based on A. Conservation of energy B. conservation of charge c. conservation of energy as well as charge D. conservation of momentum |
12 |
| 1183 | ( frac{k}{L} ) | 12 |
| 1184 | Twenty four cells each of emf ( 1.5 mathrm{V} ) and internal resistance 0.5 ohms are to be connected to a 3 ohm resistance. For maximum current through this resistance the number of rows and number of columns that you connect these cells is? A. 12 cells in series 2 rows in parallel B. 8 cells in series 3 rows in parallel c. 4 cells in series 6 rows in parallel D. 6 cells in series 4 rows in parallel |
12 |
| 1185 | When 1 coulomb of charge flows through any cross-section of a conductor in 1 second, the electric current through it is said to be 1 ampere. A. True B. False |
12 |
| 1186 | A carbon resistance has a following colour code. What is the value of the resistance? A ( .1 .64 M Omega pm 5 % ) B. ( 530 k Omega pm 5 % ) ( c cdot 64 k Omega pm 10 % ) D. ( 5.3 M Omega pm 5 % ) |
12 |
| 1187 | If three wires of equal resistance are given then number of combinations they can be made to give difference resistance is A . 4 B. 3 ( c .5 ) D. |
12 |
| 1188 | A battery has six cells in series and each cell has an electromagnetic force ( 1.5 V ) and internal resistance ( 1 Omega . ) If an external load of resistance ( 24 Omega ) is connected to it. The potential drop across the load is A. ( 7.2 V ) B. ( 0.3 V ) c. ( 6.8 V ) D. ( 0.4 V ) |
12 |
| 1189 | A potentiometer wire is ( 10 mathrm{m} ) long and a potential difference of ( 6 V ) is maintained between its ends.The emf of a cell which balances against a length of ( 180 mathrm{cm} ) of the potentiometer wire is: A . 1.8 ( v ) B. 1.1 ( v ) c. ( 1.08 mathrm{v} ) D. 1.2 |
12 |
| 1190 | Define electric current. What is its ( S I ) unit? |
12 |
| 1191 | Find the cost of operating an electric toaster for ( 2 h r s, ) if it draws a current of ( 8 A ) on a ( 110 V ) circuit. The cost of electric energy is ( boldsymbol{R} boldsymbol{s} boldsymbol{2} . boldsymbol{5} / boldsymbol{k} boldsymbol{W} boldsymbol{h} ) A. Rs 4.40 в. Rs 6 c. ( R s 8.20 ) D. Rs 2.20 |
12 |
| 1192 | Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area ( 2.5 times 10^{-7} m^{2} ) carrying a current of 2.7 A. Assume the density of conduction electrons to be ( 9 times 10^{28} m^{-3} ) |
12 |
| 1193 | How much electrical energy is transferred per second by a ( 4 V ; 0.5 A ) lamp? A. 20 J/S B. 2 J/S ( c cdot 6.8 mathrm{J} / mathrm{s} ) D. 4.8 J/S |
12 |
| 1194 | Find out the value of ( mathrm{E} ) in the circuit shown in figure. A ( .+14 V ) B . ( -14 V ) ( c .-7 V ) ( D cdot+7 V ) |
12 |
| 1195 | A light bulb uses energy at a rate of 25.0 Watts. If the current through light bulb is 2.00 A. What is the resistance of the bulb? A. 6.25 ohms B. 12.5 ohms c. 0.0800 ohms D. 50.0 ohms E. 100.0 ohms |
12 |
| 1196 | For the network shown in the figure the value of the current i is A ( cdot frac{18 V}{5} ) B. ( frac{5 v}{9} ) ( c cdot frac{9 V}{355} ) D. ( frac{5 V}{18} ) |
12 |
| 1197 | The principle involved in potentiometer is A. variation of current with variati wire on in the diameter of the potentiometer B. similar to the principle of Wheatstone bridge C. variation of resistance with temperature D. both (a) and (b) |
12 |
| 1198 | The current ( I ) drawn from the ( 5 V ) source in the given circuit will be : A. 0.33 A B. ( 0.5 mathrm{A} ) c. ( 0.67 mathrm{A} ) D. 0.17 A |
12 |
| 1199 | Using three wires of resistances 1 ohm, 2ohm and 3 ohm, number of different possible values of resistances are: A. 6 в. 4 ( c cdot 10 ) D. 8 |
12 |
| 1200 | According to Joule’s law, if the potential difference across a conductor of resistivity ( rho ) remains constant, then the heat produced in the conductor is proprotional to ( A cdot frac{1}{rho} ) в. ( frac{1}{sqrt{rho}} ) ( mathbf{c} cdot rho^{2} ) D. |
12 |
| 1201 | Find the equivalent resistance about any branch of the base of the square pyramid shown. Assume resistance of each branch is R A. ( frac{7 R}{15} ) в. ( frac{8 R}{15} ) c. ( frac{R}{2} ) D. None of these |
12 |
| 1202 | Find equivalent capacitance between ( A ) and B. |
12 |
| 1203 | Three 2 resistors, ( A, B, ) and ( C, ) are connected as shown below.Each of them dissipates and can stand a maximum power of ( 18 mathrm{W} ) without melting. Find the maximum current that can flow through the three resistors. |
12 |
| 1204 | If ( n ) is the number density of free electrons in a metallic wire, then the resistance is proportional to A ( . n ) B ( cdot n^{2} ) ( c cdot frac{1}{n} ) D. ( frac{1}{n^{2}} ) |
12 |
| 1205 | The mass of 3 copper gain is 1:3:5 and length 5: 3: 1 then the resistance? | 12 |
| 1206 | A copper wire with a cross-section area of ( 2 times 10^{-6} m^{2} ) has a free electon density equal to ( 5 times 10^{22} / c m^{2} . ) If this wire carries a current of ( 16 A ), the drift velocity of the electron is? ( mathbf{A} cdot 1 m / s ) в. ( 0.1 m / s ) c. ( 0.01 m / s ) D. ( 0.001 m / s ) E. ( 0.00001 mathrm{m} / mathrm{s} ) |
12 |
| 1207 | For a heater rated at ( 4.4 mathrm{kW} ; 220 mathrm{V} ) Calculate the energy consumed by the heater in 4 hours? A. ( 12 mathrm{kWh} ) B. 17.6 kWh ( c cdot ) okwh D. ( 4.4 mathrm{kWh} ) |
12 |
| 1208 | In a circuit shown, the average power dissipated in the resistor is (assume diode to be ideal) A ( cdot frac{E_{0}^{2}}{2 R} ) в. ( frac{E_{0}^{2}}{4 R} ) c. ( frac{E_{0}^{2}}{R} ) D. zero |
12 |
| 1209 | Electrical resistivity of a given metallic wire depends upon: A. its length B. its thickness c. its shape D. nature of the material |
12 |
| 1210 | The electrical resistivity of a conducting wire is ( mathrm{K} ). If its length and area of crosssection are doubled then the new resistivity of the wire will be : ( A cdot K ) в. 2 к c. ( K / 2 ) D. ( K / 4 ) |
12 |
| 1211 | A heater coil connected to a ( 220 mathrm{V} ) has a resistance of 150 oh ( m ). How long will it take for this coil to heat ( 1 k g ) of water from ( 20^{0} C ) to ( 60^{0} C ), assuming that all heat is taken up by water. A . 210 sec B. 420 sec ( c .520 mathrm{sec} ) D. None of these |
12 |
| 1212 | R 55 S2 my W M 5. Shown in the figure is a meter bridge set up with null deflection in the galvanometer. The value of the unknown resistor R is (a) 1102 (b) 5522 (c) 13.7522 (d) 2202 20 cm 552 (AIEEE 2008) |
12 |
| 1213 | A piece of resistance wire has resistance of ( 4 Omega . ) Its diameter is doubled. Now its resistance will be : ( mathbf{A} cdot 8 Omega ) B. 2Omega c. ( 4 Omega ) D. 12 |
12 |
| 1214 | A conducting material obeys ohm’s law when A. The resistivity of material is independent of it magnitude and direction of the applied electric field. B. The resistivity of material is dependent on the magnitude of the applied electric field C. When the resistance is dependent on the magnitude of the applied electric field D. All |
12 |
| 1215 | In the circuit shown, the ammeter reading is zero. Then, the value of the resistance R is: ( A cdot 50 Omega ) B. ( 100 Omega ) c. ( 200 Omega ) 0.4005 |
12 |
| 1216 | The resistance of a wire at temperature ( 30^{circ} mathrm{C} ) is found to be ( 10 Omega . ) Now to increase the resistance by ( 10 %, ) the temperature of the wire must be ( The temperature coefficient of resistance of the material of the wire is ( 0.002^{circ} mathrm{C}^{-1} ) and reference temperature is ( 0^{circ} C ) ). A ( cdot 35^{circ} mathrm{C} ) B . ( 36^{circ} mathrm{C} ) ( mathbf{c} cdot 33^{circ} C ) D. ( 83^{circ} mathrm{C} ) |
12 |
| 1217 | In a Wheatstone’s bridge, there resistances ( P, Q ) and ( R ) connected in the three arms and the fourth arm is formed by two resistances ( S_{1} ) and ( S_{2} ) connected in parallel. The condition for bridge to be balanced will be : ( ^{text {A } cdot frac{P}{Q}}=frac{R}{S_{1}+S_{2}} ) в. ( frac{P}{Q}=frac{2 R}{S_{1}+S_{2}} ) c. ( frac{P}{Q}=frac{Rleft(S_{1}+S_{2}right)}{S_{1} S_{2}} ) D. ( frac{P}{Q}=frac{Rleft(S_{1}+S_{2}right)}{2 S_{1} S_{2}} ) |
12 |
| 1218 | In a Wheatstone’s bridge, there resistances ( mathbf{P}, boldsymbol{O} ) and ( mathbf{R} ) connected in the three arms and the fourth arm is formed by two resistances ( mathbf{S}_{1} ) and ( mathbf{S}_{mathbf{2}} ) connected in parallel. The condition for bridge to be balanced will be A ( cdot frac{P}{O}=frac{R}{S_{1}+S_{2}} ) B. ( frac{P}{O}=frac{2 R}{S_{1}+S_{2}} ) c. ( frac{P}{O}=frac{Rleft(S_{1}+S_{2}right)}{S_{1} S_{2}} ) D. ( frac{P}{O}=frac{Rleft(S_{1}+S_{2}right)}{2 S_{1} S_{2}} ) |
12 |
| 1219 | With the help of a circuit diagram describe the method to find the value of an unknown resistance using meter bridge arrangement. |
12 |
| 1220 | The resistor of resistance ( boldsymbol{R} ) is connected between the terminals of a cell of emf ( boldsymbol{E} ) and internal resistance ( boldsymbol{r} ) The current ( I ) through the circuit is : A ( cdot frac{E}{R r} ) в. ( frac{E}{R+r} ) c. ( frac{R+r}{E} ) D. ( frac{E}{R}+r ) |
12 |
| 1221 | A and ( B ) are two conductors carrying a current ( i ) in the same direction, ( x ) and ( y ) are two electron beams moving in the same direction. There will be: A. Repulsion between ( A ) and ( B ), attraction between ( x ) and ( y ) B. Attraction between ( A ) and ( B ), repulsion between ( x ) and ( y ) C. Repulsion between ( A ) and ( B ), and also ( x ) and ( y ) D. Attraction between ( A ) and ( B ), and also ( x ) and ( y ) |
12 |
| 1222 | Two diametrically opposite points of a metal ring are connected to terminals of the left gap of meter bridge. In the right gap, resistance of ( 15 Omega ) is introduced. If the null point is obtained at a distance of ( 40 mathrm{cm} ) from the left end, find resistance of the wire that is bent in the shape of the ring. |
12 |
| 1223 | On which conservation principle is Kirchoff’s Second Law of electrical networks based? |
12 |
| 1224 | For a given circuit, it is observed that the current ( I ) is independent of the value of the resistance ( R_{6} ). Then, the resistance values must satisfy A ( cdot R_{2} R_{3}=R_{1} R_{4} ) в. ( R_{3} R_{4} R_{6}=R_{2} R_{1} R_{5} ) c. ( frac{1}{R_{3}+R_{4}}=frac{1}{R_{5}}+frac{1}{R_{6}}-frac{1}{R_{1}+R_{2}} ) D. ( R_{3} R_{1}=R_{2} R_{4}=R_{5} R_{6} ) |
12 |
| 1225 | Suppose a current carrying wire has a cross-sectional area that gradually become smaller along the wire has the shape of a very long cone as shown in figure: A. Electric current is different in different portions of wire B. Electric field at point ( A ) is same as that of point ( B ) C. Drift speed of electrons at point ( A ) is lesser than that of at point ( B ) D. Drift speed of electrons at point ( A ) is same as that of at point ( B ) |
12 |
| 1226 | A current of ( 5 A ) is passing through a metallic wire of cross-sectional area ( 4 times 10^{-6} m^{2} . ) If the density of charge carriers of the wire is ( 5 times 10^{26} m^{-3}, ) the drift velocity of the electrons will be : A. ( 1 times 10^{2} mathrm{ms}^{-1} ) В. ( 1.56 times 10^{-2} mathrm{ms}^{-1} ) c. ( 1.56 times 10^{-3} m s^{-1} ) D. ( 1 times 10^{-2} mathrm{ms}^{-1} ) |
12 |
| 1227 | The resistance of a wire is 50 ohm. Then the graph between ( log V ) and ( log I ) is :- A. straight line B. parabola c. hyperbola D. circle |
12 |
| 1228 | State the two Kirchhoff’s laws. Explain briefly, how these rules are justified? | 12 |
| 1229 | A potential difference of ( 20 mathrm{V} ) is needed to make a current of ( 0.05 mathrm{A} ) flow through a resistor. What potential difference is needed to make a current of ( 300 mathrm{mA} ) flow through the same resistor? A. ( 60 v ) B. 1200 c. ( 40 v ) D. 150V |
12 |
| 1230 | How much energy in kilowatt hour is consumed in operating ten 50 watt bulbs for 10 hours per day in a month ( (30 ) days) A . 1500 B. 5000 c. 15 D. 150 |
12 |
| 1231 | Find out the current through ( 2 Omega ) resistor in the circuit shown in figure. ( A, 2,5 A ) B. 5 A c. 1.25 A D. 2 A |
12 |
| 1232 | Two resistances ( boldsymbol{R}_{1}=(mathbf{1 0 0}+mathbf{3}) ) ohms and ( R_{2}=(200+4) ) ohms are connected in series. What is their equivalent resistance? |
12 |
| 1233 | A battery of ( 9 V ) is connected in series with resistors of ( 0.5,0.3,0.4,0.2, ) and 12 How much current would now through the 0.4 resistors? ( mathbf{A} cdot 22.5 A ) B . ( 2.25 A ) c. ( 0.67 A ) D. ( 6.7 A ) |
12 |
| 1234 | A constant potential difference is applied between the ends of the wire. If the length of the wire is elongated 4 times, then the drift velocity of electrons will be: A. increases 4 times B. decreases 4 times c. increases 2 times D. decreases 2 times |
12 |
| 1235 | A resistance of ( 4 Omega ) and a wire of length ( 5 m ) and resistance ( 5 Omega ) are joined in series and connected to a cell of e.m,f, ( mathbf{1 0} V ) and internal resistance ( 1 Omega . A ) Parallel combination of two identical cells is balanced across ( 300 mathrm{cm} ) of the wire. the e.m.f. ( boldsymbol{E} ) each cell is then: A ( .1 .5 ~ V ) в. ( 3.0 V ) ( c .0 .67 V ) 0.1 .33 |
12 |
| 1236 | A wire has a non-uniform cross-section as shown in figure. A steady current flows through it. The drift speed of electrons at points ( mathrm{P} ) and ( mathrm{Q} ) is ( v_{P} ) and ( v_{Q} ) then? ( mathbf{A} cdot v_{P}=v_{Q} ) в. ( v_{P}v_{Q} ) D. Data is insufficient |
12 |
| 1237 | Mark the correct statement: A. Resistivity is the measure of a materials ability to oppose the flow of current B. Unit of resistivity is Ohm meter C. Resistivity is constant for a particular range of temperature D. All |
12 |
| 1238 | In the figure, current through the ( 3 Omega ) resistor is 0.8 ampere, the potential drop through ( 4 Omega ) resistor is A ( .9 .6 ~ V ) B . ( 2.6 V ) c. ( 4.8 V ) D. ( 1.2 V ) |
12 |
| 1239 | and that of an ideal Voltmeter is infinite. A Voltmeter and an Ammeter are connected in the circuit as shown. Resistance of ammeter is say ( boldsymbol{R} / mathbf{1} mathbf{0} ) and that of Voltmeter is ( 10 R ). Then: A. Percentage error in the reading of Ammeter (compared to that measured, if both Ammeter and voltmeter were ideal) is ( 1.0 % ) B. Percentage error in the reading of voltmeter is ( 10.0 % ) c. Both (a) and (b) are correct D. Both (a) and (b) are wrong |
12 |
| 1240 | One Volt is equal to – A. 1 Joule B. 1 Newton/Coulomb c. 1 Joule/Coulomb D. 1 Coulomb/Newton |
12 |
| 1241 | When resistor are connected in series what remains same.? A. current B. Voltage c. Resistance D. power |
12 |
| 1242 | You have three equal resistances r. The maximum possible number of different resistance values that you can offer is ( A cdot 4 ) B. 5 ( c cdot 6 ) ( D .7 ) |
12 |
| 1243 | In figure. the galvanometer shows no deflection. What is the resistance ( X ? ) ( A cdot 7 Omega ) в. ( 14 Omega ) ( c .21 Omega ) D. ( 28 Omega ) |
12 |
| 1244 | To get maximum current through a resistance of ( 2.5 Omega ), one can use ( mathrm{m} ) rows of cells, each row having n cells. The internal resistance of each cell is ( 0.5 Omega ) What are the value of ( n ) and ( m ), if the total number of cells is ( 45 ? ) A ( . m=3, n=15 ) в. ( m=5, n=9 ) c. ( m=9, n=5 ) D. ( m=15, n=3 ) |
12 |
| 1245 | In which of the following substances the resistance decreases with the increase in temperature? A. carbon B. constantan c. copper D. Silver |
12 |
| 1246 | f ( i=0.25 ) amp. in the fig the value of ( R ) is :- ( A cdot 48 Omega ) в. ( 12 Omega ) c. ( 120 Omega ) D. ( 42 Omega ) |
12 |
| 1247 | Which of the following material has lowest resistivity? A. Manganin B. Copper c. constantan D. Silver |
12 |
| 1248 | The following graph was plotted between ( mathrm{V} ) and ( mathrm{I} ) values. What would be the values of ( V / I ) ratios when the potential difference is ( 0.5 mathrm{V} ) and ( 1 mathrm{V} ) ? |
12 |
| 1249 | Assertion For good conductors, the ( boldsymbol{I}-boldsymbol{V} ) graph is a perfect straight line inclined to current axis. Reason By Ohm’s law, voltage across the ends of a conductor is directly proportional to the resistance of the conductor. 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 |
| 1250 | In the network shown in figure, the equivalent resistance between points ( X ) and Y will be ( A ) в. ( frac{r}{2} ) ( c cdot 2 r ) D. ( frac{r}{3} ) |
12 |
| 1251 | In the figure a long uniform potentiometer wire ( A B ) is having a constant potential gradient along its length. The null points for the two primary cells of emfs ( varepsilon_{1} ) and ( varepsilon_{2} ) connected in the manner shown are obtained at a distance of ( 120 mathrm{cm} ) and ( 300 c m ) from the end ( A . ) Find (i) ( varepsilon_{1} / varepsilon_{2} ) and (ii) position of null point for the cell ( varepsilon_{1} ) How is the sensitivity of a potentiometer increased? |
12 |
| 1252 | A ( 2 V ) battery, a ( 990 Omega ) resistor and a potentiometer of ( 2 m ) length,all are connected in series of the resistance of potentiometer wire is ( 10 Omega ), then the potential gradient of the potentiometer wire is A ( cdot 0.05 V m^{-1} ) B ( .0 .5 V m^{-1} ) c. ( 0.01 V m^{-1} ) D. ( 0.001 V m^{-1} ) |
12 |
| 1253 | Resistivity of a given conductor depends upon A. temperature B. length of conductor c. area of cross section D. shape of the conductor |
12 |
| 1254 | A Wheatstone bridge consisting of four ( operatorname{arms} ) of resistances ( P, Q, R, S ) is most sensitive when : A. All the resistance are equal B. All the resistance are unequal c. The resistances ( P ) and ( Q ) are equal but ( R>>P ) and ( S>>Q ) D. The resistance ( P ) and ( Q ) are equal but ( R<<P ) and ( S< ) ( <Q ) |
12 |
| 1255 | Two identical heater wires are first connected in series and then in parallel with a source of electricity. The ratio of heat produced in the two cases is A. 2: B. 1: 2 ( c cdot 4: ) ( D cdot 1: 4 ) |
12 |
| 1256 | In effective resistance between ( C ) and ( B ) is A . ( 2 Omega ) B. 3Omega c. ( 1 Omega ) D. |
12 |
| 1257 | In the given circuit diagram, the value of resistance ( X ) in ohm when the bridge is balanced will be – 4 B. c. 10 D. 12 |
12 |
| 1258 | Two batteries of different emf and internal resistances connected in series with each other and with an external load resistor. The current is 3.0 A. When the polarity of one battery is reversed, the current becomes 1.0 A. The ratio of the emf of the two batteries is : A .2 .5: 1 ) в. 2: 1 c. 3: 2 D. 1: 1 |
12 |
| 1259 | Two cells having emf’s of ( 10 V ) and ( 8 V ) and internal resistance of ( 1 Omega ) (each) are connected as shown with an external resistance of ( 8 Omega ). Find the current flowing through the circuit. |
12 |
| 1260 | An electric current of 2.0 A passes through a wire of resistance 25 Omega. How much heat (in joule) will be developed in 1 minute? ( A cdot 6 ) B. 6000 ( c .50 ) D. 10 |
12 |
| 1261 | There are four resistors of 12 ohm each. Which of the following values is/are possible by their combinations (series and / or parallel)? This question has multiple correct options ( mathbf{A} cdot 9 ) ohm B. 16 ohm c. 12 ohm D. 30 ohm |
12 |
| 1262 | All the edges of a block with parallel faces are unequal. Its longest edge is twice its shortest edge. The ratio of the maximum to minimum resistance between parallel faces is A .2 B. 4 ( c cdot 8 ) D. indeterminate unless the length of the third edge is specified |
12 |
| 1263 | The equivalent resistance ( R ) of three resistors ( R_{1}, R_{2} ) and ( R_{3} ) joined in parallel is A ( cdot R=R_{1}+R_{2}+R_{3} ) B . ( R=1 / R_{1}+1 / R_{2}+1 / R_{3} ) ( ^{mathbf{C}} cdot_{R}=frac{R_{1} R_{2} R_{3}}{R_{1} R_{2}+R_{2} R_{3}+R_{3} R_{1}} ) D. ( R=1 /left(R_{1}+R_{2}+R_{3}right) ) |
12 |
| 1264 | 6. In the experiment of Ohm’s law. When potential difference 10.0 V is applied, current measured is 1.00 A. If length of wire of found to be 10.0 cm, and diameter of wire is 2.50 mm, then the maximum permissible error in resistivity will be (a) 1.8% (b) 10.2% (c) 3.8% (d) 5.75% |
12 |
| 1265 | An electric motor driven pump fills an overhead tank placed at a height of 20 ( mathrm{m} ) from the ground-level sump at a rate of 20,000 litre water per hour.The motor has an operating resistance of ( 22 Omega ) and is connected across a ( 220 mathrm{V} ) source.The efficiency of this motor is (Useg ( = ) ( left.9.8 m / s^{2}right) ) ( mathbf{A} cdot 12.5 % ) B. ( 73.5 % ) c. ( 49.5 % ) D. ( 22.5 % ) |
12 |
| 1266 | A ( 3 h p ) motors requires ( 2.4 k w ) to drive it; its efficiency is about: A . ( 90 % ) B. 75% c. ( 60 % ) D. 50% |
12 |
| 1267 | In the circuit above, ( boldsymbol{R}_{1}=mathbf{2} boldsymbol{R}_{3} ) and ( R_{3}=2 R_{2} . ) If the source voltage is ( V_{1} ) find the power dissipated in ( boldsymbol{R}_{mathbf{1}} ) ( mathbf{A} cdot frac{left(V_{1}right)^{2}}{7 R_{2}} ) B. ( frac{left(V_{1}right)^{2}}{14 R_{2}} ) c. ( frac{left(3 V_{1}right)^{2}}{7 R_{2}} ) D. ( frac{left(V_{1}right)^{2}}{49 R_{2}} ) E ( cdot frac{left(3 V_{1}right)^{2}}{49 R_{2}} ) |
12 |
| 1268 | When a resistor of ( 2 Omega ) is connected across the terminals of a battery a current of ( 2 A ) is found to flow. When a second resistor of ( 8 Omega ) is connected in series with the first, the current is reduced to ( 1 A . ) The emf and internal resistance of the battery are A ( .12 %, 4 Omega ) B. 10V, 2Omega ( c cdot 16 v, 6 Omega ) D. 16V, 4Omega |
12 |
| 1269 | The current ( I ) through a rod of a certain metallic oxide is given by ( boldsymbol{I}=mathbf{0 . 2} boldsymbol{V}^{mathbf{5} / mathbf{2}} ) where ( V ) is the potential difference across it. The rod is connected in series with a resistance to a ( 6 V ) battery of negligible internal resistance. What value should the series resistance have so that the power dissipated in the rod is twice that dissipated in the resistance? |
12 |
| 1270 | A resistor has resistance R. When the potential difference across the resistor is ( V ), the current in the resistor is I. The power dissipated in the resistor is P. Work W is done when charge ( Q ) flows through the resistor. What is not a valid relationship between these variables? ( mathbf{A} cdot I=frac{P}{V} ) В ( cdot Q=frac{W}{V} ) C ( cdot R=frac{P}{I^{2}} ) D ( cdot R=frac{V}{P} ) |
12 |
| 1271 | Calculate the number of electrons constitute one coulomb of charge. |
12 |
| 1272 | Table 1 Table – 2 (a) Potential difference across battery ( A quad(p) A ) (b) Potential difference across battery ( B quad(q) B ) (c) Power is supplied by battery ( (r) 14 V ) (d) Power is consumed by battery ( (s) 9 V ) none ( A cdot a-p ; b-p ; c-q ; d-r ) B. ( a-q ; b-q ; c-r ; d-s ) ( c cdot a-r, b-t, c-p, d-q ) ( D cdot a-r ; b-r ; c-s ; d-t ) |
12 |
| 1273 | When ( 5 V ) potential difference is applied across a wire length ( 0.1 m ), the drift speed of electron is ( 2.5 times 10^{-4} m s^{-1} . ) If the electron density in the wire is 8 ( times 10^{28} m^{-3}, ) the resistivity of the material is close to A ( cdot 1.6 times 10^{-8} Omega mathrm{m} ) В. ( 1.6 times 10^{-7} Omega mathrm{m} ) c. ( 1.6 times 10^{-6} Omega mathrm{m} ) D. ( 1.6 times 10^{-5} Omega ) m |
12 |
| 1274 | n Fig. circuit section, ( A B ) absorbs energy at a rate of ( 50 % ) W when a current ( i=1.0 ) A passes through it in the indicated direction. If device X does not have internal resistance, what is its emf? A. 24 v в. 48 v ( c cdot 32 v ) D. 12 V |
12 |
| 1275 | Calculate the equivalent resistance for each arrangement. Series arrangement |
12 |
| 1276 | A voltmeter and an ammeter are joined in series to an ideal cell, giving readings ( mathrm{V} ) and ( mathrm{A} ) respectively. If ( mathrm{a} ) resistance equal to the resistance of the ammeter if now joined in parallel to the ammeter This question has multiple correct options A. V will no change B. V will increase slightly c. A will become exactly half of its initial vale D. A will become slightly more than half of its initial value |
12 |
| 1277 | (a) Three resistors ( 2 Omega, 4 Omega ) and ( 5 Omega ) are combined in parallel. What is the total resistance of the combination? (b) If the combination is connected to a battery of emf ( 20 mathrm{V} ) and negligible internal resistance, determine the current through each resistor, and the total current drawn from the battery. |
12 |
| 1278 | The dimensional formula of mobility is ( mathbf{A} cdot M^{-1} L^{1} T^{2} A^{mathbf{1}} ) B. ( M^{1} L^{0} T^{-2} A^{-1} ) c. ( M^{1} L^{-1} T^{-2} A^{-1} ) D. ( M^{-1} L^{0} T^{2} A^{1} ) |
12 |
| 1279 | Resistance of a resistor at temperature ( t^{0} boldsymbol{C} ) is ( boldsymbol{R}_{t}=boldsymbol{R}_{0}left(mathbf{1}+boldsymbol{alpha} boldsymbol{t}+boldsymbol{beta} boldsymbol{t}^{2}right) . ) Here ( boldsymbol{R}_{0} ) is the resistance at ( 0^{0} C . ) The temperature coefficient of resistance at temperature ( t^{0} C ) is A ( cdot frac{left(1+alpha t+beta t^{2}right)}{alpha+2 beta t} ) в. ( alpha+2 beta t ) c. ( frac{alpha+2 beta t}{left(1+alpha t+beta t^{2}right)} ) D. ( frac{alpha+2 beta t}{2left(1+alpha t+beta t^{2}right)} ) |
12 |
| 1280 | Potentiometer measures potential more accurately because A. it measures potential in the open circuit. B. it uses sensitive galvanometer for null deflection. C. it uses high resistance potentiometer wire. D. it measures potential in the closed circuit. |
12 |
| 1281 | Find the emf and internal resistance of the equivalent cell between ( A ) and ( B ). put [ begin{array}{l} varepsilon_{1}=3 mathrm{V}, r_{1}=2 Omega varepsilon_{2}=2 V, r_{2}=1 Omega \ varepsilon_{3}=6 V, r_{3}=1 Omega end{array} ] |
12 |
| 1282 | The potential at point ( B, C ) and ( D ) in the following circuit will be A . ( 12 vee, 10 vee, 6 v ) B. ( 11 vee, 9 vee, 6 v ) c. ( 11 vee, 9 vee, ) o ( v ) D. ( 12 vee, 10 vee, ) o ( v ) |
12 |
| 1283 | A current of ( 1 A ) flows through a copper wire. The number of electrons passing through any cross-section of the wire in 1.6 ( sec ) is (charge of a electrons ( =1.6 times ) ( left.10^{-19} Cright) ) ( mathbf{A} cdot 10^{19} ) B. ( 10^{2} ) ( c cdot 10^{25} ) D. ( 10^{28} ) |
12 |
| 1284 | Ohm’s law is true: A. For metallic conductor at low temperature B. For metallic conductor at high temperature C. For electrolytes, when current passes through them D. For diode when current flows |
12 |
| 1285 | The current voltage graph for a given metallic wire at two different temperatures ( T_{1} ) and ( T_{2} ) are shown in given figure, which of the relation is correct from the following? A ( cdot T_{2}>T_{1} ) в. ( T_{1}>T_{2} ) c. ( T_{1}=T_{2} ) D. none of these |
12 |
| 1286 | The temperature coefficient resistivity of a material is ( 0.0004 / K . ) When the temperature of the material is increased by ( 50^{circ} C, ) its resistivity increases by ( 2 times 10^{-8} ) ohm – meter The initial resistivity of the material of the resistance A . ( 50 times 10^{-8} ) B. ( 90 times 10^{-8} ) c. ( 100 times 10^{-8} ) D. ( 200 times 10^{-8} ) |
12 |
| 1287 | Find out the value of I in the circuit shown in figure. ( A cdot 5 A ) в. 2.5 ( c cdot 10 A ) ( D cdot 4 A ) |
12 |
| 1288 | Heater of an electric kettle is made of a wire of length L and diameter d. It takes 4 minutes to raise the temperature of ( 0.5 mathrm{kg} ) water by ( 40 mathrm{K} . ) This heater is replaced by a new heater having two wires of the same material, each of length L and diameter 2d. The way these wires are connected is given in the options. How much time in minutes will it take to raise the temperature of the same amount of water by ( 40 mathrm{K} ? ) This question has multiple correct options A. 4 if wires are in parallel B. 2 if wires are in series c. 1 if wires are in series D. 0.5 if wires are in parallel |
12 |
| 1289 | In the circuit shown below, all the resistances are equal, each equal to ( mathrm{R} ) The equivalent resistance between points ( A ) and ( C ) is : ( A ) 8. 4 R ( c cdot R / 2 ) D. None of the above |
12 |
| 1290 | ( 1 m A= ) | 12 |
| 1291 | The terminal voltage of a cell is equal to A. potential across external resistance. B. potential across internal resistance. C . potential across sum of external resistance and internal resistance. D. emf of cell. |
12 |
| 1292 | In the circuit shown in figure. Current through ( R_{1} ) is independent of A ( . R_{2} ) в. ( R_{3} ) ( c cdot R_{4} ) D. All of these |
12 |
| 1293 | What do you mean by the sensitivity of potentiometer? | 12 |
| 1294 | After switch is closed, current drawn from the battery is ( A cdot 6 A ) 3.1 .54 ( c .3 A ) 0.44 |
12 |
| 1295 | A given resistor has the following colour scheme of the various strips on it: Brown, black, green and silver. Its value in ohm is : A ( cdot 1.0 times 10^{4} pm 10 % ) В. ( 1.0 times 10^{5} pm 10 % ) C. ( 1.0 times 10^{6} pm 10 % ) D. ( 1.0 times 10^{7} pm 10 % ) |
12 |
| 1296 | On interchanging the resistances, the balance point of a meter bridge shifts to the left by ( 10 mathrm{cm} . ) The resistance of their series combination is ( 1 k Omega ). How much was the resistance on the left slot before interchanging the resistances? A . ( 550 Omega ) в. ( 910 Omega ) ( mathbf{c} .990 Omega ) D. ( 505 Omega ) |
12 |
| 1297 | When Cu and Ge are cooled to ( -150^{circ} mathrm{C} ) then resistance of ( mathrm{Cu} )…. and that of Ge A. increases, increases B. decrease, increases c. decrease, decreases D. increases, decreases |
12 |
| 1298 | Potentiometer wire length is ( 10 m ) having a total resistance of ( 10 Omega ). If a battery of emf 2 volts (of negligible internal resistance) and a rheostat are connected to it them the potential gradient is ( 20 m V / m ; ) find the resistance imparted through the rheostat |
12 |
| 1299 | Two unknown resistrance ( X ) and ( Y ) are connected to left and right gaps of a meter bridge and the balancing point is obtained at ( 80 mathrm{cm} ) from left. When a ( 10 Omega ) resistance is connected in paralle to ( x ) the balance point is ( 50 mathrm{cm} ) from left. The values of ( X ) and ( Y ) respectively are ( A cdot 40 Omega, 9 Omega ) B. 30Omega ,7.5Omega c. ( 20 Omega, 6 Omega ) D. ( 10 Omega, 3 Omega ) |
12 |
| 1300 | Three resistors ( (2,5 text { and } 7 text { ohm }) ) are wires as shown in the diagram below. The equivalent resistance of this combination (in ohm) is: A ( cdot frac{59}{70} ) B. ( frac{70}{59} ) ( c cdot frac{1}{14} ) D. 14 E. Cannot be determined without additional information |
12 |
| 1301 | The potentiometer wire AB shown in the figure is ( 40 mathrm{cm} ) long. Where should the free end of the galvanometer be connected on AB so that the galvanometer may show zero deflection? |
12 |
| 1302 | In the given circuit the cells have zero internal resistance. The currents (in Amperes) passing through resistance ( R_{1}, ) and ( R_{2} ) respectively, are ( _{-}–1 ) A .2,2 B. 0,1 c. 1,2 D. 0.5,0 |
12 |
| 1303 | Four resistors, ( 100 Omega, 200 Omega, 300 Omega, ) and ( 400 Omega ) are connected to form four sides of a square. The resistors can be connected in any order. What is the maximum possible equivalent resistance across the diagonal of the square? A ( .210 Omega ) в. 240Omega ( mathbf{c} .300 Omega ) D. 250Omega |
12 |
| 1304 | The mobility of free electrons (charge =e, mass = m and-relaxation time ( tau ) ) in a metal is proportional to: A ( cdot frac{e}{m} tau ) в. ( frac{m}{e} tau ) ( c cdot frac{e}{m tau} ) D. ( frac{m}{e tau} ) |
12 |
| 1305 | Four resistance ( 5 Omega, 10 Omega, 15 Omega ) and an unknown ( X Omega ) are connected in series so as to form Wheatsones network. Determine the unknown resistance ( boldsymbol{X} ) if the network is balance with these numerical values of resistances. |
12 |
| 1306 | Murugan measured the electric current What unit should he use? |
12 |
| 1307 | A battery has four cells in parallel, each has an e.m.f ( 1.5 V ) and internal resistance ( 0.8 Omega . ) The current delivered by it to a load of ( 2.8 Omega ) is A. ( 0.2 A ) B. 0.4A c. ( 0.5 mathrm{A} ) D. ( 0.6 A ) |
12 |
| 1308 | The current I in the circuit shown below is ( mathbf{A} ) ( B cdot frac{1}{15} A ) ( c cdot frac{1}{10} A ) ( D cdot frac{1}{2} ) |
12 |
| 1309 | A torch bulb rated ( 4.5 mathrm{W}, 1.5 mathrm{V} ) is nnected as in figure. The emf of the ell needed to make the bulb glow at ntensity i |
12 |
| 1310 | The given image is a symbol of | 12 |
| 1311 | Derive the condition for balance of a Wheatstone’s bridge using Kirchhoff’s rules. |
12 |
| 1312 | The ( n ) rows each contaning in cells in series are joined in parallel. Maximum current is taken from this combination across an external resistance of ( 3 Omega ). If the total number of cells used is 24 and internal resistance of each cell is ( 0.5 Omega ) then A. ( m=8, n=3 ) в. ( m=6, n=4 ) c. ( m=12, n=2 ) D. ( m=2, n=12 ) |
12 |
| 1313 | Find out the total current flowing in the circuit as shown in above figure? ( A cdot 4 A ) B. 3A c. ( 2 A ) D. ( frac{4}{3} ) ( E ) |
12 |
| 1314 | Two resistance thermometers are made, one of the platinum wire and the other of germanium wire. The resistance of both the thermometers are equal at room temperatures. Now the two resistance wires are connected to a battery. The two resistance wire are heated to ( 100^{circ} mathrm{C} ). The potential drop in the two resistance is measured. Which of the following statements is correct? A. The potential drop across the platinum wire is equal to the potential drop across the germanium wire B. The potential drop across platinum wire is greater than that across germanium C. The potential drop across the platinum wire is less than that across germanium D. The nature of the potential drop can be ascertained unless the magnitude of the current is known |
12 |
| 1315 | In the following circuit, the ( 1 Omega ) resistor dissipates power P. If the resistor is replaced by ( 9 Omega ). the power dissipated in it is ( A ) B. 3P ( c cdot 9 P ) D. P/3 |
12 |
| 1316 | The resistance of a wire is 5 ohm at ( 50^{circ} ) ( mathrm{C} ) and 6 ohm at ( 100^{circ} mathrm{C} ). The resistance of the wire at ( 0^{circ} mathrm{C} ) will be: ( A cdot 2 ) ohm B. 1 ohm c. 4 ohm D. 3 ohm |
12 |
| 1317 | Two long parallel wires carrying currents ( 2.5 mathrm{A} ) and I A in the same direction (directed Into the plane of the paper) are held ( mathrm{M} mathrm{P} ) and ( mathrm{Q} ) respectively such that they are perpendicular to the plane of the paper. The points ( P ) and ( Q ) are located at a distance of ( 5 mathrm{m} ) and 2 ( mathrm{m}, ) respectively, from a collinear point ( mathrm{R} ) as shown in figure. An electron moving with a velocity of ( 4 times 10^{5} m s^{-1} ) along the positive ( X ) -direction experiences a force of magnitude ( 3.2 times 10^{-20} mathrm{N} ) at the point ( R ) The current lin wire Q is ( A cdot 1 A ) B. 2 A ( c cdot 3 A ) ( D cdot 4 A ) |
12 |
| 1318 | Three ammeters ( A, B ) and ( C ) of resistances ( boldsymbol{R}_{boldsymbol{A}}, boldsymbol{R}_{boldsymbol{B}} ) and ( boldsymbol{R}_{boldsymbol{C}} ) respectively are joined as shown. When some potential difference is applied across the terminals ( T_{1} ) and ( T_{2}, ) their readings are ( I_{A}, I_{B} ) and ( I_{C} ) respectively This question has multiple correct options ( mathbf{A} cdot I_{A}=I_{B} ) B ( cdot I_{A} R_{A}+I_{B} R_{B}=I_{C} R_{C} ) ( mathbf{C} cdot frac{I_{A}}{I_{C}}=frac{R_{C}}{R_{A}} ) D. ( frac{I_{B}}{I_{C}}=frac{R_{C}}{R_{A}+R_{B}} ) |
12 |
| 1319 | Assertion ( overrightarrow{boldsymbol{E}}=boldsymbol{E}_{boldsymbol{x}} hat{boldsymbol{i}}+boldsymbol{E}_{boldsymbol{y}} hat{boldsymbol{j}}+boldsymbol{E}_{z} hat{boldsymbol{k}}, vec{nabla} times overrightarrow{boldsymbol{E}}=mathbf{0} ) Reason ( E_{x}, E_{y}, E_{z} ) is independent. 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 |
| 1320 | fixed resistors of resistance ( 2.0 Omega ) and ( 4.0 Omega ) connected in series with a ( 3.0 Omega ) resistor fitted with a sliding contact. These are connected across a battery of e.m.f ( 9.0 mathrm{V} ) and zero internal resistance, as shown What are the maximum and the minimum output voltages of this potential divider circuit? A. maximum voltage/V : ( 4.0 ; ) minimum voltage ( / V: 2.0 ) B. maximum voltage/V : 5.0 ; minimum voltage/V : 2.0 C. maximum voltage/V : ( 9.0 ; ) minimum voltage ( / V: 0 ) D. maximum voltage/V : 9.0 ; minimum voltage/ ( V: 2.0 ) |
12 |
| 1321 | Q Type your question observation table are shown in figure. SI.No. ( quad ) R(lomegal) ( quad l(c m) ) 1000 100 1.5 1 Which of the readings is inconsistent? 4 B. 1 ( c cdot 2 ) 2 |
12 |
| 1322 | Figure shows three resistor configurations ( R 1, R 2 ) and ( R 3 ) connected to ( 3 V ) battery. If the power dissipated by the configuration ( boldsymbol{R} mathbf{1}, boldsymbol{R} mathbf{2} ) and ( R 3 ) is ( P 1, P 2 ) and ( P 3, ) respectively then A. ( P 1>P 2>P 3 ) в. ( P 1>P 3>P 2 ) c. ( P 2>P 1>P 3 ) D. ( P 3>P 2>P 1 ) |
12 |
| 1323 | f ( boldsymbol{E}=mathbf{1 2} ) volts, ( boldsymbol{X}=mathbf{9} Omega, ) then distance of balance point ( P ) from end ( A ) is A. 20 cm B. 50 ( mathrm{cm} ) c. ( 70 mathrm{cm} ) D. Data insufficient |
12 |
| 1324 | Draw the circuit and the graph of Ohm’s Law. |
12 |
| 1325 | ( frac{2}{2} ) | 12 |
| 1326 | Which of the following quantities do not change when an ohmic resistor connected to a battery is heated due to the current? A. drift speedd B. resistivity c. resistance D. number of free electrons |
12 |
| 1327 | The length of potentiometer wire is ( 10 mathrm{m} ) and is connected in series with an accumulator. The e.m.f. of a cell balances against ( 250 mathrm{cm} ) length of wire. If the length of potentiometer wire is increased by ( 1 mathrm{m} ), calculate the new balancing length of wire. |
12 |
| 1328 | A brass disc and a carbon disc of same radius are assembled alternatively to make a cylindrical conductor. The resistance of the cylinder is independent of the temperature. The ratio of thickness of the brass disc to that of the carbon disc is ( alpha ) is temperature coefficient of resistance ( & ) Neglect linear expansion A ( cdot frac{alpha_{C} rho_{C}}{alpha_{B} rho_{B}} ) в. ( frac{alpha_{C} rho_{B}}{alpha_{B} rho_{C}} ) c. ( frac{alpha_{B} rho_{C}}{alpha_{C} rho_{B}} ) D. ( frac{alpha_{B} rho_{B}}{alpha_{C} rho_{C}} ) |
12 |
| 1329 | The potential difference between points ( A ) and ( B ) in the circuit shown in figure is ( 16 mathrm{V} ). Then, This question has multiple correct options A. the current through the ( 2 Omega ) resistance is 3.5 A B. the current through the ( 4 Omega ) resistance is 2.5 A c. the current through the ( 3 Omega ) resistance is 1.5 A D. the potential difference between the terminals of the V battery is 7 V |
12 |
| 1330 | The circuit below shows six resistors in a circuit with a voltage source supplying a voltage, ( V ) Which table gives the correct voltage drops across resistor 6 and resistor ( 3 ? ) A. Voltage Drop across Resistor 6 – Voltage Drop across Resistor ( 3, V / 6-V / 6 ) B. Voltage Drop across Resistor 6 – Voltage Drop across Resistor ( 3, V-V ) c. voltage Drop across Resistor 6 – voltage Drop across Resistor ( 3.3 V-V ) D. voltage Drop across Resistor 6 – Voltage Drop across Resistor ( 3, V / 3-V ) E : ” ge Drop across Resistor 6- Voltage Drop across ( operatorname{tor} 3, V-V / 3 ) |
12 |
| 1331 | Assertion: A current carrying wire should be charged. Reason: The current in a wire is due to flow of free electrons in a definite direction. A. Both (A) and (R) are true and (R) is the correct explanation of A B. Both (A) and (R) are true but (R) is not the correct explanation of A c. (A) is true but (R) is false D. (A) is false but (R) is true |
12 |
| 1332 | An accumulator of emf 2 Volt and negligible internal resistance is connected across a uniform wire of length ( 10 mathrm{m} ) and resistance ( 30 Omega ). The appropriate terminals of a cell of emf ( mathbf{1 . 5} V ) olt and internal resistance ( 1 Omega ) is connected to one end of the wire, and the other terminal of the cell is connected through a sensitive galvanometer to a slider on the wire. If the length of the wire which is required to produce zero deflection of the galvanometer is ( frac{x}{2} m . ) Find ( x ) |
12 |
| 1333 | In copper, each atom releases one electron. If a current of ( 1.1 mathrm{A} ) is flowing in the copper wire of diameter 1mm then the drift velocity of electrons, will a pproximately be (density of copper ( = ) ( 9 times 10^{3} mathrm{Kgm}^{-3} ) and its atomic weight ( =mathbf{6 3}) ) A. ( 10.3 mathrm{mm} / mathrm{s} ) B. ( 0.1 mathrm{mm} / mathrm{s} ) c. ( 0.2 mathrm{mm} / mathrm{s} ) D. ( 0.2 mathrm{cm} / mathrm{s} ) |
12 |
| 1334 | A potentiometer having a wire of ( 4 m ) length is connected to the terminals of a battery with a steady voltage. ( A ) leclanche cell has a null point at 1 m. If the length of the potentiometer wire is increased by 1 m, the position of the null point is ( mathbf{A} cdot 1.5 m ) B. ( 1.25 mathrm{m} ) c. 10.05 m D. ( 1.31 m ) |
12 |
| 1335 | (A) Write with the help of a diagram the principle of a potentionmeter. (B) Using a potentionmeter how do you determine the internal resistance of a cell? |
12 |
| 1336 | The V-I graph for conductor at temperatures ( T_{1} ) and ( T_{2} ) are shown in the figure. ( left(T_{2}-T_{1}right) ) is proportional to A ( . cos 2 theta ) B. ( sin 2 theta ) ( c cdot cot 2 theta ) D. ( tan 2 theta ) |
12 |
| 1337 | Three resistances ( 2 Omega, 4 Omega, 5 Omega ) are combines in series and this combination is connected to a battery of ( 12 mathrm{V} ) emf and negligible internal resistance. The potential drop across these resistances are. A . (5.45,4.36,2.18) V B. (2.18,5.45,4.36) ( mathrm{v} ) c. (4.36,2.18,5.45) v D. (2.18,4.36,5.45)( vee ) |
12 |
| 1338 | If same potential difference is applied across two resistances, more heat will be produced in the large value of resistance. |
12 |
| 1339 | Effective resistance between ( A ) and ( C ) is: A . ( 2 Omega ) B. ( 6 Omega ) ( c .9 Omega ) D. None |
12 |
| 1340 | How will you represent a resistance of ( 4500 pm 10 % ) using color code? | 12 |
| 1341 | Two ideal batteries of emf ( V_{1} ) and ( V_{2} ) and three resistances ( R_{1}, R_{2} ) and ( R_{3} ) are connected as shown in the figure. The current in resistance ( boldsymbol{R}_{2} ) would be zero if This question has multiple correct options A. ( V_{1}=V_{2} ) and ( R_{1}=R_{2}=R_{3} ) B . ( V_{1}=V_{2} ) and ( R_{1}=2 R_{2}=R_{3} ) c. ( V_{1}=2 V_{2} ) and ( 2 R_{1}=2 R_{2}=R_{3} ) D. ( 2 V_{1}=V_{2} ) and ( 2 R_{1}=R_{2}=R_{3} ) |
12 |
| 1342 | The momentum acquired by all free electrons in a wire a length I when a current of i amp starts to flow is A ( cdot frac{m i l}{e} ) B. ( frac{m e l}{i} ) ( c . m i l ) D. mie |
12 |
| 1343 | If current ( I_{1}=3 A ) sinwt and ( I_{2}= ) 4 Acos( omega t, ) then ( I_{3} ) is A ( .5 A sin left(omega t+53^{circ}right) ) B. ( 5 A sin left(omega t+37^{circ}right) ) c. ( 5 A sin left(omega t+45^{circ}right) ) D. 5 Asin ( left(omega t+30^{circ}right) ) |
12 |
| 1344 | If the current passing through an electric bell is doubled, the heat produced will become A. four times B. double c. one-fourth D. half |
12 |
| 1345 | Two cylindrical rod have area of cross- section ( boldsymbol{A}_{mathbf{1}} boldsymbol{A}_{mathbf{2}} . ) If ( boldsymbol{A}_{mathbf{1}} ) is greater than ( boldsymbol{A}_{mathbf{2}} ) Then which of the following is correct? A. The resistivity of the cylinder having area of crosssection ( A_{1} ) is higher than the cylinder of cross-section ( A_{2} ) B. The resistivity of the cylinder having area of crosssection ( A_{2} ) is higher than the cylinder of cross-section ( A_{1} ) C. The resistivity of the cylinder having area of crosssection ( A_{1} ) is same as the cylinder of cross-section ( A_{2} ) D. None of the above |
12 |
| 1346 | A potentiometer wire of length ( L ) and resistance ( 10 Omega ) is connected in series with a battery of e.m.f. ( 2.5 % ) and a resistance in its primary circuit. The null point corresponding to a cell of e.m.f. ( 1 V ) is obtained at a distance ( L / 2 ) If the resistance in the primary circuit is doubled then the position of new null point will be ( mathbf{A} cdot 0.4 L ) B. ( 0.5 L ) c. ( 0.6 L ) ( mathbf{D} cdot 0.8 L ) |
12 |
| 1347 | Which of the statement is wrong:- A. when all resistance are equal, then the sensitivity of wheatstone bridge is maximum. B. when the galvanometer and the cell are interchanged, then the balancing of wheat stone bridge will be effected. C. Kirchoff’s first law for the currents meeting at the Junctions in an electric circuit shows the conservation of charge. D. Rheostat can be used as potential divider. |
12 |
| 1348 | Draw labelled circuit diagram of a potentiometer to compare emfs of two cells. Write the working formula (Derivation not required) |
12 |
| 1349 | To get maximum current in resistance of ( 3 Omega, ) one can use ( n ) parallel rows of ( m ) cells each connected in series. If the total no. of cells is 24 and the internal resistance is 0.5 ohm then: A. ( m=12, n=2 ) в. ( m=8, n=3 ) c. ( m=2, n=12 ) D. ( m=6, n=4 ) |
12 |
| 1350 | In the arrangement of resistances shown below. The effective resistance between points ( A ) and ( B ) is A . ( 20 Omega ) в. ( 30 Omega ) ( c .90 Omega ) D. ( 110 Omega ) |
12 |
| 1351 | Take the potential of the point ( B ) in the figure, to be zero. (a) Find the potentials at the points ( mathrm{C} ) and ( mathrm{D} ). (b) If a capacitor is connected between ( mathrm{C} ) and ( mathrm{D} ), What charge will appear on the capacitor? |
12 |
| 1352 | Potential difference is measured in joules. A . True B. False |
12 |
| 1353 | The resistance of the meter bridge ( A B ) is given figure is 4 Omega. With a cell of emf ( varepsilon=0.5 V ) and rheostat resistance ( R h=2 Omega ) the null point is obtained at some point ( J . ) When the cell is replaced by another one of emf ( varepsilon=varepsilon_{2} ) the same null point ( J ) is found for ( R_{h}=6 Omega ). The emf ( varepsilon ) is A ( .0 .6 ~ V ) B. ( 0.5 V ) c. ( 0.3 V ) D. ( 0.4 V ) |
12 |
| 1354 | A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an projected along the direction of the fields with a certain velocity then : A. its velocity will decrease B. its velocity will increase. c. it will turn towards right of direction of motion D. it will turn towards left of direction of motion |
12 |
| 1355 | A voltmeter having a resistance of ( 998 Omega ) is connected to a cell of emf ( 2 mathrm{V} ) and internal resistance ( 2 Omega . ) The error in the measurement of emf will be. A ( cdot 4 times 10^{-1} mathrm{V} ) B . ( 2 times 10^{-3} mathrm{V} ) c. ( 4 times 10^{-3} v ) D. ( 2 times 10^{-1} mathrm{V} ) |
12 |
| 1356 | A current of ( 16 A ) is made to pass through a conductor in which the number density of free electrons is ( 4 x ) ( 10^{28} m^{-3} ) and its area of cross section is ( 10^{-5} m^{2} . ) The average drift velocity of free electrons in the conductor is: A ( .2 .5 times 10^{-4} mathrm{ms}^{-1} ) B . ( 3.2 times 10^{-4} mathrm{ms}^{-1} ) c. ( 6.4 times 10^{-4} mathrm{ms}^{-1} ) D. ( 1.6 times 10^{-4} mathrm{ms}^{-1} ) |
12 |
| 1357 | The Sl unit of resistance is : A. Newton B. ohm c. watt D. Joule |
12 |
| 1358 | Green,blue, brown,gold are the color bands on resistors.Find its resistance? A. ( 580 Omega ) в. ( 560 Omega ) ( mathbf{c} cdot 480 Omega ) D. ( 58 Omega ) |
12 |
| 1359 | Five resistance are connected as shown in figure. If total current flowing is ( 0.5 A ) then the potential difference ( boldsymbol{V}_{boldsymbol{A}}-boldsymbol{A}_{boldsymbol{B}} ) is: ( A cdot 8 V ) в. ( 6 V ) ( c cdot 2 V ) D. ( 4 V ) |
12 |
| 1360 | Assertion If the current of a lamp increases by ( 20 % ), the percentage increase in the illumination of the lamp is ( 40 % ) Reason Illumination of the lamp is directly proportional to the square of the current through the lamp. 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 |
| 1361 | An electric iron draws a current of ( 15 A ) from a ( 220 V ) supply. What is the cost of using iron for 30 min everybody for 15 days if the cost of unit is 2 rupees? ( (1 u n i t=1 k W h) ) A . Rs 49.50 B. Rs 60 c. Rs 40 D. Rs 10 |
12 |
| 1362 | The current through the ( 10 Omega ) resistor shown in figure is ( 4 cdot 0.1 ) B. ( 0.2 mathrm{A} ) ( c cdot 0.3 mathrm{A} ) D. zer |
12 |
| 1363 | An electric cell of e.m.f. E is connected across a copper wire of diameter d and length I. The drift velocity of electrons in the wire is ( v_{d} ). If the length of the wire is changed to 21, the new drift velocity of electrons in the copper wire will be ( mathbf{A} cdot v_{d} ) в. ( 2 v_{d} ) c. ( v_{d} / 2 ) D. ( v_{d} / 4 ) |
12 |
| 1364 | The diagram shows three capacitor with their capacitances with breakdown voltages.what should be the maximum value of external emf of source such that no capacitor breaks down:- ( A cdot frac{33}{2} v o l t ) B . ( frac{11}{3} ) volt ( c cdot frac{13}{3} v o l t ) D. ( frac{11}{2} ) volt |
12 |
| 1365 | In a house, individual powers of two elements are ( $ $ 1001 mathrm{W} 11001 mathrm{W} $ $ . ) The effective power of their series combination will be : A . ( 120 mathrm{W} ) B. ( 75 W ) ( mathbf{c} .50 W ) D. ( 60 W ) |
12 |
| 1366 | The instantaneous values of alternating current and voltages in a circuit are given as ( mathrm{i}=frac{1}{sqrt{2}} sin (100 pi t) ) ampere ( mathrm{e}=frac{1}{sqrt{2}} sin (100 pi t+pi / 3) mathrm{volt} ) The average power in Watts consumed in the circuit is: A ( frac{sqrt{3}}{4} ) B. ( frac{1}{2} ) ( c cdot frac{1}{8} ) D. 4 |
12 |
| 1367 | The carbon resistor has three orange bands. The maximum value of resistance offered by the resistor will be A . ( 39.6 k . Omega ) в. ( 49.6 k Omega ) ( mathbf{c} .33 k Omega ) D. 26.4kOmega |
12 |
| 1368 | The length of potentiometer wire is ( 10 mathrm{m} ) and is connected in series with an accumulator. The e.m.f. of a cell balances against ( 250 mathrm{cm} ) length of wire. If the length of potentiometer wire is increased by ( 1 mathrm{m} ), calculate the new balancing length of wire. A . 2.00 B . 2.25 c. 2.50 D. 2.75 |
12 |
| 1369 | The effective capacitance of combination of equal capacitors between points ( A ) and ( B ) shown in figure is : ( A ) B. ( 2 C ) ( c cdot 3 c ) 0.0 9 |
12 |
| 1370 | When a steady current of ( 1 A ) flows through a copper wire, the number of electrons crossing any cross-section area of the wire in one second is A ( cdot 6.25 times 10^{16} ) B . ( 6.25 times 10^{18} ) ( mathbf{c} cdot 625 times 10^{18} ) D. ( 6.25 times 10^{20} ) |
12 |
| 1371 | Six lead-acid type of secondary cells each of emf ( 2.0 mathrm{V} ) and internal resistance of 0.015 are joined in series to provide a supply to a resistance of ( 8.5 . ) What are the current drawn from the supply and it’s terminal voltage? A. 11.8749 B. 12.8749 c. 13.1749 D. 10.5749 |
12 |
| 1372 | Three-point charges ( 1 mathrm{C}, 2 mathrm{C} ), and ( 3 mathrm{C} ) are placed at the corners of an equilateral triangle Of side ( 1 mathrm{m} ). The work required to move these charges to the corners of a smaller equilateral triangle Of side ( 0.5 mathrm{m} ) in two different ways as in fig.(A) and (B)Calculate the work done A ( cdot 9 times 10^{9} ) B ( .99 times 10^{9} ) ( mathbf{c} cdot 89 times 10^{9} ) D ( .29 times 10^{9} ) |
12 |
| 1373 | toppr ( E ) ( Q ) тур Note: the rate-flow vectors are not drawn to scale. Identify the case(es) in which the effective current through the conductor is the highest. ( mathbf{A} ) [ begin{array}{l} odot 5 mathrm{c} / mathrm{s} \ 5 mathrm{c} / mathrm{s} longleftrightarrow end{array} ] в. [ Leftrightarrow 9 mathrm{c} / mathrm{s} ] [ 1 mathrm{c} / mathrm{s} longleftrightarrow ] ( c ) [ begin{array}{l} Leftrightarrow 7 mathrm{c} / mathrm{s} \ 3 mathrm{c} / mathrm{s} longleftrightarrow(oplus) end{array} ] D [ Leftrightarrow 1 mathrm{C} / ] [ text { 9 C/s } longleftarrow ] |
12 |
| 1374 | Current in circuit, which makes bulb glow or heats up the wire, is: A. motion of charges B. motion of atoms c. motion of molecules D. none of the above |
12 |
| 1375 | A cell of emf ( E ) is connected to a resistance ( R_{1} ) for time ( t ) and the amount of heat generated in it is ( H . ) If the resistance ( R_{1} ) is replaced by another resistance ( boldsymbol{R}_{2} ) and is connected to the cell for the same time ( t, ) the amount of heat generated in ( boldsymbol{R}_{2} ) is ( 4 boldsymbol{H} ). Then internal resistance of the cell is: A. ( frac{2 R_{1}+R_{2}}{2} ) в. ( sqrt{R_{1} R_{2}} times frac{2 sqrt{R_{2}}-sqrt{R_{1}}}{sqrt{R_{2}}-2 sqrt{R_{1}}} ) c. ( sqrt{R_{1} R_{2}} times frac{sqrt{R_{2}}-2 sqrt{R_{1}}}{2 sqrt{R_{2}}-sqrt{R_{1}}} ) D. ( sqrt{R_{1} R_{2}} times frac{sqrt{R_{2}}-sqrt{R_{1}}}{sqrt{R_{2}}+sqrt{R_{1}}} ) |
12 |
| 1376 | The resistors in parallel in the following circuit are ( mathbf{A} cdot R_{2} quad ) and ( quad R_{3} ) ( mathbf{B} cdot R_{1} quad ) and ( quad R_{2} ) ( mathbf{C} cdot R_{1} quad ) and ( quad R_{3} ) ( mathbf{D} cdotleft(R_{1}+R_{2}right) quad ) with ( quad R_{3} ) |
12 |
| 1377 | The electrical resistance in ohms of a certain thermometer varies with temperature according to the approximate law: ( boldsymbol{R}=boldsymbol{R}_{boldsymbol{o}}left[mathbf{1}+boldsymbol{alpha}left(boldsymbol{T}-boldsymbol{T}_{boldsymbol{o}}right)right] ) The resistance is ( 101.6 Omega ) at the triple- point of water ( 273.16 mathrm{K}, ) and ( 165.5 Omega ) at the normal melting point of lead (600.5 K). What is the temperature when the resistance is ( 123.4 Omega ? ) |
12 |
| 1378 | ( mathbf{A} ) ( 3 Omega ) resistor as shown in fig is dipped in to a calorimeter containing ( boldsymbol{H}_{2} boldsymbol{O} ). the thermal capacity of ( H_{2} O+ ) calorimeter is 2000 J/K. If the circuit is active for 15 minutes find the rise in temperature of ( boldsymbol{H}_{2} boldsymbol{O} ) A ( cdot 2.4^{circ} mathrm{C} ) В. ( 2.9^{circ} mathrm{C} ) ( c cdot 3.4^{circ} C ) D. ( 1.9^{circ} mathrm{C} ) |
12 |
| 1379 | In a meter-bridge experiment with resistance ( R_{1} ) in left gap and resistance ( X ) in right gap, null point is obtained at ( 40 mathrm{cm} ) from left end. With a resistance ( R_{2} ) in left gap and same resistance ( X ) in right gap, null point is obtained at ( 50 mathrm{cm} ) from left end. Where will be null point if ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2} ) are put first in series and then in parallel, in the left gap and right gap still containing ( X ? ) |
12 |
| 1380 | Which among the following is the commercial unit of electric power? A. volt B. Watt c. Ampere D. Kwh |
12 |
| 1381 | ( mathbf{A} ) ( 12 Omega ) resistance is cut into three equal parts and then connected in triangular form. Determine the equivalent resistance between two ends of any side of the triangle. |
12 |
| 1382 | An ideal voltmeter is connected in Fig. The current in circuit is ( A, 2 A ) B. 2.5 c. infinity D. zero |
12 |
| 1383 | Two resistances are connected in the two gaps of a metre bridge. The balance point is ( 20 mathrm{cm} ) from the zero end. When a resistance ( 15 Omega ) is connected in series with the smaller of two resistances, the null point shifts to ( 40 mathrm{cm} . ) The smaller of the two resistances has the value. ( A cdot 8 Omega ) B. ( 9 Omega ) ( c .10 Omega ) D. 12Omega |
12 |
| 1384 | Assertion Electric conduction in gases is possible at normal pressure. Reason The electric conduction in gases depends only upon the potential difference between the electrodes. 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 |
| 1385 | A point charge ( q ) is brought from infinity(slowly so that the heat developed in the shell is negligible) and is placed at the centre of a conducting neutral spherical shell of inner radius a and outer radius ( b ), then work done by external agent is: ( A cdot O ) B. ( frac{k q^{2}}{2 b} ) c. ( frac{k q^{2}}{2 b}-frac{k q^{2}}{2 a} ) D. ( frac{k q^{2}}{2 a}-frac{k q^{2}}{2 b} ) |
12 |
| 1386 | In the potentiometer arrangement shown in figure, null point is obtained at length ( l ) Table Table – 2 (a) If ( E_{1} ) is increased (p) ( l ) should increase (b) If ( mathrm{R} ) is increased (q) ( l ) should decrease (c) If ( E_{2} ) is increased (r) ( l ) should remain the same to again get the null point A. a ( -q, b-q, c-p ) ( c cdot a-p, b-p, c-r ) D. a – q, b-p, c-p |
12 |
| 1387 | At room temperature, copper has free electron density of ( 8.4 times 10^{28} m^{-3} . ) The electron drift velocity in a copper conductor of cross-sectional area of ( 10^{-6} m^{2} ) and carrying a current of 5.4 ( mathbf{A}, mathbf{w} ) ill be A ( cdot 4 m s^{-1} ) B. ( 0.4 mathrm{ms}^{-1} ) ( mathrm{c} cdot 4 mathrm{cms}^{-1} ) D. ( 0.4 mathrm{mms}^{-1} ) |
12 |
| 1388 | 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 |
| 1389 | Explain with the help of a labelled diagram the distribution of a magnetic field due to a current through a circular loop. Why is it that if a current carrying loop has n turns the field produced at any point is ( n ) times as large as that produced by a single turn? |
12 |
| 1390 | The electric current in a circuit is given by ( i=frac{i_{0} t}{tau} ) for some time. The rms current for the period ( t=0 ) to ( t=tau ) will be ( mathbf{A} cdot i_{0} sqrt{frac{T}{3}} ) B. ( frac{i_{0}}{sqrt{3}} ) ( c cdot frac{i_{0}}{2} ) D. ( frac{i_{0}}{3} ) |
12 |
| 1391 | In making an Ohm’s law circuit, which of the following connection is correct? A. Voltmeter is series and ammeter in parallel B. Voltmeter in parallel and ammeter in series c. voltmeter and ammeter both are in parallel D. Voltmeter and ammeter both are in series |
12 |
| 1392 | A potentiometer wire of length ( 1 mathrm{m} ) has a resistnce of ( 10 Omega ).It is connected to a 6 v battery in series with a resistance of ( 5 Omega ) Determine the emf of the primary cell which gives a balance point at ( 40 mathrm{cm} ) |
12 |
| 1393 | The power supplied by the battery will be: A. ( 15 mathrm{w} ) B. 24 W c. ( 3.6 mathrm{w} ) D. 20 W |
12 |
| 1394 | Find the equivalent resistance across ( A B ) for the given circuit: A . ( 1 Omega ) B. ( 2 Omega ) ( c .3 Omega ) D. ( 4 Omega ) |
12 |
| 1395 | The unit of resistivity of the material is A . ( Omega ) в. ( Omega m ) ( c . Omega / m ) D. ( m / Omega ) |
12 |
| 1396 | 10. If resistance S in RB = 30092, then the balanced length is found to be 25.0 cm from end A. The diameter of unknown wire is 1mm and length of the unknown wire is 31.4 cm. The specific resistivity of the wire should be (a) 2.5 x 10-2-m (b) 3.5 x 1042-m (c) 4.5 x 10-2-m (d) None of these |
12 |
| 1397 | State the working principle of a potentiometer with the help of the circuit diagram, explain how a potentiometer is used to compare the emf’s of the two primary cell obtain the required expression used for comparing the emf’s. |
12 |
| 1398 | The resistivity of a wire varies with its A . length B. cross-section c. mass D. material |
12 |
| 1399 | Q Type your question. resistance of ( 12 Omega ) are connected thick conducting strips, as shown in the figure. A battery and a galvanometer (With a sliding jockey connected to it) are also available connections are to be made to measure the unknown resistance ( boldsymbol{X} ) using the principle of Wheatstone bridge. Answer the following questions. (a) Are there positive and negative terminals on the galvanometer (b) copy the figure is your answer book and show the battery and the galvanometer (With jockey) connected at appropriate points. (c) After appropriate connections are made, it is found that no deflection takes place in the galvanometer when the sliding jockey touches the wire at a distance of ( 60 mathrm{cm} ) from ( A . ) Obtain the value of the resistance of ( boldsymbol{X} ) |
12 |
| 1400 | Which of the following is used for the formation of thermistor? A. copper oxide B. Nickel oxide c. Iron oxide D. All of the above |
12 |
| 1401 | What is the p.d. across the terminals ( left(V_{T}right) ) of a cell with emf ( E ) for open circuit ( ? ) A ( cdot V_{T}E ) c. ( V_{T}=0 ) D. ( V_{T}=E ) |
12 |
| 1402 | A motor rated ( 500 mathrm{W}, 230 mathrm{V} ) utilizes 3 units of electrical energy. Calculate the time for which the motor works. |
12 |
| 1403 | toppr Q Type your question circuited and the current i is measured. Which of the following graphs give correct relationship between i and n? ( A ) ( B ) ( c ) ( D ) |
12 |
| 1404 | A cylindrical conductor is placed near other positively charged conductor. The net charge acquired by the cylindrical conductor will be : A. Positive only B. Negative only c. zero D. Either positive or negative |
12 |
| 1405 | A resistor connected to a battery is heated due to current through it. Which of the following quantity does not vary? A . resistance B. drift velocity c. resistivity D. number of free electrons |
12 |
| 1406 | The areas of cross section of two wires of the same material are in the ratio 1: 2 and their lengths are in the ratio 2: 1 If their ends have the same potential differences then currents through them will be in the ratio of A .1: 2 B . 2: 1 c. 1: 4 D. 4: 1 |
12 |
| 1407 | If the current in the primary circuit is decreased,then balancing length is obtained in the potentiometer is at: A. Lower length B. Higher length c. Same length D. 1/3rd length |
12 |
| 1408 | In a meter bridge, the wire of length ( 1 mathrm{m} ) has a non-uniform cross-section such that, the variation ( frac{d R}{d l} ) of its resistance ( R ) with length ( l ) is ( frac{d R}{d l} propto frac{1}{sqrt{l}} . ) Two equal resistances are connected as shown in the figure. The galvanometer has zero deflection when the jockey is at point ( P ) What is the length ( A P: ) ( A cdot 0.2 m ) В. ( 0.3 m ) c. ( 0.25 m ) D. ( 0.35 m ) |
12 |
| 1409 | The length and area of cross-section of a conductor are doubled, its resistance is A. unchanged B. halvedd c. doubled D. quadrupled |
12 |
| 1410 | A current of ( 5 mathrm{A} ) is passing through a metallic wire of length ( 5 mathrm{m} ) and crosssectional area of ( 10^{-5} m^{2} . ) If the density of the electrons in the wire is ( 6.25 x ) ( 10^{26} m^{3}, ) find the time taken by the electrons to travel from one end of the wire to the other. |
12 |
| 1411 | Two dimetrically opposite points of a metal ring are connected to two terminals of the left gap of metrebridge. The resistance of ( 11 Omega ) is connected in right gap. If null point is obtained at a distance of ( 45 mathrm{cm} ) from the left end, find the resistance of metal ring. |
12 |
| 1412 | In a potentiometer using two cells in series gives a balance length of ( 600 mathrm{cm} ) When the same cells are connected opposing each other then balance length is ( 100 mathrm{cm} ). The ratio of emf of larger to smaller cell is: A .7: 5 в. 5: 7 ( c cdot 6: 1 ) D. 1: 6 |
12 |
| 1413 | In the given (a) calculate the effective resistance of the circuit and (b) calculate the reading of the ammeters ( A_{1} A_{2} ) and ( A_{1} ) If ( R_{1}=10 Omega ) and ( R_{2}=6 Omega ) and ( boldsymbol{E}=mathbf{1 0} boldsymbol{V} ) |
12 |
| 1414 | A battery of emf ( E_{0}=12 mathrm{V} ) is connected across a ( 4 mathrm{m} ) long uniform wire having resistance ( frac{4 Omega}{m} . ) The cells of small emfs ( varepsilon_{1} ) ( =2 V ) and ( varepsilon_{2}=4 V ) having internal resistance ( 2 Omega ) and ( 6 Omega ) respectively, are connected as shown in the figure. If galvanometer shows no deflection at the point ( mathrm{N} ), find the distance of point ( mathrm{N} ) from the point ( mathbf{A} ) |
12 |
| 1415 | A wire of uniform cross-section has a resistance of ( boldsymbol{R} ) Omega. What would be the resistance of a similar wire, made of the same material, but twice as long and of twice the diameter? A ( cdot frac{3}{2} R ) в. ( frac{5}{2} R ) c. ( frac{1}{2} R ) D. ( frac{1}{4} R ) |
12 |
| 1416 | What is the resistance, under normal working conditions, of an electric lamp rated ‘240 ( V, 60 mathrm{W} ) ? If two such lamps are connected in series across a ( 240 mathrm{V} ) mains supply, explain why each one appears less bright. |
12 |
| 1417 | ( frac{2}{2} ) | 12 |
| 1418 | A given resistor has the following colour code of the various strips on it : Brown, black, green and silver. The value of its resistance in ohm is A ( cdot 1.0 times 10^{4} pm 10 % ) B . ( 1.0 times 10^{7} pm 5 % ) C. ( 1.0 times 10^{6} pm 10 % ) D. ( 1.0 times 10^{5} pm 5 % ) E . ( 1.0 times 10^{3} pm 10 % ) |
12 |
| 1419 | Name the instrument used to control the current in an electric circuit. A. Rheostat B. Voltmeter c. Ammeter D. Galvanometer |
12 |
| 1420 | Resistance of a resistor at temperature ( t^{circ} boldsymbol{C} ) is ( boldsymbol{R}_{t}=boldsymbol{R}_{0}left(mathbf{1}+boldsymbol{alpha} boldsymbol{t}+boldsymbol{beta} boldsymbol{t}^{2}right), ) where ( boldsymbol{R}_{0} ) is the resistance at ( 0^{circ} mathrm{C} ). The temperature coefficient of resistance at temperature ( t^{circ} C ) is A ( cdot frac{left(1+alpha t+beta t^{2}right)}{alpha+2 beta t} ) B. ( (alpha+2 beta t) ) c. ( frac{alpha+2 beta t}{left(1+alpha t+beta t^{2}right)} ) D. ( frac{alpha+2 beta t}{2left(1+alpha t+beta t^{2}right)} ) |
12 |
| 1421 | All free charges are integral multiple of a basic unit charge ( e . ) Then quantization rule of electric charge implies ( mathbf{A} cdot Q=e ) в. ( Q=frac{1}{e} ) c. ( Q=n e ) D. ( Q=e^{2} ) |
12 |
| 1422 | When current flows through a conductor, then the order of drift velocity of electrons will be:- ( mathbf{A} cdot 10^{10} mathrm{cms}^{-1} ) B. ( 10^{-2} mathrm{cms}^{-1} ) ( mathbf{c} cdot 10^{4} c m s^{-1} ) D. ( 10^{-1} mathrm{cms}^{-1} ) |
12 |
| 1423 | Derive the balancing condition of a Wheatstone bridge. |
12 |
| 1424 | How much greater is one micro coulomb compared to an electronic charge? A ( cdot 10^{13} ) times B. ( 10^{10} ) times ( mathbf{c} cdot 10^{11} ) times D. ( 10^{6} ) times |
12 |
| 1425 | Kirchoffs 1st and 2nd laws are based on conservation of A. Energy and charge respectively B. Charge and energy respectively c. Mass and charge respectively D. None of these above |
12 |
| 1426 | Color of the four strips of carbon resistor are respectively orange, green golden, silver. Then its resistance is : ( mathbf{A} cdot 2.5 pm 10 % ) ohm B. ( 3.5 pm 5 % ) ohm c. ( 3.5 pm 10 % ) ohm ( mathbf{D} cdot 350 pm 10 % ) ohm |
12 |
| 1427 | Constantan wire is used for making standard resistance, because it has A. high melting point. B. low specific resistance C . high specific resistance. D. negligible temperature coefficient of resistance. |
12 |
| 1428 | Three resistances are joined together to form a letter ( Y ) as shown in the figure.If the potentials of the terminals ( mathbf{A}, mathbf{B} ) and ( mathrm{C} ) are ( mathrm{V}_{1}, mathrm{V}_{2} ) and ( mathrm{V}_{3} ) respectively, then determine the potential of the node ( boldsymbol{O} ) ( ^{mathbf{A}} cdotleft[frac{V_{1}}{R_{1}^{frac{1}{1}}}+frac{V_{2}}{R_{2}^{2}}+frac{V_{3}}{R_{3}^{3}}right]left[frac{1}{R_{1}}+frac{1}{R_{2}}+frac{1}{R_{3}}right]^{-2} ) ( ^{mathbf{B}} cdotleft[frac{V_{1}}{R_{1}}+frac{V_{2}}{R_{2}}+frac{V_{3}}{R_{3}}right]left[frac{1}{R_{1}}+frac{1}{R_{2}}+frac{1}{R_{3}}right]^{-1} ) ( mathbf{C} cdotleft[frac{V_{1}}{R_{1}}+frac{V_{2}}{R_{2}}+frac{V_{3}}{R_{3}}right]left[R_{1}+R_{2}+R_{3}right] ) D. ( left[frac{V_{1}}{R_{2}^{2}}+frac{V_{2}}{R_{2}^{2}}+frac{V_{3}}{R_{2}}right]left[R_{1}^{2}+R_{2}^{2}+R_{3}^{2}right] ) |
12 |
| 1429 | If resistance of wire at ( 50^{circ} mathrm{C} ) is ( 5 mathrm{R} Omega ) and ( 100^{circ} mathrm{C} ) is ( 6 mathrm{R} Omega, ) find resistance of ( 0^{circ} mathrm{C} ) |
12 |
| 1430 | N lamps each of resistance ( r, ) are fed by a machine of resistance R. If light emitted by any lamp is proportional to the square of the heat produced, prove that the most efficient way of arranging them is to place them in parallel arcs, each containing n lamps, where n is the integer nearest to. ( ^{mathbf{A}} cdotleft(frac{r}{N R}right)^{3 / 2} ) ( ^{mathbf{B}} cdotleft(frac{N R}{r}right)^{1 / 2} ) ( mathbf{C} cdot(N R r)^{3 / 2} ) D. ( (N R r)^{1 / 2} ) |
12 |
| 1431 | A house is fitted with ten lamps of each ( 60 W . ) Each lamp burns for 5 hrs a day on an average. The cost of consumption in a month of 30 days at 2.80 rupees per unit is: A . Rs.152 B. Rs.252 c. ( R s .352 ) D. Rs.452 |
12 |
| 1432 | In an experiment, the resistance of a material is plotted as a function of temperature (in some range). As shown in the figure, it is a straight line. One may conclude that: A ( cdot R(T)=frac{T_{0}}{T^{2}} ) B . ( R(T)=R_{0} e^{-T^{2} / T_{0}^{2}} ) C ( cdot R(T)=R_{0} e^{-T_{0}^{2} / T^{2}} ) D. ( R(T)=R_{0} e^{T^{2} / T_{0}^{2}} ) |
12 |
| 1433 | In a potentiometer experiment, the balancing length of potentiometer of a cell of e.m.f ( 1.5 mathrm{V} ) in the secondary is 440 cm. A resistance ( 5 Omega ) is connected between the terminals of cell, the balancing length is ( 400 mathrm{cm} . ) Then a) internal resistance of the cell is ( 0.5 Omega ) b) terminal voltage of the cell is ( 15 / 11 v ) c) Potential gradient of the potentiometer wire is ( frac{1.5}{40} V / c m ) d) potential difference across the potoentiometer wire of length ( 10 mathrm{m} ) is nearly ( 3.4 mathrm{V} ) A. a,b are correct B. a,b and c are correct ( c . ) a, b and d are correct D. a,b,c and d are correct |
12 |
| 1434 | A current of ( 5 A ) passes through a copper conductor (resistivity ( =1.7 times ) ( 10^{-8} Omega m ) ) of radius of cross-section 5 ( m ) m. Find the mobility of the charges if their drift velocity is ( 1.1 times 10^{-3} m / s ) A ( cdot 1.3 m^{2} / V s ) B. ( 1.5 mathrm{m}^{2} / mathrm{Vs} ) ( mathbf{c} cdot 1.8 m^{2} / V s ) D. ( 1.0 m^{2} / V s ) |
12 |
| 1435 | The potentiometer wire AB is made of two equal parts ( A N ) and ( N B ) of cross sectional radius ( 2 r ) and ( r ) respectively.The material of both parts is same. A cell is connected between ( mathbf{A} ) and B. The potential gradient in the part AN is ( 1 V / m . ) Potential difference between two points ( C ) and ( D ) (shown in figure) separated by ( 20 mathrm{cm} ) is found to be ( 0.5 V . ) The separation between ( C ) and ( mathrm{N} ) is ( frac{t}{3} mathrm{cm} . ) Then ( t ) is |
12 |
| 1436 | The number of free electrons per ( 10 mathrm{mm} ) ordinary copper wire is about ( 2 times 10^{21} ) The average drift speed of the electrons is ( 0.25 mathrm{mm} ) current flowing is: A. ( 0.8 mathrm{A} ) B. 8 A ( c .80 mathrm{A} ) D. 5 A |
12 |
| 1437 | For the following circuits, the potential difference between ( X ) and ( Y ) in volt is: 4 B. 4 3 ( c ) D. 5 |
12 |
| 1438 | A piece of wire of resistance ( 4 Omega ) is bent through ( 180^{circ} ) at its mid point and the two halves are twisted together, then resistance is : A . ( 1 Omega ) B. 2Omega c. ( 5 Omega ) D. 8Omega |
12 |
| 1439 | Refer to teh circuit shown. What will be the total power dissipation in the circuit if ( boldsymbol{P} ) is the power dissipated in ( R_{1} ? ) It is given that ( R_{2}=4 R_{1} ) and ( R_{3}= ) ( 12 R_{1} ) A ( .4 P ) в. ( 7 P ) c. ( 13 P ) D. ( 17 P ) |
12 |
| 1440 | A ( 10 V ) olts battery of internal resistance one ohm is connected to a ( 20 mathrm{V} ) olt battery of internal resistance 2ohm. The combination is put across a resistance of 30 oh ( m . ) Find the current through each battery |
12 |
| 1441 | State whether given statement is True or False.
Silver is a good conductor of electricity. |
12 |
| 1442 | ( mathbf{A} ) ( 1 k W ) heater is meant to operate at ( 200 V . ) How many units of electrical energy will it consume in a month (of 30 days) if it operates 10 h daily at the specified voltage ( (200 vee) ? ) |
12 |
| 1443 | Calculate the power of an electric bulb which consumes 2400 Jin a minute ( A cdot 80 w ) B. 120 W ( c cdot 60 w ) D. ( 40 mathrm{w} ) |
12 |
| 1444 | Five identical resistor are initially arranged a shown in the figure be clear lines. If two similar resistances are added as shown by the dashed lines then change in resistance in final and initial arrangement is ( mathbf{A} cdot 2 Omega ) B. ( 1 Omega ) ( c cdot 3 Omega ) D. ( 4 Omega ) |
12 |
| 1445 | A cylindrical rod is reformed to half of its original length keeping volume constant. If its resistance before this change were ( R ), then the resistance after reformation of rod will be. ( A cdot R ) в. ( R / 4 ) c. ( 3 R / 4 ) D. ( R / 2 ) |
12 |
| 1446 | Human nails are good insulators A . True B. False |
12 |
| 1447 | In the following figure the current through ( 4 Omega ) resistor is ( 4 cdot 1.4 mathrm{A} ) B. ( 0.4 mathrm{A} ) ( c cdot 1.0 A ) D. 0.7 |
12 |
| 1448 | What is the current drawn from the source in the given circuit? ( A cdot 2 A ) B. 1.5 ( c cdot 4 A ) D. 3 A |
12 |
| 1449 | A transformer with turns ratio ( frac{N_{1}}{N_{2}}= ) ( mathbf{5 0} ) ( frac{w}{1} ) is connected to a 120 volt ( A C ) supply If primary and secondary circuit resistance are ( 1.5 k Omega ) and ( 1 Omega ) respectively then find out power out put A ( .5 .76 mathrm{w} ) B. ( 11.4 mathrm{w} ) c. ( 2.89 mathrm{w} ) D. ( 7.56 mathrm{w} ) |
12 |
| 1450 | The electron beam in a television picture tube travels a distance lin evacuated space of the tube. If the speed of the electrons is ( v ) and the beam current is i, then the number of electrons in the beam at any instant will be A. ( frac{i l}{e v} ) в. ( frac{i}{l e v} ) c. ( frac{v}{i l e} ) D. ( frac{e}{i l v} ) |
12 |
| 1451 | Two cells of the same emf ( e ) but difference internal resistances ( r_{1} ) and ( r_{2} ) are connected in series with an external resistance ( R ). The potential drop across the first cell is found to be zero. The external resistance ( boldsymbol{R} ) is A ( cdot r_{1}-r_{2} ) в. ( r_{1} / r_{2} ) ( c cdot r_{1} r_{2} ) D. ( r_{1}+r_{2} ) |
12 |
| 1452 | A 10 m long potentiometer wire is connected to a battery having a steady voltage. A Leclanche cell is balanced at ( 4 m ) length of the wire. If the length is kept the same, but its cross-section is doubled, the null point will be obtained at: ( mathbf{A} cdot 8 m ) в. ( 4 m ) c. ( 2 m ) D. None of these |
12 |
| 1453 | For a cell the graph between the potential difference (V) across the terminals of the cells and the current (I) drawn from the cell is shown in the figure. The emf and the internal resistance of the cell are: |
12 |
| 1454 | In a potentiometer of 10 wires, the balance point is obtained on the ( 7^{t h} ) wire. To shift the balance point to ( 9^{t h} ) wire, we should. A. Decrease resistance in the main circuit B. Increase resistance in the main circuit c. Decrease resistance in series with the cell whose emf is to be measured D. Increase resistance in series with the cell whose emf is to be determined |
12 |
| 1455 | A circular conductor is made of a uniform wire of resistance ( 2 times ) ( 10^{-3} ) ohm / meter and the diameter of this circular conductor is 2 meter. Then the resistance measured between the ends of the diameter is (in ohms): A ( cdot pi times 10^{-3} ) В. ( 2 pi times 10^{-3} ) c. ( 4 pi times 10^{-3} ) D. ( 4 times 10^{-3} ) |
12 |
| 1456 | Find emf of the cell ( E_{2} ) A. ( 2 v ) B. 1.5 ( c cdot 1 v ) D. 1.75 V |
12 |
| 1457 | Potentiometer wire Pq of length Im is connected to a standard cell ( boldsymbol{E}_{1} ) Another cell of E2 of emf1.02v/s connected as shown in the circuit diagram with a resistance ‘r’ and with a switch ‘s’. With the switch ( mathrm{S} ) open, null position is obtained at a distance of ( 51 mathrm{cm} ) from p,Calculate A. Potential gradient of the wire. B. emf of the cell C. When switch S is closed, will null point moves towards p or ( Q ? ) D. insufficient data |
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| 1458 | For determination of resistance of a coil which of two methods is better Ohm’s Law method or metre bridge method? |
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| 1459 | Three equal resistors, connected across a source of e.m.f. together dissipate 10 watt of power. What will be the power dissipated in watts if the same resistors are connected in parallel across the same source of e.m.f. A . ( 10 V ) в. ( 10 / 3 V ) c. ( 30 V ) D. ( 90 V ) |
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| 1460 | An electric heater operating at ( 220 mathrm{V} ) boils ( 5 l ) of water in 5 minutes. If it is used on a ( 110 mathrm{V} ) line, it will boil the same amount of water in: A . 10 minutes B. 20 minutes c. 5 minutes D. 1 minute |
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| 1461 | toppr Q Type your question the following: 4 B. ( c ) ( D ) |
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| 1462 | Plot a graph showing the variation of current ( I ) versus resistance ( R ) connected to a cell of emf ( E ) and internal resistance ( r ) |
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| 1463 | How much current is drawn by the motor of 1 H.P. from 220 volt supply. A. 3.4A B. 2A ( c cdot 6 A ) D. 22A |
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| 1464 | A metal wire of diameter ( 4 mathrm{mm} ) and length ( 100 mathrm{m} ) has a resistance of ( mathbf{0 . 4 0 8} mathbf{Omega} ) at ( mathbf{1 0}^{circ} mathbf{C} ) and ( mathbf{0 . 5 0 8} mathbf{Omega} ) at ( mathbf{1 2 0}^{circ} boldsymbol{C} ) Find the value of a. temperature coefficient of resistance b. its resistance at ( 0^{circ} mathrm{C} ) c. its resistivities at ( 0^{circ} mathrm{C} ) and ( 120^{circ} mathrm{C} ) |
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| 1465 | Consider the potentiometer circuit arranged as in figure. The potentiometer wire is ( 600 mathrm{cm} ) long. At what distance from the point ( A ) should the jockey touch the wire to get zero deflection in the galvanometer? |
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| 1466 | To draw a maximum current from a combination of cells,how should the cells be grouped? A. Parallel B. Series c. Mixed grouping D. Depends upon the relative values of internal and external resistances |
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| 1467 | As the temperature of a metallic resistor is increased, the product of resistivity and conductivity: A . increases B. decreases c. may increase or decrease D. remains constant |
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| 1468 | A cell supplies a current of ( 0.9 A ) through a ( 2 Omega ) resistor and a current of ( 0.3 A ) through a ( 7 Omega ) resistor. The internal resistance of the cell is :- ( mathbf{A} cdot 1.0 Omega ) B. ( 0.5 Omega ) c. ( 2.0 Omega ) D. ( 1.2 Omega ) |
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| 1469 | Which of the following wires of the same material will have higher resistance :- A. radius is 1 ( mathrm{mm} ) and the length is 40 ( mathrm{m} ) B. radius is 2 ( mathrm{mm} ) and the length is 40 ( mathrm{m} ). c. radius is ( 1 mathrm{mm} ) and the length is ( 80 mathrm{m} ) D. radius is 2 ( mathrm{mm} ) and the length is 80 ( mathrm{m} ). |
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| 1470 | In the given circuit, the steady state voltage drop across the capacitor ( C ) is ( A cdot frac{V r_{r}}{r_{2}+r_{3}} ) B. ( frac{V r_{r}}{r_{1}+r_{3}} ) ( c cdot frac{V r_{r}}{r_{1}+r_{2}} ) D. ( frac{V r_{r}}{r_{1}+r_{2}} ) |
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| 1471 | Two identical cells, each of emf ( mathrm{E} ), having negligible internal resistance are connected in parallel with each other across an external resistance ( R ) what is the current through this resistance? |
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| 1472 | Three equal resistors connected in series across a source of e.m.f. together dissipate 10 watt of power. What would be the power dissipated if the same resistors are connected in parallel across the same source of e.m.f.? A. 90 watts B. 80 watts c. 70 watts D. 75 watts |
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| 1473 | Current is flowing with a current density ( J=480 ) amp ( / mathrm{cm}^{2} ) in a copper wire. Assuming that each copper atom contribution one free electron and gives that Avogadro number ( =mathbf{6 . 0} times ) ( 10^{23} ) atoms/mole Density of copper ( = ) ( 9.0 g / c m^{3} . ) Atomic weight of copper ( = ) ( 64 g / ) mole Electronic charge ( =1.6 times ) ( 10^{-19} ) coulomb. The drift velocity of electrons is: ( mathbf{A} cdot 1 mathrm{mm} / mathrm{s} ) B. ( 2 mathrm{mm} / mathrm{s} ) c. ( 0.5 mathrm{mm} / mathrm{s} ) D. ( 0.36 mathrm{mm} / mathrm{s} ) |
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| 1474 | A resistor of ( 6 k Omega ) with tolerance ( 10 % ) and another of ( 4 k Omega ) with tolerance |