1) As per Faraday's law of electromagnetic induction, the value of induced electromotive force in a circuit is directly proportional to the rate of change of the number of a. potential difference b. electromagnetic difference c. magnetic lines of force d. electromagnetic induction
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2) The direction of induced current always a. opposes the cause b. remains same as that of cause c. equal to cause that produces it d. directs the cause
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3) If a coil is rotated in a magnetic field, there will be induced a a. current b. wave c. friction d. stress
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4) Soft iron can be easily a. magnetized only b. demagnetized only c. convert into gas d. magnetized and demagnetized
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5) The direction of the magnetic field is governed by the direction of a. voltage b. Electromotive force (EMF) c. current d. none of above
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6) An electromagnet is a. permanent b. temporary c. insulator d. conductor
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7) When the plane of the coil is parallel to the lines of magnetic force, the number of lines of magnetic force passing through the coil will be a. minimum b. maximum c. zero d. none of above
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8) In coil, the change in the number of magnetic field lines will induce an a. electromotive force b. potential difference c. electromagnetic force d. none of above
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9) The power is transmitted over long distances and high voltages to a. minimize the energy loss b. maximize the energy loss c. make energy content constant d. preserve energy
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10) To increase or decrease AC voltages, we use a. fuse b. circuit breaker c. transformer d. generator
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11) The magnitude of induced e.m.f in a circuit depends on the a. speed of relative motion of coil b. speed of relative motion of magnet c. number of turns of the coil d. all of above
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12) The value of induced Electromotive force (EMF) is directly proportional to a. current through coil b. voltage applied c. no. of field lines d. resistivity
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13) When the surface is held parallel to the magnetic lines of force, the number of lines of force is a. negative b. zero c. maximum d. minimum
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14) The number of magnetic lines of force passing through any surface is called a. nature of magnetic field b. strength of magnetic field c. work of magnetic field d. weakness of magnetic field
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15) If the secondary voltage is smaller than the primary voltage, the transformer is called a a. positive transformer b. step-up transformer c. negative transformer d. step-down transformer
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16) A device that converts electric energy into rotational kinetic energy is called a. circuit breaker b. transformer c. generator d. electric motor
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17) The loop in magnetic field rotates due to a. Electromotive force (EMF) b. frequency c. resistance d. torque
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18) If the coil is placed perpendicular to field lines then the number of lines passing through the coil is a. minimum b. maximum c. zero d. may be max. or min.
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19) If a transformer is used to supply voltage to a 15 V model train which draws a current of 0.7 A. If the voltage of the A.C source is 210 V, the current in the primary should be a. 0.04 A b. 0.05 A c. 0.03 A d. 0.02 A
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20) If the AC source is 240 V and a transformer supplies 12 V to a model train which draws a current of 0.8 A then primary current is a. 0.4 A b. 0.04 A c. 0.0416666666666667 d. 0.0833333333333333
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