Electromagnetic Induction Mock Test – Class 12 Physics

1. For a rotating coil with , , , and , the peak induced emf is

2. A secondary coil of resistance is linked to a primary coil with . If the primary current changes uniformly at , the heat produced in the secondary in is

3. A straight conducting rod of length moves with speed perpendicular to a uniform magnetic field . The motional emf across its ends is

4. The relation is consistent with Faraday's law because induced emf is related to

5. Magnetic flux through a surface gives a measure of

6. For a single-turn loop, an - graph is a rectangle: from to . The change in magnetic flux during this interval is

7. A south pole is moved away from a closed coil. Viewed from the magnet side, the near face of the coil must become a north pole. The induced current as seen from that side is

8. In a simple generator arrangement, the emf induced in the rotating coil is internally alternating, but the external output becomes unidirectional because

9. Use the graph description below.

At current , the slope of the - graph is

10. A similar -turn coil of area is placed so that its area vector is parallel to a magnetic field. The field decreases uniformly from to in . If the coil resistance is , the induced current magnitude is

11. A rectangular loop is pulled into a magnetic field region at constant speed. The magnetic force on the loop during entry is best described as

12. A magnet is first pushed into a coil and then pulled out along the same line. The galvanometer deflections are opposite because

13. A conducting rod of length moves on rails in a uniform magnetic field with speed . The total circuit resistance is . If the speed is doubled and the resistance is tripled, the new power dissipated compared with the original power is

14. For a closed circuit of resistance , an induced emf produces an induced current given by

15. Study the table about eddy current reduction.

The row with the faulty statement is

16. A pair of coaxial solenoids has , , common area , common length , and . Their mutual inductance is

17. A secondary coil links of flux per turn when the primary current is . If the secondary has turns, the mutual inductance is

18. A conducting plate has narrow slots cut in it before it is allowed to swing through a magnetic field. The plate experiences less damping because the slots

19. A derivation of magnetic energy density for a long solenoid uses the steps below.

The faulty step is

20. If the speed of rotation of a simple generator is doubled while , , and remain unchanged, both the peak emf and frequency

21. A derivation of contains one faulty step:

The faulty step is

22. An inductor stores of energy when it carries . Its inductance is

23. For a generator coil rotating in a magnetic field, the flux linkage is . The generated emf at is closest to

24. A fixed coil of resistance has turns, each of area . Its area vector is parallel to a magnetic field increasing at . The induced current magnitude is

25. A rectangular loop of height , resistance , and speed enters a uniform magnetic field . During entry, the power dissipated in the loop is

26. A coil with inductance is connected to a source, and the current changes at a constant rate. The magnitude of self-induced emf depends on

27. A thick metal block and a thin metal sheet of the same material are moved in similar changing magnetic-flux conditions. Eddy currents are usually stronger in the thick block because

28. For a generator coil with , , , and , if , the instantaneous emf is

29. A rectangular loop has height , resistance , and enters a uniform magnetic field at . The external force needed to maintain constant speed during entry is

30. In an circuit, the current grows as . At time , the fraction of final magnetic energy stored in the inductor is

31. A rectangular loop has height and total resistance . It enters a uniform magnetic field of at . The field is perpendicular to the loop. During entry, the induced current magnitude is

32. In a mutual-induction experiment, the primary current is first increased uniformly and then decreased uniformly at the same rate. The induced emf in the secondary during the decrease is

33. The current growth in a series circuit connected to a source is

34. A closed circuit has induced emf and total resistance . If the resistance is changed to without changing the flux-change rate, the new current is

35. A circuit is placed in a magnetic field so that the flux linked with it changes uniformly. If the same total flux change is made in a shorter time, the induced emf magnitude becomes

36. A source is connected to a series circuit containing and . At the instant when the current is during growth, the magnitude of is

37. The distinction between magnetic flux and flux linkage is best expressed by

38. Use the arrangement described below. A coil is viewed from the side facing an approaching north pole of a magnet. If the near face of the coil must behave as a north pole, the induced current as seen from the magnet side is

39. A circular loop of radius has turns and total resistance . It is placed with its area vector parallel to a magnetic field that changes as . The induced current magnitude at is closest to

40. In a coil, increasing the number of turns increases the induced emf for the same rate of change of flux per turn because

41. For a generator coil with , , , and angular speed , the peak emf is

42. A current-time graph for the primary coil is described below.

During which interval is the induced emf in the secondary expected to be zero?

43. A pair of coils has . The primary current varies as , where is in . The magnitude of secondary induced emf is

44. In a sliding-rod generator, the mechanical power supplied at constant speed is equal to

45. A generator coil is changed from turns to turns, and its angular speed is reduced to half. If and remain unchanged, the peak emf

46. Read the situation below.

What is the induced current as seen from above the table?

47. A coil is connected to an ideal voltmeter but not to a closed conducting circuit. The magnetic flux linked with the coil changes with time. The most suitable statement is that

48. A rectangular loop is in a uniform magnetic field perpendicular to its plane. The magnetic field is steady, but the area of the loop increases with time. The induced emf appears because

49. In a device core, the same induced emf is produced around a possible eddy-current path. If the effective resistance of that path is made four times larger, the eddy current becomes

50. A compact rule for magnet-coil direction questions is: first decide whether the coil must repel or attract the magnet, then use the right-hand grip rule. This works because