Electromagnetic Induction Mock Test – Class 12 Physics

1. Study the table about factors affecting self-inductance.

The row with the faulty statement is

2. For a coil with turns, the phrase “same flux through all turns” is important because

3. The energy stored in an inductor of self-inductance carrying current is

4. An inductor of inductance carries current . If the current is increased to , the increase in magnetic energy stored is

5. A coil current falls rapidly when a switch is opened. A spark may appear at the switch because

6. A rectangular loop of height and resistance enters a magnetic field at . During entry, the power dissipated and the magnetic force opposing motion are respectively

7. A rod moves at in a magnetic field. The angle between and is , and the standard oblique motional-emf geometry applies. The emf is

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

9. A primary-secondary coil pair is moved farther apart without changing the coils themselves. The mutual inductance generally decreases because

10. A magnetic core used for strong coupling between coils is laminated and made from soft magnetic material. These two design choices mainly reduce

11. A rectangular surface of area is placed in a magnetic field of . The magnetic flux through it is . The angle between and is

12. A -turn coil has flux through each turn changing at a rate of . The total resistance of the closed coil circuit is . Ignoring sign, the induced current is

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

14. A rectangular loop enters a uniform magnetic field region and later leaves it at the same speed. The field is into the page. The induced magnetic force on the loop is

15. A secondary circuit of resistance carries a mutually induced current of . The electrical power dissipated as heat in the secondary resistance is

16. The emf induced in a rotating generator coil is maximum when

17. Two coils are wound close together on a common soft iron core. Compared with the same coils far apart in air, their mutual inductance is usually

18. A current in an circuit is decaying after the source is removed. The current has the form

19. For a single turn, Faraday's law is represented by

20. A loop lies in the plane of the page. Using the right-hand grip rule, a clockwise current in the loop produces a magnetic field

21. The average value of induced emf over a time interval can be obtained from an - graph by

22. A transmission line sends of power. Compare the line current at and .

23. A coil connected to a galvanometer is placed near another coil carrying current. A momentary galvanometer deflection is observed when the current in the nearby coil is switched on. The deflection occurs because

24. A generator coil is at the position where its plane is perpendicular to the magnetic field. At this instant, the flux and emf are respectively

25. In motional emf, a straight conductor moving through a magnetic field develops a potential difference mainly because

26. A generator produces an emf . The time interval between two successive positive peaks is

27. Two coils have mutual inductance . The primary current increases uniformly from to in . The magnitude of the secondary induced emf is

28. A graph of position of a sliding rod against time is a straight line of slope . The rod length is , and the magnetic field is perpendicular to the rail plane. The slope of the magnetic flux-time graph is

29. A claim says, “Lenz's law reduces the induced current to zero in every practical situation.” The better interpretation is that Lenz's law

30. A closed coil has resistance . A changing magnetic flux induces an emf of magnitude in the coil. The magnitude of induced current is

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

32. In comparing self-induction and mutual induction, the correct pairing is

The two correct rows are

33. A series circuit has time constant . During current decay, the current becomes approximately of its initial value after

34. Study the table for circuits under changing magnetic flux.

The row that is not consistent with electromagnetic induction is

35. Magnetic flux linked with a single-turn loop changes uniformly from to in . The magnitude of average induced emf is

36. 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

37. A final device comparison is shown below.

The best conclusion from the table is that

38. A coil has turns, but only half of the turns link a flux ; the remaining half link negligible flux. The total flux linkage is

39. A sinusoidal flux links a -turn coil. The rms induced emf is , and . The peak flux per turn is

40. A simple generator output is often described as pulsating rather than perfectly steady because

41. The emf of a generator coil is described by , with peak emf . At , the flux linkage is most consistent with

42. A graph of current against time for a series circuit after switching on a source is best described as

43. A generator converts mechanical energy into electrical energy mainly through

44. Two coil pairs are compared. Pair P has coaxial coils wound close together on a soft iron core, while Pair Q has coils far apart with axes at right angles. The larger mutual inductance is expected for

45. 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

46. A hand-driven generator produces electrical output when its coil is rotated in a magnetic field. This device is based mainly on

47. The dimensional formula of self-inductance can be obtained from . If , then is

48. In mutual induction, the coil in which current is changed is often called the primary coil, while the coil in which emf is induced is called the secondary coil. The induced emf in the secondary depends directly on

49. The induced emf in the secondary coil due to changing primary current is

50. Use the graph description below.

The induced emf graph begins from