Magnetism and Matter Mock Test – Class 12 Physics

1. A short bar magnet has magnetic dipole moment . Find the axial magnetic field at a point from its centre. Take .

2. The reverse magnetic intensity required to reduce the residual magnetisation of a ferromagnetic material to zero is called

3. The strongest contrast between Gauss's law for electricity and Gauss's law for magnetism is that

4. A permanent magnet is accidentally dropped several times and then heated. Its magnetic field becomes weaker. The explanation most consistent with the domain model is that

5. At a place, Earth's total magnetic field is and the dip angle is . A short bar magnet of moment is placed with . Taking , the distance of an equatorial neutral point from the magnet's centre is approximately

6. A magnetic shield is made thicker using the same high-permeability material. In a qualitative design sense, the shielding usually improves because

7. A material has . Its susceptibility is

8. The vector direction of magnetisation in a uniformly magnetised specimen is along

9. A dipole of moment is in a field . It is rotated slowly from to . The external work done is

10. Use the field description below.

The resulting field at that point is along

11. A naturally occurring magnetic mineral that can attract small pieces of iron is best described as

12. A circular coil has turns, radius , and current . Its magnetic dipole moment is

13. A paramagnetic material obeys Curie's law. If its absolute temperature is doubled, its susceptibility becomes

14. Assertion: A bar magnet in a uniform magnetic field can rotate but does not experience a net force.
Reason: In a uniform field, the magnetic effects on the two poles can be equal and opposite but separated in space.

15. A ferromagnetic material has a narrow hysteresis loop and small coercivity. A student suggests using it for a permanent magnet. The best objection is that the material

16. Use the arrangement described below.

The main purpose of the soft iron box is to

17. Study the table and choose the correct device-material match.

18. A freely suspended compass needle settles approximately along the geographic north-south direction because Earth has

19. The vector symbol commonly used for magnetic field is

20. A ferromagnetic material has a wide hysteresis loop and large coercivity. It is more suitable for making

21. A dipole is rotated slowly in a uniform magnetic field from to . The change in potential energy is

22. The axial field formula is applied to a point whose distance from the magnet's centre is comparable to its magnetic length. The main issue is that

23. A claim says, "At a point far from a bar magnet, the magnetic field is exactly as strong as it is near the pole because the same field lines continue there." The best correction is that

24. In a shielded room, a sensitive magnetic sensor reads a much smaller magnetic field than outside. The shield is most likely effective because

25. Match the magnetic material with a suitable example.

26. A ferromagnetic core has hysteresis energy loss per cycle. If its volume is and it is cycled at , the total power loss is

27. A short magnet is placed with opposite to . Its axial neutral-point distance is . If the magnetic moment is increased to , with unchanged, the new axial neutral distance is

28. A small current loop and a short bar magnet can be compared because both produce, at large distances, a magnetic field pattern like that of

29. A magnetic dipole of moment is placed in a uniform magnetic field . The torque on it is represented by

30. A bar magnet loses much of its magnetisation after being heated strongly. The most suitable explanation is that heating

31. For a linear isotropic magnetic material, the relation between relative permeability and magnetic susceptibility is

32. A ferromagnetic material is required for a relay core that should attract an armature when current flows and release it when current stops. The best choice is a material with

33. Magnetic susceptibility is dimensionless because

34. Study the table and identify the row that correctly matches a quantity with its unit.

35. A material has , and another has . In a non-uniform magnetic field, their expected responses are respectively

36. A short magnetic dipole has axial field at a distance . Another dipole has twice the magnetic moment and is observed at distance on its axial line. Compared with , the new field is

37. A learner says, "Since magnetic field lines are closest near the poles, two lines may cross there." The better correction is that

38. A circular loop of radius carries a current . Its magnetic dipole moment is

39. A short bar magnet is placed with its magnetic moment parallel to Earth's horizontal magnetic field . Neutral points are expected on the equatorial line because the dipole field there is

40. In a hysteresis loop, the magnetisation left in a ferromagnetic specimen when the applied magnetic intensity is reduced to is called

41. Assertion: A diamagnetic material has slightly less than .
Reason: For a diamagnetic material, is small and negative, and .

42. A measurement report says , but . The implied dip angle is

43. Study the table for a short bar magnet in Earth's horizontal magnetic field.

The unsupported rows are

44. A short bar magnet of moment is placed with . At a neutral point on its equatorial line, the distance from the centre is . The relation used to find is

45. At a place, and . A short magnet of moment is placed with opposite to . Taking , the total Earth field and axial neutral distance are respectively

46. A closed spherical surface is imagined around a point in space. If an isolated magnetic monopole existed inside it, the magnetic flux would not necessarily be zero. In ordinary magnetism, the reason this case is not used is that

47. A short magnetic dipole of moment has an axial field at distance . Another dipole has moment . At what axial distance from the second dipole will the axial field again be ?

48. A short bar magnet has magnetic length and pole strength . It is placed with , where . Taking , the equatorial neutral distance is

49. The direction of the magnetic dipole moment of a bar magnet is taken

50. A ferromagnetic core has hysteresis loss per cycle. A second core of the same volume is chosen with loop area per cycle. If both are operated at the same frequency, the power loss in the second core is