Magnetism and Matter Mock Test – Class 12 Physics

1. A ferromagnetic material is near saturation. A small increase in causes only a very small increase in . On the curve, this corresponds to

2. Consider the following statements about .
Statement I: It applies only to closed surfaces.
Statement II: It means must be zero at every point on the surface.
Statement III: It is connected with the absence of isolated magnetic poles.

3. A bar magnet has its -pole on the left and -pole on the right. At a point on the axial line just beyond the -pole, the direction of the magnetic field outside the magnet is

4. Consider the following statements about temperature and magnetic behaviour.
Statement I: Paramagnetic susceptibility generally follows .
Statement II: A ferromagnetic material becomes paramagnetic above its Curie temperature.
Statement III: Diamagnetic susceptibility is normally large and strongly temperature-dependent.

5. A sample has . In a magnetising field , its magnetisation is

6. Earth's magnetic field at a place has and . The total field is

7. Match the field-line feature with the physical meaning.

8. In deriving the axial field of a short magnetic dipole, the two pole contributions are subtracted rather than simply added because

9. A magnetic dipole is in a uniform magnetic field. Its potential energy is minimum when

10. A bar magnet is replaced by a current loop with the same magnetic moment . At a far equatorial point at the same distance and same orientation, the magnetic field

11. Study the field-line behaviour in different materials.

The unsupported row is

12. A long material sample is placed in a magnetising arrangement. When the applied magnetic intensity is increased, the sample's magnetisation also changes. This observation mainly shows that

13. Consider the following statements about points near a bar magnet.
Statement I: Field lines are usually more crowded near the poles.
Statement II: At a point on a field line, the tangent gives the direction of .
Statement III: A weaker field region must contain intersecting field lines.

14. A soft magnetic material is preferred in devices where magnetisation must follow a changing current because

15. The magnetic meridian at a place is the vertical plane containing

16. A compass placed at two different towns does not point at exactly the same angle relative to geographic north. The most suitable reason is that

17. Two bar magnets are brought close to each other. Their -poles are facing each other. What should be observed?

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

19. A place has dip angle and total Earth's field . The values of and are

20. Use the arrangement described below.

The direction of the magnetic field at P is

21. A magnetic dipole is rotated slowly from to in a uniform magnetic field. The work done by the external agent is

22. The direction of is

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

24. A magnetic material is described by the statement: "The applied magnetising field is strong, but the magnetic moment per unit volume produced in the material is small." In symbols, this compares

25. 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

26. A single-turn loop carries current and has area . It is replaced by another single-turn loop carrying current and having area . The magnetic dipole moment changes to

27. A closed surface is placed around only one side of a current loop, so that several magnetic field lines pass through it. According to Gauss's law for magnetism, the net magnetic flux through the closed surface is

28. A magnetic field around a magnet is best understood as the region where

29. A map gives true north, but a compass at the same place points east of true north. The magnetic declination is best written as

30. A small iron pin is placed near one end of a bar magnet and gets attracted. This attraction is an example of

31. A material is made of many tiny magnetic dipoles. In an unmagnetised ferromagnetic sample, the domains are usually arranged so that

32. A hollow shield made of soft iron reduces the magnetic field inside it. If the shield is replaced by a material with much lower permeability but the same shape, the shielding becomes poorer mainly because

33. A hysteresis loop has area per cycle. If the material undergoes magnetisation cycles each second, the power loss per unit volume is

34. At a place where the dip angle is , the components of Earth's magnetic field satisfy

35. A dipole with is placed in a uniform field of . Compare the torque at with the torque at .

36. A graph is drawn for a short magnetic dipole with on the vertical axis and on the horizontal axis, keeping constant.

The straight-line nature shows that

37. The SI unit of magnetic intensity is

38. A material has when . In the same linear range, the magnetic field inside is written as . The relative permeability is

39. In the far-field axial formula for a short magnetic dipole, a student keeps in while using SI values for all other quantities. The most likely problem is that

40. A circular current loop is very small compared with the distance of observation. Its magnetic field pattern at large distances resembles that of

41. A uniformly magnetised rod has net magnetic moment directed from its left end toward its right end. The direction of its magnetisation is

42. A current loop is viewed from one side, and the current is seen to flow anticlockwise. The face viewed behaves as

43. A short magnetic dipole has moment . At an axial point from its centre, the field is . At an equatorial point from the same dipole, the magnetic field magnitude is

44. For a magnetic dipole in a uniform magnetic field, the potential energies at , , and are respectively

45. Assertion: A bar magnet is called a magnetic dipole.
Reason: Its -pole and -pole behave as a pair, and an isolated magnetic pole is not obtained by cutting the magnet.

46. Curie's law for a paramagnetic material is commonly written as

47. In a closed cubical surface, flux values through five faces are , , , , and . The flux through the sixth face is

48. Bar magnets are often stored in pairs with soft iron keepers across their ends. The keepers are used mainly to

49. 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

50. A short magnetic dipole produces at distance . At an axial point of the same dipole at distance , the magnetic field magnitude is