1. Angle of dip where earth's magnetic field is vertical is: [BP 2014]
2. The magnetic susceptibility is negative for [BP 2013,12]
- Paramagnetic
- Diamagnetic
- Ferromagnetic
- Ferrimagnetic substance
3. ' Magnetic moment of a magnet decreases by 19%, then time period:
- increases by 10%
- decreases by 10%
- Increases by 20%
- decreases by 20%
4. The value of Bohr magneton is [BP 2013]
- 9.27×10-27 J/ tesla
- 9.27×10-31 J/ tesla
- 1.27 × 10-18 J/ tesla
- 9.27 × 10-23 J/ tesla
5. Permanent magnets are made up of [BP 2010]
- Steel
- Soft iron
- Copper
- Tungsten
6. When a magnet is heated, its magnetic moment is [BP 2010]
- Halved
- Doubled
- One fourth
- Same
7. A magnetic needle is kept in a non-uniform magnetic field. It experience [MOE 2014]
- A force and torque
- A force not a torque
- A torque not a force
- No torque, no force.
8. A magnetic material aligns perpendicular to uniform magnetic field then the substance is: [MOE 2014]
- Diamagnetic
- Paramagnetic
- Ferromagnetic
- Antiferromagnetic
9. Susceptibility above Curie's temperature is valid for: [MOE 2010]
- Ferromagnetic
- Paramagnetic
- Diamagnetic
- Ferrimagnetic.
10. A unit magnetic pole placed at a point on the perpendicular bisector line of a bar magnet placed in magnetic meridian experiences a force due to the magnet. The direction of the force experienced by it will be: [MOE 2011]
- 45° to the magnetic axis.
- 90° to the magnetic axis.
- Parallel to the magnetic axis.
- 60° to the magnetic axis.
11. When 2 A current is passed through tangent galvanometer, it gives a deflection of 30°. For deflection of 60°, the current must be. [MOE 2013]
12. A compass needle is allowed to move horizontal plane is taken to a geomagnetic pole. It [KU 2012]
- Will stay in north - south direction only.
- Will stay in east - west direction only.
- Will become rigid showing non movement.
- Will stay in any position
13. The substance which when placed in external magnetic field are feebly magnetized in opposite direction to that of the magnetizing field are: [KU 2011]
- Paramagnetic substance.
- Diamagnetic substance.
- Ferromagnetic substance.
- Both (a) and (c).
14. Magnetic meridian is- [IE 2013]
- Point source.
- Horizontal line.
- Vertical line.
- A line directed from N - S
15. S.I unit equivalent to the magnetic field Tesla (T) may be [MOE 09]
16. The value of magnetizing field (H) when magnetic flux density (B) = 0 is called [Bangladesh 09]
- Retentivity
- Curie's temperature
- Coercivity
- Curie's temp.
17. At a place the vertical and horizontal component of earth's magnetic field are equal. The angle of dip at that place is [KU 08]
18. Area of hysteresis curve indicates. [KU 08]
- Retentivity
- Loss of energy per cycle
- Coercivity
- all of the above
19. Soft iron is a suitable material for the core of transformer because it has
- high hysteresis, high permeability
- high hysteresis, low permeability
- low hysteresis, high permeability
- low hysteresis, low permeability
20. The apparent angles of dip at two meridians perpendicular to each other about magnetic meridian are 45° and 45°. Then cot of the true angle of dip at that place is [BPKIHS 02]
21. The magnetic field strength at a distance d from a short bar magnet in longitudinal to transverse position are in the ratio of: [BPKIHS 05]
22. Above curie temperature ? [BP 2006/2016]
- Ferromagnetic substance become paramagnetic
- Paramagnetic substance become ferromagnetic
- Paramagnetic substance becomes diamagnetic
- Diamagnetic substance becomes paramagnetic
23. The time period of magnet is 2 sec. It is cut into two equal parts by cutting it parallel to its length. What is the new time period of each part when vibrated in the same magnetic field? [BPKIHS-06]
24. Why are laminated core placed in transformer? [BPKIHS-97]
- to reduce hysteresis loss
- to reduce eddy current
- to reduce magnetic effect
- all of the above
25. Which of the following is used in the core of an electromagnet [BPKIHS 1999]
- soft iron
- soft steel
- soft aluminium
- soft zinc
26. When the temperature increase, magnetic moment of a magnet [BPKIHS 1999]
- increases
- decreases
- remains the same
- sometimes increases and sometimes decreases
27. Null point is observe at the equatorial line of a bar magnet then the north pole of bar magnet must have faced [IE-03]
- geographical north pole
- geographical south pole
- east
- west
28. If a magnetic material moves from stronger to weaker parts of a magnetic field, then it is
- diamagnetic
- paramagnetic
- ferromagnetic
- anti-ferromagnetic
29. When a thin bar magnet is cut in length into two equal halves and joined one above another facing same pole together the final time period of magnet is equal to: (if initial time period of magnet =T) [IOM 03]
30. The ratio of the magnetic moment of two short magnets, which give null deflection in tan B position at 12cm and 18 cm from the centre of a deflection magnetometer is [MOE 2000]
31. What is the net magnetic moment of two identical magnets each of magnetic moment Mo, inclined at 60° with each other?
32. A thin bar magnet of length 2L and magnetic moment M is bent at mid-point so that the angle between them is 60°. The new magnetic moment is
33. A magnetized steel wire having dipole moment M is bent at 30° at mid-point. Find the dipole moment of new wire.
34. The ratio of magnetic fields due to a small bar magnet at a given distance in the end on position to broad side on position is
35. A bar magnet is cut into two equal halves by a plane parallel to the magnetic axis. Of the following physical quantities, the one which remains unchanged is .
- Pole strength
- Magnetic moment
- Intensity of magnetisation
- Moment of inertia
36. The points A and B are situated perpendicular to the axis of 2cm long bar magnet at large distances x and 3x from the centre on opposite sides. The ratio of magnetic fields at A and B will be approximately equal to
37. Two points A and B are situated at a distance x and 2x respectively from the nearer pole of magnet 2cm long. The ratio of magnetic field at A and B is
- 4:1 exactly
- 4:1 approximately
- 8:1 approximately
- 1:1 approximately
38. The ratio of magnetic potentials due to magnetic dipole in the end on position to that in broad on position for the same distance from it is
39. The magnetic potential at a point distant 10cm from the middle point of a magnetic dipole on a line inclined at an angle of 60° with the axis is 3 e.m.u. Then the magnetic moment of magnet is
- 600 ab-amp cm2
- 300 ab-amp cm2
- 150 ab-amp cm2
- 300√3 ab-amp cm2
40. The magnet of pole strength m and magnetic moment M is cut into two pieces along its axis. Its pole strength and magnetic moment now become
41. A large magnet is broken into two pieces so that their lengths are in the ratio 2:1. The pole strengths of the two pieces will have ratio
42. A magnetic dipole is placed at right angles to the direction of lines of for magnetic induction B. If it is rotated through an angle of 180°, then the work done is
43. Calculate force exerted on a point N pole of a 3200A-m placed 10cm away from a point south pole of 40A-m in air
44. Two magnets of equal magnetic moment M each are placed as shown in figure. The resultant magnetic moment is
45. A bar magnet is held at right angle to a uniform magnetic field. The couple acting on a magnet is to be halved by rotating it from this position. The angle of rotation is
46. Torques τ1, and τ2 are required for a magnetic needle to remain perpendicular to the magnetic fields B1 and B2 at two different places. The ratio is B1/B2 is
- τ2/τ1
- τ1/τ2
- (τ1+τ2)/(τ1−τ2 )
- (τ1−τ2)/(τ1+τ2 )
47. The distance between the poles of a horse shoe magnet is 4cm. The pole strength of each pole is 40 units. The magnetic potential midway between the poles is
- 80 units
- 10 units
- 20 units
- zero
48. The force between two short bar magnets with magnetic moments M1 and M2 whose centres are r metre apart is 8N, when their axes are in the same line. If the separation is increased to 2r, the force between them is reduced to
49. A magnetic needle lying parallel to a magnetic field required W units of work to turn it through 60°. The torque required to maintain the needle in this position is
50. A thin magnet is cut into two equal parts by cutting it parallel to its length. If the original time period of vibration is 4sec, the time period of each part in the same field will be
51. At a certain place, horizontal component is √3 times the vertical component. The angle of dip at this place is
52. Two bar magnets of the same mass, same length and breadth but having magnetic moments M and 2M are joined together pole for pole and suspended by a string. The time period of assembly in a magnetic field of strength H is 30 seconds. If now the polarity of one of the magnets is reversed and the combination is again made to oscillate in the same field, the time of oscillation is
- 3 sec
- 3√3 sec
- 3/√3 sec
- 6 sec.
53. In end on and broadside on position of deflection magnetometer, if θ_1 and θ_2 are the deflections produced by short magnets at equal distances, then tanθ_1 /tanθ_2 is
54. At a place of latitude 5°, the angle of dip is nearly
55. Two short magnets have equal pole strengths but one is twice as long as the other. The shorter magnet is placed 20cm in tan A position from the compass needle. The longer magnet must be placed on the other side of the magnetometer for no deflection at a distance equal to
- 20cm
- 20 (2)^(1/3) cm
- 20 (2)^(2/3) cm
- 20 (2)^(3/3) cm
56. A magnetic dipole is placed in two perpendicular magnetic field B ⃗ and H ⃗ and is in equilibrium making angle θ with B ⃗ Then,
- B=H.
- B cosθ=H sinθ
- B sinθ=H cosθ
- B=H tanθ
57. A circular coil of radius 20cm and 20 turns of wire is mounted vertically with its plane in magnetic meridian. A small magnetic needle is placed at the centre of the coil and is deflected through 45° when a current is passed through the coil. When horizontal component of earth's field is 0.34×10^-4 T, the current in the coil is
58. When 2A current is passed through a tangent galvanometer, it gives a deflection of 30°. For deflection of 60°, the current must be
59. Horizontal component of earth's field at a height of 1m from the surface of earth is H. Its value at a height of 10m from the surface of earth is
60. A superconductor exhibits perfect
- diamagnetism
- paramagnetism
- ferromagnetism
- antiferromagnetism
61. For a diamagnetic material
- μ_r>1, χ_m>1
- μ_r>1, χ_m<1
- μ_r<1, χ_m<0
- μ_r<1, χ_m>0
62. The moment of magnet (15cm×2cm×1cm) is 1.2 A-m2. What is its intensity of magnetization?
- 4×104 Am−1
- 2×104 Am−1
- 104 Am−1
- None
63. The core of an electromagnet is made of soft iron, because
- the susceptibility of soft iron is very high
- coercivity of soft iron is very low
- both of these
- none of these
64. The hysteresis cycle for the material of permanent magnet is
- short and wide
- tall and narrow
- tall and wide
- short and narrow
65. A magnetizing field of 2×103 amp/m produces a magnetic flux density of 8π tesla in a rod. The relative permeability of the rod will be
66. Two magnets are held together in a vibration magnetometer and are allowed to oscillate in the earth's magnetic field with like poles together. 12 oscillations per minute are made but for unlike poles together only 4 oscillations per minute are executed. The ratio of their magnetic moments is
67. When a thin bar magnet is cut in length into equal halves and joined one above the other facing same pole together, the final time period of the magnet is equal to (if the initial time period =T)
68. A magnet of magnetic moment M is revolved end for end in a uniform magnetic field B. The change in kinetic energy of the magnet will be
69. A magnet of length 2l is bent at mid at 60°. Find the new length of the magnet
70. If a magnet is revolved end for end in a uniform magnetic field, the kinetic energy of magnet
- increase
- decreases
- remains constant
- zero
71. Material A is used as a permanent magnet. It means [MOE Curriculum]
- A has high coercivity
- A has high retentivity
- A has low coercivity
- A has low retentivity
72. Which of the following is paramagnetic? [IOM 2015]
- Bismuth
- Chromium
- Antimony
- Water
