Class 12 Magnetism And Matter CBSE Questions & Answers

1

A bar magnet of magnetic moment 1.5 J/T lies aligned with the direction of a uniform magnetic field of 0.22 T. What is the amount of work required by an external torque to turn the magnet so as to align its magnetic moment opposite to the field direction?

A
0.56J
B
0.86J
C
0.66J
Correct
D
0.76J nC

2

A bar magnet of magnetic moment 1.5 J/T lies perpendicular to the direction of a uniform magnetic field of 0.22 T. What is the torque acting on it?

A
0.33J
Correct
B
0.38J
C
0.23J
D
0.43J

3

A bar magnet of magnetic moment 1.5 J/T lies parallel to the direction of a uniform magnetic field of 0.22 T. What is the torque acting on it?

A
0.3J
B
-0.3J
C
0.23J
Correct
D
0.0J

4

A closely wound solenoid of 2000 turns and area of cross-section \({\rm{1}}.{\rm{6 }} \times {\rm{ 1}}{0^{-{\rm{4}}}}{{\rm{m}}^{\rm{2}}}\), carrying a current of 4.0 A, is suspended through its centre allowing it to turn in a horizontal plane. What is the magnetic moment associated with the solenoid?

A
\({\rm{1}}.0{\rm{8 A }}{{\rm{m}}^{\rm{2}}}\)
B
\({\rm{1}}.{\rm{18 A }}{{\rm{m}}^{\rm{2}}}\)
C
\({\rm{1}}.{\rm{38 A }}{{\rm{m}}^{\rm{2}}}\)
D
\({\rm{1}}.{\rm{28 A }}{{\rm{m}}^{\rm{2}}}\)
Correct

5

A closely wound solenoid of 2000 turns and area of cross-section \({\rm{1}}.{\rm{6 }} \times {\rm{ 1}}{0^{-{\rm{4}}}}{{\rm{m}}^{\rm{2}}}\) , carrying a current of 4.0 A, is suspended through its centre allowing it to turn in a horizontal plane. If a uniform horizontal magnetic field of \({\rm{7}}.{\rm{5 }} \times {\rm{ 1}}0-{\rm{2}}\) T is set up at an angle of \({\rm{3}}0\) with the axis of the solenoid,force and torque on the solenoid are

A
0.0N,0.058 Nm
B
0.5N,0.068 Nm
C
0.0N,0.048 Nm
Correct
D
0.5N,0.078 Nm

6

A circular coil of 16 turns and radius 10 cm carrying a current of 0.75 A rests with its plane normal to an external field of magnitude \({\rm{5}}.0{\rm{ }} \times {\rm{ 1}}{0^{ - {\rm{2}}}}\) T. The coil is free to turn about an axis in its plane perpendicular to the field direction. When the coil is turned slightly and released, it oscillates about its stable equilibrium with a frequency of 2.0 \({{\rm{s}}^{ - {\rm{1}}}}\). What is the moment of inertia of the coil about its axis of rotation

A
\({\rm{1}}.{\rm{2 }} \times {\rm{1}}{0^{ - {\rm{4}}}}{\rm{kg}}{{\rm{m}}^{\rm{2}}}\)
Correct
B
\({\rm{2}}.0{\rm{ }} \times {\rm{1}}{0^{ - {\rm{4}}}}{\rm{kg}}{{\rm{m}}^{\rm{2}}}\)
C
\({\rm{1}}.{\rm{4 }} \times {\rm{1}}{0^{ - {\rm{4}}}}{\rm{kg}}{{\rm{m}}^{\rm{2}}}\)
D
\({\rm{2}}.{\rm{2 }} \times {\rm{1}}{0^{ - {\rm{4}}}}{\rm{kg}}{{\rm{m}}^{\rm{2}}}\)

7

A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip pointing down at \({22^0}\) with the horizontal. The horizontal component of the earth’s magnetic field at the place is known to be 0.35 G. Determine the magnitude of the earth’s magnetic field at the place.

A
0.38G
Correct
B
0.58G
C
0.48G
D
0.28G

8

A short bar magnet has a magnetic moment of 0.48 J/T .Magnetic field produced by the magnet at a distance of 10 cm from the centre of the magnet on the axis has a direction and magnitude of .

A
0.96 G along S-N direction.
Correct
B
0.86 G along S-N direction.
C
0.76 G along S-N direction.
D
1.06 G along S-N direction.

9

A short bar magnet has a magnetic moment of 0.48 J/T. Magnetic field produced by the magnet at a distance of 10 cm from the centre of the magnet on the equatorial lines (normal bisector) of the magnet has a direction and magnitude of

A
0.55 G along N-S direction
B
0.43 G along N-S direction
C
0.48 G along N-S direction
Correct
D
0.38 G along N-S direction

10

A toroidal solenoid with 500 turns is wound on a ring with a mean radius of 2.90 cm. Find the current in the winding that is required to set up a magnetic field of 0.350 T in the ring if the ring is made of annealed iron \({{\rm{K}}_{\rm{m}}} = {\rm{14}}00\)

A
79.5mA
B
72.5mA
Correct
C
69.5mA
D
82.5mA

11

A toroidal solenoid with 500 turns is wound on a ring with a mean radius of 2.90 cm. Find the current in the winding that is required to set up a magnetic field of 0.350 T in the ring if the ring is made of silicon steel \({{\rm{K}}_{\rm{m}}} = {\rm{52}}00\)

A
21.5mA
B
19.5mA
Correct
C
22.5mA
D
23.5mA

12

A toroidal solenoid with 500 turns is wound on a ceramic ring with a mean radius of 2.90 cm. Find the current in the winding that is required to set up a magnetic field of 0.350 T in the ring

A
121.5 A
B
121.5 mA
C
101.5 mA
D
101.5 A
Correct

13

A long solenoid with 60 turns of wire per centimeter carries a current of 0.15 A. The wire that makes up the solenoid is wrapped around a solid core of silicon steel \({{\rm{K}}_{\rm{m}}} = {\rm{52}}00\) (The wire of the solenoid is jacketed with an insulator so that none of the current flows into the core.) For a point inside the core, find the magnitude of the magnetic field due to the solenoid current;

A
2.83mT
B
2.13mT
C
1.13mT
Correct
D
3.13mT

14

A long solenoid with 60 turns of wire per centimeter carries a current of 0.15 A. The wire that makes up the solenoid is wrapped around a solid core of silicon steel \({{\rm{K}}_{\rm{m}}} = {\rm{52}}00\) (The wire of the solenoid is jacketed with an insulator so that none of the current flows into the core.) the magnetization inside the core is

A
4.48MA/m
B
4.68MA/m
Correct
C
4.28MA/m
D
4.88MA/m

15

A long solenoid with 60 turns of wire per centimeter carries a current of 0.15 A. The wire that makes up the solenoid is wrapped around a solid core of silicon steel \({{\rm{K}}_{\rm{m}}} = {\rm{52}}00\) (The wire of the solenoid is jacketed with an insulator so that none of the current flows into the core.) For a point inside the core, find the magnitudesof the total magnetic field

A
5.00T
B
5.88T
Correct
C
6.88T
D
4.88T