Electromagnetic Induction · Question 5

[figure] In the above diagram, a strong bar magnet is moving towards solenoid-2 from solenoid-1. The direction of induced current in solenoid-1 and that in solenoid-2, respectively, are through the directions:

1. AB and DC
2. BA and CD
3. AB and CD
4. BA and DC

A sheet is placed on a horizontal surface in front of a strong magnetic pole. A force is needed to: Choose the correct statement(s) from the options given below:

1. B and D only
2. A and C only
3. A, C and D only
4. C only

Let us consider two solenoids A and B, made from same magnetic material of relative permeability r and equal area of cross-section. Length of A is twice that of B and the number of turns per unit length in A is half that of B. The ratio of self inductances of the two solenoids, LA : LB is

1. 1 : 2
2. 2 : 1
3. 8 : 1
4. 1 : 8

The magnetic energy stored in an inductor of inductance 4 carrying a current of 2 A is :

1. 4 mJ
2. 8 mJ
3. 8
4. 4

A square loop of side 1 m and resistance 1 is placed in a magnetic field of 0.5 T. If the plane of loop is perpendicular to the direction of magnetic field, the magnetic flux through the loop is

1. 2 weber
2. 0.5 weber
3. 1 weber
4. Zero weber

A big circular coil of 1000 turns and average radius 10 m is rotating about its horizontal diameter at 2 rad s-1. If the vertical component of earth's magnetic field at that place is 2 10-5 T and electrical resistance of the coil is 12.56 , then the maximum induced current in the coil will be

1. 0.25 A
2. 1.5 A
3. 1 A
4. 2 A

The magnetic flux linked to a circular coil of radius R is = 2t3 + 4t2 + 2t + 5 Wb The magnitude of induced emf in the coil at t = 5 s is

1. 192 V
2. 108 V
3. 197 V
4. 150 V

Two conducting circular loops of radii R1 and R2 are placed in the same plane with their centres coinciding. If R1 >> R2, the mutual inductance M between them will be directly proportional to :

1. R22R1
2. R1R2
3. R2R1
4. R12R2

A 800 turn coil of effective area 0.05 m2 is kept perpendicular to a magnetic field 5 10-5 T. When the plane of the coil is rotated by 90 around any of its coplanar axis in 0.1 s, the emf induced in the coil will be :

1. 0.2 V
2. 0.02 V
3. 2 V
4. 2 10-3 V

In which of the following devices, the eddy current effect is not used?

1. magnetic braking in train
2. electromagnet
3. electric heater
4. induction furnace