A current of 3A flowing in the primary coil is reduced to zero in 0.001s, the induced e.m.f. in the secondary is 15000 V. The mutual inductance between the two coils is
0.5 H
5 H
1.5 H
10 H
A 100 mH coil carries a current of 1 A. Energy stored in the magnetic field is
0.5 J
1 J
0.1 J
0.05 J
A long solenoid has 200 turns/cm and carries a current I. The magnetic field at its centre is 5.28 x 10-2 Wbm-2. Another long solenoid has 100 turns/cm and it carries a current I/3. The value of the magnetic field at its centre is
1.05 x 10-2 Wb m-2
1.05 x 10-5 Wb m-2
1.05 x 10-3 Wb m-2
1.05 x 10-4 Wb m-2
A coil has an area of 0.05 m2 and has 800 turns. After placing the coil in a magnetic field of strength 4 x 10-5 Wbm-2, perpendicular to the field, the coil is rotated by 90o in 0.1s.The average emf induced is :
zero
0.016 V
0.01 V
0.032 V
The north pole of a long horizontal bar magnet is being brought closer to vertical conducting plane along the perpendicular direction. The induced current in the conducting plane is
anticlockwise
clockwise
horizontal
vertical
The inductance of a coil is directly proportional to
its length
the number of turns
the resistance of the coil
the square of the number of turns
A coil of area 100 cm2 has 500 turns. Magnetic field of 0.1 Wb/m2 is perpendicular to the coil. The field is reduced to zero in 0.1s. The induced e.m.f. in the coil is
5 V
1 V
50 V
Two coils have a mutual inductance of 0.005 H. The current changes in the first coil according to the equation I = I0 sin ωt where I0 = 10A and ω = 100π rad/sec. The maximum value of e.m.f. in the second coil is
5π volts
2π volts
π volts
4π volts
A horizontal straight wire, 10m long, extending along the east and west direction, is falling at right angles to the horizontal component of the earth's magnetic field, 0.30 x 10-4 Wbm-2. If the induced emf is 1.5 x 10-3, the velocity of the wire is :
5 x10-4 ms-1
5 x 102 ms-1
50 ms-1
5 ms-1
The magnetic energy in an inductor changes from maximum value to minimum value in 5 ms when connected to an a.c. source. The frequency of the source is
50 Hz
200 Hz
500 Hz
20 Hz
