A current of 3 A 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 rectangular coil of 20 turns and area of cross-section 25 cm2 has a resistance of 100 Ω. If a magnetic field which is perpendicular to the plane of the coil changes at the rate of 1000 T per second, the current in the coil is
1 A
50 A
0.5 A
5 A
A circuit has a self inductance of 1 H and carries a current of 2 A. To prevent sparking when the circuit is broken, a capacitor which can withstand 400 V is used. The capacitance of the capacitor is
25 μF
125 μF
100 pF
50 μF
Two circuits have mutual inductance of 0.09 H. Average e.m.f. induced in the secondary by a change of current from 0 to 20 A in 0.006 second in the primary will be
300 V
200 V
180 V
120 V
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 resistance R and inductance L is connected to a battery of e.m.f. E volts. The final current in the coil is
A deutron of kinetic energy 50 keV is describing a circular orbit of radius 0.5 m in a plane perpendicular to magnetic field B. The kinetic energy of the proton that describes a circular orbit of radius 0.5 m in the same plane with the same B is
25 keV
50 keV
200 keV
100 keV
Current is flowing in a coil of area A and number of turns N, then magnetic moment of the coil, M is equal to
NiA
Ni/A
N2Ai
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
During a current change from 2A to 4A in 0.05 second, 8 V of e.m.f. is developed in the coil. The coefficient of self induction is
0.1 H
0.4 H
0.8 H
0.2 H
