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
Two inductors each of inductance L are connected in parallel. What is their equivalent inductance?
2L
L
L/2
L/4
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
A 100 mH coil carries a current of 1 A. Energy stored in the magnetic field is
0.5 J
I J
0.1 J
0.05 J
The time constant of C - R circuit is
1/CR
C/R
CR
R/C
An AC supply gives 30 Vrms which passes through a 10 Ω resistance. The power dissipated in it is
90 √2 W
90 W
45√2 W
45 W
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
An aircraft has a wing span of 35 m. It is flying horizontally with a speed of 9.ms-1 and the vertical component of earth's magnetic field is 4 x 10-5T. The potential difference between the tips of the wings will be
12.6 V
0.126 V
1.26 V
0.013 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
In an AC circuit, the rms value of current, irms is related to the peak current, i0 by the relation
irms = √2i0
irms = πi0
irms = i0/π
irms = 1/√2 i0
