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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

(A)

25 μF

(B)

125 μF

(C)

100 pF

(D)

50 μF

Question-2

During a current change from 2 A to 4 A in 0.05 second, 8 V of e.m.f. is developed in the coil. The coefficient of self induction is

(A)

0.1 H

(B)

0. 4H

(C)

0. 8

(D)

0. 2 H

Question-3

A rectangular coil of 20 turns and area of cross-section 25 cm^{2} 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

(A)

1 A

(B)

50 A

(C)

0. 5 A

(D)

5 A

Question-4

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

(A)

300 V

(B)

200 V

(C)

180 V

(D)

120 V

Question-5

The inductance of a coil is directly proportional to

(A)

its length

(B)

the number of turns

(C)

the resistance of the coil

(D)

the square of the number of turns

Question-6

An alternating voltage E = 200 sin 300 t is applied across a series combination of R = 10 Ω and an inductor 800 mH. The power factor of the circuit is

(A)

0.022

(B)

0. 065

(C)

0.042

(D)

0. 084

Question-7

A magnet is allowed to fall through a metallic ring. During fall, its acceleration is

(A)

less than g

(B)

equal to g

(C)

equal to 2g

(D)

greater than g

Question-8

Energy needed to establish an alternating current I in a coil of self inductance L is

(A)

L di/dt

(B)

Zero

(C)

LI^{2}/2

(D)

IL^{2}/2

Question-9

A current varying at the rate of 3A/s in a coil generates an e.m.f. of 8mV in a nearby coil. The mutual inductance of hte two coils is

(A)

2.66 H

(B)

2.66 x 10^{-3 }mH

(C)

0.266 H

(D)

2.66 mH

Question-10

In an a.c. circuit, the current is i = 5 sin (100t -π/2) amp and the a.c. voltage is v = 200 sin (100 t) volts. Then power consumption is

(A)

200 W

(B)

0 W

(C)

40 W

(D)

1000 W

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