Question

The average e.m.f. induced in a coil in which the current changes from 2 ampere to 4 ampere in 0.05 second is 8 volt. What is the self inductance of the coil ?(a) 0.1 H(b) 0.2 H(c) 0.4 H(d) 0.8 H

Answer 1

Correct Answer : OPTION B: 0.2H

Explanation:

e= 8 volts

i= 4- 2 A

T=0.05 S

e= −Ldi/dt

8=L(4−2)/0.05

L=0.2 H

Answer 2

Answer:

b) 0.2H

Explanation:

Change in current = 2 to 4 amperes (Given)

Time taken = 0.05 seconds (Given)

EMF = e = 8 volts (Given)

Time = i = 4- 2 A  ( due to the change)

According to the Faraday's law, the Induced EMF is equal to the rate of change of the magnetic flux.

Magnetic flux = Magnetic field strength x Area = BA.

Therefore, the induces EMF = (change in Magnetic Flux Density x Area)/change in Time.

EMF = (change in flux)/ time

e = −Ldi/dt

8 = L(4−2)/0.05

0.4 = L(2)

L = 0.2 H

Thus, the self inductance of the coil is 0.2H.