Consider a pair of coils arranged coaxially parallel to each other, in a vertical plane. When the current in one coil increases from 0 to 10 A in 0.5 s, the emf induced in the other coil is 20 V. The mutual inductance of the coils is:

Question

Question

This question was previously asked in

AAI ATC Junior Executive 27 July 2022 Shift 2 Official Paper

Answer 1

Concept:

When two coils are arranged in such a way that a change of current in one coil causes an emf to be induced in the other, the coils are said to have mutual inductance.
The mutual inductance is denoted letter M and measured in Henry.
Induced emf in the coil is \(e = M\frac {di}{dt}\)
Where, di = change in current, dt = change in time, M = mutual inductance

Calculation:

Given, change in current, di = 10 A, change in time, dt = 0.5 s emf induced in the other coil, e = 20 V

So, from the equation \(e = M\frac {di}{dt}\)

\(⇒ 20 = M\frac {10}{0.5}\)

⇒ M = 1.0 H