Question

An average emf of $20\text{V}$ is induced in an inductor when the current in it is changed from $2.5\text{A}$ in one direction to $5.5\text{A}$ in the opposite direction, in $0.1\text{s}$. Find the self-inductance of the inductor.

• A. $0.75\text{H}$
• B. $0.85\text{H}$
• C. $0.25\text{H}$
• D. $0.45\text{H}$

Answer 1

The correct option is C $0.25\text{H}$

Given:

$E=20\text{V}$

$dI=I_2-I_1=(-5.5)-2.5=-8\text{A}$

$dt=0.1\text{s}$

Now,

$E=-L\frac{dI}{dt}$

$\Rightarrow 20=-L\frac{-8}{0.1}$

$\Rightarrow L=0.25\text{H}$