Question

An average emf of $32V$ is induced in a coil in which the current drops from $10A$ to $2A$ in $0.1s$. The inductance of the coil is:

• A. $0.32H$
• B. $0.4H$
• C. $4H$
• D. $0.04H$

Answer 1

The correct option is B $0.4H$

$emf=L\frac{di}{dt}$
$emf=L\frac{△i}{△t}$
So, $L=emf\times \frac{△t}{△i}$
= $32\times \frac{0.1}{8}$
$=0.4H$