Question

The induced emf in a coil of $10$ Henry inductance in which current varies from $9A$ to $4A$ in $0.2$,second is

• A. 200 V
• B. 250 V
• C. 300 V
• D. 350 V

Answer 1

Answer: (B)

Included emf $e=-L\frac{di}{dt}$
Given, $L=10H,\Delta i=9-4=5A,dt=0.2s$
$e=10\times \frac{5}{0.2}=250V$