Question

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

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

Answer 1

Answer: (B)

250 V

Answer 2

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