Question

The average self-induced emf in a $25mH$ solenoid when the current in it falls from $0.2A$ to $0A$ in $0.01$ second, is

• A. $0.05V$
• B. $0.5V$
• C. $500V$
• D. $50V$

Answer 1

The correct option is B $0.5V$

$emf=L\frac{di}{dt}$
$=25\times {10}^{-3}\times \frac{0.2}{0.01}$
$=0.5V$