Question

The magnitude of the induced emf in a coil of inductance $30 \,mH$ in which the current changes from $6 A$ to $2 A$ in $2 s$ is

• A. 0.06 V
• B. 0.6 V
• C. 1.06 V
• D. 6 V

Answer 1

Answer: (A)

The magnitude of induced emf,
$|e| =-L \frac{d i}{d t} \Rightarrow e=-30 \times 10^{-3} \times\left(\frac{6-2}{2}\right) $
$=-30 \times 10^{-3} \times \frac{4}{2}=-0.06 \,V$