Question

The current in a coil of inductance $0.2 \,H$ changes from $5A$ to $2A$ in $0.5\,sec$. The magnitude of the average induced emf in the coil is

• A. 0.6 V
• B. 1.2 V
• C. 30 V
• D. 0.3 V

Answer 1

Answer: (B)

1.2 V

Answer 2

Average induced emf, $\epsilon= L dl / dt$
$=0.2((5-2) / 0.5)=2 / 5 \times 3=1.2 V$