Question

When the current in a coil changes from $8\, A$ to $2\, A$ in $3 \times 10^{-2} s$, the e.m.f. induced in the coil is $2$ volt. The self-inductance of the coil (in millihenry) is

• A. 1
• B. 5
• C. 20
• D. 10

Answer 1

Answer: (D)

$e=-L \frac{d i}{d t} \Rightarrow 2=-L\left(\frac{2-8}{3 \times 10^{-2}}\right)$
$\Rightarrow L=0.01\, H =10\, mH$