Q. Average energy stored in a pure inductance $L$ when a current $i$ flows through it, is
A) $Li^{2}$
B) $2Li^{2}$
C) $\frac{Li^{2}}{4}$
D) $\frac{2i^{2}}{2}$
Explanation
(d) As we know $e = - \frac{d\phi}{dt} = - L\frac{di}{dt}$
Work done against back e.m.f. $e$ in time $dt$ and current $i$ is
$dW = - eidt = L\frac{di}{dt}idt = Li\ di\ \Rightarrow W = L\int_{0}^{i}{i\ di = \frac{1}{2}Li^{2}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.