MCQ
Average energy stored in a pure inductance $L$ when a current $i$ flows through it, is
- A$L i^2$
- B$(b) $2 L i^2$
- C$\frac{L i^2}{4}$
- ✓$\frac{L i^2}{2}$
✓
Answer
Correct option: D.
$\frac{L i^2}{2}$
As we know $e=-\frac{d \phi}{d t}=-L \frac{d i}{d t}$Work done against back e.m.f. $e$ in time $d t$ and current $i$ is$d W=-e i d t=L \frac{d i}{d t} i d t=L i d i \Rightarrow W=L \int_0^i i d i=\frac{1}{2} L i^2$
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