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Question: Answered & Verified by Expert
Average energy stored in a pure inductance $L$ when a current $i$ flows through it, is
PhysicsElectromagnetic InductionJEE Main
Options:
  • A $L i^2$
  • B $2 L i^2$
  • C $\frac{L i^2}{4}$
  • D $\frac{L i^2}{2}$
Solution:
1627 Upvotes Verified Answer
The correct answer is: $\frac{L i^2}{2}$
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 dt 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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