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Question: Answered & Verified by Expert
If a current flowing in a coil is reduced to half of its initial value, the relation between the new energy $\left(\mathrm{E}_2\right)$ and the original energy $\left(E_1\right)$ stored in the coil will be
PhysicsElectromagnetic InductionMHT CETMHT CET 2021 (22 Sep Shift 1)
Options:
  • A $E_2=\frac{E_1}{4}$
  • B $E_2=\frac{E_1}{2}$
  • C $\mathrm{E}_2=\mathrm{E}_1$
  • D $\mathrm{E}_2=\mathrm{4E}_1$
Solution:
2525 Upvotes Verified Answer
The correct answer is: $E_2=\frac{E_1}{4}$
$\begin{aligned} & E_1=\frac{1}{2} L_1^2, \quad E_2=\frac{1}{2} L_2^2 \\ & \therefore \frac{E_2}{E_1}=\left(\frac{I_2}{I_1}\right)^2=\left(\frac{1}{2}\right)^2=\frac{1}{4} \\ & \therefore E_2=\frac{E_1}{4}\end{aligned}$

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