Question

An inductor has a coefficient of self-induction of $40mH$. What is the energy stored in it, when a current of $2A$ is passing through it?

• A. $40mJ$
• B. $80mJ$
• C. $20mJ$
• D. $100mJ$

Answer 1

The correct option is B

$80mJ$

Step 1: Given data.

Self-inductance of the inductor, $L=40mH=40\times {10}^{-3}H$

Current passing through the inductor, $i=2A$

Step 2: Find the stored energy in the inductor.

Formula used:

$U=\frac{1}{2}L{i}^2$ $\left[\because U=storedenergy\right]$

Now,

$U=\frac{1}{2}\times 40\times {10}^{-3}\times 2^2$

$\Rightarrow$$U=80\times {10}^{-3}J$

$\Rightarrow$$U=80mJ$

Hence, option B is correct