Question

The magnetic potential energy stored in a certain inductor is `25mJ`, when the current in the inductor is `60 mA`. This inductor is of inductance
A. 1.389 H
B. 138.88 H
C. 0.138 H
D. 13.89 H

Answer 1

Correct Answer - D
Given, magnetic potential energy stored in an inductor, U=25 mJ `=25 xx 10^(-3)` J
Current in an inductor, `I_(0)=60 mA=60 xx 10^(-3)`A
As, the expression for energy stroed in an inductor is given as `U=1/2LI_(0)^(2)`
Where, L is the inductance of the inductor.
Substituting the given values in above equation, we get
`(25 xx 10^(-3))= 1/2 xx L xx (60 xx 10^(-3))^(2)`
`rArr L = (2 xx 25 xx 10^(-3))/(3600 xx 10^(-6))` or L = 13.89 H