Question

When current in a coil changes from 2 A to 5 A in a time of 0.3 s, if the emf induced in the coil is 40 mV, then the self-inductance of the coil is

• A. 4 H
• B. 4 mH
• C. 40 mH
• D. 4 μH

Hint:

For inductance problems, use the formula for induced emf and rearrange to solve for $L$.

Answer 1

The Correct Option is B

The emf induced in the coil is given by: $$ \mathcal{E} = -L \frac{dI}{dt} $$ where $L$ is the inductance, and $\frac{dI}{dt}$ is the rate of change of current. Substituting the given values, we can calculate the self-inductance $L$ to be 4 mH.