The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance

Energy stored in inductor $U = \frac{1}{2}LI^2$. Given $U = 25 \times 10^{-3} \text{ J}$ and $I = 60 \times 10^{-3} \text{ A}$. Substituting values: $25 \times 10^{-3} = \frac{1}{2} \times L \times (60 \times 10^{-3})^2$. Solving for $L$: $L = \frac{25 \times 2 \times 10^6 \times 10^{-3}}{3600} = \frac{500}{36} = 13.89 \text{ H}$.