AIIMS 2018 Physics Inductance MCQ Question

The expression for self-inductance $L$ is derived from the formula $L = \mu_0 \mu_r \frac{N^2 A}{\ell}$, where $\mu_0$ is the permeability of free space, $\mu_r$ is the relative permeability, $N$ is the number of turns, $A$ is the cross-sectional area, and $\ell$ is the length of the coil. This formula indicates that self-inductance is directly proportional to the square of the number of turns and the area, and inversely proportional to the length of the coil. Since the other options are marked as N/A, they do not provide relevant or correct information regarding the self-inductance expression.