Physics · PYQ NEET UG 2026

Consider a long solenoid of length $l$ and radius $r$. If $n$ is the number of turns per unit length and $\mu_0$ is the permeability of free space, the inductance of the solenoid is :

1. A
   $\mu_0 \pi n^2 r^2 l$
2. B
   $\mu_0 n^2 r^2 l$
3. C
   $(\mu_0 / 2\pi) n^2 r^2 l$
4. D
   $2\mu_0 \pi n^2 r^2 l$