Question

A 500-turn solenoid have a cross-sectional area 20 m^2. If its self-inductance

is 20H, then find the length of the solenoid.

Answer 1

$$L=\frac{\mu_0N^2A}{l}$$

$$l=\frac{\mu_0N^2A}{L}=\frac{4\pi*10^{-7}*500^2*20}{20}=0.314\:\rm m$$