Q 12-06-020NEETJEE MainMedium
The self-inductance of a solenoid is $L$. If the number of turns is doubled, keeping its length and area the same, the self-inductance becomes
Answer: (B) $4L$
Concept. For a solenoid $L = \dfrac{\mu_0N^2A}{l} \propto N^2$.
Step 1. Double $N$. $L \to 4L$.
Answer. $4L$ (Option B).
Solution by Sreeraj P, M.Sc Physics