Question

The self inductance $L$ of a solenoid of length $l$ and area of cross-section $A$, with a fixed number of turns $N$ increases as

• A. $l$ and $A$ increase
• B. $l$ decreases and $A$ increases.
• C. $l$ increases and $A$ decreases.
• D. both $l$and $A$ decrease

Answer 1

Answer: (B)

$l$ decreases and $A$ increases.

Answer 2

The self inductance $L$ of a solenoid of length $l$ and area of cross section $A$ with fixed number of turns $N$ is $L = \frac{\mu_o N^2 A}{l}$ So, $L$ increases when $l$ decreases and $A$ increases.