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

Options

A. Both l and A increase
B. l decrease and A increase
C. l increase and A decrease
D. bBoth l and A decrease

Answer

B

Explanation

The self-inductance of a long solenoid of cross-sectional area A and length l, having n turns per unit length, filled the inside of the solenoid wih a material of relative permeability (e.g., soft iron, which has a high value of relative permeability) is given by
`L=mu_(r)mu_(0)n^(2)Al=(mu_(r)mu_(0)N^(2)A)/(l)`