Question

A (solenoid) coil is wound on a core of square cross-section. If all the linear dimensions of core are increased 2 times, but the number of turns per unit length of the coil, remains same, the self inductance would increases by a factor of

(1) 2

(2) 4

(3) 8

(4) 16

Answer 1

(3) 8

The self inductance of the coil is given by

The self inductance, therefore, increases by a factor of 8.