Q.

A circular current loop of radius R is placed inside square loop of side length L(L≫R) such that they are co-planar and their centers coincide. The permeability of free space is μ0. The mutual inductance between circular loop and square loop is ________.            [2026]

1 22μ0L2R  
2 2μ0L2R  
3 2μ0R2L  
4 22μ0R2L  

Ans.

(4)

B at center of square loop=

=4×μ0I4πL2(12+12)

⇒2μ0IπL×22

=22μ0IπL

ϕ=22μ0IπL×πR2

M=ϕI=22μ0R2L