Question

A small square loop of wire of side l is placed inside a large square loop of wire of side `L(Lgtgtl)`. The loops are co-planer and their centres coincide. The mutual inductance of the system is proportional to
A. `l/L`
B. `(l^(2))/L`
C. `L/l`
D. `(L^(2))/l`

Answer 1

Correct Answer - B
`phi=Mi`
`(4mu_(0)i)/(4pi(L//2))[1/(sqrt(2))+1/(sqrt(2))]xxl^(2)=Mi`
`M=(2sqrt(2) mu_(0)l^(2))/(piL)`
`M prop (l^(2))/L`