Question

Two concentric and coplanar coils have radii a and `b ( gt gt a)` as shows in Fig. Resistance of the inner coil is `R`. Current in the outer coil is increased from `0` to `i`, then the total charge circulating the inner coil is

Answer 1

Correct Answer - `(mu_(0)ia^(2)pi)/(2Rb)`
`Deltaq=-N/R Deltaphi=(phi_(1)-phi_(2))/R=(0-BA)/R`
`=1/R[mu_(0)/(4pi)(2pii)/bpia^(2)]=(mu_(0)ia^(2)pi)/(4Rb)`