question_answer

Two concentric and coplanar circular coils have radii a and b \[(>>a)\] as shown in figure. Resistance of the inner coil is R. Current in the outer coil is increased from 0 to /, then the total charge circulating in the inner coil is

A)  \[\frac{{{\mu }_{0}}l{{a}^{2}}}{2Rb}\]

B)  \[\frac{{{\mu }_{0}}lab}{2R}\]

C)  \[\frac{{{\mu }_{0}}l}{2a}\frac{\pi {{b}^{2}}}{R}\]   

D) \[\frac{{{\mu }_{0}}lb}{2\pi R}\]