A solid sphere of radius R has total charge Q. The charge is distributed in spherically symmetric manner in the sphere. The charge density is zero at the centre and increases linearly with distance from the centre. (a) Find the charge density at distance r from the centre of the sphere. (b) Find the magnitude of electric field at a point ‘P’ inside the sphere at distance `r_1` from the centre.

Answer

(a). `rho(r)=(Q)/(piR^(4))r`
(b) `(Qr_(1)^(2))/(4pi in_(0)R^(4))`