Q. A sphere of charge of radius R carries a positive charge whose volume charge density depends only on the distance *r* from the ball’s centre as ρ = ρ_{0} (1 − r/R). Where ρ_{0} is a constant. Assume ε as the permittivity of space. The magnitude of electric field as a function of the distance *r* inside the sphere is given by

(a)

(b)

(c)

(d)

Ans: (a)

Sol: charge inside a sphere of radius r (r < R)