An insulating solid sphere of radius a has a uniform volume charge density and carries a total positive charge Q. A spherical Gaussian surface of radius r, which shares a common center with the insulating sphere, is inflated starting from r = 0.
(a) Find an expression for the electric flux passing through the surface of the Gaussian sphere as a function of r for r < a.
(b) Find an expression for the electric flux for r > a.
(c) Plot the flux versus r.