## Within a spherical charge distribution of charge density $ρ(r)$, N equipotential surfaces of potential $V_{0},V_{0}+ΔV,V_{0}+2ΔV,.....,V_{0}+NΔV(ΔV>0)$, are drawn and have increasing radii $r_{0},r_{1},r_{2},.....r_{N}$, respectively. If the difference in the radii of the surfaces is constant for all values of $V_{0}$ and $ΔV$ then :