A region in space contains a total positive charge Q that is distributed spherically such that the volume charge density rho (r) is given by
rho (r)=3 alpha r/(2R) {rm for} ;; rleq R/2
rho (r)= alpha [1-(r/R)^{2}] {rm for} ;; R/2 leq r leq R
rho (r)=0 {rm for} ;; r geq R
Here alpha is a positive constant having units of {rm C}/{rm m}^{3}.