1. The problem statement, all variables and given/known data Ast stated above: Biut i just cant get the correct answer! radius of sphere = a charge ze contained 2. Relevant equations by gauss: E= (ze)*r/4pi(epsilon)*a^3 at any point within the sphere. and dv=r^2*sin(theta)dTheta*dphi*dr Energy density= 0.5*epsilon*E^2 3. The attempt at a solution letting energy= integral(energy density)dv with limits: r= 0-a, theta= 0-pi, phi=0- 2pi i get wrong answer: (ze)^2/80epsilon*pi*a ration between top and bottom, should be 3(ze)^2/20epsilon*pi*a any ideas? many thanks!