Can anybody help me with this problem? A spherical conductor of radius a is located at the center of a spherical conducting shell of inner radius b. The space between the inner conductor and and conducting shell is filled with an insulator of resistivity rho. A thin wire is passed through the outer conductor and insulator shells to the center conductor and voltage V is then applied between the inner conductor and the conducting shell. How much current is drawn from the voltage source? Integrate the power density (sigma E^2) over the insulator volume and compare the integral power to the power drawn from the voltage source (I V).