A sphere of radius a in free space contains charge of density rhov = rho0 r/a, where rho0 is a constant. (a) Find the electric field intensity, EI, inside the sphere. (b) Find the electric field intensity, EII, outside the sphere. (c) A spherical shell of radius b is positioned concentrically around the sphere. What surface charge density, rhos , must exist on the shell so that the electric field at locations r > b is zero? (d) What electrostatic force per unit area is exerted by the solid sphere on the spherical shell? 3