1. The problem statement, all variables and given/known data Hi all. Please take a look at #2 in http://www.physics.utoronto.ca/~hori/Courses/P352F/hw6.pdf (this is not homework, I'm just training). Ok, I can find the electric field inside the cavity y superposition and it is E = (-1/ 3*e_o)*P. I know that the bound surface charge is P*cos(theta), where theta is the usual spherical coordinate. My question is: Is the total charge on the inner surface P*cos(theta)*4*Pi*(R_0)^2?