Excuse me, may i know how should one calculate the electric potential of two conductors placed together? one inner sphere(radius a) together with another outer shell(radius b). Why is the "electric potential between the sphere and shell" equal to the electric potential in the sphere? LEts put the charge of inner one be q1 and outer one be q2. How we find the potential everywhere? For a>r, a<r<b, and also b<r. I understand about finding the outermost potential only.