Boundary-Value Problems in Electrostatics: II — John David Jackson
Physics — E&M · mean-value-theorem-polyhedron
Problem
A closed volume is bounded by conducting surfaces that are the n sides of a regular polyhedron (n=4,6,8,12,20). The n surfaces are at different potentials Vi, i=1,2,…,n. Prove in the simplest way you can that the potential at the center of the polyhedron is the average of the potential on the n sides. This problem bears on Problem 2.23b, and has an interesting similarity to the result of Problem 1.10.