what is the general derivation given for a system of n charges in space?? what is the derivation for a system of n charges in space?? what is the derivation for a system of n charges in space??

A point charge q in the electric field of another charge Q.

Let''s start first with one point charge q in the presence of only one point charge Q. The electrostatic potential energy, U_E, of one point charge q in the presence of a point charge Q, taking an infinite separation between the charges as the reference position, is:,