 This may also be written using Coulomb constant .The work "W" required to move "q" from "A" to any point "B" in the electrostatic force field is given by the potential function

The potential energy is a function of the state a system is in, and is defined relative to that for a particular state.This reference state is not always a real state; it may also be a limit, such as with the distances between all bodies tending to infinity, provided that the energy involved in tending to that limit is finite, such as in the case of inverse-square law forces.