Coulomb force between two (stationary) charges is also a conservative
force This is not surprising, since both have inverse-square dependence
on distance and differ mainly in the proportionality constants – the
masses in the gravitational law are replaced by charges in Coulomb’s
law Thus, like the potential energy of a mass in a gravitational
field, we can define electrostatic potential energy of a charge in an
electrostatic field Consider an electrostatic field E due to some charge configuration