ABSTRACT
This chapter considers only the electrostatic energy. An overview of electrodynamics—the mechanics of charged particles and electromagnetic fields in interaction—is now before us. With the further omission of the time derivative terms, what remains (apart from a minus sign) is the energy of the field in the presence of prescribed charges and currents. That the presence of a uniform dielectric medium reduces the energy by a factor is familiar in elementary presentations of electrostatics as the corresponding reduction in the strength of the force between charges. An arrangement of objects with different values that are in contact with each other provides the simplest example of an inhomogeneous dielectric constant.
