ABSTRACT
This chapter derives the form of a dispersion relation starting from general physical principles and assuming the medium to be nonmagnetic. In a linear, isotropic, dielectric medium, the displacement, the polarization, and the electric field are related. An additional property of the dielectric constant may be inferred by considering the high-frequency limit. In this situation, the effect of binding on the electrons can be neglected, leaving us with the response of free electrons to the applied electric field.
