For a source-free polarized medium where p = 0, u=po. but where there is a volume density of polarization P, a single vector potential e may be defined such that H = jose Vxe (e is known as the electric Hertz potential). As stated in lectures, potentials are somewhat arbitrary; the Hertz potential is just another example of expressing fields in terms of potentials. (a) Express the electric field E in terms of (b) Show that n. satisfies a non-homogeneous Helmholtz wave E