Equivalent dipole distributions for dielectric spheroidal scatterers

Equivalent source distributions are identified for dielectric spheroids when immersed in a homogeneous electrostatic field. It is shown that for a prolate spheroid, the volume polarization shrinks into a line dipole distribution lying between the foci of the spheroid. The equivalent charge distributions responsible for the field scattered by an oblate spheroid arise on the circular disk of focal radius.
The solutions give rise to an alternative way of calculating electromagnetic fields near spheroidal particles in the regime of the quasi-static approximation.