The field scattered by a homogeneous isotropic dielectric of finite extent illuminated by a low-frequency plane electromagnetic wave is expressed in terms of a single polarizability tensor which is a function of only the geometry of the body and a parameter τ representing either the relative permittivity or permeability of the dielectric. Integral equations from which to compute the individual tensor elements are derived. Some of the properties of the tensor, including bounds on its diagonal elements, are also developed, and data are presented for the special case of a spheroidal body.