On the Molecular Theory of Electrostriction

In order to obtain a better understanding of the phenomenon of electrostriction, the particular case of a sphere of fluid dielectric, subjected to a uniform external field, is considered. The problem is discussed from both macroscopic and microscopic points of view. That part of the spur of the stress tensor 3Δ P which depends quadratically on the applied field is calculated for both non-polar and dipolar dielectrics. It is found that the Lorenz-Lorentz and Debye theories of dielectrics lead to the singular result that Δ P is zero. The reason for this is discussed, and it is shown that the more modern theories of Yvon and Kirkwood and of Onsager do not lead to such a result.