Interaction Energy of a Dielectric in an Electrostatic Field

A straightforward computation of the interaction field energy of a dielectric in a uniform external electrostatic field appears to yield a result different from that given by a general theorem. It is shown here that the discrepancy can be resolved by considering the uniform field of infinite extent to be the limit of a field of finite extent. A recent paper by M. S. Plesset and G. Venezian is discussed (Am. J. Phys. 32:860, (1964)).