On the electromagnetic force on a dielectric medium

The study of the mechanical effects of light on a dielectric medium has led to two quite distinct forms for the force density: one based on the microscopic distribution of charges and the other on the distribution of atomic dipoles. Both approaches are based directly on the Lorentz force, but it has been suggested that they lead, in a number of cases, to significantly different predictions. In this paper we address this paradoxical situation and show that in the majority of problems the force densities lead to identical results. Where the theories do differ we attempt to determine which of the two descriptions is the more reliable.