Remarks on forces and the energy-momentum tensor in macroscopic electrodynamics

The conservation laws which follow from the field equations and their relation to the energy and momentum conservation laws are discussed. On the basis of the electrodynamics of slowly moving bodies, an expression is derived for the density of the force which acts on an isotropic inhomogeneous medium in an electromagnetic field. Attention is concentrated on elucidating the difference between the energymomentum tensors of Minkowski and Abraham. It is emphasized either of these can be used in practice to consider the exchange of energy and momentum between an emitter and a medium in which the emitter is placed. However, to analyze the processes in the medium itself, Abraham's should be used because it takes into account Abraham's volume force, which acts even on a homogeneous medium (whereas according to Minkowski no force acts at all on a transparent, homogeneous medium with density-independent permittivity in an electromagnetic field).