Comment on 'Covariant formulation of electrodynamics in isotropic media'

A recent paper Pal (2022 Eur. J. Phys.43 015204) puts into covariant form an extension of relativistic classical electromagnetism from free space to a linearly polarizable medium. The paper is based on the assumption that the relativistic tensor, F-mu nu, which is a tensor in free space, will also be a tensor in a linear medium. Pal constructs a proposed covariant formulation that gives for a medium moving with constant velocity, v, in terms of F-mu nu for the medium at rest. However, although F-mu nu has been proven to be a relativistic tensor in free space, we show that it is not a tensor in a linear medium. This means that the covariant extension proposed by Pal fails.