Lorentz transformation of a charge-current density and “relativistic polarization” of a moving current loop

Abstract

We show that the claim by Franklin (Int. J. Mod. Phys. A 35, 2050061 (2020)) with respect to the vanishing charge distribution over the perimeter of an electrically neutral moving current loop is erroneous and is based on a misinterpretation of physical meaning of Lorentz transformations. Moreover, we show that the development of nonvanishing electric dipole moment by a moving current loop (which we named as “relativistic polarization”) represents a direct implication of covariant formulation of classical electrodynamics of material media. In this respect, we analyze some subtle effects related to the motion of magnetic dipoles in an electromagnetic field and disclose their physical meaning.