Maxwell's Equations in Superconductors

A discussion is given of the various ways of defining fields in normal metals and superconductors. Josephson and Evetts used different approaches but they lead to the same results. The Evetts formulation, based on the chemical potential of a vortex line, leads to the development of thermo-electric equations using irreversible thermodynamics. The magnetic field terms in the Ginzburg-Landau free energy are discussed. An alternative is to use macroscopic quantities rather local ones. These are the external field and total moment of a body.