Entropy of electromagnetic polarization.
The entropy of electromagnetic polarization is considered in this paper. It is shown that unless the non-field entropy, and not the total entropy, is used as the independent variable in the expression for the internal energy, the first law is violated and the meaning of heat flow, as given by the second law, is contradicted. The total entropy and its field and non-field components are shown to be state functions. The field entropy comprises contributions from the field generated by the contents of the system and stored within as well as outside its boundaries. The contribution of the field stored outside the system boundaries is derived and demonstrated for the case of a uniformly polarized sphere. Finally, expressions are derived for field entropies and entropy densities, in composite systems, using the concept of interaction entropy. The results are shown to be fundamentally different compared to those used in the current literature.
Zimmels
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Environmental and Water Resources Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel.