Abstract:
Some methodological aspects of the thermodynamics of dielectrics are discussed. In particular, it is noted that in the general case neither the electric displacement D nor the electric field strength E can be taken as the thermodynamic parameter defining the state of a polarized medium and that the electric polarization P is the appropriate choice. The relation between D and E as defined by the material equation of a medium is shown to be valid only in the state of thermodynamic equilibrium and hence is violated by fluctuations of P. In such an event, the material equation of a dielectric is not an analogue of the equation of state of the substance, which relates the pressure to the volume.