Abstract
The presence of a finite conductivity results in the appearance of an electric current proportional to the strength of the electric field. In turn, this current leads to the appearance of a magnetic field. For the thermodynamic description of these phenomena, it is proposed to consider the free energy of a ferroelectric material containing both scalar and vector potentials in accordance with the Landau theory. The heat equation is derived, which includes both the conductivity itself and its temperature derivative. It is shown that the main contribution of conductivity is the existence of Joule heat.