**16. References**


**1. Introduction**

systems.

the simple thermodynamic systems).

shall use the neo-gibbsian thermodynamics) [16].

The systems which contain electric or magnetic media have besides the electric (respectively magnetic) properties also the common properties of a thermodynamic systems (that is thermal, volumic, chemical); moreover, there are correlations between the electric (magnetic) properties and the thermal or volumic properties. Because there are a great variety of situations with the corresponding properties, we shall present briefly only the most important characteristics of the simplest electric or magnetic systems. For these systems there are supplementary difficulties (comparing to the simple neutral fluid) because the inherent non-homogeneity of these systems and also because the special coupling between the electric (respectively magnetic) degree of freedom and the volumic degree of freedom. These difficulties have let to the use of different methods of study in the literature, being necessary to modify some standard thermodynamic quantities (introduced in the standard textbooks for

In order to have a relation with the presentations of other works, we shall discuss the electric (respectively the magnetic) systems with many methods and we shall note some improper use of the different concepts which had been introduced initially in the standard thermodynamics. Although the most of the electric or magnetic systems are solid, in order to maintain a short and also an intelligible exposition we shall present explicitly only the case when the system is of the fluid type, and when it contain a single chemical species, therefore neglecting the

We remark that for the thermodynamics of quasi-static processes must be considered only equilibrium states, so that we will deal only with electrostatic or magneto-static fields. Although there are interference effects between the electric and magnetic phenomena, these are very small; therefore, in order to simplify the exposition, we shall study separately the electric and the magnetic systems, emphasizing the formal similitude between these type of

There are many textbooks which present the basic problems of thermodynamics, some of the most important of them used the classical point of new [1-12], and also other used the neo-gibbsian point of view [13-15]; in the following we shall use the last point of view (i.e. we

anisotropy effects and the complications introduced by the theory of elasticity.

*Romania*

Radu Paul Lungu

**Thermodynamics of Electric**

*Department of Physics, University of Bucharest, M˘agurele-Bucharest,*

**and Magnetic Systems**

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