Condensed medium dielectric properties

Power factor, like the dielectric constant, is a property that represents a power loss that takes place when a wire insulation becomes the dielectric of a condenser because of a surrounding sheath or other conducting medium. 

We choose the total system to be the condenser and the entire dielectric medium. The condenser is immersed in the medium which, for purposes of this discussion, is taken to be a single-phase, multicomponent system. The pressure on the system is the pressure exerted by the surroundings on a surface of the dielectric. In setting up the thermodynamic equations we omit the properties of the metal plates, because these remain constant except for a change of temperature. The differential change of energy of the system is expressed as a function of the entropy, volume, and mole numbers, but with the addition of the new work term. Thus,... 

It is well-known that the simplest approach to the study of the optical properties of condensed media is the macroscopic electrodynamics approach, making use of the concept of the dielectric constant tensor f..tJ (oj, k) where w and k are the frequency and the wavevector of the light wave. Calculation of this tensor for a specific medium is, however, a problem of microscopic theory. For instance, the procedures for calculating the tensor k) for the excitation region of the... 

The representation of the macroscopic properties of bodies by symbolic operators may be applied in other contexts. In electrostatics, for example, if we interpret Q as the charge on a conducting body, and T as the electric potential, then iA in Eq. (302) may be interpreted as the symbolic capacitance of the body, viewed as a condenser k then plays the role of the dielectric constant (capacitivity) of the medium external to the body, this medium being assumed homogeneous and isotropic. 

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