The dielectric constant is a characteristic quantity of a given dielectric substance, sometimes called the
relative permittivity (Bekefi and Barrett 1987, p. 418). In general, the dielectric constant is a complex constant, with
the real part Eric Weisstein's World of Math giving reflective surface properties (Fresnel reflection coefficients), and the
imaginary part Eric Weisstein's World of Math giving the radio absorption coefficient
In cgs,
where is the electric susceptibility. In MKS,
where is the electric permittivity and is the permittivity of free space.
The corresponding quantity for magnetism is called the relative permeability
Electric Permittivity, Electric Susceptibility, Fresnel Reflection Coefficients, Radio Absorption Coefficient, Relative Permeability
References
Bekefi, G. and Barrett, A. H. Electromagnetic Vibrations, Waves, and Radiation. Cambridge, MA: MIT Press, pp. 418-420, 1987.
