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The relative static permittivity of a solvent is a relative measure of its chemical polarity. For example, water is very polar, and has a relative static permittivity of 80.10 at 20 °C while n - hexane is non-polar, and has a relative static permittivity of 1.89 at 20 °C. [ 26 ]
The Lorentz–Lorenz equation is similar to the Clausius–Mossotti relation, except that it relates the refractive index (rather than the dielectric constant) of a substance to its polarizability. The Lorentz–Lorenz equation is named after the Danish mathematician and scientist Ludvig Lorenz , who published it in 1869, and the Dutch ...
The relative permittivity of a material can be found by a variety of static electrical measurements. The complex permittivity is evaluated over a wide range of frequencies by using different variants of dielectric spectroscopy , covering nearly 21 orders of magnitude from 10 −6 to 10 15 hertz .
Putting B = μH and D = ϵE, as above, we can eliminate B and D to obtain equations in only E and H: = =. If the material parameters ϵ and μ are real (as in a lossless dielectric), these equations show that k, E, H form a right-handed orthogonal triad, so that the same equations apply to the magnitudes of the respective vectors.
where R is the molar refractivity, is the Avogadro constant, is the electronic polarizability, p is the density of molecules, M is the molar mass, and = / is the material's relative permittivity or dielectric constant (or in optics, the square of the refractive index).
The real (blue solid line) and imaginary (orange dashed line) components of relative permittivity are plotted for model with parameters = 3.2 eV, = 4.5 eV, = 100 eV, = 1 eV, and = 3.5. The Tauc–Lorentz model is a mathematical formula for the frequency dependence of the complex-valued relative permittivity , sometimes referred to as the ...
In the new SI system, only c keeps its defined value, and the electron charge gets a defined value. In materials with relative permittivity, ε r, and relative permeability, μ r, the phase velocity of light becomes =, which is usually [note 5] less than c.
If a dielectric material is a linear dielectric, then electric susceptibility is defined as the constant of proportionality (which may be a tensor) relating an electric field E to the induced dielectric polarization density P such that [3] [4] =, where