Search results
Results From The WOW.Com Content Network
The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field.
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 ...
In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field.When a dielectric material is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor, because they have no loosely bound, or free, electrons that may drift through the material, but instead they ...
Another common term encountered for both absolute and relative permittivity is the dielectric constant which has been deprecated in physics and engineering [3] as well as in chemistry. [ 4 ] By definition, a perfect vacuum has a relative permittivity of exactly 1 whereas at standard temperature and pressure , air has a relative permittivity of ...
[13] [16] Hence, the term "dielectric constant of vacuum" for the electric constant ε 0 is considered obsolete by most modern authors, although occasional examples of continuing usage can be found. As for notation, the constant can be denoted by either ε 0 or ϵ 0, using either of the common glyphs for the letter epsilon.
The following are Maxwell's equations without sources (which are treated separately in the scope of plasma oscillations), in Gaussian units: =; =; =; = +. Then = = = or = (+) which is an electromagnetic wave equation for a continuous homogeneous medium with dielectric constant () in the Helmoltz form = where the refractive index is () = and the ...
Therefore, the dielectric constant (and the conductivity) has contributions from both terms. This approach can be generalized to compute the frequency dependent dielectric function. [38] It is possible to calculate dipole moments from electronic structure theory, either as a response to constant electric fields or from the density matrix. [39]
The Cole–Cole equation is a relaxation model that is often used to describe dielectric relaxation in polymers.. It is given by the equation = + + ()where is the complex dielectric constant, and are the "static" and "infinite frequency" dielectric constants, is the angular frequency and is a dielectric relaxation time constant.