# Electric Constant

(redirected from absolute permittivity)
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## electric constant

[i¦lek·trik ′kän·stənt]
(electricity)
The permittivity of empty space, equal to 1 in centimeter-gram-second electrostatic units and to 107/4π c 2 farads per meter or, numerically, to 8.854 × 10-12 farad per meter in International System units, where c is the speed of light in meters per second. Symbolized ε0.

## Electric Constant

(or permittivity of free, or empty, space), the constant of proportionality ∊0 in Coulomb’s law, which gives the force of interaction between two point charges at rest.

In the International System of Units (SI), ∊0 = 10 7/4πC 2 farads per meter (F/m) = 8.85418782 ± 0.00000007 F/m, where c is the speed of light in m/sec. In the centimeter-gram-second (cgs) electrostatic system and in the Gaussian system, ∊0 is taken to be a dimensionless factor equal to unity.

In contrast to the dielectric constant ∊, which depends on the type of substance, temperature, pressure, and other parameters, the electric constant ∊0 depends only on the choice of a system of units.

References in periodicals archive ?
where [rho] is the effective polarizability of the particle, [upsilon] is the volume, [[epsilon].sub.m] is the absolute permittivity of the medium, [F.sub.CM] is the Clausius-Mossotti factor and R is the radius of the particle .
Substitution of Equations (18)-(21) into Equation (15) by use of the total electric flux density [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] at z < 0 and the transmitted electric flux density [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] at z > 0 ([[epsilon].sup.TE.sub.eff] is the effective absolute permittivity of the metamerial) results in the effective magnetic surface susceptibilities at the interface A:
For isotropic linear media, the scalar complex relative permittivity [[epsilon].sub.r] is defined in terms of the absolute permittivity [epsilon] and the permittivity of vacuum [[epsilon].sub.0] (F/m), as follows [epsilon] ([omega]) = [[epsilon].sub.0][[epsilon].sub.r] ([omega]), where [[epsilon].sub.r] ([omega]) = [[epsilon] [.sub.r[infinity]] + [X.sub.r] ([omega]) = [[epsilon]'.sub.r] ([omega]) - i[[epsilon]".sub.r] ([omega]), and [[epsilon] [.sub.r[infinity]] is the optical-limit of the relative permittivity.

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