# 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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

## 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.