electric constant

(electricity) The permittivity of empty space, equal to 1 in centimeter-gram-second electrostatic units and to 10⁷/4πc² 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.

physics. Symbol ɛ₀. SI The adopted value for electric permittivity of vacuum = (4π·c²)^-1 × 10⁷F·m^-1 = 8.854 2~ × 10^-12 C²·m^-1·J^-1.