## Dr. Ahmed G. Abo-Khalil

Electrical Engineering Department

## Vacuum permittivit

The vacuum permittivity ε0 (also called permittivity of free space or the electric constant) is the ratio D/E in free space. It also appears in the Coulomb force constant 1/4πε0.

Its value is[1]

egin{align} varepsilon_0 & stackrel{mathrm{def}}{=} frac{1}{c_0^2mu_0} = frac{1}{35950207149.4727056pi} frac ext{F} ext{m} approx 8.8541878176ldots imes 10^{-12} frac ext{F} ext{m} end{align}

where

c0 is the speed of light in free space,
µ0 is the vacuum permeability.

Constants c0 and μ0 are defined in SI units to have exact numerical values, shifting responsibility of experiment to the determination of the meter and the ampere. (The approximation in the second value of ε0 above stems from π being an irrational number.)

Monday 10 -2

Tuesday 10-12

Thursday 11-1

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email: a.abokhalil@mu.edu.sa

a_galal@yahoo.com

Phone: 2570

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