 The formula for capacitance in a parallel plate capacitor is written as

where formula_21 is the area of one plate, formula_22 is the distance between the plates, and formula_5 is the permittivity of the medium between the two plates.For a capacitor with relative permittivity formula_24, it can be said that

Permittivity is connected to electric flux (and by extension electric field) through Gauss's law.Gauss's law states that for a closed Gaussian surface, s

where formula_27 is the net electric flux passing through the surface, formula_28 is the charge enclosed in the Gaussian surface, formula_2 is the electric field vector at a given point on the surface, and formula_30 is a differential area vector on the Gaussian surface.