# Formula: Electric Field in Matter Polarization field    Polarization    Vacuum Permittivity

## Polarization field

Unit
Polarization field is an electric field created due to polarization $$\class{red}{P}$$, which is directed against the external electric field $$\class{purple}{E}$$.

## Polarization

Unit
Polarization describes the density of electric dipoles in a material (number per volume) and induces a polarization field $$\class{purple}{E_{\text{p}}}$$, which can be aligned either opposite or in the same direction as the external electric field, thereby amplifying or weakening the external electric field.

## Vacuum Permittivity

Unit
The vacuum permittivity is a physical constant that appears in equations involving electromagnetic fields. It has the following experimentally determined value: $$\varepsilon_0 ~\approx~ 8.854 \, 187 \, 8128 ~\cdot~ 10^{-12} \, \frac{\mathrm{As}}{\mathrm{Vm}}$$

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