# Formula: Electric (Electrostatic) Potential of a Point Charge Distance    Electric charge    Relative permittivity

## Electric Potential

Unit
Electric potential at a distance from a charge $$\class{red}{Q}$$ which generates this potential. The potential indicates the potential energy that a test charge gains or must release when placed from an infinite distance to a distance $$r$$ from the source charge.

## Distance

Unit
Distance of a test charge from the source charge $$\class{red}{Q}$$.

## Source charge

Unit
Electric charge generating potential $$V_{\text e}$$.

## Relative permittivity

Unit
Relative permittivity describes the medium in which the two charges are located. If the two charges are in vacuum then $$\varepsilon_{\text r} = 1$$. And, for example, if they are in lukewarm water then $$\varepsilon_{\text r} = 80$$. The greater the relative permittivity of the medium, the more this medium weakens the potential.

## 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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