# Formula Plate capacitor Electrical energy    Volume    Electric field

## Electrical energy

Unit
The energy that is 'stored' in the plate capacitor. The energy is stored in the electric field between the plates.

## Volume

Unit
The volume enclosed by the two capacitor plates.

## Electric field

Unit
The E-field indicates how large the electric force on a test charge would be if it were placed at a specific location between the capacitor plates.

## Relative permittivity

Unit
Relative permittivity is a dimensionless quantity that characterizes the dielectric (non-conductive material) between the capacitor plates. Depending on the material used, the dielectric can be used to effect the capacitance of the capacitor, for example.

In vacuum, the permittivity by definition has the value $$\varepsilon_{\text r} = 1$$. The water has approximately a value of $$\varepsilon_{\text r} \approx 80$$.

## Electric field constant

Unit
This natural constant always occurs when electromagnetic fields are involved. Electric field constant has the value: $$\varepsilon_0 = 8.854 \cdot 10^{-12} \, \frac{ \text{As} }{ \text{Vm} }$$.