# Symbols:Greek/Epsilon/Vacuum Permittivity

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## Vacuum Permittivity

- $\varepsilon_0$

The **vacuum permittivity** is the physical constant denoted $\varepsilon_0$ defined as:

- $\varepsilon_0 := \dfrac {e^2} {2 \alpha h c}$

where:

- $e$ is the elementary charge
- $\alpha$ is the fine-structure constant
- $h$ is Planck's constant
- $c$ is the speed of light defined in $\mathrm m \, \mathrm s^{-1}$

Of the above, only the fine-structure constant $\alpha$ is a measured value; the others are defined.

It can be defined as the capability of an electric field to permeate a vacuum.

From Value of Vacuum Permittivity, it has the value:

- $\varepsilon_0 = 8 \cdotp 85418 \, 78128 (13) \times 10^{-12} \, \mathrm F \, \mathrm m^{-1}$ (farads per metre)

The $\LaTeX$ code for \(\varepsilon_0\) is `\varepsilon_0`

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### Variant

- $\Gamma_e$

**Vacuum permittivity** can also be seen denoted as $\Gamma_e$ in some older works.

The $\LaTeX$ code for \(\Gamma_e\) is `\Gamma_e`

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## Sources

- 1969: J.C. Anderson, D.M. Hum, B.G. Neal and J.H. Whitelaw:
*Data and Formulae for Engineering Students*(2nd ed.) ... (previous) ... (next): $3.$ Physical Constants