Definition:Vacuum Permittivity/Also known as
Vacuum Permittivity: Also known as
The vacuum permittivity is also known by the terms:
- permittivity of free space
- permittivity of empty space
- permittivity in (or of) vacuum
- distributed capacitance of the vacuum
The term electric constant has now apparently been accepted by many standards organisations worldwide.
However, as from $20$ May $2019$, the definition of $\varepsilon_0$ is no longer as a defined constant, but derived ultimately from the fine-structure constant, which is a measured value.
Hence many authorities (including $\mathsf{Pr} \infty \mathsf{fWiki}$) prefer not to use electric constant.
The following terms are more or less obsolete:
- dielectric constant
- dielectric constant of vacuum
Note that the term dielectric constant is also still used sometimes to mean the absolute permittivity (of a material), and so suffers the additional problem of being ambiguous.
Some sources use $\epsilon_0$ instead of $\varepsilon_0$.
Either symbol is acceptable, but $\mathsf{Pr} \infty \mathsf{fWiki}$ (having to choose one or the other) has settled on $\varepsilon_0$ as standard.
Some sources denote the vacuum permittivity with the symbol $\Gamma_e$.
Sources
- 1964: Milton Abramowitz and Irene A. Stegun: Handbook of Mathematical Functions ... (previous) ... (next): $2$. Physical Constants and Conversion Factors
- 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
- 1990: I.S. Grant and W.R. Phillips: Electromagnetism (2nd ed.) ... (previous) ... (next): Chapter $1$: Force and energy in electrostatics: $1.1$ Electric Charge