Natural Units are widely used in quantum field theory. In this unit system, speed of light in vacuum c, reduced Planck constant and vacuum electric permittivity ε0 are defined as 1, and energy (usually in eV) is the only base quantity.
Under the 2019 redefinition of the SI base units:
(exact)
Some conversions of units in mechanics are: [1]
- velocity:
- angular momentum:
- mass:
(
)
- momentum:
(
)
- angular frequency:
(
)
- time:
- length:
(
)
- force:
(
)
The electric charge in natural units is a dimensionless quantity, according to Coulomb's law:
where F has the dimension of 2 (eV2) and r has the dimension of -1 (eV-1).
The elementary charge in natural units is: [1]
according to the fine-structure constant:
Some conversions of units in electromagnetism are: [1]
- charge:
- electric field:
(
)
- magnetic B field:
(
) [2]