{| class="wikitable" |- ! Units ! Condition |- | SI units (weber convention)Jackson 1999, section 6.11, equation (6.153), p. 275 | |- | SI units (ampere-meter convention) | |- | Gaussian-cgs units | |- |} where is the vacuum permittivity, is the reduced Planck constant, is the speed of light, and is the set of integers.
{| class="wikitable" |-  Units  Condition |- | SI units (weber convention)Jackson 1999 section 611 equation (6153) p 275 | |- | SI units (ampere-meter convention) | |- | Gaussian-cgs units | |- |} where is the vacuum permittivity is the reduced Planck constant is the speed of light and is the set of integers