The statmho is the unit of
electrical conductance
The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual paralle ...
in the
electrostatic system of units (ESU), an extension of the
centimeter-gram-second (CGS) system to cover electrical units. It is sometimes called the statsiemens, with symbol statS.
Conversion
In the ESU system, the
permittivity of free space is set to unity by definition. This results in unit conversions to the SI system containing a power of the
speed of light
The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit ...
, ''c'', as well as a power of 10. In the case of the statmho, the conversion from
siemens (S) is given by:
[Donald Fenna, ''A Dictionary of Weights, Measures, and Units'', pp. 83–84, Oxford University Press, 2002 .]
:1
S ≘ ''c''
2 × 10
−5 s
2/m
2 × 1 statmho.
The value of ''c'' in the SI system is metres per second exactly by definition. However, in the era in which the ESU system was in use, the speed of light was determined by measurement and was taken to be approximately centimetres per second.
[
:1 statmho ≘ 1.112650 pS.][Fenna, p. 76]
The sign ≘ denotes 'correspondence' between quantities. Equality does not apply, since the systems of quantities underlying the two systems of units are mutually incompatible.
References
Centimetre–gram–second system of units
Electricity
{{Measurement-stub