Siemens (unit)

siemens
siemens
Unit system	SI
Unit of	electric conductance
Symbol	S
Named after	Ernst Werner von Siemens
Conversions
1 S in ...	... is equal to ...
SI base units	kg−1⋅m−2⋅s3⋅A2
inverse ohm	1 Ω−1
mho	1 ℧

The siemens (symbol: S) is the unit of electric conductance, electric susceptance, and electric admittance in the International System of Units (SI). Conductance, susceptance, and admittance are the reciprocals of resistance, reactance, and impedance respectively; hence one siemens is equal to the reciprocal of one ohm ( $Ω -1$ ) and is also referred to as the mho. The siemens was adopted by the IEC in 1935,^[1] and the 14th General Conference on Weights and Measures approved the addition of the siemens as a derived unit in 1971.^[2]

The unit is named after Ernst Werner von Siemens. In English, the same word siemens is used both for the singular and plural.^[3] Like other SI units named after people, the symbol (S) is capitalized but the name of the unit is not. For the siemens this distinguishes it from the second, symbol (lower case) s.

The related property, electrical conductivity, is measured in units of siemens per metre (S/m).

^ Minutes (PDF). 14th General Conference on Weights and Measures. 1971. p. 53.
^ Minutes (PDF). 14th General Conference on Weights and Measures. 1971. p. 78.
^ "Chapter 9: Rules and Style Conventions for Spelling Unit Names". NIST Guide to the SI (Report). National Institute of Standards and Technology. 2008. Archived from the original on 2019-05-06. Retrieved 2017-12-22.

[1] Minutes (PDF). 14th General Conference on Weights and Measures. 1971. p. 53.

[CGPM14-2] Minutes (PDF). 14th General Conference on Weights and Measures. 1971. p. 78.

[3] "Chapter 9: Rules and Style Conventions for Spelling Unit Names". NIST Guide to the SI (Report). National Institute of Standards and Technology. 2008. Archived from the original on 2019-05-06. Retrieved 2017-12-22.

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