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The siemens (symbol: S) is the SI derived unit of electric conductance. It is named after the German inventor and industrialist Ernst Werner von Siemens, and is equivalent to the previously used designation of this unit, the mho. In English, the term siemens is used both for the singular and plural. The 14th General Conference on Weights and Measures approved the addition of the siemens as an SI derived unit in 1971. Image File history File links Question_book-3. ... Look up si, Si, SI in Wiktionary, the free dictionary. ... Electrical conductance is an electrical phenomenon where a material contains movable particles with electric charge, which can carry electricity. ... Werner von Siemens Ernst Werner von Siemens (known as Werner von Siemens) (December 13, 1816 – December 6, 1892) was a German inventor and industrialist. ... The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures (CGPM, never GCWM). ...

Look up si, Si, SI in Wiktionary, the free dictionary. ... Werner von Siemens Ernst Werner von Siemens (known as Werner von Siemens) (December 13, 1816 – December 6, 1892) was a German inventor and industrialist. ... Majuscules or capital letters (in the Roman alphabet: A, B, C, ...) are one type of case in a writing system. ... Minuscule, or lower case, is the smaller form (case) of letters (in the Roman alphabet: a, b, c, ...). Originally alphabets were written entirely in majuscule (capital) letters which were spaced between well-defined upper and lower bounds. ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ...

Definition

For a physical object, typically an electronic device, with electrical resistance R, the conductance G is defined as Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ... Electrical conductance is the reciprocal of electrical resistance. ...

where

• G is the conductance,
• R is the resistance,
• I is the current through the object and
• V is the voltage (electrical potential difference) across the object.

The unit siemens for the conductance G is defined by Electrical conductance is the reciprocal of electrical resistance. ... Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ... In electricity, current refers to electric current, which is the flow of electric charge. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ...

Note that the last term is in SI base units where A is the abbreviation for ampere, the unit of electric current; kg is the abbreviation for kilogram; m is the abbreviation for metre; and s is the abbreviation for the time unit second. The SI system of units defines seven SI base units: physical units defined by an operational definition. ... For other uses, see Ampere (disambiguation). ... Electric current is the flow (movement) of electric charge. ... “Kg” redirects here. ... This article is about the unit of length. ... This article is about the unit of time. ...

So for a device with conductance one siemens, then the electric current through it with one volt across it is one ampere, and for each extra volt across it the electric current through it increases by one ampere. Electric current is the flow (movement) of electric charge. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... For other uses, see Ampere (disambiguation). ...

Example: The conductance of a resistor with resistance six ohms is G = 1/(6 Ω) = 0.166^• S. A multimeter can be used to measure resistance in ohms. ...

Smith (ψ)

• ψ is the unit denoted Smith.

A Smith (ψ) is equal to how much volume 40 picosiemens (pS) occupies in a cylinder. Generally, the Smith is a very versatile function as it is used in both the mechanical and electrical fields of study. The background as to why the Smith was created is quite essential to the physical world. The sole purpose of the Smith was to make the use of Siemen universal. Most, if not all engineers use Siemen on an everyday basis, all due to the unit Smith.

The unit Smith is defined by the equation:

Mho

The siemens is equivalent to the previously used term mho unit, which was derived from spelling ohm backwards and written with an upside-down capital Greek letter Omega: , Unicode symbol is U+2127 (℧). The term siemens, as it is an SI unit, is used universally in science and primarily in electrical applications, while mho is still used primarily in electronic applications. The upside down ohm symbol, while not an official SI unit, has the advantage of being less likely to be confused with a variable than the letter S when doing algebraic calculations by hand, where the usual typographical distinctions (such as italic for variables and Roman for unit names) are difficult to maintain. Furthermore, in some industries (like electronics) it is common to write the symbol for second incorrectly as S instead of s, causing potential confusion. This article is about the engineering discipline. ... This article is about the unit of time. ...

References

Prentiss, Barry. "MD Abbreviations by Abbreviation" _SLAC_. 25-02-1999, SLAC Mechanical Design Department, 09-11-2007. Note: Ms = Millisecond, mS = Millisiemens.