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Siemens (unit)

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	Topics Siemens (unit) Topic Home The siemens (symbol: S) is the SISi Summary Si, si, or SI may stand for:... derived unitSI derived unit SI derived units are part of the SI system of measurement units and are derived from the seven SI base units.... of electric conductance. It is equal to inverse ohmOHM Sorry, no overview for this topic . It is named after the GermanGermany Germany , officially the Federal Republic of Germany , is a country in central Europe.... inventor and industrialist Ernst Werner von SiemensErnst Werner von Siemens Ernst Werner von Siemens was a German inventor and industrialist. ... , and was previously called the mho. In English, the term siemens is used both for the singular and plural. The 14th General Conference on Weights and MeasuresGeneral Conference on Weights and Measures The General Conference on Weights and Measures is the English name of the Confrence gnrale des poids et mesures .... approved the addition of the siemens as an SI derived unitSI derived unit SI derived units are part of the SI system of measurement units and are derived from the seven SI base units.... in 1971. Definition For a physical object, typically an electronic device, with electrical resistanceElectrical resistance Electrical resistance is a measure of the degree to which an object opposes the passage of an electric current.... R, the conductanceElectrical conductance Electrical conductance is the reciprocal of electrical resistance.... G is defined as where I is the current through the object and V is the voltageVoltage Summary Voltage is the difference of electrical potential between two points of an electrical network, expressed in volts .... (electrical potential difference) across the object. The unit siemens for the conductance G is defined by Note that the last term is in SI base unitSI base unit The SI system of units defines seven SI base units: physical units defined by an operational definition.... s where A is the symbol for ampereAmpere The ampere is the SI base unit of electric current.... , the unit of electric currentElectric current Electric current is by definition the flow of electric charge.... ; kg is the symbol for kilogramKilogram The kilogram or kilogramme, is the SI base unit of mass.... , the unit of massMass Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to.... ; m is the symbol for metreMetre The metre, or meter , is a measure of length.... , the unit of lengthLength Length is the long dimension of any object.... ; and s is the symbol for the timeTime Two distinct views exist on the meaning of time.... unit secondSecond The second is the name of a unit of time, and today refers to the International System of Units base unit of time.... . C is the symbol for the SI derived unitSI derived unit Overview SI derived units are part of the SI system of measurement units and are derived from the seven SI base units.... of electric chargeElectric charge Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic inte... , the coulomb; V is the symbol for the SI derived unitSI derived unit Summary SI derived units are part of the SI system of measurement units and are derived from the seven SI base units.... of voltageVoltage Voltage is the difference of electrical potential between two points of an electrical network, expressed in volts .... , the voltVolt The volt is the SI derived unit of electric potential difference or electromotive force .... ; and O is the symbol for the SI derived unitSI derived unit SI derived units are part of the SI system of measurement units and are derived from the seven SI base units.... of electrical resistanceElectrical resistance Electrical resistance is a measure of the degree to which an object opposes the passage of an electric current.... , the ohm. So for a device with conductance one siemens, then the electric currentElectric current Electric current is by definition the flow of electric charge.... through it with one voltVoltage Overview Voltage is the difference of electrical potential between two points of an electrical network, expressed in volts .... across it is one ampereAmpere The ampere is the SI base unit of electric current.... , and for each extra volt across it the electric current through it increases by one ampere. Example: The conductance of a resistor with resistance six ohmOHM Sorry, no overview for this topic s is G = 1/(6 O) 0.167 S. Historical/Deprecated Since 1860 to the middle of 20th century, siemens or siemens mercury unit, was the unit of electrical resistance. It was defined as the resistance of mercury column of 1 meter long and 1 mm squared at 0 degrees Celsius. It was equivalent to 0.953 Ohm approximately. Officially, it ceased usage after 1881, but was widely used in telegraph and telephone services until WWII. Mho The siemens was previously referred to by the term mho, which was derived from spelling ohm backwards and written with an upside-down capital GreekGreek alphabet The Greek alphabet is an alphabet that has been used to write the Greek language since about the 9th century BC.... letter Omega: , Unicode symbol 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 inverted Omega, while not an official SI abbreviation, 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 electronicsElectronics The field of electronics comprises the study and use of systems that operate by controlling the flow of electrons in device... ) it is common to write, contrary to common established and SI-dictated practice, the symbol S instead of s where second is meant, potentially causing confusion.