  Communication
New! Download Unionpedia on your Android™ device!
Free Faster access than browser!

# Siemens (unit)

The siemens (symbol: S) is the derived unit of electric conductance, electric susceptance and electric admittance in the International System of Units (SI). 

## Admittance

In electrical engineering, admittance is a measure of how easily a circuit or device will allow a current to flow.

## Ampere

The ampere (symbol: A), often shortened to "amp",SI supports only the use of symbols and deprecates the use of abbreviations for units.

## Electric current

An electric current is a flow of electric charge.

## Electrical impedance

Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied.

## Electrical reactance

In electrical and electronic systems, reactance is the opposition of a circuit element to a change in current or voltage, due to that element's inductance or capacitance.

## Electrical resistance and conductance

The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor.

## General Conference on Weights and Measures

The General Conference on Weights and Measures (Conférence générale des poids et mesures – CGPM) is the supreme authority of the International Bureau of Weights and Measures (Bureau international des poids et mesures – BIPM), the inter-governmental organization established in 1875 under the terms of the Metre Convention (Convention du Mètre) through which Member States act together on matters related to measurement science and measurement standards.

## Greek alphabet

The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BC.

## International Bureau of Weights and Measures

The International Bureau of Weights and Measures (Bureau international des poids et mesures) is an intergovernmental organization established by the Metre Convention, through which Member States act together on matters related to measurement science and measurement standards.

## International System of Units

The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.

## Kilogram

The kilogram or kilogramme (symbol: kg) is the base unit of mass in the International System of Units (SI), and is defined as being equal to the mass of the International Prototype of the Kilogram (IPK, also known as "Le Grand K" or "Big K"), a cylinder of platinum-iridium alloy stored by the International Bureau of Weights and Measures at Saint-Cloud, France.

## Metre

The metre (British spelling and BIPM spelling) or meter (American spelling) (from the French unit mètre, from the Greek noun μέτρον, "measure") is the base unit of length in some metric systems, including the International System of Units (SI).

## National Institute of Standards and Technology

The National Institute of Standards and Technology (NIST) is one of the oldest physical science laboratories in the United States.

## Ohm

The ohm (symbol: Ω) is the SI derived unit of electrical resistance, named after German physicist Georg Simon Ohm.

## Pentode

A pentode is an electronic device having five active electrodes.

## Second

The second is the SI base unit of time, commonly understood and historically defined as 1/86,400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each.

## SI base unit

The International System of Units (SI) defines seven units of measure as a basic set from which all other SI units can be derived.

## SI derived unit

SI derived units are units of measurement derived from the seven base units specified by the International System of Units (SI).

## Siemens (unit)

The siemens (symbol: S) is the derived unit of electric conductance, electric susceptance and electric admittance in the International System of Units (SI).

## Siemens mercury unit

The Siemens mercury unit is an obsolete unit of electrical resistance.

## Susceptance

In electrical engineering, susceptance (B) is the imaginary part of admittance, where the real part is conductance.

## Transconductance

Transconductance (for transfer conductance), also infrequently called mutual conductance, is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device.

## Volt

The volt (symbol: V) is the derived unit for electric potential, electric potential difference (voltage), and electromotive force.

## Voltage

Voltage, electric potential difference, electric pressure or electric tension (formally denoted or, but more often simply as V or U, for instance in the context of Ohm's or Kirchhoff's circuit laws) is the difference in electric potential between two points.

## Werner von Siemens

Ernst Werner Siemens (von Siemens from 1888;; 13 December 1816 – 6 December 1892) was a German inventor and industrialist.

## William Thomson, 1st Baron Kelvin

William Thomson, 1st Baron Kelvin, (26 June 1824 – 17 December 1907) was a Scots-Irish mathematical physicist and engineer who was born in Belfast in 1824.

## References

Hey! We are on Facebook now! »