19th  Top energy abbreviations 
The volt (symbol: V) is the SI derived unit of electromotive force, commonly called "voltage".^{[1]} It is also the unit for the related but slightly different quantity electric potential difference (also called "electrostatic potential difference"). It is named in honor of the Italian physicist Alessandro Volta (1745–1827), who invented the voltaic pile, possibly the first chemical battery.
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The volt is defined as the value of the voltage across a conductor when a current of one ampere dissipates one watt of power in the conductor. ^{[2]} It can be written in terms of SI base units as: m^{2} · kg · s^{−3} · A^{−1}. It is also equal to one joule of energy per coulomb of charge, J/C.
Since 1990 the volt has been maintained internationally for practical measurement using the Josephson effect, where a conventional value is used for the Josephson constant, fixed by the 18th General Conference on Weights and Measures as:
In the water flow analogy sometimes used to explain electric circuits by comparing them to waterfilled pipes, voltage difference is likened to water pressure difference – the difference determines how quickly the electrons will travel through the circuit. Current (in amperes), in the same analogy, is a measure of the volume of water that flows past a given point per unit time (volumetric flow rate). The flow rate is determined by the width of the pipe (analogous to electrical resistance), and the pressure difference between the front end of the pipe and the exit is analogous to voltage. The analogy extends to power dissipation: the power given up by the water flow is equal to flow rate times pressure, just as the power dissipated in a resistor is equal to current times the voltage drop across the resistor (amperes x volts = watts).
The relationship between voltage and current (in ohmic devices) is defined by Ohm's Law.
Nominal voltages of familiar sources:
Note: Where RMS (root mean square) is stated above, the
peak voltage is
times greater than the RMS voltage for a sinusoidal signal
centered around zero voltage.
In 1800, as the result of a professional disagreement over the galvanic response advocated by Luigi Galvani, Alessandro Volta developed the socalled Voltaic pile, a forerunner of the battery, which produced a steady electric current. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver. In the 1880s, the International Electrical Congress, now the International Electrotechnical Commission (IEC), approved the volt as the unit for electromotive force. At that time, the volt was defined as the potential difference [i.e., what is nowadays called the "voltage (difference)"] across a conductor when a current of one ampere dissipates one watt of power.
The international volt was defined in 1893 as 1/1.434 of the emf of a Clark cell. This definition was abandoned in 1908 in favor of a definition based on the international ohm and international ampere until the entire set of "reproducible units" was abandoned in 1948.
Prior to the development of the Josephson junction voltage standard, the volt was maintained in national laboratories using specially constructed batteries called standard cells. The United States used a design called the Weston cell from 1905 to 1972.
This SI unit is named after Alessandro Volta. As with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is uppercase (V). When an SI unit is spelled out in English, it should always begin with a lowercase letter (volt), except where any word would be capitalized, such as at the beginning of a sentence or in capitalized material such as a title. Note that "degree Celsius" conforms to this rule because the "d" is lowercase.—Based on The International System of Units, section 5.2.


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"The Chevrolet Volt has joined baseball and apple pie as an unassailable, nonpartisan symbol of American cando and knowhow. General Motors won't start selling the plugin hybrid for another 18 months (at least), but that hasn't kept it from becoming the most important political accessory since the flag lapel pin."
Volt
This German entry was created from the translations listed at volt. It may be less reliable than other entries, and may be missing parts of speech or additional senses. Please also see Volt in the German Wiktionary. This notice will be removed when the entry is checked. (more information) January 2009
[[File:thumbJosephson junction array chip developed by NIST as a standard volt.]]
The volt (symbol: V) is the SI derived unit of electric potential difference or electromotive force ^{[1]}. It is named in honor of the Italian physicist Alessandro Volta (1745–1827), who invented the voltaic pile, the first chemical battery.
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The volt is defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power. Hence, it is the base SI representation m^{2} · kg · s^{3} · A^{1}, which can be equally represented as one joule of energy per coulomb of charge, J/C.
In the hydraulic analogy sometimes used to explain electric circuits by comparing them to waterfilled pipes, voltage is likened to water pressure  it determines how fast the electrons will travel through the circuit. Current (in amperes), in the same analogy, is a measure of the volume of water that flows past a given point, the rate of which is determined by the voltage, and the total output measured in watts. The equation that brings all three components together is: volts × amperes = watts
[[File:150pxthumb1.5 V Ccell batteries]]
Nominal voltages of familiar sources:
Note: Where 'RMS' (root mean square) is stated above, the peak voltage is $\backslash sqrt\{2\}$ times greater than the RMS voltage for a sinusoidal signal.
In 1800, as the result of a professional disagreement over the galvanic response advocated by Luigi Galvani, Alessandro Volta developed the socalled Voltaic pile, a forerunner of the battery, which produced a steady electric current. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver. In the 1880s, the International Electrical Congress, now the International Electrotechnical Commission (IEC), approved the volt for electromotive force. The volt was defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power.
