digplanet beta 1: Athena
Share digplanet:

Agriculture

Applied sciences

Arts

Belief

Business

Chronology

Culture

Education

Environment

Geography

Health

History

Humanities

Language

Law

Life

Mathematics

Nature

People

Politics

Science

Society

Technology

Volt
NISTvoltChip.jpg
Josephson junction array chip developed by the National Bureau of Standards as a standard volt
Unit information
Unit system SI derived unit
Unit of Electric potential, electromotive force
Symbol V
Named after Alessandro Volta
In SI base units: 1 V = 1 kg·m2·s-3·A-1

The volt (symbol: V) is the derived unit for electric potential (voltage), electric potential difference, and electromotive force.[1] The volt is named in honour of the Italian physicist Alessandro Volta (1745–1827), who invented the voltaic pile, possibly the first chemical battery.

Definition[edit]

One volt is defined as the difference in electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points.[2] It is also equal to the potential difference between two parallel, infinite planes spaced 1 meter apart that create an electric field of 1 newton per coulomb. Additionally, it is the potential difference between two points that will impart one joule of energy per coulomb of charge that passes through it. It can be expressed in terms of SI base units (m, kg, s, and A) as:

volt equals kilogram times meter squared per ampere per second cubed

It can also be expressed as amperes times ohms (current times resistance, Ohm's law), watts per ampere (power per unit current, Joule's law), or joules per coulomb (energy per unit charge):

volt equals ampere times ohm, watt per ampere, and joules per coulomb

Josephson junction definition[edit]

The "conventional" volt, V90, defined 1988 by the 18th General Conference on Weights and Measures and in use from 1990, is calibrated using the Josephson effect for exact voltage-to-frequency conversion, combined with the cesium frequency standard. For the Josephson constant, KJ = 2e/h (where e is the elementary charge and h is the Planck constant), the "conventional" value KJ-90 is used:

K J-90 equals 0.4835979 gigahertz per microvolt

This standard is typically realized using an array of several thousand or tens of thousands of junctions, excited by microwave signals between 10 and 80 GHz (depending on the array design).[3] Empirically, several experiments have shown that the method is independent of device design, material, measurement setup, etc., and no correction terms are required in a practical implementation.[4]

Water flow analogy[edit]

In the water flow analogy sometimes used to explain electric circuits by comparing them with water-filled pipes, voltage (difference in electric potential) is likened to difference in water pressure.

The relationship between voltage and current is defined (in ohmic devices) by Ohm's Law.

Common voltages[edit]

A multimeter can be used to measure the voltage between two positions.
1.5 V C-cell batteries

Nominal voltages of familiar sources:

Note: Where RMS (root mean square) is stated above, the peak voltage is \sqrt{2} times greater than the RMS voltage for a sinusoidal signal centered around zero voltage.

History[edit]

Alessandro Volta

In 1800, as the result of a professional disagreement over the galvanic response advocated by Luigi Galvani, Alessandro Volta developed the so-called 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 is 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. They made the volt equal to 108 cgs units of voltage, the cgs system at the time being the customary system of units in science. They chose such a ratio because the cgs unit of voltage is inconveniently small and one volt in this definition is approximately the emf of a Daniell cell, the standard source of voltage in the telegraph systems of the day.[6] 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 International System of Units (SI) unit whose name is derived from the proper name of a person, the first letter of its symbol is upper case (V). However, when an SI unit is spelled out in English, it should always begin with a lower case letter (volt), except in a situation where any word in that position 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.

See also[edit]

Notes and references[edit]

  1. ^ "SI Brochure, Table 3 (Section 2.2.2)". BIPM. 2006. Retrieved 2007-07-29. 
  2. ^ BIPM SI Brochure: Appendix 1, p. 144
  3. ^ Burroughs, Charles J.; Benz, Samuel P. (1999-06-01), "1 Volt DC Programmable Josephson Voltage Standard", IEEE transactions on applied superconductivity 9 (3): 4145–4149, ISSN 1051-8223 
  4. ^ Keller, Mark W (2008-01-18), "Current status of the quantum metrology triangle", Metrologia 45 (1): 102–109, Bibcode:2008Metro..45..102K, doi:10.1088/0026-1394/45/1/014, ISSN 0026-1394, "Theoretically, there are no current predictions for any correction terms. Empirically, several experiments have shown that KJ and RK are independent of device design, material, measurement setup, etc. This demonstration of universality is consistent with the exactness of the relations, but does not prove it outright." 
  5. ^ Bullock, Orkand, and Grinnell, pp. 150–151; Junge, pp. 89–90; Schmidt-Nielsen, p. 484
  6. ^ Hamer, Walter J. (January 15, 1965). Standard Cells: Their Construction, Maintenance, and Characteristics. National Bureau of Standards Monograph #84. US National Bureau of Standards. 

External links[edit]


Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Volt — Please support Wikipedia.
A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
1000000 videos foundNext > 

2013 Chevrolet Volt Range Extending EV / Plug In Hybrid Review

Join us as we take an in-depth look at General Motors' first plug-in hybrid which they prefer to call an EV with a range extender. We talk infotainment, driv...

Chevy Volt one year owner interview

In this video I am interviewing a owner of a Chevrolet Volt 2012, he had this car for about a year now and I enjoyed talking to him about his car and experie...

Volt: De echte eerste kus

Een filmpje waarin wildvreemden mekaar kussen werd door miljoenen mensen bekeken. Toen bleek dat het een reclamestunt is voor een nieuw kledingmerk. De 'wild...

2013 Chevy Volt Test Drive

Watch more and discuss: http://stamford.itsrelevant.com/content/13832/2013-chevy-volt-test-drive Take a test drive in the new 2013 Chevrolet Volt. See the Vo...

2014 Chevy Volt Test Drive & Plug-In Hybrid Car Video Review

http://www.autobytel.com/chevrolet/volt/2014/ For commuters that average less than 40 miles, the Chevrolet Volt is the perfect car as you have just enough ju...

Chevrolet Volt Review Special

Cali and John each drove a Chevrolet Volt for two weeks to get a good feel for the electric car. In this GeekBeat special, they share their reactions.

Is the Cadillac ELR worth it?

Eight Months ago, Matt got a Chevy Volt as a daily driver, and won't shut up about how awesome it is. The problem is, it's rather dull looking, so no one und...

2014 Chevrolet Volt Review - TEST/DRIVE

Chris Harris reviews the 2014 Chevrolet Volt. Scored by all TEST/DRIVE hosts.

Volt - Extrait n°1

Retrouvez le premier extrait de Volt qui décide de venir secourir Mittene avec l'aide de son plus grand Fan... Rhino...au cinéma le 4 Février...

Gillette: Volt reclametest

Fragment uit het programma Volt www.volt.be volt reclametest Neem ook eens een kijkje op mijn site: http://www.flabbergasted.be.

1000000 videos foundNext > 

107995 news items

GM Authority (blog)

Green Car Reports
Tue, 22 Apr 2014 04:03:45 -0700

Chevrolet's range-extended electric vehicle, the Volt, has been on sale for more than three years now. Its sales of 58,000 units so far are still small compared to more conventional vehicles, but many people will have seen one on the road by now--and ...
 
CleanTechnica
Mon, 21 Apr 2014 05:00:54 -0700

The total was recorded by Guinness officials but while we're waiting for confirmation, let's note that Driver Guy of the Volt fan site GM-Volt.com estimated more than 200 Volts in attendance. Branchez-vous 2014 - 18 avril - Grand rassemblement record ...

Carscoops (blog)

CNET
Sat, 12 Apr 2014 13:22:05 -0700

The Volt, first introduced in December 2010, is a plug-in hybrid (or can be more technically described as an electric car with a range extending gasoline powered generator) that can go between 30 and 40 miles on battery. After that, a range-extender ...

Ubergizmo

Engadget
Tue, 15 Apr 2014 20:22:30 -0700

When it comes to electric vehicles, the Chevrolet Volt is as mainstream a brand as it gets. But despite GM's efforts to make the Volt a top choice among EV buyers, demand for it hasn't been what the company expected since it began production in 2010 ...

GM Authority (blog)

Edmunds.com
Thu, 17 Apr 2014 07:30:35 -0700

The 2014 Chevrolet Volt plug-in hybrid has one powertrain, but the redesigned model debuting in late 2015 will give buyers two choices, Edmunds has learned. The base model likely will carry a lower sticker price. The next-generation battery pack and ...

Forbes

Reuters
Tue, 08 Apr 2014 13:17:56 -0700

DETROIT (Reuters) - Hoping to boost demand for its slow-selling Volt hybrid, Chevrolet is planning to sell two versions of the redesigned 2016 Volt, including a lower-priced model with a smaller battery pack and shorter driving range, supplier sources ...
 
CleanTechnica
Mon, 14 Apr 2014 09:51:32 -0700

In an effort to boost sales and find a wider appeal, a lower-priced, shorter range version of the Chevy Volt is reportedly planned. With GM investing $450 million into the Hamtramck factory where the Volt is built, the automaker is doubling down on a ...

ExtremeTech

ExtremeTech
Tue, 15 Apr 2014 10:00:49 -0700

The first thing you notice about the BMW Concept X5 eDrive is how normal BMW's biggest SUV feels on the road: quick, quiet, sure-footed, roomy. It is a plug-in hybrid with a battery pack under the rear load floor that is good for up to 30 kilometers ...
Loading

Oops, we seem to be having trouble contacting Twitter

Talk About Volt

You can talk about Volt with people all over the world in our discussions.

Support Wikipedia

A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia. Please add your support for Wikipedia!