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| {{About|the unit of measurement|the former settlement in California|Farad, California}}
| | Andera is what you can contact her but she never truly liked that name. One of the extremely very best issues in the globe for him is performing ballet and he'll be starting something else alongside with it. Invoicing is what I do for a living but I've usually wanted my personal company. Some time in the past he selected to reside in North Carolina and he doesn't plan on changing it.<br><br>Also visit my site - clairvoyance ([http://www.dabuckchannel.com/users/MSchonell http://www.dabuckchannel.com/]) |
| {{Distinguish|faraday (unit)}}
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| {{lead too short|date=December 2012}}
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| {{Infobox Unit
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| | bgcolour =
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| | name = Farad
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| | image = [[File:OneFarad5.5Velectrolyticcapacitor.jpg|300px]]
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| | caption = A comparatively small 1 farad capacitor, for low voltages and current transfers.
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| | standard = [[SI derived unit]]
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| | quantity = [[Capacitance]]
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| | symbol = F
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| | dimension = M<sup>−1</sup>⋅L<sup>−2</sup>⋅T<sup>4</sup>⋅I<sup>2</sup>
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| | namedafter = [[Michael Faraday]]
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| | extralabel = In [[SI base unit]]s:
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| | extradata = 1 F = 1 [[second|s]]{{Smallsup|4}}·[[ampere|A]]{{Smallsup|2}}·[[meter|m]]{{Smallsup|−2}}·[[kilogram|kg]]{{Smallsup|−1}}
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| }}
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| [[File:Capacitors Various.jpg|thumb|right|Examples of various types of capacitors.]]
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| The '''farad''' (symbol: F) is the [[SI derived unit]] of electrical [[capacitance]]. It is named after the English physicist [[Michael Faraday]].
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| == Definition ==
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| One farad is the value of [[capacitance]] that produces a potential difference of one [[volt]] when it has been [[electric charge|charged]] by one [[coulomb]]. A coulomb is equal to the amount of charge (electrons) produced by a current of one [[ampere]] flowing for one [[second]]. For example, the voltage across the two terminals of a 47 nF [[capacitor]] will increase linearly by 1 V when a current of 47 nA flows through it for 1 s. | |
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| For most applications, the farad is an impractically large unit of capacitance, although capacitors measured in farads are now used, especially for backing up memory. The most commonly used [[SI prefix]]es for electrical and electronic applications are:
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| * 1 millifarad (mF) = one thousandth ({{10^|−3}}) of a farad or {{gaps|1|000}} μF
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| * 1 microfarad (μF, or MFD in industrial use) = one millionth ({{10^|−6}}) of a farad, or {{gaps|1|000|000}} pF, or {{gaps|1|000}} nF
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| * 1 nanofarad (nF) = one billionth ({{10^|−9}}) of a farad, or {{gaps|1|000}} pF
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| * 1 picofarad (pF) = one trillionth ({{10^|−12}}) of a farad
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| === Equalities ===
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| A farad has the base SI representation of:
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| [[Second|s]]{{sup|4}} × [[ampere|A]]{{sup|2}} × [[meter|m]]{{sup|−2}} × [[kilogram|kg]]{{sup|−1}}
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| It can further be expressed as:
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| :<math>\mbox{F}
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| = \,\mathrm{\frac{A \cdot s}{V}
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| = \dfrac{\mbox{J}}{\mbox{V}^2}
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| = \dfrac{\mbox{W} \cdot \mbox{s}}{\mbox{V}^2}
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| = \dfrac{\mbox{C}}{\mbox{V}}
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| = \dfrac{\mbox{C}^2}{\mbox{J}}
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| = \dfrac{\mbox{C}^2}{\mbox{N} \cdot \mbox{m}}
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| = \dfrac{\mbox{s}^2 \cdot \mbox{C}^2}{\mbox{m}^{2} \cdot \mbox{kg}}
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| = \dfrac{\mbox{s}^4 \cdot \mbox{A}^2}{\mbox{m}^{2} \cdot \mbox{kg}}
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| = \dfrac{\mbox{s}}{\Omega}}
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| </math>
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| where A=[[ampere]], V=[[volt]], C=[[coulomb]], J=[[joule]], m=[[metre]], N=[[newton (unit)|newton]], s=[[second]], W=[[watt]], kg=[[kilogram]], Ω=[[ohm]].
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| == History ==
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| The term "farad" was coined by [[Josiah Latimer Clark]] in the year of 1861, in honor of [[Michael Faraday]], but it was for a unit of quantity of charge.
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| == Explanation ==
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| Values of capacitors are usually [[SI prefix#List of SI prefixes|specified in ranges]] of '''farads''' (F), '''millifarads''' (mF), '''microfarads''' (μF, or MFD in industrial use<ref>In texts prior to 1960, '''mf''' rather than the modern '''µF''' frequently represented microfarads. Similarly, '''mmf''' represented picofarads.</ref>), '''nanofarads''' (nF) or '''picofarads''' (pF).<ref name="Braga">{{cite book |title=Robotics, Mechatronics, and Artificial Intelligence |last=Braga |first=Newton C. |year=2002 |accessdate=2008-09-17 |publisher=Newnes |page=21 |url=http://books.google.com/books?id=yqb-f-HKem0C&pg=PA21&q=microfarad+common+measurement |isbn=0-7506-7389-3 |quote=Common measurement units are the microfarad (μF), representing 0.000,001 F; the nanofarad (nF), representing 0.000,000,001 F; and the picofarad (pF), representing 0.000,000,000,001 F.}}</ref>
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| The size of commercially available capacitors ranges from around 100 fF (femtofarads, {{10^|−15}} F) to 5 kF (kilofarads, {{10^|3}} F) [[supercapacitor]]s. Designers of high performance integrated circuits are concerned about [[parasitic capacitance]] measured in femtofarads, while makers of high performance test equipment are able to detect changes in capacitance on the order of tens of attofarads ({{10^|−18}}).<ref>{{cite book |title=Analog MOS Integrated Circuits for Signal Processing |last=Gregorian |first=Roubik |year=1976 |publisher=John Wiley & Sons |page=78}}</ref>
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| A ''picofarad'' is sometimes referred to as a ''"puff"'' or ''"pic"'', as in "a ten puff capacitor".<ref>{{cite web |title=Puff |url=http://scienceworld.wolfram.com/physics/Puff.html |publisher=Wolfram Research |accessdate=2009-06-09}}</ref> If [[Mu (letter)|the Greek letter μ]] is not available, the notation ''uF'' is often used as a substitute for ''μF'' in electronics literature. A ''micro-microfarad'' (μμF, and confusingly often mmf or MMF), an obsolete unit sometimes found in older texts, is the equivalent of a ''picofarad''. The ''millifarad'' is less used in practice, so that a capacitance of 4.7{{e|−3}} F, for example, is sometimes written as {{gaps|4|700}} µF; industrial parts at times use the abbreviation MFD instead of µF.<ref>{{cite web |title=Microfarad |url=http://www.thefreedictionary.com/Microfarad |publisher=The Free Dictionary |accessdate=2012-08-13}}</ref> North American usage also avoids ''nanofarads'': a capacitance of 1{{e|−9}} F will frequently be indicated as {{gaps|1|000}} pF; and a capacitance of 1{{e|−7}} F as 0.1 μF.
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| The reciprocal of capacitance is called [[electrical elastance]], the (non-standard, non-SI) unit of which is the [[daraf]].<ref>{{cite web |title=Daraf |url=http://www.websters-dictionary-online.com/definitions/daraf |publisher=Webster's Online Dictionary |accessdate=2009-06-19}}</ref>
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| A capacitor consists of two conducting surfaces, frequently referred to as plates, separated by an insulating layer usually referred to as a [[dielectric]]. The original capacitor was the [[Leyden jar]] developed in the 18th century. It is the accumulation of electric charge on the plates that results in [[capacitance]]. Modern capacitors are constructed using a range of manufacturing techniques and materials to provide the extraordinarily wide range of capacitance values used in [[electronics]] applications from femtofarads to farads, with maximum-voltage ratings ranging from a few [[volt]]s to several kilovolts.
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| One picofarad is about the smallest value of capacitor available for general use in electronic design, since smaller capacitors would be dominated by the parasitic capacitances ([[stray capacitance]]) of other components, wiring or [[printed circuit board]]s. When capacitance values of 1 pF or lower are required, engineers sometimes create their own capacitors by twisting two short lengths of insulated wire together.<ref>{{cite web |title=What's All This Femtoampere Stuff, Anyhow? |url=http://electronicdesign.com/test-amp-measurement/whats-all-femtoampere-stuff-anyhow |last=Pease |first=Bob |authorlink=Bob Pease |publisher=Electronic Design |date=2 September 1993 |accessdate=2013-03-09}}</ref><ref>{{cite web |title=What's All This Best Stuff, Anyhow? |url=http://electronicdesign.com/analog/whats-all-best-stuff-anyhow |last=Pease |first=Bob |publisher=Electronic Design |date=1 December 2006 |accessdate=2013-03-09}}</ref>
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| The capacitance of the Earth's [[ionosphere]] with respect to the ground is calculated to be about 1 F.<ref>{{cite web |url=http://konfluence.org/efield.pdf |title=Electrical Properties of the Fair-Weather Atmosphere and the Possibility of Observable Discharge on Moving Objects |last=Williams |first=L. L. |date=January 1999 |accessdate=2012-08-13}}</ref>
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| ==CGS units==
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| The '''abfarad''' (abbreviated abF) is an obsolete [[CGS]] unit of capacitance equal to {{10^|9}} farads (1 gigafarad, GF). This very large unit is used in medical terminology only.
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| The '''statfarad''' (abbreviated statF) is a different and also rarely used CGS unit of capacitance that corresponds to approximately 1.1126 picofarads. It is equivalent to the capacitance of a capacitor with a charge of 1 statcoulomb across a potential difference of 1 statvolt.
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| == See also ==
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| *[[Supercapacitor]]
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| == Notes ==
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| {{Reflist|33em}}
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| == External links ==
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| * [http://www.translatorscafe.com/cafe/units-converter/electrostatic-capacitance/c/ Farad unit conversion tool]
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| {{SI units}}
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| [[Category:SI derived units]]
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| [[Category:Units of electrical capacitance]]
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| [[Category:Michael Faraday]]
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Andera is what you can contact her but she never truly liked that name. One of the extremely very best issues in the globe for him is performing ballet and he'll be starting something else alongside with it. Invoicing is what I do for a living but I've usually wanted my personal company. Some time in the past he selected to reside in North Carolina and he doesn't plan on changing it.
Also visit my site - clairvoyance (http://www.dabuckchannel.com/)