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What is a Farad? An Explanation
What is a Farad? An Explanation
Published: 2016/04/16
Channel: Step-by-Step Science
The FARAD Ultracapacitor
The FARAD Ultracapacitor
Published: 2017/08/10
Channel: Farad Cryptoken
FARAD Cryptoken Token Swap Program Roadshow - Kuala Lumpur
FARAD Cryptoken Token Swap Program Roadshow - Kuala Lumpur
Published: 2017/08/14
Channel: Farad Cryptoken
DJ Farad - Na imię ona ma Karyna (szerszeń)
DJ Farad - Na imię ona ma Karyna (szerszeń)
Published: 2017/07/12
Channel: DJ Farad
DJ Farad - Laska jak z obrazka
DJ Farad - Laska jak z obrazka
Published: 2017/08/29
Channel: DJ Farad
Neues farad
Neues farad
Published: 2012/02/05
Channel: philip5451
DJ Farad - Oj, oj, oj, podział się jej boj
DJ Farad - Oj, oj, oj, podział się jej boj
Published: 2017/02/28
Channel: DJ Farad
What is FARAD Cryptoken?
What is FARAD Cryptoken?
Published: 2017/08/26
Channel: Farad Cryptoken
DJ Farad - Nie wyrwałem nic
DJ Farad - Nie wyrwałem nic
Published: 2016/01/17
Channel: DJ Farad
DJ Farad - Będę wyrywał Renatę
DJ Farad - Będę wyrywał Renatę
Published: 2016/07/24
Channel: DJ Farad
Презентация автобокса Farad Crub N18
Презентация автобокса Farad Crub N18
Published: 2014/06/18
Channel: BgznkRu
DJ Farad - Coś fajnego ⇨ TELEDYSK ⇦
DJ Farad - Coś fajnego ⇨ TELEDYSK ⇦
Published: 2014/05/24
Channel: DJ Farad
Farad Roofbox Fitting
Farad Roofbox Fitting
Published: 2013/02/20
Channel: Roofboxrental
DJ Farad - Utraciłaś mą parówę
DJ Farad - Utraciłaś mą parówę
Published: 2016/07/02
Channel: DJ Farad
DJ Farad - Nie wyrwałem nic (TELEDYSK)
DJ Farad - Nie wyrwałem nic (TELEDYSK)
Published: 2016/05/10
Channel: DJ Farad
montaggio bauli portatutto FARAD
montaggio bauli portatutto FARAD
Published: 2009/10/29
Channel: FARADworld
FARAD Cryptoken - Tony Morris of American Maglev Technology
FARAD Cryptoken - Tony Morris of American Maglev Technology
Published: 2017/08/22
Channel: Farad Cryptoken
DJ Farad - Janusz ma parawan
DJ Farad - Janusz ma parawan
Published: 2016/09/11
Channel: DJ Farad
DJ Farad - Zapytana mówi nie
DJ Farad - Zapytana mówi nie
Published: 2016/05/29
Channel: DJ Farad
DJ Farad - Foki
DJ Farad - Foki
Published: 2017/01/14
Channel: DJ Farad
DJ Farad - Drogą kupna nabył piwo
DJ Farad - Drogą kupna nabył piwo
Published: 2017/03/23
Channel: DJ Farad
DJ FARAD - TANIEC NA RURZE (Stalowa Rura Fi 6) OFFICIAL VIDEO
DJ FARAD - TANIEC NA RURZE (Stalowa Rura Fi 6) OFFICIAL VIDEO
Published: 2011/10/08
Channel: DJ Farad
Informatie video Farad dakkoffer Marlin N7 & N6 (680 en 480 liter)
Informatie video Farad dakkoffer Marlin N7 & N6 (680 en 480 liter)
Published: 2016/06/05
Channel: www.alleskanmee.nl
DJ Farad - Awantura
DJ Farad - Awantura
Published: 2017/06/16
Channel: DJ Farad
DDS Farad geintegreerde dakdragers
DDS Farad geintegreerde dakdragers
Published: 2016/10/18
Channel: Dakdragerspecialist.nl
Explanation of the DC 500K uf or micro farad capacitor used in my solar set up
Explanation of the DC 500K uf or micro farad capacitor used in my solar set up
Published: 2013/03/11
Channel: Guy Brown
FARAD Martinice a letní kino Turnov 1990
FARAD Martinice a letní kino Turnov 1990
Published: 2014/03/30
Channel: Antonín Šrajer Composer
Farad Dachträger für integrierte Dachreling
Farad Dachträger für integrierte Dachreling
Published: 2017/03/13
Channel: Dachträgeronline.de
Секретки FARAD
Секретки FARAD
Published: 2016/10/18
Channel: Coleso UKRAINE
Rabah Salam Farad 3amad
Rabah Salam Farad 3amad
Published: 2011/01/14
Channel: Ridouan rifeño rifeño
KAMILA M & Dj Farad - Siedzę tutaj sama (Official Video)
KAMILA M & Dj Farad - Siedzę tutaj sama (Official Video)
Published: 2016/04/15
Channel: discokoncerty.pl
DJ Farad - Zobaczyłem beja
DJ Farad - Zobaczyłem beja
Published: 2016/10/18
Channel: DJ Farad
Farad Meaning
Farad Meaning
Published: 2015/04/13
Channel: SDictionary
How to install a car audio capacitor?
How to install a car audio capacitor?
Published: 2014/09/15
Channel: Rockville Audio
Homemade 3 6 Farad Supercapacitor
Homemade 3 6 Farad Supercapacitor
Published: 2015/03/29
Channel: Robert Murray-Smith
Wheel locks Farad
Wheel locks Farad
Published: 2014/02/04
Channel: FARADworld
Montagefilm Farad dakdragers glad dak
Montagefilm Farad dakdragers glad dak
Published: 2016/03/14
Channel: Dakdragerland.nl
Farad секретки для колесных дисков на любые автомобили
Farad секретки для колесных дисков на любые автомобили
Published: 2015/11/20
Channel: Александр Репин
Antifurto para rodas StarLock FARAD
Antifurto para rodas StarLock FARAD
Published: 2014/07/28
Channel: FARADBRASIL
1 Farad Electrolytic Capacitor Rapid Discharge
1 Farad Electrolytic Capacitor Rapid Discharge
Published: 2013/03/26
Channel: Nolan Reker
FARAD roof boxes and bars
FARAD roof boxes and bars
Published: 2014/08/04
Channel: FARADworld
Capacitors - Electrostatic Field, Dielectric, Capacitor Types, FARAD,
Capacitors - Electrostatic Field, Dielectric, Capacitor Types, FARAD,
Published: 2012/12/11
Channel: Mike Stratton
FARAD wind deflectors on Audi Q5
FARAD wind deflectors on Audi Q5
Published: 2013/01/17
Channel: FARADworld
7/10 - 5pm - Farad & Aspen Fires; Weather
7/10 - 5pm - Farad & Aspen Fires; Weather
Published: 2017/07/11
Channel: KTVN Channel 2 News
DJ Farad - W najlepszym klubie
DJ Farad - W najlepszym klubie
Published: 2017/06/16
Channel: DJ Farad
montaggio deflettori FARAD
montaggio deflettori FARAD
Published: 2009/10/29
Channel: FARADworld
4.5 Farad Hybrid Digital Capacitor | VM Audio SRCAP4.5
4.5 Farad Hybrid Digital Capacitor | VM Audio SRCAP4.5
Published: 2013/02/25
Channel: vminnovations
AudioQuart 3farad Capacitor Challenge to Critical Mass 1.2 and 1.5 farad capacitor.
AudioQuart 3farad Capacitor Challenge to Critical Mass 1.2 and 1.5 farad capacitor.
Published: 2013/08/05
Channel: kok winfei
Professor Farad - Imam W. Deen Mohammed 2
Professor Farad - Imam W. Deen Mohammed 2
Published: 2017/06/09
Channel: BilalianSpeaks
Unboxing maleiro de teto Farad 400L
Unboxing maleiro de teto Farad 400L
Published: 2017/01/08
Channel: Espero ter ajudado!
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WIKIPEDIA ARTICLE

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Farad
OneFarad5.5Velectrolyticcapacitor.jpg
A one farad modern super-capacitor
Unit information
Unit system SI derived unit
Unit of Capacitance
Symbol F, ℱ 
Named after Michael Faraday
In SI base units: s4A2m−2kg−1

The farad (symbol: F, sometimes stylized as ℱ) is the SI derived unit of electrical capacitance, the ability of a body to store an electrical charge. It is named after the English physicist Michael Faraday.

Definition[edit]

One farad is defined as the capacitance across which, when charged with one coulomb, there is a potential difference of one volt.[1] Equally, one farad can be described as the capacitance which stores a one-coulomb charge across a potential difference of one volt.[2]

The relationship between capacitance, charge and potential difference is linear. For example, if the potential difference across a capacitor is halved, the quantity of charge stored by that capacitor will also be halved.

For most applications, the farad is an impractically large unit of capacitance. Most electrical and electronic applications are covered by the following SI prefixes:

  • 1 mF (millifarad, one thousandth (10−3) of a farad) = 1000 μF = 1000000 nF
  • 1 μF (microfarad, one millionth (10−6) of a farad) = 0.000 001 F = 1000 nF = 1000000 pF
  • 1 nF (nanofarad, one billionth (10−9) of a farad) = 0.001 μF = 1000 pF
  • 1 pF (picofarad, one trillionth (10−12) of a farad)

Equalities[edit]

A farad is represented in terms of SI base units as s4A2m−2kg−1

It can further be expressed as:

where F = farad, A = ampere, V = volt, C = coulomb, J = joule, m = metre, N = newton, s = second, W = watt, kg = kilogram, Ω = ohm, H = henry.

History[edit]

The term "farad" was originally coined by Latimer Clark and Charles Bright in 1861,[3] in honor of Michael Faraday, for a unit of quantity of charge but by 1873, the farad had become a unit of capacitance.[4] In 1881 at the International Congress of Electricians in Paris, the name farad was officially used for the unit of electrical capacitance.[5][6]

Explanation[edit]

Examples of different types of capacitors

A capacitor generally 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 volts to several kilovolts.

Values of capacitors are usually specified in farads (F), microfarads (μF), nanofarads (nF) and picofarads (pF).[7] The millifarad is rarely used in practice (a capacitance of 4.7 mF (0.0047 F), for example, is instead written as 4700 µF), while the nanofarad is uncommon in North America.[8] The size of commercially available capacitors ranges from around 0.1 pF to 5000F (5 kF) supercapacitors. Parasitic capacitance in high-performance integrated circuits can be measured in femtofarads (1 fF = 0.001 pF = 1015 F), while high-performance test equipment can detect changes in capacitance on the order of tens of attofarads (1 aF = 10−18 F).[9]

A value of 0.1 pF is about the smallest available in capacitors for general use in electronic design, since smaller ones would be dominated by the parasitic capacitances of other components, wiring or printed circuit boards. Capacitance values of 1 pF or lower can be achieved by twisting two short lengths of insulated wire together.[10][11]

The capacitance of the Earth's ionosphere with respect to the ground is calculated to be about 1 F.[12]

Informal and deprecated terminology[edit]

The picofarad is sometimes colloquially pronounced as "puff" or "pic", as in "a ten-puff capacitor".[13] Similarly, "mic" (pronounced "mike") is sometimes used informally to signify microfarads. If 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. In texts prior to 1960, and on capacitor packages even much more recently, "mf" or "MFD" rather than the modern "µF" frequently represented microfarads. Similarly, "mmf" or "MMFD" represented picofarads.

Related concepts[edit]

The reciprocal of capacitance is called electrical elastance, the (non-standard, non-SI) unit of which is the daraf.[14]

CGS units[edit]

The abfarad (abbreviated abF) is an obsolete CGS unit of capacitance equal to 109 farads (1 gigafarad, GF).[15]

The statfarad (abbreviated statF) is a rarely used CGS unit equivalent to the capacitance of a capacitor with a charge of 1 statcoulomb across a potential difference of 1 statvolt. It is 1/(10−5c2) farad, approximately 1.1126 picofarads.

See also[edit]

Notes[edit]

  1. ^ The International System of Units (SI) (PDF) (8th ed.). Bureau International des Poids et Mesures (International Committee for Weights and Measures). 2006. p. 144. 
  2. ^ Peter M B Walker, ed. (1995). Dictionary of Science and Technology. Larousse. ISBN 0752300105. 
  3. ^ As names for units of various electrical quantities, Bright and Clark suggested "ohma" for voltage, "farad" for charge, "galvat" for current, and "volt" for resistance. See:
  4. ^ Sir W. Thomson, etc. (1873) "First report of the Committee for the Selection and Nomenclature of Dynamical and Electrical Units," Report of the 43rd Meeting of the British Association for the Advancement of Science (Bradford, September 1873), pp. 222-225. From p. 223: "The "ohm," as represented by the original standard coil, is approximately 109 C.G.S. units of resistance ; the "volt" is approximately 108 C.G.S. units of electromotive force ; and the "farad" is approximately 1/109 of the C.G.S. unit of capacity."
  5. ^ (Anon.) (September 24, 1881) "The Electrical Congress," The Electrician, 7 : 297. From p. 297: "7. The name farad will be given to the capacity defined by the condition that a coulomb in a farad gives a volt."
  6. ^ Tunbridge, Paul (1992). Lord Kelvin : his influence on electrical measurements and units. London: Peregrinus. pp. 26, 39–40. ISBN 9780863412370. Retrieved 5 May 2015. 
  7. ^ Braga, Newton C. (2002). Robotics, Mechatronics, and Artificial Intelligence. Newnes. p. 21. ISBN 0-7506-7389-3. Retrieved 2008-09-17. 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. 
  8. ^ Platt, Charles (2009). Make: Electronics: Learning Through Discovery. O'Reilly Media. p. 61. ISBN 9781449388799. Retrieved 2014-07-22. Nanofarads are also used, more often in Europe than in the United States. 
  9. ^ Gregorian, Roubik (1976). Analog MOS Integrated Circuits for Signal Processing. John Wiley & Sons. p. 78. 
  10. ^ Pease, Bob (2 September 1993). "What's All This Femtoampere Stuff, Anyhow?". Electronic Design. Retrieved 2013-03-09. 
  11. ^ Pease, Bob (1 December 2006). "What's All This Best Stuff, Anyhow?". Electronic Design. Retrieved 2013-03-09. 
  12. ^ Williams, L. L. (January 1999). "Electrical Properties of the Fair-Weather Atmosphere and the Possibility of Observable Discharge on Moving Objects" (PDF). Retrieved 2012-08-13. 
  13. ^ "Puff". Wolfram Research. Retrieved 2009-06-09. 
  14. ^ "Daraf". Webster's Online Dictionary. Archived from the original on 2011-10-04. Retrieved 2009-06-19. 
  15. ^ Graf, Rudolf F. (1999). Modern Dictionary of Electronics. Newnes. p. 1. ISBN 9780080511986. Retrieved 2016-04-15. 

External links[edit]

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