関: F

WordNet

the capacitance of a capacitor that has an equal and opposite charge of 1 coulomb on each plate and a voltage difference of 1 volt between the plates (同)F
the 6th letter of the Roman alphabet (同)f
a unit of capacitance equal to one thousandth of a farad
a unit of capacitance equal to one trillionth of a farad
a unit of capacitance equal to one millionth of a farad
a capacitance unit equal to one billion farads
to an advanced stage or point; "a young man who will go very far"
at or to a certain point or degree; "I can only go so far before I have to give up"; "how far can we get with this kind of argument?"
at or to or from a great distance in space; "he traveled far"; "strayed far from home"; "sat far away from each other"
being of a considerable distance or length; "a far trek"
being the animal or vehicle on the right or being on the right side of an animal or vehicle; "the horse on the right is the far horse"; "the right side is the far side of the horse"
beyond a norm in opinion or actions; "the far right"
located at a great distance in time or space or degree; "we come from a far country"; "far corners of the earth"; "the far future"; "a far journey"; "the far side of the road"; "far from the truth"; "far in the future"
remote in time; "if we could see far into the future"; "all that happened far in the past"
to a considerable degree; very much; "a far far better thing that I do"; "felt far worse than yesterday"; "eyes far too close together"

PrepTutorEJDIC

ファラッド(静電気容量の実用単位)
ファラデー(電気分解に用いられる電気量の単位)
《距離》『遠くに』,遠くへ,はるかに / 《時間》『ずっと後まで(に),ずっと先まで(に)』 / 《程度》《形容詞・副詞[句],およびその比較級を修飾して》『ずっと』,はるかに(much),たいそう / 《おもに文・詩》(場所が)『遠くにある』,遠い / (二つのうち)『遠いほうの』,向こう側の / 長距離(長時間)にわたる / (政治的に)極端な

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/08/28 13:12:54」(JST)

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This article is about the unit of measurement. For the former settlement in California, see Farad, California.

Examples of various types of capacitors.

The farad (symbol: F) is the SI derived unit of electrical capacitance. It is named after the English physicist Michael Faraday.

Definition[edit source | edit]

One farad is the value of capacitance that produces a potential of one volt when it has been charged by one coulomb. A coulomb is equal 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.

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 prefixes for electrical and electronic applications are:

1 millifarad (mF) = one thousandth (10⁻³) of a farad or 1000 μF
1 microfarad (μF, or MFD in industrial use) = one millionth (10⁻⁶) of a farad, or 1000000 pF, or 1000 nF
1 nanofarad (nF) = one billionth (10⁻⁹) of a farad, or 1000 pF
1 picofarad (pF) = one trillionth (10⁻¹²) of a farad

Equalities[edit source | edit]

A farad has the base SI representation of: s⁴ × A² × m⁻² × kg⁻¹

It can further be expressed as:

$\mbox{F} = \,\mathrm{\frac{A \cdot s}{V} = \dfrac{\mbox{J}}{\mbox{V}^2} = \dfrac{\mbox{W} \cdot \mbox{s}}{\mbox{V}^2} = \dfrac{\mbox{C}}{\mbox{V}} = \dfrac{\mbox{C}^2}{\mbox{J}} = \dfrac{\mbox{C}^2}{\mbox{N} \cdot \mbox{m}} = \dfrac{\mbox{s}^2 \cdot \mbox{C}^2}{\mbox{m}^{2} \cdot \mbox{kg}} = \dfrac{\mbox{s}^4 \cdot \mbox{A}^2}{\mbox{m}^{2} \cdot \mbox{kg}} = \dfrac{\mbox{s}}{\Omega}}$

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

History[edit source | edit]

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.

Explanation[edit source | edit]

Values of capacitors are usually specified in ranges of farads (F), millifarads (mF), microfarads (μF, or MFD in industrial use^[a]), nanofarads (nF) or picofarads (pF).^[1]

The size of commercially available capacitors ranges from around 100 fF (femtofarads, 10⁻¹⁵ F) to 5 kF (kilofarads, 10³ F) ultracapacitors. 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).^[2]

A picofarad is sometimes referred to as a "puff" or "pic", as in "a ten puff capacitor".^[3] 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), 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 4.7×10⁻³ F, for example, is sometimes written as 4700 µF; industrial parts at times use the abbreviation MFD instead of µF.^[4] North American usage also avoids nanofarads: a capacitance of 1×10⁻⁹ F will frequently be indicated as 1000 pF; and a capacitance of 1×10⁻⁷ F as 0.1 μF.

The 'farad' should not be confused with the faraday, which is the electric charge carried by one mole of singly charged ions.

The reciprocal of capacitance is called electrical elastance, the (non-standard, non-SI) unit of which is the daraf.^[5]

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 volts to several kilovolts.

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 boards. 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.^[6]^[7]

The capacitance of the Earth's ionosphere with respect to the ground is calculated to be about 1 F.^[8]

CGS units[edit source | edit]

The abfarad (abbreviated abF) is an obsolete CGS unit of capacitance equal to 10⁹ farads (1 gigafarad, GF). This very large unit is used in medical terminology only.

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.

Notes[edit source | edit]

^ In texts prior to 1960, mf rather than the modern µF frequently represented microfarads. Similarly, mmf represented picofarads.

References[edit source | edit]

^ 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."
^ Gregorian, Roubik (1976). Analog MOS Integrated Circuits for Signal Processing. John Wiley & Sons. p. 78.
^ "Puff". Wolfram Research. Retrieved 2009-06-09.
^ "Microfarad". The Free Dictionary. Retrieved 2012-08-13.
^ "Daraf". Webster's Online Dictionary. Retrieved 2009-06-19.
^ Pease, Bob (2 September 1993). "What's All This Femtoampere Stuff, Anyhow?". Electronic Design. Retrieved 2013-03-09.
^ Pease, Bob (1 December 2006). "What's All This Best Stuff, Anyhow?". Electronic Design. Retrieved 2013-03-09.
^ Williams, L. L. (January 1999). "Electrical Properties of the Fair-Weather Atmosphere and the Possibility of Observable Discharge on Moving Objects". Retrieved 2012-08-13.

External links[edit source | edit]

Farad unit conversion tool

English Journal

Development and application of a multiroute physiologically based pharmacokinetic model for oxytetracycline in dogs and humans.

Lin Z1, Li M, Gehring R, Riviere JE.
Journal of pharmaceutical sciences.J Pharm Sci.2015 Jan;104(1):233-43. doi: 10.1002/jps.24244. Epub 2014 Nov 18.
Oxytetracycline (OTC) is a commonly used tetracycline antibiotic in veterinary and human medicine. To establish a quantitative model for predicting OTC plasma and tissue exposure, a permeability-limited multiroute physiologically based pharmacokinetic model was developed in dogs. The model was calib
PMID 25407474

Autoimmune disorders and quadrivalent human papillomavirus vaccination of young female subjects.

Grimaldi-Bensouda L1, Guillemot D, Godeau B, Bénichou J, Lebrun-Frenay C, Papeix C, Labauge P, Berquin P, Penfornis A, Benhamou PY, Nicolino M, Simon A, Viallard JF, Costedoat-Chalumeau N, Courcoux MF, Pondarré C, Hilliquin P, Chatelus E, Foltz V, Guillaume S, Rossignol M, Abenhaim L; PGRx-AID Study Group.
Journal of internal medicine.J Intern Med.2014 Apr;275(4):398-408. doi: 10.1111/joim.12155. Epub 2013 Nov 22.
OBJECTIVES: The aim of this study was to investigate whether the quadrivalent human papillomavirus (HPV) vaccine Gardasil is associated with a change in the risk of autoimmune disorders (ADs) in young female subjects.DESIGN: Systematic case-control study of incident ADs associated with quadrivalent
PMID 24206418

Effects of new sampling protocols on procaine penicillin G withdrawal intervals for cattle.

DeDonder KD1, Gehring R, Baynes RE, Tell LA, Vickroy TW, Apley MD, Riviere JE.
Journal of the American Veterinary Medical Association.J Am Vet Med Assoc.2013 Nov 15;243(10):1408-12. doi: 10.2460/javma.243.10.1408.
PMID 24171369

The effect of ultrasonic and HNO3 treatment of activated carbon from fruit stones on capacitive and pseudocapacitive energy storage in electrochemical supercapacitors.

Venhryn BY1, Stotsko ZA, Grygorchak II, Bakhmatyuk BP, Mudry SI.
Ultrasonics sonochemistry.Ultrason Sonochem.2013 Sep;20(5):1302-7. doi: 10.1016/j.ultsonch.2013.02.009. Epub 2013 Mar 7.
The effect of ultrasonic treatment and modification with nitric acid of activated carbon obtained from fruit stones, on the parameters of electric double-layer (EDL) as well as on farad-volt characteristics of its boundary with electrolyte 7.6 m KОН, 4 m KI and 2 m ZnI2 aqueous solutions has been
PMID 23541908

Japanese Journal

フェーズドアレー衛星実験用電波暗室AMETLAB(宇宙科学ミッション・衛星技術,及び一般)

篠原真毅,坂本栄樹
電子情報通信学会技術研究報告. SANE, 宇宙・航行エレクトロニクス 112(17), 53-58, 2012-04-19
衛星搭載用の大口径のフェーズドアレーを正確に測定できる測定装置、及び電波暗室は国内で非常に少ない。京都大学生存圈研究所では2010年度に直径10mφのフェーズドアレー(max10kWCW)の性能を測定できる電波暗室AMETLAB及び近傍界測定装置を導入した。本講では装置の概要及び測定例について紹介する。
NAID 110009564489

ノンポーラスカーボンによる新しい電気二重層キャパシタ : ノンファラデーデバイスであるキャパシタの可能性(電池技術関連, 一般)

山岸政章,岡村廸夫
電子情報通信学会技術研究報告. EE, 電子通信エネルギー技術 105(538), 31-36, 2006-01-13
1996年に著者の一人でもある岡村が発見したノンポーラスカーボンを使ったキャパシタは従来の活性炭を使ったキャパシタでは実現できなかった高いエネルギー密度と優れた出力密度特性を備えていることが解ってきた。2004年にスタートした経産省NEDOにおけるこのキャパシタの先導研究の中間成果から近い将来のキャパシタが見えてくる。
NAID 110004082826

ノンポーラスカーボンによる新しい電気二重層キャパシタ : ノンファラデーデバイスであるキャパシタの可能性(電池技術関連, 一般)

山岸政章,岡村廸夫
電子情報通信学会技術研究報告. CPM, 電子部品・材料 105(539), 31-36, 2006-01-13
1996年に著者の一人でもある岡村が発見したノンポーラスカーボンを使ったキャパシタは従来の活性炭を使ったキャパシタでは実現できなかった高いエネルギー密度と優れた出力密度特性を備えていることが解ってきた。2004年にスタートした経産省NEDOにおけるこのキャパシタの先導研究の中間成果から近い将来のキャパシタが見えてくる。
NAID 110004078804

PL-2 International Harmonization of Certification for Toxicologists.(Proceedings of the 27th Annual Meeting)

Arthur CRAIGMILL
Journal of toxicological sciences 25(4), 241, 2000-10-31
NAID 110001806643

「far」

	Farad
	A comparatively small 1 farad capacitor, for low voltages and current transfers.
	Unit information
Unit system:	SI derived unit
Quantity:	Capacitance
Symbol:	F
Dimension:	M−1⋅L−2⋅T4⋅I2
Named after:	Michael Faraday
In SI base units:	1 F = 1 s4·A2·m−2·kg−1

　　[★] 　　　　　　　　　　

[1] In texts prior to 1960, mf rather than the modern µF frequently represented microfarads. Similarly, mmf represented picofarads.

[Braga-2] 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."

[3] Gregorian, Roubik (1976). Analog MOS Integrated Circuits for Signal Processing. John Wiley & Sons. p. 78.

[4] "Puff". Wolfram Research. Retrieved 2009-06-09.

[5] "Microfarad". The Free Dictionary. Retrieved 2012-08-13.

[6] "Daraf". Webster's Online Dictionary. Retrieved 2009-06-19.

[7] Pease, Bob (2 September 1993). "What's All This Femtoampere Stuff, Anyhow?". Electronic Design. Retrieved 2013-03-09.

[8] Pease, Bob (1 December 2006). "What's All This Best Stuff, Anyhow?". Electronic Design. Retrieved 2013-03-09.

[9] Williams, L. L. (January 1999). "Electrical Properties of the Fair-Weather Atmosphere and the Possibility of Observable Discharge on Moving Objects". Retrieved 2012-08-13.

Farad

A comparatively small 1 farad capacitor, for low voltages and current transfers.
Unit information
Unit system:	SI derived unit
Quantity:	Capacitance
Symbol:	F
Dimension:	M⁻¹⋅L⁻²⋅T⁴⋅I²
Named after:	Michael Faraday
In SI base units:	1 F = 1 s⁴·A²·m⁻²·kg⁻¹

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案内

farad