関: A

WordNet

the basic unit of electric current adopted under the Systeme International dUnites; "a typical household circuit carries 15 to 50 amps" (同)amp, A
a former unit of electric current (slightly smaller than the SI ampere) (同)international ampere
the 1st letter of the Roman alphabet (同)a
the blood group whose red cells carry the A antigen (同)type_A, group A
not held in check or subject to control; "unhampered dissemination of news"; "this would give black people the opportunity to live unhampered by racism"
not slowed or blocked or interfered with; "an outlet for healthy and unhampered action"; "a priest unhampered by scruple"; "the new stock market was unhampered by tradition" (同)unhindered
a unit of electrical power in an AC circuit equal to the power dissipated when 1 volt produces a current of 1 ampere (同)var
someone who pampers or spoils by excessive indulgence (同)spoiler, coddler, mollycoddler
an industrial city in south central Finland (同)Tammerfors

PrepTutorEJDIC

アンペア(電流の強さの単位;{略}amp.)
answer / ampere
ミリアンペア(1アンペアの1000分の1)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/02/28 17:23:22」(JST)

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For other uses, see Ampere (disambiguation).

The ampere (SI unit symbol: A), often shortened to amp,^[1] is the SI unit of electric current^[2]^[3] (quantity symbol: I,i)^[4] and is one of the seven^[5] SI base units. It is named after André-Marie Ampère (1775–1836), French mathematician and physicist, considered the father of electrodynamics.

In practical terms, the ampere is a measure of the amount of electric charge passing a point in an electric circuit per unit time with 6.241 × 10¹⁸ electrons, or one coulomb per second constituting one ampere.^[6]

The practical definition may lead to confusion with the definition of a coulomb (i.e., 1 ampere-second), but in practical terms this means that measures of a constant current (e.g., the nominal flow of charge per second through a simple circuit) will be defined in amperes (e.g., "a 20 mA circuit") and the flow of charge through a circuit over a period of time will be defined in coulombs (e.g., "a variable-current circuit that flows a total of 10 coulombs over 5 seconds"). In this way, amperes can be viewed as a flow rate, i.e. number of particles (charged) transiting per unit time, and coulombs simply as the number of particles.

Definition

Illustration of the definition of the ampere unit

Ampère's force law^[7]^[8] states that there is an attractive or repulsive force between two parallel wires carrying an electric current. This force is used in the formal definition of the ampere, which states that it is "the constant current that will produce an attractive force of 2 × 10^–7 newton per metre of length between two straight, parallel conductors of infinite length and negligible circular cross section placed one metre apart in a vacuum".^[2]^[9]

The SI unit of charge, the coulomb, "is the quantity of electricity carried in 1 second by a current of 1 ampere".^[10] Conversely, a current of one ampere is one coulomb of charge going past a given point per second:

In general, charge Q is determined by steady current I flowing for a time t as Q = It.

History

The ampere was originally defined as one tenth of the CGS system electromagnetic unit of current (now known as the abampere), the amount of current that generates a force of two dynes per centimetre of length between two wires one centimetre apart.^[11] The size of the unit was chosen so that the units derived from it in the MKSA system would be conveniently sized.

The "international ampere" was an early realization of the ampere, defined as the current that would deposit 0.001118000 grams of silver per second from a silver nitrate solution.^[12] Later, more accurate measurements revealed that this current is 0.99985 A.

Realization

The standard ampere is most accurately realized using a watt balance, but is in practice maintained via Ohm's Law from the units of electromotive force and resistance, the volt and the ohm, since the latter two can be tied to physical phenomena that are relatively easy to reproduce, the Josephson junction and the quantum Hall effect, respectively.^[13]

At present, techniques to establish the realization of an ampere have a relative uncertainty of approximately a few parts in 10⁷, and involve realizations of the watt, the ohm and the volt.^[13]

Proposed future definition

Main article: New SI definitions

Rather than a definition in terms of the force between two current-carrying wires, it has been proposed to define the ampere in terms of the rate of flow of elementary charges.^[8] Since a coulomb is approximately equal to 6.2415093×10¹⁸ elementary charges (such as electrons), one ampere is approximately equivalent to 6.2415093×10¹⁸ elementary charges moving past a boundary in one second, or the reciprocal of the value of the elementary charges in coulombs.^[14] The proposed change would define 1 A as being the current in the direction of flow of a particular number of elementary charges per second. In 2005, the International Committee for Weights and Measures (CIPM) agreed to study the proposed change. The new definition is expected to be formally proposed at the 25th General Conference on Weights and Measures (CGPM) in 2014.^[15]

Everyday examples

Main article: Orders of magnitude (current)

The current drawn by typical constant-voltage energy distribution systems is usually dictated by the power (watts) consumed by the system and the operating voltage. For this reason the examples given below are grouped by voltage level.

Portable gadgets

Hearing aid (typically 1 mW at 1.4 V): 0.7 mA

Motor vehicles – 12 V DC

A typical motor vehicle has a 12 V battery. The various accessories that are powered by the battery might include:

Instrument panel light (typically 2 W): 166 mA.
Headlights (typically 60 W): 5 A each.
Starter Motor (typically 1–2 kW): 80-160 A

North American domestic supply – 120 V AC

Most United States, Canada and Mexico domestic power suppliers run at 120 V.

Household circuit breakers typically provide a maximum of 15 A or 20 A of current to a given set of outlets.

22-inch/56-centimeter portable television (35 W): 290 mA
Tungsten light bulb (60–100 W): 500–830 mA
Toaster, kettle (2 kW): 16.6 A
Immersion heater (4.6 kW): 38.3 A

European domestic supply – 230 V AC

Most European domestic power supplies run at 230 V, so the current drawn by a particular European appliance (in Europe) will be less than for an equivalent North American appliance.^{[Note 1]}

The current drawn by a number of typical appliances are:

22-inch/56-centimeter Portable Television (35 W): 150 mA
Tungsten light bulb (60–100 W): 250–450 mA
Compact Fluorescent Lamp (13–30 W): 58–112 mA
Toaster, kettle (2 kW): 9 A
Immersion heater (4.6 kW): 20 A

Notes

^ The formula for power is given by

$P(t) = I(t) \cdot V(t) \,$

so it follows that if the voltage is doubled and the power remains the same, the current will be halved.

References

^ SI supports only the use of symbols and deprecates the use of abbreviations for units."Bureau International des Poids et Mesures" (PDF). 2006. p. 130. http://www.bipm.fr/utils/common/pdf/si_brochure_8_en.pdf. Retrieved 2011-11-21.
^ ^a ^b "2.1. Unit of electric current (ampere)", SI brochure (8th ed.), BIPM, http://www.bipm.org/en/si/si_brochure/chapter2/2-1/ampere.html, retrieved 19 November 2011
^ Base unit definitions: Ampere. Physics.nist.gov. Retrieved on 2010-09-28.
^ "2. SI base units", SI brochure (8th ed.), BIPM, http://www.bipm.org/en/si/si_brochure/chapter2/2-1/, retrieved 19 November 2011
^ The other six are the metre, kelvin, second, mole, candela, and kilogram
^ Bodanis, David (2005), Electric Universe, New York: Three Rivers Press, ISBN 978-0‐307‐33598‐2
^ Serway, Raymond A; Jewett, JW (2006). Serway's principles of physics: a calculus based text (Fourth ed.). Belmont, CA: Thompson Brooks/Cole. p. 746. ISBN 0‐53449143‐X. http://books.google.com/books?id=1DZz341Pp50C&pg=RA1-PA746&dq=wire+%22magnetic+force%22&lr=&as_brr=0&sig=4vMV_CH6Nm8ZkgjtDJFlupekYoA#PRA1-PA746,M1.
^ ^a ^b Beyond the Kilogram: Redefining the International System of Units, USA: National Institute of Standards and Technology, 2006, archived from the original on 21 March 2008, http://www.nist.gov/public_affairs/newsfromnist_beyond_the_kilogram.htm, retrieved March 2008.
^ Monk, Paul MS (2004), Physical Chemistry: Understanding our Chemical World, John Wiley & Sons, ISBN 0‐471‐49180‐2, http://books.google.com/books?vid=ISBN0471491802&id=LupAi35QjhoC&pg=PA16&lpg=PA16&ots=IMiGyIL-67&dq=ampere+definition+si&sig=9Y0k0wgvymmLNYFMcXodwJZwvAM.
^ (PDF) The International System of Units (SI) (8th ed.), Bureau International des Poids et Mesures, 2006, p. 144, http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf.
^ Kowalski, L, A short history of the SI units in electricity, Montclair, http://alpha.montclair.edu/~kowalskiL/SI/SI_PAGE.HTML.
^ History of the ampere, Sizes, http://www.sizes.com/units/ampHist.htm
^ ^a ^b "Appendix 2: Practical realization of unit definitions: Electrical quantities", SI brochure, BIPM, http://www.bipm.org/en/si/si_brochure/appendix2/electrical.html.
^ "Value", Physics, USA: NIST, http://physics.nist.gov/cgi-bin/cuu/Value?e.
^ "General Conference on Weights and Measures approves possible changes to the International System of Units, including redefinition of the kilogram." (Press release). Sèvres, France: General Conference on Weights and Measures. 23 October 2011. http://www.bipm.org/utils/en/pdf/Press_release_resolution_1_CGPM.pdf. Retrieved 25 October 2011.

External links

The NIST Reference on Constants, Units, and Uncertainty
A short history of the SI units in electricity^{[dead link]}
NIST Definition of ampere and μ₀

English Journal

Monitoring the endocytosis of magnetic nanoparticles by cells using permanent micro-flux sources.

Osman O, Zanini LF, Frénéa-Robin M, Dumas-Bouchiat F, Dempsey NM, Reyne G, Buret F, Haddour N.SourceAmpère Laboratory, CNRS - Université Claude Bernard Lyon 1- Ecole Centrale de Lyon, 69134, Ecully, France, osman.osman@ec-lyon.fr.
Biomedical microdevices.Biomed Microdevices.2012 Oct;14(5):947-54.
Trapping of cells is essential to perform basic handling operations in cell-based microsystems, such as media exchange, concentration, cell isolation and cell sorting. Cell trapping by magnetophoresis typically requires cell labeling with magnetic nanoparticles. Here we report on endocytotic uptake
PMID 22773161

In situ TCE degradation mediated by complex dehalorespiring communities during biostimulation processes.

Dugat-Bony E, Biderre-Petit C, Jaziri F, David MM, Denonfoux J, Lyon DY, Richard JY, Curvers C, Boucher D, Vogel TM, Peyretaillade E, Peyret P.SourceClermont Université, Université Blaise Pascal, Laboratoire Microorganismes: Génome et Environnement, BP 10448, F63000, Clermont-Ferrand, France. UMR CNRS 6023, Université Blaise Pascal, 63000 Clermont-Ferrand, France. Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, EA 18, Conception, Ingénierie et Développement de l'Aliment et du Médicament, BP10448, F63000 Clermont-Ferrand, France. Clermont Université, Université d'Auvergne, UFR Pharmacie, Clermont-Ferrand, France. Clermont Université, Université Blaise Pascal, LIMOS, BP 10448, F-63000 Clermont-Ferrand, France. UMR CNRS 6158, LIMOS, F-63173 Aubière, France. Environmental Microbial Genomics, Laboratoire Ampère, Ecole Centrale de Lyon, Université de Lyon, 69134 Ecully, France. SITA Remediation (SUEZ Environnement company), 17 rue du périgord, 69330 MEYZIEU, France. Clermont Université, Université d'Auvergne, Laboratoire Microorganismes: Génome et Environnement, BP 10448, F63000, Clermont-Ferrand, France.
Microbial biotechnology.Microb Biotechnol.2012 Sep;5(5):642-653. doi: 10.1111/j.1751-7915.2012.00339.x. Epub 2012 Mar 21.
The bioremediation of chloroethene contaminants in groundwater polluted systems is still a serious environmental challenge. Many previous studies have shown that cooperation of several dechlorinators is crucial for complete dechlorination of trichloroethene to ethene. In the present study, we used a
PMID 22432919

The Management of Diabetic Foot.

Caravaggi C, Sganzaroli A, Galenda P, Bassetti M, Ferraresi R, Gabrielli L.SourceDiabetic Foot Clinic Istituto Clinico Città Studi Via Ampère 47, 20131 Milano, Italy. caravaggi@me.com.
Current diabetes reviews.Curr Diabetes Rev.2012 Aug 24. [Epub ahead of print]
Diabetes is a chronic disease with a worldwide increasing trend. Foot complications, closely related to neuropathy and obstructive peripheral vascular disease, are responsible for more than 1 million of leg amputations every year. Foot infection can dramatically increase the risk of amputation. Al
PMID 22934545

Japanese Journal

Exchange bias controlled by electric current: Interplay of Joule heating and the induced field

Jpn. J. Appl. Phys. 55(7), 070304, 2016-06-21
NAID 150000112757

アンペールの法則の応用とその問題点 (電磁界理論)

電子情報通信学会技術研究報告 = IEICE technical report : 信学技報 116(75), 21-25, 2016-06-03
NAID 40020880911

Kiselman's principle, the Dirichlet problem for the Monge-Ampere equation, and rooftop obstacle problems

Journal of the Mathematical Society of Japan 68(2), 773-796, 2016-04
NAID 40020805333

Evaluation of the Effect of Graphite Powder in Decreasing the Internal Resistance for Microbial Fuel Cell Using Soil

Journal of Water and Environment Technology 14(3), 141-148, 2016
NAID 130005156727

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リンク元	「アンペア」
拡張検索	「milliampere」「kiloampere」「nanoampere」

「アンペア」

	Ampere
	Current can be measured by a galvanometer, via the deflection of a magnetic needle in the magnetic field created by the current.
	Unit information
Unit system:	SI base unit
Unit of...	Electric current
Symbol:	A

　　[★]

英: ampere, A
関: 電流

「milliampere」

　　[★]

ミリアンペア

関: mA

「kiloampere」

　　[★]

キロアンペア

関: kA

「nanoampere」

　　[★]

ナノアンペア

関: nA

[16] The formula for power is given by

$P(t) = I(t) \cdot V(t) \,$

so it follows that if the voltage is doubled and the power remains the same, the current will be halved.

[BIPM2006-1] SI supports only the use of symbols and deprecates the use of abbreviations for units."Bureau International des Poids et Mesures" (PDF). 2006. p. 130. http://www.bipm.fr/utils/common/pdf/si_brochure_8_en.pdf. Retrieved 2011-11-21.

[BIPMdefinition-2] "2.1. Unit of electric current (ampere)", SI brochure (8th ed.), BIPM, http://www.bipm.org/en/si/si_brochure/chapter2/2-1/ampere.html, retrieved 19 November 2011

[3] Base unit definitions: Ampere. Physics.nist.gov. Retrieved on 2010-09-28.

[4] "2. SI base units", SI brochure (8th ed.), BIPM, http://www.bipm.org/en/si/si_brochure/chapter2/2-1/, retrieved 19 November 2011

[5] The other six are the metre, kelvin, second, mole, candela, and kilogram

[6] Bodanis, David (2005), Electric Universe, New York: Three Rivers Press, ISBN 978-0‐307‐33598‐2

[Serway-7] Serway, Raymond A; Jewett, JW (2006). Serway's principles of physics: a calculus based text (Fourth ed.). Belmont, CA: Thompson Brooks/Cole. p. 746. ISBN 0‐53449143‐X. http://books.google.com/books?id=1DZz341Pp50C&pg=RA1-PA746&dq=wire+%22magnetic+force%22&lr=&as_brr=0&sig=4vMV_CH6Nm8ZkgjtDJFlupekYoA#PRA1-PA746,M1.

[Beyond-8] Beyond the Kilogram: Redefining the International System of Units, USA: National Institute of Standards and Technology, 2006, archived from the original on 21 March 2008, http://www.nist.gov/public_affairs/newsfromnist_beyond_the_kilogram.htm, retrieved March 2008.

[9] Monk, Paul MS (2004), Physical Chemistry: Understanding our Chemical World, John Wiley & Sons, ISBN 0‐471‐49180‐2, http://books.google.com/books?vid=ISBN0471491802&id=LupAi35QjhoC&pg=PA16&lpg=PA16&ots=IMiGyIL-67&dq=ampere+definition+si&sig=9Y0k0wgvymmLNYFMcXodwJZwvAM.

[10] (PDF) The International System of Units (SI) (8th ed.), Bureau International des Poids et Mesures, 2006, p. 144, http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf.

[11] Kowalski, L, A short history of the SI units in electricity, Montclair, http://alpha.montclair.edu/~kowalskiL/SI/SI_PAGE.HTML.

[12] History of the ampere, Sizes, http://www.sizes.com/units/ampHist.htm

[Electrical_quantities-13] "Appendix 2: Practical realization of unit definitions: Electrical quantities", SI brochure, BIPM, http://www.bipm.org/en/si/si_brochure/appendix2/electrical.html.

[14] "Value", Physics, USA: NIST, http://physics.nist.gov/cgi-bin/cuu/Value?e.

[15] "General Conference on Weights and Measures approves possible changes to the International System of Units, including redefinition of the kilogram." (Press release). Sèvres, France: General Conference on Weights and Measures. 23 October 2011. http://www.bipm.org/utils/en/pdf/Press_release_resolution_1_CGPM.pdf. Retrieved 25 October 2011.

Ampere

Current can be measured by a galvanometer, via the deflection of a magnetic needle in the magnetic field created by the current.
Unit information
Unit system:	SI base unit
Unit of...	Electric current
Symbol:	A

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ampere