# User Contributed Dictionary

# Extensive Definition

The ampere, in practice often shortened to amp,
(symbol: A) is a unit of electric
current, or amount of electric
charge per second. The ampere is an SI base
unit, and is named after André-Marie
Ampère, one of the main discoverers of electromagnetism.

## Definition

One ampere is defined to be the constant current which will produce a 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. For a description of this force law, see Serway. See also Ampère's force law. The ampere is a base unit, along with the metre, kelvin, second, mole, candela and the kilogram: it is defined without reference to the quantity of electric charge.The S.I. unit of charge, the coulomb, is defined to be the
quantity of charge displaced by a one ampere per second. Conversely, an ampere is
one coulomb of charge going past a given point in the duration of
one second; that is, in general, charge Q is determined by steady
current I flowing per unit time t as:

- Q=It \!\

## Realization

The ampere is most accurately realized using a watt balance, but is in practice maintained via Ohm's Law from the units of EMF 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. The official realization of a standard ampere is discussed in NIST Special publication 330 Barry N Taylor (editor) Appendix 2, p. 56.## Proposed future definition

Since a coulomb is approximately equal to 6.24150948×1018 elementary charges, one ampere is approximately equivalent to 6.24150948×1018 elementary charges, such as electrons, moving past a boundary in one second.As with other SI base units, there
have been proposals to redefine the kilogram in such a way as to
define some presently measured physical
constants to fixed values. One proposed definition of the
kilogram is:

The kilogram is the mass
which would be accelerated at precisely 2×10-7 m/s2 if subjected to
the per metre force between two straight parallel conductors of
infinite length, of negligible circular cross section, placed 1
metre apart in vacuum, through which flow a constant current of
exactly 6 241 509 479 607 717 888 elementary charges per
second. This redefinition of the kilogram has the effect of
fixing the elementary
charge to be e = 1.60217653 C and would result in a
functionally equivalent definition for the coulomb as being the sum of
exactly 6 241 509 479 607 717 888 elementary charges and the ampere
as being the electrical current of exactly 6 241 509 479 607 717
888 elementary charges per second. This is consistent with the
current 2002 CODATA value for the elementary charge which is
1.60217653×10-19 ± 0.00000014×10-19 C.

### CIPM recommendation

International Committee for Weights and Measures (CIPM) Recommendation 1 (CI-2005): Preparative steps towards new definitions of the kilogram, the ampere, the kelvin and the mole in terms of fundamental constantsThe International Committee for Weights and
Measures (CIPM),

- approve in principle the preparation of new definitions and mises en pratique of the kilogram, the ampere and the kelvin so that if the results of experimental measurements over the next few years are indeed acceptable, all having been agreed with the various Consultative Committees and other relevant bodies, the CIPM can prepare proposals to be put to Member States of the Metre Convention in time for possible adoption by the 24th CGPM in 2011;
- give consideration to the possibility of redefining, at the same time, the mole in terms of a fixed value of the Avogadro constant;
- prepare a Draft Resolution that may be put to the 23rd CGPM in 2007 to alert Member States to these activities;

## See also

## References

## External links

milliamp in Arabic: أمبير

milliamp in Asturian: Amperiu

milliamp in Belarusian: Ампер

milliamp in Belarusian (Tarashkevitsa):
Ампэр

milliamp in Bengali: অ্যাম্পিয়ার

milliamp in Bosnian: Amper

milliamp in Breton: Amper

milliamp in Bulgarian: Ампер

milliamp in Catalan: Ampere

milliamp in Czech: Ampér

milliamp in Danish: Ampere

milliamp in German: Ampere

milliamp in Estonian: Amper

milliamp in Modern Greek (1453-): Αμπέρ (μονάδα
μέτρησης)

milliamp in Spanish: Amperio

milliamp in Esperanto: Ampero

milliamp in Basque: Anpere

milliamp in Persian: آمپر (یکا)

milliamp in French: Ampère (unité)

milliamp in Friulian: Ampere

milliamp in Irish: Aimpéar

milliamp in Galician: Ampere

milliamp in Korean: 암페어

milliamp in Hindi: एम्पीयर

milliamp in Croatian: Amper

milliamp in Indonesian: Ampere

milliamp in Icelandic: Amper

milliamp in Italian: Ampere

milliamp in Hebrew: אמפר

milliamp in Kazakh: Ампер (өлшем бірлік)

milliamp in Swahili (macrolanguage): Ampea

milliamp in Kurdish: Ampère

milliamp in Latvian: Ampērs

milliamp in Luxembourgish: Ampere
(Eenheet)

milliamp in Lithuanian: Amperas

milliamp in Hungarian: Amper

milliamp in Marathi: अँपियर

milliamp in Malay (macrolanguage): Ampere

milliamp in Dutch: Ampère

milliamp in Japanese: アンペア

milliamp in Norwegian: Ampere

milliamp in Norwegian Nynorsk: Ampere

milliamp in Low German: Ampere

milliamp in Polish: Amper

milliamp in Portuguese: Ampère

milliamp in Romanian: Amper

milliamp in Russian: Ампер

milliamp in Albanian: Amperimetri

milliamp in Simple English: Ampere

milliamp in Slovak: Ampér

milliamp in Slovenian: Amper

milliamp in Serbian: Ампер

milliamp in Serbo-Croatian: Amper

milliamp in Finnish: Ampeeri

milliamp in Swedish: Ampere

milliamp in Thai: แอมแปร์

milliamp in Vietnamese: Ampe

milliamp in Turkish: Amper

milliamp in Ukrainian: Ампер

milliamp in Chinese: 安培