Back Ampere Afrikaans Ampere ALS أمبير Arabic أمپير ARY এম্পিয়াৰ Assamese Amperiu AST Amper Azerbaijani آمپر AZB Ampere BAR Ампер (адзінка вымярэння) Byelorussian
| ampere | |
|---|---|
 Demonstration model of a moving iron ammeter. As the current through the coil increases, the plunger is drawn further into the coil and the pointer deflects to the right. | |
| General information | |
| Unit system | SI |
| Unit of | electric current |
| Symbol | A |
| Named after | André-Marie Ampère |
The ampere (/ˈæmpɛər/ AM-pair, US: /ˈæmpɪər/ AM-peer;[1][2][3] symbol: A),[4] often shortened to amp,[5] is the unit of electric current in the International System of Units (SI). One ampere is equal to 1 coulomb (C) moving past a point per second.[6][7][8] It is named after French mathematician and physicist André-Marie Ampère (1775–1836), considered the father of electromagnetism along with Danish physicist Hans Christian Ørsted.
As of the 2019 revision of the SI, the ampere is defined by fixing the elementary charge e to be exactly 1.602176634×10−19 C,[6][9] which means an ampere is an electric current equivalent to 1019 elementary charges moving every 1.602176634 seconds or 6.241509074×1018 elementary charges moving in a second. Prior to the redefinition the ampere was defined as the current passing through two parallel wires 1 metre apart that produces a magnetic force of 2×10−7 newtons per metre.
The earlier CGS system has two units of current, one structured similarly to the SI's and the other using Coulomb's law as a fundamental relationship, with the CGS unit of charge defined by measuring the force between two charged metal plates. The CGS unit of current is then defined as one unit of charge per second.[10]
- ^ Jones, Daniel (2011), Roach, Peter; Setter, Jane; Esling, John (eds.), Cambridge English Pronouncing Dictionary (18th ed.), Cambridge University Press, ISBN 978-0-521-15255-6
{{citation}}: CS1 maint: overridden setting (link) - ^ Wells, John C. (2008), Longman Pronunciation Dictionary (3rd ed.), Longman, ISBN 978-1-4058-8118-0
- ^ "ampere", Merriam-Webster.com Dictionary, Merriam-Webster, retrieved 29 September 2020
- ^ "2. SI base units", SI brochure (8th ed.), BIPM, archived from the original on 7 October 2014, retrieved 19 November 2011
- ^ 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, archived from the original (PDF) on 14 August 2017, retrieved 21 November 2011
- ^ a b BIPM (20 May 2019), "Mise en pratique for the definition of the ampere in the SI", BIPM, retrieved 18 February 2022
- ^ "2.1. Unit of electric current (ampere)", SI brochure (8th ed.), BIPM, archived from the original on 3 February 2012, retrieved 19 November 2011
- ^ "Base unit definitions: Ampere", Physics.nist.gov, archived from the original on 25 April 2017, retrieved 28 September 2010
- ^ Draft Resolution A "On the revision of the International System of units (SI)" to be submitted to the CGPM at its 26th meeting (2018) (PDF), archived from the original (PDF) on 29 April 2018, retrieved 28 October 2018
- ^ Bodanis, David (2005), Electric Universe, New York: Three Rivers Press, ISBN 978-0-307-33598-2