IEVref: 112-02-07 ID: Language: en Status: Standard Term: ampere Synonym1: Synonym2: Synonym3: Symbol: A Definition: SI unit of electric current, equal to the electric current corresponding to the flow of (1/1,602 176 634) × 1019 elementary electric charges per second Note 1 to entry: The definition in the SI Brochure is: "The ampere, symbol A, is the SI unit of electric current. It is defined by taking the fixed numerical value of the elementary charge e to be 1,602 176 634 × 10−19 when expressed in the unit C, which is equal to A s, where the second is defined in terms of ΔνCs." Note 2 to entry: The definition of the ampere in IEV 112-02-07:2010-01 was: "SI unit of electric current, equal to the direct current which, if maintained constant in two straight parallel conductors of infinite length, of circular cross-section with negligible area, and placed 1 metre apart in vacuum, would produce between these conductors a force per length equal to 2 × 10−7 N/m". Note 3 to entry: The new definition of the ampere fixes the value of the elementary charge e instead of that of the magnetic constant, μ0. As a consequence, the value of μ0 has to be determined experimentally. Note 4 to entry: The ampere is one of the seven SI base units: second (s), metre (m), kilogram (kg), ampere (A), kelvin (K), mole (mol) and candela (cd). Publication date: 2020-12 Source: SI Brochure, 9th edition, 2019, 2.3.1, modified – The definition in the SI Brochure has been revised to comply with the IEV rules. Notes 1 to 4 to entry have been added. Replaces: 112-02-07:2010-01 Internal notes: CO remarks: TC/SC remarks: VT remarks: Domain1: Domain2: Domain3: Domain4: Domain5: