the ampere is that constant electric current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in a vacuum, would produce between these conductors a force equal to 2 × 10^−7 newton per metre of length, a unit of electric current flow equivalent to the motion of 1 coulomb of charge or 6.24 X 10[18 th power] electrons past any cross section in 1 second, SI elektrivoolu ühik, mis võrdub sellise konstantse vooluga kahes sirges lõpmata pikas ja tühise ümara ristlõikega paralleelses vaakumis vahekaugusega 1 meeter paiknevas juhis, mis tekitab nende juhtide vahel jõu 2 × 10^–7 njuutonit meetri kohta