The basic unit of electric current, equal to one coulomb per second and equivalent to the current, flowing in two straight parallel wires of negligible cross section separated by a distance of one meter, that produces a force between the wires of 2.0 × 10^-7 newtons per meter of length. The value of an ampere in the International System differs very slightly from that in the meter-kilogram-second-ampere system of units. See Table at measurement.