The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2x10-7 newton per meter of length.
This definition was adopted by the 9th General Conference on Weights and Measures in 1948. Ampere is one of the greatest French scientists, a member of the Paris Academy of Sciences, one of the founders of electrodynamics, the creator of the electrodynamic theory and the theory of magnetism, the discoverer of a law named after him. James Maxwell rightfully called Ampere “the Newton of electricity.” As for his other achievements, Ampere invented the term “kinematics” and in 1830 – just imagine that – introduced the term “cybernetics” into scientific circulation, but its meaning was different from the modern one. According to Ampere, cybernetics is the science of the government of a state meant to provide citizens with diverse benefits.
Like all great scientists, Andre-Marie Ampere was completely immersed in his thoughts and always had a piece of chalk at hand to make a calculation, if necessary. They say that once Ampere performed a calculation on the back of a horse-drawn carriage that left him together with the formula.