Ampere Ampere The ampere (; symbol: A), often shortened to "amp", is the base unit of electric current in the International System of Units (SI). It is named after André-Marie Ampère (1775–1836), French mathematician and physicist, considered the father of electrodynamics. The International System of Units defines the ampere in terms of other base units by measuring the electromagnetic force between electrical conductors carrying electric current. The earlier CGS measurement system had two different definitions of current, one essentially the same as the SI's and the other using electric charge as the base unit, with the unit of charge defined by
Stilb (unit) meter. The current national standard for SI in the United States discourages the use of the stilb. formula_1 formula_2 formula_3 formula_4 formula_5 Other units of luminance: Stilb (unit) The stilb (sb) is the CGS unit of luminance for objects that are not self-luminous. It is equal to one candela per square centimeter or 10 nits (candelas per square meter). The name was coined by the French physicist André Blondel around 1920. It comes from the Greek word "stilbein" meaning "to glitter". It was in common use in Europe up to World War I. In North America self-explanatory terms such as