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[a] This system underlies the International System of Units (SI) [b] but does not itself determine the units of measurement used for the quantities. The system is formally described in a multi-part ISO standard ISO/IEC 80000 (which also defines many other quantities used in science and technology), first completed in 2009 and subsequently ...
ISO/IEC 80000, Quantities and units, is an international standard describing the International System of Quantities (ISQ). It was developed and promulgated jointly by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC).
In the International System of Units (SI), electric current is expressed in units of ampere (sometimes called an "amp", symbol A), which is equivalent to one coulomb per second. The ampere is an SI base unit and electric current is a base quantity in the International System of Quantities (ISQ).
The original "International Ampere" was defined electrochemically as the current required to deposit 1.118 milligrams of silver per second from a solution of silver nitrate. I kelvin: K thermodynamic temperature "The kelvin, symbol K, is the SI unit of thermodynamic temperature.
The International System of Units, internationally known by the abbreviation SI (from French Système international d'unités), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official status in nearly every country in the world, employed in science ...
The SI system after the 2019 definition: Base units as defined in terms of physical constants and other base units. Here, means is used in the definition of . The SI system after 1983, but before the 2019 redefinition: Base unit definitions in terms of other base units (for example, the metre is defined as the distance travelled by light in a specific fraction of a second), with the constants ...
The first table lists the fundamental quantities used in the International System of Units to define the physical dimension of physical quantities for dimensional analysis. The second table lists the derived physical quantities. Derived quantities can be expressed in terms of the base quantities.
Many scientists have been recognized with the assignment of their names as international units by the International Committee for Weights and Measures or as non-SI units. The International System of Units (abbreviated SI from French : Système international d'unités ) is the most widely used system of units of measurement.