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Concept
MKS system of units
Résumé
The MKS system of units is a physical system of measurement that uses the metre, kilogram, and second (MKS) as base units. The modern International System of Units (SI) was originally created as a formalization of the MKS system, and although the SI has been redefined several times since then and is now based entirely on fundamental physical constants, it still closely approximates the original MKS system for most practical purposes.
By the mid-19th century, there was a demand by scientists to define a coherent system of units. A coherent system of units is a system of units where all units are directly derived from a set of base units, without the need of any conversion factors. The United States customary units are an example of a non-coherent set of units. In 1874, the British Association for the Advancement of Science (BAAS) introduced the CGS system, a coherent system based on the centimetre, gram and second. These units were inconvenient for electromagnetic applications, since electromagnetic units derived from these did not correspond to the commonly used practical units, such as the volt, ampere and ohm. After the Metre Convention of 1875, work started on international prototypes for the kilogram and the metre, which were formally sanctioned by the General Conference on Weights and Measures (CGPM) in 1889, thus formalizing the MKS system by using the kilogram and metre as base units.
In 1901, Giovanni Giorgi proposed to the Associazione elettrotecnica italiana (AEI) that the MKS system, extended with a fourth unit to be taken from the practical units of electromagnetism, such as the volt, ohm or ampere, be used to create a coherent system using practical units.
This system was strongly promoted by electrical engineer George A. Campbell. The CGS and MKS systems were both widely used in the 20th century, with the MKS system being primarily used in practical areas, such as commerce and engineering. The International Electrotechnical Commission (IEC) adopted Giorgi's proposal as the M.K.S.
Source officielle
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