Engineers work with volts, amperes, ohms, farads, and coulombs, which are of great practical utility, while the centimetre-gram-second (CGS) units, which are fine for theoretical physics can be inconvenient for electrical engineering usage and are largely unfamiliar to householders using appliances rated in volts and watts. A profound cultural difference between physicists and engineers, especially radio engineers, existed prior to the adoption of the metre-kilogram-second (MKS) system and hence its descendent, SI. In some countries, the informal cup measurement has become 250 mL, and prices for items are sometimes given per 100 g rather than per kilogram. For example, bread is sold in one-half, one or two kilogram sizes in many countries, but you buy them by multiples of one hundred grams in the former USSR. Scientifically, it provides ease when dealing with very large and small quantities because it lines up so well with our decimal numeral system.Ĭultural differences can be represented in the local everyday uses of metric units.
International factors also affected the adoption of the metric system, as many countries increased their trade. The swift worldwide adoption of the metric system as a tool of economy and everyday commerce was based mainly on the lack of customary systems in many countries to adequately describe some concepts, or as a result of an attempt to standardize the many regional variations in the customary system. It is administered by the standards organisation: the Bureau International des Poids et Mesures (International Bureau of Weights and Measures). The International System is now either obligatory or permissible throughout the world.
The seventh base unit, the mole, was added in 1970 by the 14th CGPM. In 1960, the 11th CGPM named the system the International System of Units, abbreviated SI from the French name: Le Système International d'Unités. The six base units recommended were the metre, kilogram, second, ampere, Kelvin degree (later renamed the kelvin), and the candela. As a result the 9th General Conference on Weights and Measures (CGPM), in 1948, asked the International Committee for Weights and Measures (CIPM) to conduct an international study of the measurement needs of the scientific, technical, and educational communities.īased on the findings of this study, the 10th CGPM in 1954 decided that an international system should be derived from six base units to provide for the measurement of temperature and optical radiation in addition to mechanical and electromagnetic quantities. It was recognised that additional steps were needed to promote a worldwide measurement system. Some of these systems were metric system variations whilst others were based on the Imperial and American systems. During the history of the metric system a number of variations have evolved and their use spread around the world replacing many traditional measurement systems.īy the end of World War II a number of different systems of measurement were still in use throughout the world. The metric system was officially adopted in France after the French Revolution. the US and UK) have defined many of the modern units in terms of SI units. Those countries that still give recognition to non-SI units (e.g. In the United Kingdom, conversion to metric units is official policy but not yet complete. In the United States the use of SI is increasing but is still limited. With a few exceptions (such as draught beer sales in the United Kingdom) the system is legally being used in every country in the world and many countries do not maintain definitions of other units. It is common for people to describe non-SI units as 'metric', although there is no authority that maintains a current definition of metric system other than SI. The SI authority describes SI as the modern metric system where modern means post-1960. The SI is not static, it is a living set of standards where units are created and definitions are modified with international agreement. Various new units were created at that time. In 1960, the SI was developed from a subset of the existing Metre-Kilogram-Second systems of units (MKS), rather than the older Centimetre-Gram-Second system (CGS). It is the most common system for everyday commerce in the world, and is almost universally used in the realm of science. The International System of Units (abbreviated SI from the French phrase, Système International d'Unités) is the most widely used system of units. The conversions on this site require the use of JavaScript so please enable before continuing.įor assistance in enabling JavaScript, please contact the webmaster.
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