International System of Units

International System of Units (SI) is the modern form of the metric system and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units, which are the second, meter, kilogram, ampere, kelvin, mole, and candela.

History

The International System of Units was developed from the metric system at the General Conference on Weights and Measures (CGPM) in 1960. The conference recognized the need for a single, coherent system of units that could be used worldwide. The SI system was designed to be as simple and consistent as possible, and to be applicable to all fields of science and technology.

Base Units

The SI system is based on seven base units, which are the second (s), meter (m), kilogram (kg), ampere (A), kelvin (K), mole (mol), and candela (cd). These units are defined in terms of constants of nature and are intended to be as stable and reproducible as possible.

Derived Units

In addition to the base units, the SI system includes a number of derived units, which are formed by combining the base units according to the rules of algebra. Examples of derived units include the newton (N), which is a unit of force, and the joule (J), which is a unit of energy.

Symbols and Prefixes

Each unit in the SI system has a symbol, and these symbols are used in combination with prefixes to indicate multiples and submultiples of the units. For example, the prefix kilo- (k) indicates a multiple of 1000, so a kilometer is 1000 meters.

See Also

• Metric system
• Measurement
• Science
• Technology

References

• Bureau International des Poids et Mesures (2019). The International System of Units (SI) (9th ed.). ISBN 978-92-822-2272-0.

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  SI Base Units and Constants
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