# kelvin

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## SI units

the units of measurement generally accepted for all scientific and technical uses; together they make up the International System of Units. (See also metric system.) The abbreviation SI, from the French

SI is a

The metric prefixes can be attached to any unit in order to make a unit of a more convenient size. The symbol for the prefix is attached to the symbol for the unit, e.g., nanometer (nm) = 10

Only one prefix is used with a unit; the use of units such as the millimicrometer is no longer acceptable. When a unit is raised to a power, the power applies to the prefix as well, e.g., a cubic millimeter (mm

Owing to the force of tradition, one noncoherent unit, the liter, equal to 10

*Système International d'Unités,*is used in all languages. There are seven base SI units, defined by specified physical measurements, and two supplementary units. Units are derived for any other physical quantities by multiplication and division of the base and supplementary units. The derived units with special names are shown in the accompanying table.SI is a

*coherent*system. This means that units are always combined without conversion factors. The derived unit of velocity is the meter per second (m/s); the derived unit of volume is the cubic meter (m^{3}). If you know that pressure is force per unit area, then you know that the SI unit of pressure (the pascal) is the unit of force divided by the unit of area and is therefore equal to 1 newton per square meter.The metric prefixes can be attached to any unit in order to make a unit of a more convenient size. The symbol for the prefix is attached to the symbol for the unit, e.g., nanometer (nm) = 10

^{−9}m. The units of mass are specified in terms of the gram, e.g., microgram (μg) = 10^{−9}kg.Only one prefix is used with a unit; the use of units such as the millimicrometer is no longer acceptable. When a unit is raised to a power, the power applies to the prefix as well, e.g., a cubic millimeter (mm

^{3}) = 10^{−9}m^{3}. When a prefix is used with a ratio unit, it should be in the numerator rather than in the denominator, e.g., kilometers/second (km/s) rather than meters/millisecond (m/ms). Only prefixes denoting powers of 10^{3}are normally used. Hecto-, deka-, deci-, and centi- are usually attached only to the metric system units gram, meter, and liter.Owing to the force of tradition, one noncoherent unit, the liter, equal to 10

^{−3}m^{3}, or 1 dm^{3}, is generally accepted for use with SI. The internationally accepted abbreviation for liter is the letter l; however, this can be confused with the numeral 1, especially in typescript. For this reason, the capital letter L is also used as a symbol for liter. The lower case letter is generally used with prefixes, e.g., dl, ml, fl. The symbols for all other SI units begin with a capital letter if the unit is named after a person and with a lower case letter otherwise. The name of a unit is never capitalized.## Kel·vin

(kel'vĭn),William Thomson, Scottish physicist, 1824-1907. See: kelvin, Kelvin scale.

## kel·vin (K),

(kel'vĭn),A unit of thermodynamic temperature equal to 273.16

^{-1}of the thermodynamic temperature of the triple point of water. See: Kelvin scale. [Lord

*Kelvin*]## kelvin

/kel·vin/ (K) (kel´vin) the base SI unit of temperature, equal to 1/273.16 of the absolute temperature of the triple point of water.## kel·vin

**(K)**(kel'vin)

A unit of thermodynamic temperature equal to 1/273.16 of the thermodynamic temperature of the triple point of water.

See also: Kelvin scale

See also: Kelvin scale

[Lord

*Kelvin*]## scale

device marked at regular intervals, used for measuring;*celsius scale; centigrade scale; °C**fahrenheit scale; °F**kelvin scale; K*