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Related to kelvin: Kelvin scale, Lord Kelvin

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 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 (m3). 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 (mm3) = 10−9 m3. 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 103 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 m3, or 1 dm3, 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.


William Thomson, Scottish physicist, 1824-1907. See: kelvin, Kelvin scale.

kel·vin (K),

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]


/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.


(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
[Lord Kelvin]
References in periodicals archive ?
I have been building up a social history of Cullercoats," says Kelvin, who has amassed a database of around 10,000 names of people with links to the village.
As a mark of respect for Kelvin, and to show our support for Kelvin's family, the company will observe a minute's silence at the time of the funeral on Friday, 14th June, at 12.
As Jim Brandes of Multitest noted in a 26-page tutorial 1 on Kelvin measurements, a typical IC test system will include a DC measurement unit (DCMU) set up to force current and measure voltage.
Kelvin rarely displays his emotions but he sat in that room crying as his dream of going to America was taken away.
Anne Upton and Kelvin Thomas after their wedding at Nolton Church in Bridgend PICTURE: Colin Littley, Maybury Studios
He added: "I appeal to Reece and Kelvin to contact the police or a friend or relative.
Bluebirds manager Jones said: "We are really pleased to get Kelvin - he's a Premier League player coming into the club.
And Kelvin, who joined Emmerdale when he was 12, abandoned several planned nights out with pals to stay in and work on his lines.
Kelvin also had to produce a concept chair that would not be made, but contained innovative design concepts.
Dwi'n meddwl mai'r gwahaniaeth nath ddenu Mari at Kelvin yn y lle cynta'.
Last night Kelvin, 54, paid tribute to his Veronica and Charlotte, and spoke about the charity he has set up in his daughter's name, which will help to educate thousands of underprivileged children in Africa.