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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 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.


Charles A. de, French physicist, 1736-1806. See: coulomb.

cou·lomb (C, Q),

The unit of electrical charge, equal to 3 × 109 electrostatic units; the quantity of electricity delivered by a current of 1 A in 1 s equal to 1/96,485 faraday.
[CA de Coulomb, Fr. physicist, 1736-1806]


/cou·lomb/ (C) (koo´lom) the SI unit of electric charge, defined as the quantity of electric charge transferred across a surface by 1 ampere in 1 second.

coulomb (C)

Etymology: Charles A. de Coulomb, French physicist, 1736-1806
the SI unit of electricity equal to the quantity of charge transferred in 1 second across a conductor in which there is a constant current of 1 ampere, or 1 ampere-second.


(C) (kū'lom)
The SI unit of electrical charge, equal to 3 × 109 electrostatic units; the quantity of electricity delivered by a current of 1 ampere in 1 sec; equal to 1/96,485 faraday; also used to measure radiation.
See also: roentgen
[CA de Coulomb, Fr. physicist, 1736-1806]


1. the unit of electrical charge, defined as the quantity of electrical charge transferred by 1 ampere in 1 second. Symbol C.
2. the SI unit of exposure to radiation. 1 coulomb per kilogram = 3876 roentgen; abbreviated C/kg.
References in periodicals archive ?
Notice that the Coulomb gauge dyadic Green's function [[bar.
Segun Coulomb, la estructura administrativa y presupuestal del nuevo organismo estaria compuesta por una direccion general y por las areas tecnico-administrativas "estrictamente necesarias".
Coulomb also provides ChargePoint Network service plans and cloud-based solutions that handle all driver billing and support.
The ChargePoint service plans are groundbreaking for the electric vehicle market, as they provide the missing ingredient needed to obtain a rapid scaling of feature-rich charging infrastructure,' said Pat Romano, president and CEO of Coulomb Technologies.
Our ChargePoint America program has seen tremendous success with new charging locations added to the ChargePoint Network every day," said Pat Romano, president and CEO at Coulomb.
No obstante, como un capitalino mas, Coulomb suena con un Centro Historico rehabilitado, con una intensa vida cultural, sitio de encuentro y actividad nocturna, y acude a los ejemplos de Paris, Madrid, Roma y Barcelona e incluso cita el caso de Quito y La Habana.
Coulomb works closely with automobile manufacturers including Nissan, BMW, Ford, GM, and Fisker Automotive enabling their customers to easily find, reserve and pay for EV charging services.
Chevrolet, a subsidiary of General Motors Corporation (NYSE: GM), has collaborated with Coulomb Technologies, a provider of electric vehicle charging systems and application services.
The method, called Coulomb explosion imaging, takes advantage of the large electrical repulsion between the nuclei within molecules rapidly stripped of all or most of their electrons.
Fuji Electric Corporation of America announced today that it has collaborated with Coulomb Technologies to integrate Coulomb's ChargePoint[R] Network into its DC Quick Charging Stations.
Auto Business News-4 June 2010-Ford collaborates with Coulomb Technologies(C)2010 ENPublishing - http://www.
Coulomb Technologies announced today that the new electric vehicle (EV) charging station unveiled at Discovery World in Milwaukee is part of Coulomb's ChargePoint[R] Network, the largest network of independently owned charging stations in the world.