AskDefine | Define coulomb

Dictionary Definition



1 a unit of electrical charge equal to the amount of charge transferred by a current of 1 ampere in 1 second [syn: C, ampere-second]
2 French physicist famous for his discoveries in the field of electricity and magnetism; formulated Coulomb's Law (1736-1806) [syn: Charles Augustin de Coulomb]

User Contributed Dictionary

see Coulomb



Named after the French physicist Charles-Augustin de Coulomb.


  1. In the International System of Units, the derived unit of electric charge; the amount of electric charge carried by a current of 1 ampere flowing for 1 second. Symbol: C
    He is charged up with enough coulombs to make his hair stand on end.




  1. () coulomb

Extensive Definition

The coulomb (symbol: C) is the SI unit of electric charge. It is named after Charles-Augustin de Coulomb.


1 coulomb is the amount of electric charge transported by a current of 1 ampere in 1 second.
1 \ \mathrm = 1 \ \mathrm \cdot 1 \ \mathrm
It can also be expressed in terms of capacitance and voltage, where one coulomb is equal to one farad of capacitance times one volt of electric potential difference:
1 \ \mathrm = 1 \ \mathrm \cdot 1 \ \mathrm


In principle, the coulomb could be defined in terms of the charge of an electron or elementary charge. Since the values of the Josephson (CIPM (1988) Recommendation 1, PV 56; 19) and von Klitzing (CIPM (1988), Recommendation 2, PV 56; 20) constants have been given conventional values (KJ ≡ 4.835 979 Hz/V and RK ≡ 2.581 280 7 Ω), it is possible to combine these values to form an alternative (not yet official) definition of the coulomb. A coulomb is then equal to exactly 6.241 509 629 152 65 elementary charges. Combined with the present definition of the ampere, this proposed definition would make the kilogram a derived unit.
In everyday situations, positive and negative charges are usually balanced out. According to Coulomb's Law, two point charges of +1 C, one meter apart, would experience a repulsive force of 9 N, roughly the equivalent of 900,000 metric tons of weight.

Historical note

The ampere was historically a derived unit—being defined as 1 coulomb per second. Therefore the coulomb, rather than the ampere, was the SI base electrical unit.
In 1960 the SI system made the ampere the base unit.

SI multiples


  • The electrical charge of one mole of electrons (approximately 6.022, or Avogadro's number) is known as a faraday (actually –1 faraday, since electrons are negatively charged). One faraday equals 96.485 341 5 kC (the Faraday constant). In terms of Avogadro's number (NA), one coulomb is equal to approximately 1.036 × NA elementary charges.
  • One statcoulomb (statC), the CGS electrostatic unit of charge (esu), is approximately 3.3356 C or about 1/3 nC.
  • 1 coulomb is the amount of electrical charge in 6.241506 electrons or other elementary charged particles.

See also


coulomb in Arabic: كولوم
coulomb in Asturian: Culombiu
coulomb in Bengali: কুলম্ব
coulomb in Belarusian: Кулон
coulomb in Belarusian (Tarashkevitsa): Кулон
coulomb in Bosnian: Kulon
coulomb in Breton: Coulomb
coulomb in Bulgarian: Кулон
coulomb in Catalan: Coulomb
coulomb in Czech: Coulomb
coulomb in Danish: Coulomb
coulomb in German: Coulomb
coulomb in Modern Greek (1453-): Κουλόμπ (μονάδα μέτρησης)
coulomb in Spanish: Culombio
coulomb in Esperanto: Kulombo
coulomb in Basque: Coulomb
coulomb in French: Coulomb
coulomb in Galician: Coulomb
coulomb in Korean: 쿨롱
coulomb in Hindi: कूलम्ब
coulomb in Croatian: Kulon
coulomb in Indonesian: Coulomb
coulomb in Icelandic: Kúlomb
coulomb in Italian: Coulomb
coulomb in Hebrew: קולון
coulomb in Kurdish: Coulomb
coulomb in Lithuanian: Kulonas
coulomb in Hungarian: Coulomb
coulomb in Dutch: Coulomb (eenheid)
coulomb in Japanese: クーロン
coulomb in Norwegian: Coulomb
coulomb in Norwegian Nynorsk: Coulomb
coulomb in Polish: Kulomb
coulomb in Portuguese: Coulomb
coulomb in Romanian: Coulomb (unitate)
coulomb in Russian: Кулон
coulomb in Simple English: Coulomb
coulomb in Slovak: Coulomb
coulomb in Slovenian: Coulomb
coulomb in Serbian: Кулон (јединица)
coulomb in Serbo-Croatian: Kulon
coulomb in Finnish: Coulombi
coulomb in Swedish: Coulomb
coulomb in Vietnamese: Coulomb (đơn vị)
coulomb in Turkish: Coulomb (birim)
coulomb in Ukrainian: Кулон (одиниця СІ)
coulomb in Chinese: 库仑
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