Coulomb

DEFINITION

1 coulomb is the amount of electric charge carried by a Current of 1 Ampere flowing for 1 Second .
:

1 \ \mathrm{C} = 1 \ \mathrm{A} \cdot \mathrm{s}

EXPLANATION

The coulomb is also the unit of Electric Flux . (See Gauss Law ).

The coulomb could in principle 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 (K_J ≡ 4.835 979 Hz/V and R_K ≡ 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 current definition of the ampere, this proposed definition would make the Kilogram a derived unit.

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,

Recently (1960) the SI system made the ampere the base unit (See http://alpha.montclair.edu/~kowalskiL/SI/SI_PAGE.HTML).

SI MULTIPLES

CONVERSIONS

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 (N_A), one coulomb is equal to approximately 1.036 × N_A elementary charges.

one Ampere-hour = 3600 C

The elementary charge is approximately 160.2176 zC.

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 6.241 electrons or other elementary charged particles.

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Coulomb