(SI unit symbol
: A), often shortened to "amp", is the SI unit of electric
current (dimension symbol: I) and is one of the seven SI base units. It is named after André-Marie Ampère (1775–1836), French mathematician and physicist, considered the father
The ampere is equivalent to one coulomb (roughly ×1018
times the elementary charge) per second. Amperes are used to express 6.242flow rate
of electric charge. For any point experiencing a current, if the number of charged particles passing through it — or the charge on the particles passing through it — is increased, the amperes of current at that point will proportionately increase.
The ampere should not be confused with the coulomb (also called "ampere-second") or the ampere hour
(A⋅h). The ampere is a unit of current, the amount of charge transiting per unit time
, and the coulomb is a unit of charge. When SI units are used, constant
, instantaneous and average current are expressed in amperes (as in "the charging current is 1.2 A") and the charge accumulated, or passed through a circuit over a period of time is expressed in coulombs (as in "the battery charge is 000 C
"). The relation of the ampere (C/s) to the coulomb is the same as that of the 30watt
(J/s) to the joule.