##### From Wikipedia, the free encyclopedia

An ampere is the unit for the electric current; the flow of electrons. One amp is 1 coulomb passing in one second. One amp is produced by an electric force of 1 volt acting across a resistance of 1 ohm. Sometimes this is abbreviated as I for intensity.

The ampere is equivalent to one coulomb (roughly 6.241×10^{18} times the elementary charge) per second.^{[6]} Amperes are used to express flow 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 ofcharge. 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 30000 C“). The relation of the ampere (C/s) to the coulomb is the same as that of the watt (J/s) to the joule

## Definition[edit]

Ampère’s force law^{[7]}^{[8]} states that there is an attractive or repulsive force between two parallel wires carrying an electric current. This force is used in the formal definition of the ampere, which states that the ampere is the constant current that will produce an attractive force of 2 × 10^{−7}newtons per metre of length between two straight, parallel conductors of infinite length and negligible circular cross section placed one metre apart in avacuum.^{[2]}^{[9]}

The SI unit of charge, the coulomb, “is the quantity of electricity carried in 1 second by a