Current (Electrical Current)

Electrical current is the rate of movement of electrical charge and is measured in coulombs per second or amperes (A).

Equation: I = Q / t

Current flow is most commonly due to the movement of negatively charged electrons (as in a copper wire), where electrons move in a direction opposite to that supposed in the notion of 'classical' current flow (which assumes positive charge carriers). However, electrical current may also be due to the combined movement of positive and negative charges, each moving in opposite directions (examples include battery electrolytes, fuel cells and ionised gases or plasmas).

The ampere is the SI unit of electrical current, but this is often abbreviated to "amps" when spoken. The unit symbol is named after French scientist / mathematician André-Marie Ampere (1775 – 1836) so is written in upper case (e.g. 5.2 A). The quantity symbol for DC current is I (e.g. I = 5.2 A), but a lower case quantity symbol is used for AC values [e.g. i = 5.2 sin(ωt)].

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