Both alternating current and direct are measured in ampers. But how is the ampere defined for an alternating current ?

Explanation

In general, current is defined as amount of charge flowing per unit time. But in case of AC, there is no net flow of charge in any direction, hence this definition cannot be used to define current in AC. The AC current must be defined in such a term which is independent of the direction of current . one such property is Joule.s heating effect and square root of `I^(2)` averaged over a cycle is used to define rms value of AC.