alternating current (AC)Fr.: courant alternatifAn → electric current that reverses direction of flow at regular intervals. The typical alternating current is → sinusoidal in shape. Alternating current has the advantage over → direct current in that its → voltage magnitude can be changed easily through a → transformer. Moreover, it is safer to transfer over the longer city distances and can provide more → power. The frequency of alternating current is 50 Hz (Europe) or 60 Hz (USA).