What is an alternating current

Alternating current (AC) is an electrical current in which the direction of the flow of electrons periodically reverses direction. This occurs because an AC supply creates an electromotive force (EMF) that periodically reverses its polarity. Most power grids and home appliances use an alternating current, as alternating current is more efficient than direct current (DC) for long-distance transmission. Consequently, AC is the most common form of electrical power used in the world today.