Alternating Current (AC) is a type of electrical current that periodically changes direction, causing the voltage level to also reverse along with the current. AC is commonly used to deliver power to homes, office buildings, and other structures. AC can be generated using an alternator, which is a type of electrical generator designed to produce alternating current. The amplitude of the AC waveform describes the maximum voltage that the sine wave can reach in either direction, while the frequency tells how many times a particular wave form occurs within one second. The phase is a measure of how shifted the waveform is with respect to time. AC is used to power electric motors, which convert electrical energy into mechanical energy.