Alternating current (AC) is an electrical current that changes direction and magnitude periodically. AC is used in power lines and household electricity, and most devices connected to the electrical grid operate on AC.  AC is different from direct current (DC), which flows only in one direction. In AC, electrons move back and forth at regular intervals, starting at zero, reaching the maximum positive value, and then dropping to zero. AC is generated by rotating a magnetic field or magnet along a stationary set of coils, or the rotation of a coil around a stationary magnetic field.  AC has... Show more

Alternating current (AC) is an electrical current that changes direction and magnitude periodically. AC is used in power lines and household electricity, and most devices connected to the electrical grid operate on AC. 

AC is different from direct current (DC), which flows only in one direction. In AC, electrons move back and forth at regular intervals, starting at zero, reaching the maximum positive value, and then dropping to zero. AC is generated by rotating a magnetic field or magnet along a stationary set of coils, or the rotation of a coil around a stationary magnetic field. 

AC has many advantages over DC, including:
Energy efficient: AC has lower energy losses than DC over distances more than a few meters.
Cheap voltage stepping: AC provides cheap voltage stepping.
Large distance transmission: AC can transmit power over large distances without great loss of energy. 

In the U.S., the standard AC current is 60 cycles per second. 

You can calculate AC using the peak current (determined by dividing the peak voltage by the resistance), the angular frequency, and the time. 

Examples of AC include:
Current produced by generators or turbines
Current obtained from home power sockets
Most electrical appliances, such as fans, bulbs, air conditioners, and motors
Audio signal
Radio signal 

Show less