Current direction and size over time is called AC.Our daily life using electricity is AC.
Power plant sent to the AC generator,AC transformer can be used to change the voltage to high voltage substations (such as 10,000 volts) through the transformer into a 220 volt AC power,our lives are mostly used with electric AC.AC has many advantages can be used to facilitate the changes required transformer voltage.Facilitate long-distance transport.AC motor simple structure.Three-phase alternating current can produce a rotating magnetic field,three-phase AC motor simple structure.Where available with DC power rectifier from the AC obtained.DC has not changed the direction and size.DC is mainly used in power electronic devices,electrolysis,electroplating,battery charger and DC motors