Alternating current (AC) is an electric current that changes direction and magnitude periodically with time, and is presenting in Hertz (Hz), meaning the frequency in cycles per second. The frequency may vary depending on the country. Alternating current can be transmitted effectively with less loss-producing, and can convert the mechanical energy into electrical energy. Through a voltage transformer, the AC voltage can be adjusted; therefore, AC is the type of electric current that is mostly used by electric power companies for transmitting electricity.