An alternating current is an electric current whose direction reverses cyclically, as opposed to direct current whose direction remains constant. Alternative Current voltage may be increased or decreased with a transformer. The usual waveform of an alternative current power circuit is a sine wave, as these results in the most efficient transmission of energy level. The frequency of the electrical system varies by country; most electric power is generated at either 50 or 60 Hz.
In alternating current of any frequency, the current is forced towards the outer surface of the wire, and away from the center. An alternating current is made of electric charge under periodic acceleration, which causes radiation of electromagnetic waves. Energy that is radiated represents a loss. Depending on the frequency, different techniques are used to minimize the loss due to radiation. In audio and radio signals carried on electrical wires are a best examples of alternating current.
