Direct Current is the flow of electric charge in one direction through an electric circuit. The magnitude of the driving force is measured in VOLTS and the quantity of charge transported in a given time interval is measured in AMPERES.

Alternating Current is the flow of electric charge through an electric circuit that constantly reverses direction. One complete reversal is a cycle, and the number of cycles per second is the frequency of the alternating current. Frequency is measured in HERTZ. The magnitude of the driving force is measured in VOLTS and the quantity of charge transported in a given time interval is measured in AMPERES in the same way as with DC.

The watt is the unit of power employed in electricity. The power (watts) developed in an electrical circuit is equal to the VOLTS times the AMPERES.

The volt is the unit of electromotive or driving force.

The ampere is the unit of charge transported in a given time interval.

Hertz is the frequency of Alternating Current. 1 Hz equals 1 cycle per second. In North America the standard frequency is 60 Hz. In Europe and Africa the standard frequency is 50 Hz.

A transformer can either decrease or increase the supplied voltage. A Step-Down transformer will decrease the voltage, a Step-Up transformer will increase the voltage. A transformer CANNOT change the Hertz.

A rectifier will change Alternating Current into Direct Current.

An inverter will change Direct Current into Alternating Current.