Alternating Current - Electric current that repeatedly reverses direction, twice each cycle. Usually at 60 cycles per second, or hertz (Hz), in North America, or 50 hertz elsewhere.
Ampere - SI unit of electric current. A flow of one coulomb of charge per second is one ampere (symbol A).
Diode - An electronic device that restricts current to flow in a single direction in an electric circuit.
Direct Current - Electric Current whose flow of charge is always in one direction
Electric Current - The flow of electric charge; measure in amperes (C/s)
Electric Power - The rate at which electrical energy is converted into another for, such as light, heat, or mechanical energy (or converted from another form into electrical energy).
Electric Resistance - The resistance of a material to the flow of electric current through it; measured in ohms.
Ohm - (OM) The SI unit of electric resistance. One ohm is the resistance of a device that draws a current of one ampere when a voltage of one volt is impressed across it.
Ohm's Law - The statement that the current in a circuit is directly proportional to the voltage impressed across the circuit, and is inversely proportional to the resistance of the circuit.
Potential Difference - The difference in an electric potential (voltage) between two points. Free charge flows when there is a difference, and will continue until bot points reach a common potential.
Voltage Source - A device, such as dry cell or generator, that provides a potential difference.