Servomechanism, automatic device used to correct the performance of a mechanism by means of an…

Superconductivity, complete disappearance of electrical resistance in various solids when they are cooled below a characteristic temperature.…

Electromotive force, abbreviation E or emf, energy per unit electric charge that is imparted by an energy source, such as an electric generator or…

Voltmeter Voltmeter, instrument that measures voltages of either direct or alternating electric current on a scale usually…

Rheostat, adjustable resistor used in applications that require the adjustment of current or the varying of resistance in an electric circuit. The…

Alternating current, abbreviation AC, flow of electric charge that periodically reverses. It starts, say, from zero, grows to…

Resistor, electrical component that opposes the flow of either direct or alternating current, employed to protect,…

Electric heater, device for heating rooms that converts electric current to heat by means of resistors that emit radiant energy. Resistors may…

Lamp, a device for producing illumination, consisting originally of a vessel containing a wick soaked in combustible material,…

Electric current, any movement of electric charge carriers, such as subatomic charged particles (e.g., electrons having negative charge, protons having positive charge), ions (atoms that have…