A capacitor is an electronic device that stores electrical energy in an electric field by accumulating electric charges on two closely spaced surfaces that are insulated from each other. It is a passive electronic component with two terminals. The effect of a capacitor is known as capacitance. While some capacitance exists between any two electrical conductors in proximity in a circuit, a capacitor is a component designed to add capacitance to a circuit.
A capacitor is a device capable of storing energy in the form of an electric charge. It is constructed out of two metal plates, separated by an insulating material called dielectric. The plates are conductive and they are usually made of aluminum, tantalum or other metals, while the dielectric can be made out of any kind of insulating material such as paper, glass, ceramic or anything that obstructs the flow of the current.
Capacitors can be used in electronic circuits for blocking direct current while allowing alternating current to pass. In analog filter networks, they smooth the output of power supplies. In resonant circuits, they tune radios to particular frequencies. Capacitors can be manufactured to serve any purpose, from the smallest plastic capacitor in your calculator to an ultra-capacitor that can power a commuter bus.
