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. Capacitors are widely 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.
A capacitor is constructed out of two metal plates, separated by an insulating material called dielectric. The plates are conductive and 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. If we connect a power source or a battery to the metal plates of the capacitor, a current will try to flow, or the electrons from the plate connected to the positive lead of the battery will flow to the other plate. Capacitors can store much smaller amounts of energy compared to a battery, around 10,000 times smaller, but they are useful enough for many circuit designs.
