CAPACITORS AND CAPACITANCE

A capacitor is a device used to store electric charge and, along with it, electrostatic potential energy. In its simplest form it consists of two conducting objects (commonly plates or sheets) placed near each other but electrically isolated, separated by either vacuum, air, or an insulating dielectric material. When a capacitor is connected to a source of potential difference, such as a battery, equal and opposite charges accumulate on its two conductors; for any given capacitor, the amount of charge Q stored is always directly proportional to the potential difference V applied across it, and the constant of proportionality, C = Q/V, is called the capacitance of that capacitor. Capacitance depends only on the capacitor's own geometry (the size, shape, and separation of its two conductors) and on the permittivity of whatever material fills the gap between them -- never on the amount of charge or voltage actually applied at any given moment. Capacitors of many …