A
capacitor (originally known as a
condenser) is a
passive two-terminal electrical component used to store electrical
energy temporarily in an
electric field. The forms of practical capacitors vary widely, but all contain at least two
electrical conductors (plates) separated by a
dielectric (i.e. an
insulator that can store energy by becoming
polarized). The conductors can be thin films, foils or sintered beads of metal or conductive electrolyte, etc. The nonconducting dielectric acts to increase the capacitor's charge capacity. Materials commonly used as dielectrics include
glass,
ceramic,
plastic film,
air,
vacuum,
paper,
mica, and
oxide layers. Capacitors are widely used as parts of
electrical circuits in many common electrical devices. Unlike a
resistor, an ideal capacitor does not dissipate energy. Instead, a capacitor stores
energy in the form of an
electrostatic field between its plates.
