Applications of capacitors

Because a capacitor can be charged relatively slowly and then discharged very rapidly, releasing its entire stored energy in a short burst, capacitors are used throughout electronics wherever a sudden pulse of energy or current is needed. A flash capacitor inside a digital camera is charged gradually by the camera's battery over roughly a second, then discharged almost instantaneously through the flash bulb when a photograph is taken, producing a burst of light far brighter and faster than the battery alone could ever supply directly, since batteries are limited in how quickly they can deliver current. A heart defibrillator uses a much larger capacitor, charged over a few seconds, to deliver a single large, carefully controlled and extremely rapid pulse of electrical energy through a patient's chest via two paddle electrodes, powerful enough to momentarily stop a dangerously irregular heart rhythm and give the heart's own natural pacemaker a chance to resume a normal beat. Capacitors are also used in the ordinary keys of a computer keyboard: each key sits above a small parallel-plate capacitor whose plate separation shrinks the moment the key is physically pressed down, and since capacitance is inv …