How Does a Capacitor Work?


Quick Answer

Capacitors work by accumulating charge at the surface of two electrical conductors separated by an insulator in the presence of an electric potential. The positive capacitor plate accumulates positive charges, while the negative plate accumulates negative charges

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Full Answer

Capacitors can store static charge once the voltage difference used to induce the charge is removed. They are similar to batteries in their charge-storage capabilities, the difference being that batteries store charge in the form of chemical energy, which is slowly released as the electrical energy driving current through the circuit. Capacitors release their energy much more quickly: in seconds or milliseconds.

Camera flash is an example of the rapid energy release capabilities of capacitors. A capacitor attached to the flashgun charges up from the battery. Once the capacitor is charged, it can release the accumulated energy almost instantaneously through a xenon flash bulb, generating a short, intense burst of light.

Capacitors can function as timers, because they take a predictable time to fill up and discharge. They are also used as filters, accumulating electrical signals that designers want to remove from a circuit. They can also function as power regulators, removing voltage differences by absorbing excess voltage or compensating for voltage drops. As of 2015, large, energy-dense supercapacitors are being developed to replace batteries.

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