Difference between revisions of "Capacitor"
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A '''capacitor''' is a element in an electrical [[circuit]] which stores charge ([[electron]]s). | A '''capacitor''' is a element in an electrical [[circuit]] which stores charge ([[electron]]s). | ||
| − | When [[voltage]] is first applied | + | When [[voltage]] is first applied across a capacitor, [[current]] flows, as electrons move into the capacitor. Depending on the size of the capacitor, this will continue for a period, and then tail off, as the capacitor fills up. |
Unlike resistors, capacitors show infinite [[impedance]] to [[direct current]]; to [[alternating current]], their response depends on the [[frequency]] - high frequency signals can pass through a capacitor, but not low frequency. The larger the capacitor, the lower the frequencies which can pass through it. | Unlike resistors, capacitors show infinite [[impedance]] to [[direct current]]; to [[alternating current]], their response depends on the [[frequency]] - high frequency signals can pass through a capacitor, but not low frequency. The larger the capacitor, the lower the frequencies which can pass through it. | ||
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| + | ==Construction== | ||
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| + | Capacitors are usually formed by having two conducting surfaces separated by a layer of insulation; the larger the surface, the larger the ability to store electrons (i.e. the capacitance). | ||
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| + | Over time, techniques have been developed to pack large surfaces into small volumes. One of the most common is the elecrolytic capacitor, which separates two long, narrow layers of metal foil with an electrolye; the foil pair is then rolled up into a cylinder. | ||
==See also== | ==See also== | ||
Revision as of 15:07, 23 March 2018
A capacitor is a element in an electrical circuit which stores charge (electrons).
When voltage is first applied across a capacitor, current flows, as electrons move into the capacitor. Depending on the size of the capacitor, this will continue for a period, and then tail off, as the capacitor fills up.
Unlike resistors, capacitors show infinite impedance to direct current; to alternating current, their response depends on the frequency - high frequency signals can pass through a capacitor, but not low frequency. The larger the capacitor, the lower the frequencies which can pass through it.
Construction
Capacitors are usually formed by having two conducting surfaces separated by a layer of insulation; the larger the surface, the larger the ability to store electrons (i.e. the capacitance).
Over time, techniques have been developed to pack large surfaces into small volumes. One of the most common is the elecrolytic capacitor, which separates two long, narrow layers of metal foil with an electrolye; the foil pair is then rolled up into a cylinder.
