capacitance

capacitance, in electricity, capability of a body, system, circuit, or device for storing electric charge. Capacitance is expressed as the ratio of stored charge in coulombs to the impressed potential difference in volts. The resulting unit of capacitance is the farad [for Michael Faraday]. In an electric circuit the device designed to store charge is called a capacitor. An ideal capacitor, i.e., one having no resistance or inductance, may be spoken of as a capacitance. When an alternating current flows through a capacitor, the capacitor produces a reactance that resists the current (see impedance). While every element of a circuit has some capacitance, it is a goal of good design to reduce such unwanted or stray capacitance to a minimum.

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capacitance

Property of a pair of electric conductors separated by a nonconducting material (such as air) that permits storage of electric energy by the separation of electric charge, and that is measured by the amount of separated charge that can be stored per unit of electric potential between the conductors. If electric charge is transferred between two initially uncharged conductors, they become equally (but oppositely) charged. A potential difference is set up between them and some of the electricity can be stored. Capacitance C is the ratio of the amount of charge q on one of the conductors to the potential difference V between the conductors, or C = q/V. The unit of capacitance is coulombs per volt (C/V), or farads (F).

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capacitance

The property of a capacitor or other device to hold a charge. It is measured in Farads (F). See Farad.

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capacitance

1. Electronics the property of a system that enables it to store electric charge

2. a measure of this, equal to the charge that must be added to such a system to raise its electrical potential by one unit.

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capacitance [kə′pas·ə·təns]

(electricity)

The ratio of the charge on one of the conductors of a capacitor (there being an equal and opposite charge on the other conductor) to the potential difference between the conductors. Symbolized C. Formerly known as capacity.

(engineering)

In a closed feedwater heater, the volume of water required for proper operation of the drain control valve.

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Capacitance

The ratio of the charge q on one of the plates of a capacitor (there being an equal and opposite charge on the other plate) to the potential difference v between the plates; that is, capacitance (formerly called capacity) is C = q/v.

In general, a capacitor, often called a condenser, consists of two metal plates insulated from each other by a dielectric. The capacitance of a capacitor depends on the geometry of the plates and the kind of dielectric used, since these factors determine the charge which can be put on the plates by a unit potential difference existing between the plates.

In an ideal capacitor, no conduction current flows between the plates. A real capacitor of good quality is the circuit equivalent of an ideal capacitor with a very high resistance in parallel or, in alternating-current (ac) circuits, of an ideal capacitor with a low resistance in series. See Capacitor, Dielectric materials