| Capacitor (component) |
Article Index for Capacitor |
Information AboutCapacitor (component) |
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CAPACITOR CONSTRUCTION Capacitors have thin conducting plates (usually made of metal), separated by a layer of dielectric, then stacked or rolled to form a compact device. Many types of capacitor are available commercially, with capacitances ranging from the picofarad range to more than a farad, and voltage ratings up to many kilovolts. In general, the higher the capacitance and voltage rating, the larger the physical size of the capacitor and the higher the cost. Tolerance s in capacitance value for discrete capacitors are usually specified as a percentage of the nominal value. Tolerances ranging from 50% (electrolytic types) to less than 1% are commonly available. Another figure of merit for capacitors is stability with respect to time and temperature, sometimes called ''drift''. Variable capacitors are generally less stable than fixed types. The electrodes need round edges to avoid Field Emission . Air has low breakdown voltage, so any air inside a capacitor - especially at the edges - will reduce the voltage rating. Even closed air bubbles in the insulator or between the insulator and the electrode lead to Gas Discharge in High Frequency applications.
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