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Encyclopedia > Farad
Examples of various types of capacitors.
Examples of various types of capacitors.

The farad (symbol: F) is the SI unit of capacitance. It is named after the British physicist Michael Faraday. Image File history File linksMetadata Download high-resolution version (2592x1456, 520 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Farad Capacitor Metadata This file contains additional information, probably added from the digital camera or scanner used to... Image File history File linksMetadata Download high-resolution version (2592x1456, 520 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Farad Capacitor Metadata This file contains additional information, probably added from the digital camera or scanner used to... Look up si, Si, SI in Wiktionary, the free dictionary. ... Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ... Michael Faraday, FRS (September 22, 1791 – August 25, 1867) was an English chemist and physicist (or natural philosopher, in the terminology of that time) who contributed significantly to the fields of electromagnetism and electrochemistry. ...

Contents

Definition

The farad is defined as the amount of capacitance for which a potential difference of two volts results in a static charge of one coulomb. It has the base SI representation of s4 · A2 · m-2 · kg-1. Since an ampere is the rate of electrical flow (current) of one coulomb per second, an alternate definition is that a farad is the amount of capacitance that requires one second for a one ampere flow of charge to change the voltage by one volt. Further equalities follow: Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ... Potential difference is a quantity in physics related to the amount of energy that would be required to move an object from one place to another against various types of force. ... The volt is the SI derived unit for electric potential and voltage (derived from the ampere and watt). ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... The coulomb (symbol: C) is the SI unit of electric charge. ... Look up second in Wiktionary, the free dictionary. ... Current can be measured by a galvanometer, via the deflection of a magnetic needle in the magnetic field created by the current. ... The metre or meter is a measure of length. ... The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. It was assigned to the United States in 1889 and is periodically recertified and traceable to the primary international standard, The Kilogram, held at the Bureau International des Poids et... Current can be measured by a galvanometer, via the deflection of a magnetic needle in the magnetic field created by the current. ... Electric current is the flow (movement) of electric charge. ... Josephson junction array chip developed by NIST as a standard volt. ...

mbox{F} = dfrac{mbox{C}}{mbox{V}} = ,mathrm frac{A cdot s}{V} = dfrac{mbox{C}^2}{mbox{J}} = dfrac{mbox{C}^2}{mbox{N} cdot mbox{m}} = dfrac{mbox{s}^4 cdot mbox{A}^2}{mbox{m}^{2} cdot mbox{kg}}

Explanation

Since the farad is a very large unit compared to typical requirements in electronic devices, values of capacitors are usually in range of microfarads (μF), nanofarads (nF), or picofarads (pF). The picofarad is sometimes comically called a "puff", as in "a ten puff capacitor". A micro-microfarad (μμF) as found in older texts is the same as a picofarad. The millifarad is rarely used in practice, so that a capacitance of 4.7×10−3 F, for example, is usually written as 4700 µF. North American usage also avoids nanofarads. A capacitance of 1×10­−9 F will frequently be indicated as 1000 pF. A capacitance of 1×10−7 F will frequently be indicated as 0.1 μF. Very small capacitance values, such as those used in integrated circuits may also be expressed in femtofarads, one femtofarad being equal to 1×10−15 F. A new technology called supercapacitors offers devices up to the kilofarad range. Capacitors: SMD ceramic at top left; SMD tantalum at bottom left; through-hole tantalum at top right; through-hole electrolytic at bottom right. ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ... A supercapacitor or an ultracapacitor is an electrochemical capacitor that has an unusually large amount of energy storage capability relative to its size when compared to common capacitors. ...


The farad should not be confused with the faraday, an old unit of charge nowadays superseded by the coulomb. In physics, the faraday (not to be confused with the farad) is a unit of electrical charge; one faraday is equal to the charge of 6. ... The coulomb (symbol: C) is the SI unit of electric charge. ...


The reciprocal of capacitance is called electrical elastance, the (non-standard, non-SI) unit of which is the daraf. Electrical elastance is the inverse of capacitance. ... The daraf is the unit of electrical elastance (symbol: F-1), the ability of an electric potential to charge a capacitor; it is the reciprocal of the farad. ...


A capacitor consists of two conducting surfaces, frequently referred to as plates, separated by an insulating layer usually referred to as a dielectric. The original capacitor was the Leyden jar developed in the 18th century. It is the accumulation of charge on the plates that results in capacitance. Modern capacitors are constructed using a range of manufacturing techniques and materials to provide the extraordinary wide range of capacitance values used in practical electronics applications from femtofarads to farads and voltage withstand capabilities from a few volts to several kilovolts. Capacitors: SMD ceramic at top left; SMD tantalum at bottom left; through-hole tantalum at top right; through-hole electrolytic at bottom right. ... A dielectric, or electrical insulator, is a substance that is highly resistant to electric current. ... Original capacitor The Leyden jar was the original capacitor, invented in 1745 by Pieter van Muschenbroek (1700–1748) and used to conduct many early experiments in electricity. ... (17th century - 18th century - 19th century - more centuries) As a means of recording the passage of time, the 18th century refers to the century that lasted from 1701 through 1800. ... Capital accumulation ... Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ... Capacitors: SMD ceramic at top left; SMD tantalum at bottom left; through-hole tantalum at top right; through-hole electrolytic at bottom right. ... Electronics is the study of the flow of charge through various materials and devices such as, semiconductors, resistors, inductors, capacitors, nano-structures, and vacuum tubes. ... Josephson junction array chip developed by NIST as a standard volt. ...


One picofarad is about the smallest value of capacitor available for general use in electronic design, since smaller capacitors would be dominated by the parasitic capacitances (stray capacitance) of other components, wiring or printed circuit boards. When requiring capacitance values of 1 pF or lower, engineers sometimes create their own capacitors by twisting two short lengths of insulated wire together.[1][2] // Definition Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ... Part of a 1983 Sinclair ZX Spectrum computer board. ...


References

  1. ^ [1]
  2. ^ [2]

External links

Farad unit conversion tool


  Results from FactBites:
 
Farad - Wikipedia, the free encyclopedia (193 words)
The farad (symbol: F) is the SI unit of capacitance.
Since the farad is a very large unit, values of capacitors are usually in range of microfarads (μF), nanofarads (nF), or picofarads (pF).
The farad should not be confused with the faraday, an old unit of charge nowadays superseded by the coulomb.
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