# farad

The

The farad should not be confused with the faraday, an old unit of charge nowadays superseded by the coulomb.

The reciprocal of capacitance is called electrical elastance, the (non-standard, non-SI) unit of which is the daraf.

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.

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.

In

Michael Faraday, portrait by Thomas Phillips c1841-1842

Born September 22 1791

SI prefixes are frequently combined with the word

SI units

1000 mm 0 cm

US customary / Imperial units

0 ft 0 in The

**farad**(symbol: F) is the SI unit of capacitance. It is named after the British physicist Michael Faraday.## Definition

The farad is defined as the amount of capacitance for which a potential difference of one volt results in a static charge of one coulomb. It has the base SI representation of s^{4}· A^{2}· 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:## 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 4.710^{−3}F, for example, is usually written as 4700 µF. North American usage also avoids nanofarads. A capacitance of 110^{−9}F will frequently be indicated as 1000 pF. A capacitance of 110^{−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 110^{−15}F. A new technology called supercapacitors offers devices up to the kilofarad range.The farad should not be confused with the faraday, an old unit of charge nowadays superseded by the coulomb.

The reciprocal of capacitance is called electrical elastance, the (non-standard, non-SI) unit of which is the daraf.

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.

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]}## References

## External links

Farad unit conversion tool**Si**,

**si**, or

**SI**may refer to (all SI unless otherwise stated):

In

**language**:

- One of two Italian words:
*sì*(accented) for "yes"*si*

**.....**Click the link for more information.

**Capacitance**is a measure of the amount of electric charge stored (or separated) for a given electric potential. The most common form of charge storage device is a two-plate capacitor.

**.....**Click the link for more information.

**Michael Faraday**

Michael Faraday, portrait by Thomas Phillips c1841-1842

^{[2]}

Born September 22 1791

**.....**Click the link for more information.

**Capacitance**is a measure of the amount of electric charge stored (or separated) for a given electric potential. The most common form of charge storage device is a two-plate capacitor.

**.....**Click the link for more information.

In physics, the

**potential difference**is a quantity related to the amount of energy that would be required to move an object from one place to another against various types of forces.**.....**Click the link for more information.**volt**(symbol: V) is the SI derived unit of electric potential difference or electromotive force.

^{[1]}

^{[2]}It is named in honor of the Italian physicist Alessandro Volta (1745–1827), who invented the voltaic pile, the first modern chemical battery.

**.....**Click the link for more information.

**Flavour in particle physics**

**.....**Click the link for more information.

The

**coulomb**(symbol: C) is the SI unit of electric charge. It is named after Charles-Augustin de Coulomb.## Definition

1 coulomb is the amount of electric charge transported by a current of 1 ampere in 1 second.**.....**Click the link for more information.**second**(SI symbol:

**s**), sometimes abbreviated

**sec.**, is the name of a unit of time, and is the International System of Units (SI) base unit of time.

SI prefixes are frequently combined with the word

*second*to denote subdivisions of the second,

*e.g.*

**.....**Click the link for more information.

**ampere**, in practice often shortened to

**amp**, (symbol: A) is a unit of electric current, or amount of electric charge per second. The ampere is an SI base unit, and is named after André-Marie Ampère, one of the main discoverers of electromagnetism.

**.....**Click the link for more information.

**1 metre**=

SI units

1000 mm 0 cm

US customary / Imperial units

0 ft 0 in

**metre**or

**meter**

^{[1]}(symbol:

**m**) is the fundamental unit of length in the International System of Units (SI).

**.....**Click the link for more information.

**kilogram**or

**kilogramme**(symbol:

**kg**) is the SI base unit of mass. The kilogram is defined as being equal to the mass of the

*International Prototype Kilogram*(IPK), which is almost exactly equal to the mass of one liter of water.

**.....**Click the link for more information.

**ampere**, in practice often shortened to

**amp**, (symbol: A) is a unit of electric current, or amount of electric charge per second. The ampere is an SI base unit, and is named after André-Marie Ampère, one of the main discoverers of electromagnetism.

**.....**Click the link for more information.

**Electric current**is the flow (movement) of electric charge. The SI unit of electric current is the ampere (A), which is equal to a flow of one coulomb of charge per second.

## Definition

The amount of electric current (measured in amperes) through some surface, e.g.**.....**Click the link for more information.

**volt**(symbol: V) is the SI derived unit of electric potential difference or electromotive force.

^{[1]}

^{[2]}It is named in honor of the Italian physicist Alessandro Volta (1745–1827), who invented the voltaic pile, the first modern chemical battery.

**.....**Click the link for more information.

**capacitor**is an electrical/electronic device that can store energy in the electric field between a pair of conductors (called "plates"). The process of storing energy in the capacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity,

**.....**Click the link for more information.

**integrated circuit**(also known as

**IC**,

**microcircuit**,

**microchip**,

**silicon chip**, or

**chip**) is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a

**.....**Click the link for more information.

**supercapacitor**or

**ultracapacitor**is an electrochemical capacitor that has an unusually high energy density when compared to common capacitors. They are of particular interest in automotive applications for electric (including hybrid electric) vehicles and as supplementary

**.....**Click the link for more information.

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 6.02 × 10^{23}electrons (one mole).**.....**Click the link for more information. The

**coulomb**(symbol: C) is the SI unit of electric charge. It is named after Charles-Augustin de Coulomb.## Definition

1 coulomb is the amount of electric charge transported by a current of 1 ampere in 1 second.**.....**Click the link for more information.**Electrical elastance**is the inverse of capacitance. The SI unit is the reciprocal farad. Although the term

*daraf*(farad spelled backwards) is sometimes used, this is not approved by SI.

**.....**Click the link for more information.

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.**.....**Click the link for more information.**capacitor**is an electrical/electronic device that can store energy in the electric field between a pair of conductors (called "plates"). The process of storing energy in the capacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity,

**.....**Click the link for more information.

A

**dielectric**is a physical model commonly used to describe how an electric field behaves inside a material. It is characterised by how an electric field interacts with an atom. It is possible to approach dielectrics from either a classical interpretation or a quantum one.**.....**Click the link for more information. The

**Leyden jar**is a device for storing electric charge invented in 1745 by Pieter van Musschenbroek (1700–1748). It was the first capacitor. Leyden jars were used to conduct many early experiments in electricity.**.....**Click the link for more information. The

Historians sometimes specifically define the 18th Century otherwise for the purposes of their work.

**18th Century**lasted from 1701 through 1800 in the Gregorian calendar.Historians sometimes specifically define the 18th Century otherwise for the purposes of their work.

**.....**Click the link for more information. Most generally, the

**accumulation of capital**refers simply to the gathering or amassment of objects of value; the increase in wealth; or the creation of wealth. Capital can be generally defined as assets invested for profit.**.....**Click the link for more information.**Capacitance**is a measure of the amount of electric charge stored (or separated) for a given electric potential. The most common form of charge storage device is a two-plate capacitor.

**.....**Click the link for more information.

**capacitor**is an electrical/electronic device that can store energy in the electric field between a pair of conductors (called "plates"). The process of storing energy in the capacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity,

**.....**Click the link for more information.

**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. All applications of electronics involve the transmission of power and possibly information.

**.....**Click the link for more information.

This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.