A farad is the charge in coulombs which a capacitor will accept for the potential across it to change 1 volt. A coulomb is 1 ampere second. Example: A 47 mA current causes the voltage across a capacitor to increase by 1 volt per second. It therefore has a capacitance of 47 mF. It has the base SI representation of s4·A2·m−2·kg−1. Further equalities follow:

The unit of capacitance in the meter-kilogram-second system equal to the capacitance of a capacitor having an equal and opposite charge of 1 coulomb on each plate and a potential difference of 1 volt between the plates. See Table at measurement.

The Farad was coined by Josiah Latimer Clark in the year of 1861, in honor of Michael Faraday, but it was for a unit of quantity of charge. Values of capacitors are usually specified in ranges of farads (F), microfarads (μF or MFD, one millionth or 10^-6 of a farad), nanofarads (nF, 10^-9 farad), or picofarads (pF, 10^-12 farad). The size of commercially available capacitors ranges from around 100 fF (femtofarads, 10^-15) to 5 kF (kilofarads, 10^3) ultracapacitors.

A capacitor's storage potential, or capacitance, is measured in units called farads. A 1-farad capacitor can store one coulomb (coo-lomb) of charge at 1 volt. A coulomb is 6.25e18 (6.25 * 10^18, or 6.25 billion billion) electrons. One amp represents a rate of electron flow of 1 coulomb of electrons per second, so a 1-farad capacitor can hold 1 amp-second of electrons at 1 volt.

A 1-farad capacitor would typically be pretty big. It might be as big as a can of tuna or a 1-liter soda bottle, depending on the voltage it can handle. For this reason, capacitors are typically measured in microfarads (millionths of a farad).

The unit of capacitance in the obsolete electrostatic system of units.ttle='statfarad';xiunt='farad';yiunt='statfarad';mconv=1.113e-12;cconv=0.0; See also: Farad, Stat-.

- Definition of the faraday. A unit of electric charge, symbol, F. This entry also treats the Faraday constant, symbol F

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