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farad (F)




The derived unit of electrical capacitance in the SI system of units. One farad (F) is the capacitance of an electric capacitor between the two plates of which there appears a difference of electric potential of one volt when it is charged by a quantity of electricity equal to one coulomb (F = C/V). The unit is named after the British scientist Michael Faraday.

One farad is an exceptionally large capacitance: the entire Earth, considered as a spherical conductor of radius 4,000 miles, has a calculated capacitance of only 0.0007 farad. Capacitances that are actually encountered are expressed in microfarads or picofarads.


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   • ELECTRICITY AND MAGNETISM
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