Farad
A farad is the standard unit of capacitance. It is defined as the capacitance required to create one coulomb of static charge for every volt of potential difference. Another definition is the capacitance that would change it's potential difference by one volt if one ampere of current flowed for one second.
History of the Farad
The farad was formally defined at an international conference in 1881, and is named after Michael Faraday (1791-1867), a British physicist. The symbol is F, and is always written in uppercase. The farad is sometimes confused with the faraday, an old unit of charge that has been replaced by coulomb.
Measuring Farads
Farads are measured with a capacitance meter or multimeter. A proper capacitance meter is required to measure capacitor leakage, inductance, and equivalent series resistance.
Microfarad, Nanofarad, and Picofarad
The farad is a large value compared to other standard units. Typical values are usually a fraction of a farad. The microfarad is one millionth of a farad, the nanofarad is one thousandth of a microfarad, and a picofarad is one millionth of a microfarad. Large industrial capacitors can store many thousands of farads, while picofarad capacitors are the smallest available.
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