What does farad mean?
The farad is the standard international (SI) unit of electrical capacitance, the property that determines how much electric charge a capacitor can store per volt applied across its plates. Formally, a capacitor has a capacitance of one farad if one coulomb of charge raises its potential difference by one volt. The unit honours Michael Faraday, the pioneering nineteenth-century English scientist whose experiments in electricity and electromagnetism laid much of the groundwork for modern technology. Because one farad describes an enormous capacity to hold charge, everyday electronic components are typically specified in microfarads, nanofarads, or picofarads, while large 'supercapacitors' capable of reaching full-farad values are used in applications from backup power to energy recovery systems. The word appears mainly in technical writing, data sheets, and physics education rather than general conversation.
nounThe SI derived unit of electrical capacitance, equal to the capacitance of a capacitor that holds one coulomb of charge at a potential difference of one volt.
- The SI unit of electrical capacitance, defined as one coulomb per volt.
"A supercapacitor rated at one farad can store far more charge than a typical ceramic capacitor measured in microfarads."
"The smoothing capacitors in the power supply are rated at several thousand microfarads each."
"Because one farad represents an enormous capacitance, most practical circuits use components in the picofarad to millifarad range."
Regular plural; used when stating capacitance values greater than one farad.
"These ultracapacitors offer several farads of capacitance in a small package."
Named after Michael Faraday — a bookbinder's apprentice with almost no formal schooling who became the greatest experimental physicist of his age.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of farad
The farad was adopted as a unit of electrical capacitance in the late nineteenth century and was named after the English scientist Michael Faraday (1791–1867), whose work on electricity and electrochemistry was foundational to the field. It was incorporated into the International System of Units as the SI derived unit of capacitance, defined in terms of coulombs and volts. A closely related term honouring the same scientist, the faraday, denotes a unit of electric charge and shares this common eponymous origin.
How farad is actually used
A technical term used almost exclusively in physics, electronics, and engineering contexts. In practice, the farad is so large that real-world capacitances are usually expressed in subunits such as the microfarad (µF), nanofarad (nF), or picofarad (pF).
Easily confused with farad
A farad measures capacitance, while the faraday (named for the same scientist) is a non-SI unit of electric charge equal to the charge on one mole of electrons.