The Farad (F)
The SI unit of electrical capacitance.
What is the Farad?
The Farad (symbol: F) is the SI derived unit of electrical capacitance, the ability of a body to store an electric charge. It is named after the English physicist Michael Faraday. One Farad is defined as the capacitance of a capacitor that has a charge of one Coulomb when a potential difference of one Volt is applied across it (1 F = 1 C/V).
Common Sub-units of Farad
Since the Farad is a very large unit, capacitance values are typically expressed in smaller sub-units:
| Unit | Symbol | Conversion to Farads |
|---|---|---|
| Millifarad | mF | 1 mF = 10-3 F |
| Microfarad | µF | 1 µF = 10-6 F |
| Nanofarad | nF | 1 nF = 10-9 F |
| Picofarad | pF | 1 pF = 10-12 F |
Relationship with Charge and Voltage
Where:
• Q = Charge in Coulombs (C)
• C = Capacitance in Farads (F)
• V = Voltage in Volts (V)
Frequently Asked Questions
Why are capacitors usually measured in microfarads or nanofarads?
A Farad is a very large unit of capacitance. Even a 1-Farad capacitor would be physically very large and expensive. Most capacitors used in electronic circuits have capacitance values in the microfarad, nanofarad, or picofarad range.
What is the difference between capacitance and capacitor?
Capacitance is the property of an electrical component (or circuit) to store electric charge. A capacitor is the actual electronic component designed to possess capacitance.