Farad

Definition

A farad (F) is the SI unit of capacitance, defined as one coulomb of electric charge stored per one volt of potential difference. It quantifies a capacitor's ability to store electrical energy.

5 Must Know Facts For Your Next Test

1. One farad is a large unit; practical capacitors usually have values in microfarads ($\mu F$), nanofarads (nF), or picofarads (pF).
2. Capacitance (C) in farads can be calculated using the formula $C = \frac{Q}{V}$, where Q is the charge in coulombs and V is the voltage in volts.
3. The capacitance value depends on the surface area of the plates, the distance between them, and the dielectric material used.
4. In series circuits, total capacitance decreases: $\frac{1}{C_{total}} = \frac{1}{C_1} + \frac{1}{C_2} + ...$
5. In parallel circuits, total capacitance increases: $C_{total} = C_1 + C_2 + ...$

Review Questions

• What is the definition of one farad?
• How would you calculate capacitance using charge and voltage?
• Explain how total capacitance changes in series and parallel circuits.

Related terms

Capacitor: A device that stores electrical energy in an electric field, consisting of two conductive plates separated by an insulating material.

Dielectric: An insulating material placed between the plates of a capacitor that increases its capacitance by reducing the electric field.

Electric Field: $E$, a vector field representing the force per unit charge exerted on a positive test charge at any point in space.