Capacitors

Summary

A capacitor is …
- a device for storing separated electric charges.
- a pair of oppositely charged conductors (called plates even if they aren't flat) separated by an insulator (called a dielectric).
The capacitance (C) of an electrostatic system is, by definition, the ratio of the quantity of charge separated (Q) to the potential difference applied (V).

C = Q

V
The SI unit of capacitance is the farad [F], which is equivalent to the coulomb per volt [C/V].
- One farad is generally considered a large capacitance.

The energy stored in a capacitor can be calculated using one of the following equations …

The capacitance of a cylindrical capacitor is given by

where

The capacitance of a spherical capacitor is given by

where