Capacitors

Made of two conductive plates separated by a dielectric layer.

In an ideal capacitor, the charge imbalance is proportional to the voltage across the plates.

The proportionality constant is the capacitance (), in terms of physical dimensions:

Here:

• : permittivity of the material in-between
• : distance between the plates
• : area of a plate

v and i

Current passing through the capacitor and the voltage across the capacitor are related by:

Energy stored

Suppose voltage across an initially uncharged capacitor rises from to during a time period of .