A prototype for a capacitor is a parallel-plate capacitor. We can establish a potential difference across the two plates by connecting them to a battery.

The idea or purpose of a capacitor is to store charge so we define

Capacitance is measured in units of farads, in honor of Michael Faraday,

F = C / V

one farad is one coulomb per volt

You already know that one coulomb is a great deal of charge. That means one farad is a very large capacitance. Therefore, many of the capacitors we encounter will have capacitances that are measured in microfarads,

1 F = 10 - 6 F

Multiple Charges


Return to Ch 18, Electric Potential and Capacitors
(c) Doug Davis, 2002; all rights reserved