Again, recall details of gravitational potential energy,
Likewise, for the electric potential energy,
That is, the change in electric PE as we go from A to B is the PE at B minus the PE at A. PEA and PEB are the electric PE's measured relative to some PE = 0 reference state.
Remember how we moved from the idea of electric force on a particular charge to the idea of an electric field at a point in space. Likewise, we will define the electric potential difference as the difference in PE as charge q moves from A to B divided by that charge q,
This means the electric potential difference has units of Joules per Coulomb; we define this as a volt,
1 V = 1 J / C
Batteries are good examples -- and good sources -- of an electric potential difference.
(c) Doug Davis, 2002; all rights reserved
Return to Ch 18, Electric Potential and Capacitors