# Total electric potential of systems of point charges

1. Feb 9, 2006

### Atomos

suppose there existed 3 point charges with known charges and separating distances. I know you can determine the total potential of the system by using one charge as a reference (give it a potential of 0J), calculate the potential of another charge with respect to that charge (x J), and then calculate the last charges with respect to both charges (y J), and then the potential would be given as 0 J + x J + y J.

This seems perfectly logical to me, but I cant quite wrap my mind around why calculating the potential with respect to the other two of each charge and then adding is wrong.

2. Feb 10, 2006

### Tom Mattson

Staff Emeritus
That does not give you the total potential energy. It just gives you the potential energy that the first charge sees. To get the total you have to repeat the process for the other two charges and add the results.

See the following web page:

http://teacher.nsrl.rochester.edu/phy122/Lecture_Notes/Chapter26/Chapter26.html