# Show that the potential at a generic point for x positive is zero

1. Jul 24, 2011

### blueyellow

1. The problem statement, all variables and given/known data

Show that in this set-up, the potential at a generic point (-x, 0, 0) (for x positive) is zero:

two point charges placed at (-a, 0, +a) and (-a, 0, -a)
the mirror charges are (a, 0, +a) and (a, 0, -a)

3. The attempt at a solution

V=(q/(4 pi epsilon0)) ((1/(sqrt((x^2 -a^2)+a^2))+(1/(sqrt((x^2 -a^2)+a^2)))

this does not equal zero

by the way, please DO NOT DELETE THIS POST, MODS, I ASSURE YOU I HAVE NOT POSTED THE SAME QUESTION. IT IS A TOTALLY DIFFERENT PART OF A QUESTION I POSTED EARLIER.

2. Jul 24, 2011

### Mike Pemulis

Yeah, you're right, the voltage is not zero. That's weird. Are you sure the charges are supposed to be the same? Opposite charges at those locations would give V = 0.

3. Jul 24, 2011

### blueyellow

thanks, sorry, i wasn't paying attention to the part of the question that said 'two point charges +q and -q'