How Does Charge Placement Affect Electric Potential and Potential Energy?

[squissv]

This question is similar to the one that I posted previously:

Two point charges each of magnitude 2.09 micro Coulombs, are located on the x-axis. One is at x=1.38 m and the other is at x=-1.38 m.

a) Determine the electric potential on the y-axis at y=0.511 m.

b) Calculate the electric potential energy of a third charge, of -3.08 micro Coulombs, placed on the y-axis at y=0.511 m.

I used the same approach for this question as I did for the other question that I posted, i.e. using the summation of Coulomb's Law and various other creative yet ineffective approaches. Any help would be greatly appreciated. Thanks!

 

[dynamicsolo]

Once again, draw a diagram of where the three charges are. This time, you'll find that they are all on either the x- or y-axes and form right triangles. What are the distances of the two charges on the x-axis from the third one on the y-axis? (That is, what do you use to find out?)

It would also be a good idea when you ask for help on this Forum to show some work you attempted. It's hard to tell you why something you tried didn't work if we can't see it...