Given a point charge of 500pC at the origin, find the potential difference between points a and b at distances 5m and 15m respectively along the x-axis.
Coulomb's law, I think?
The Attempt at a Solution
The reason I thought coulombs law was relevant was because it was mentioned in the first part of the equation. I tried to apply Coulomb's law, but got nowhere, as I don't have a charge for a and b, and also, I think that would ignore the charge at the origin, so it was probably the wrong way to go about it. To be honest, it just doesn't seem to me like there is enough information given to do anything with it, really.
All help gratefully received.