# V=kq/d or W=qEd

1. Jun 16, 2009

### Procrastinate

I'm really confused about these two equations; are they the same or do they denote different things?

I know they are both to do with electric potential, but in what context do I employ them in? Our teacher told us to use one of them in a uniform field and another one of them in a non-uniform field but I don't remember which one is which.

The formula $V=k\frac{q}{d}$ gives the potential at a distance d. This formula is only valid for point charges. The formula $W=qEd$ is the work needed to move a charge q in an electrical field E a distance d. The general formula is W=qV, for a uniform electrical field V=Ed. Therefore you can only use W=qEd for a point charge in a uniform electrical field.