# Electric Field Question

1. Dec 17, 2012

### BlueCardBird

For the equation ε=ΔV/r, does this work only between 2 parallel plates or would it work for point charges as well?

2. Dec 18, 2012

### CWatters

3. Dec 18, 2012

### Xidike

I love Electrostatics <3

4. Dec 18, 2012

### Khashishi

Do you know calculus? Your equation seems to be another way of writing $|E| = \Delta V/\Delta r$, which is only an approximation. The correct value is gotten by taking the limit as Delta goes to 0. Then you get:
$E=-\nabla V$
In the special case of infinite parallel plate, they give the same answer, but for a curved E field you get a more accurate answer for smaller step size.

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