# Electric Field Question

by BlueCardBird
Tags: electric field, electric field lines
 P: 25 For the equation ε=ΔV/r, does this work only between 2 parallel plates or would it work for point charges as well?
 P: 2,793
 P: 72 I love Electrostatics <3
P: 790

## Electric Field Question

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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