# Infinite sheet with a hole

1. Sep 28, 2011

### auk411

1. The problem statement, all variables and given/known data

If you have an infinite (non-conducting) sheet of uniform positive charge, except for a perfectly round hole in the middle, and you are trying to find the electric field above the circle, then is that the same as trying to find the electric field of the sheet with the circle filled in with negative charge (uniform) at the same spot?

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Sep 29, 2011

### Spinnor

I think you are close. Say we have an infinite sheet of charge. You can figure the electric field for that. Now add to that sheet of charge a disc of negative charge. I think you just need to add the superimposed fields. Do you know the electric field along the axis of symmetry of a disc of uniform charge? Add that to the field of the infinite sheet.

Corrections welcome %^)