# E-field due to a large circular plane of uniform distribution

1. May 19, 2007

### iontail

E-field due to a large circular plane of uniform distribution!!!

Hi Imagine i have a circular disc of radius R with uniform charge density, and a small charge x meters away from its center. The idea is to calculate the e field for this charged disc on the small charge. I can solve this problem if i solve the problem by integrating with respect to r. But i was told this can also be done by using solid angles. Would some one please help me?

2. May 19, 2007

### Mindscrape

Hmm, what do you mean by solid angles? If you know the potential, you can get to the E-field.

Integrating is really the way to do it, and whatever way works for you (apparently integration) is a good way.

3. May 20, 2007

### maverick280857

First of all, you mean the force on the charge (and not the field on the charge, which does not make sense). So you need to figure out the field at the location of the point charge and then multiply it by the magnitude of the charge to get the force.

Secondly, forget about the alternate method first and try to work out the field due to a circular disc of radius R at a point on the axis distant x units from the center. Can you do this?

(Do you have ideas for the solid angle method? If so, try it and post your solution here...)