# Homework Help: Uniformly Charged Slab

1. Mar 18, 2006

### ovoleg

Hey guys I was wondering if anyone could help me with this problem

A slab of insulating material has thickness 2d and is oriented so that its faces are parallel to the yz-plane and given by the planes x = d and x = -d. The y- and z dimensions of the slab are very large compared to d and may be treated as essentially infinite. The slab has a uniform positive charge density p(rho). Using Gauss's law, find the electric field between -d<x<d

This is what I did but the system states I am wrong.

pV=Qenclosed

EA=Qenclosed/epsilon

E(r^2)=(rho*r^2*2d)/epsilon

E=rho*2d/epsilon

Thanks anyone :)

2. Mar 18, 2006

### ovoleg

I also thought it might be zero since its inside the material but I am getting that as an incorrect answer as well

3. Mar 18, 2006

### ovoleg

This is how I trully feel about this problem: This slab is composed of insulating material, and insulating material does not permit easy movement of charge through them(can we assume that they don't move at all and are at rest?). Then, if all the charges are at rest, the field(E) at every point in the interior of the material is zero. With that, when -d < x < d wouldn't the field(E) be zero since for these x values we are talking about the interior of the slab?

4. Mar 18, 2006

5. Sep 5, 2011

### nakovanda

E=[|Rho|x]/Epsilon naught