# Homework Help: Gauss's law; large sheet

1. Feb 8, 2009

### Seraph404

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

Two very large, nonconducting plastic sheets, each 10.0 cm thick, carry uniform charge densities $$\sigma$$1, $$\sigma$$2, $$\sigma$$3, & $$\sigma$$4 on their surfaces, as shown in the figure .

These surface charge densities have the values $$\sigma$$1= -6.00E-6 C/m^2, $$\sigma$$2= +5.00E-6 C/m^2,$$\sigma$$3= +2.00E-6 C/m^2, and $$\sigma$$4= +4.00E-6 C/m^2.

A) Use Gauss's law to find the magnitude of the electric field at the point A, 5.00 cm from the left face of the left-hand sheet.

2. Relevant equations

Gauss's Law

3. The attempt at a solution

Well, at first this confused me because I'm pretty sure I remember that in Gauss's law, electric field depends only on the enclosed charge. But this problem gives me a lot of distances. So I guess the formula

E = $$\sigma$$/(2*$$\epsilon$$0 )

doesn't work. That's what I tried, anyway, and got the wrong answer. So, how do I approach a problem like this?

2. Feb 8, 2009

### Seraph404

Okay, I changed the problem.

Last edited: Feb 8, 2009