Uniform Charge Density: Homework Solution

[sister007]

Homework Statement

ou've hung two very large sheets of plastic facing each other with distance d between them, as shown in the figure View Figure . By rubbing them with wool and silk, you've managed to give one sheet a uniform surface charge density eta_1= - \eta _{0} and the other a uniform surface charge density eta_2= + 3 \eta _{0} . What is the electric field strength at
POINT 1 (TO THE LEFT OF THE NEGATIVE PLATE)
POINT 2 (BETWEEN THE PLATES)
POINT 3 (TO THE RIGHT OF THE POSITIVE PLATE)

Specific distances are not given, all the the distances ("radius's") from the plates are the same.

Homework Equations

I was under the impression that only parrallel plate capacitors have uniform charge. So indeed all the charges will be different.
Would the point 1 be Net charge=o? Or would it be 1(nu)-3(nu)=-2nu?

The Attempt at a Solution

Im my book it says Efield of plane= N/(2xEpsilon) Using that info, I said point 2 is equal to 3/2 (n/E). I was wrong, SO obviously I don't know what I am doing. Help. :yuck:

 

[Mentz114]

There's no figure.

 

[Meir Achuz]

-1-(+3)=-4.