Finding the electric field of following setup

[brainslush]

Homework Statement

Assume two perpendicular planes one with charge density \sigma and the other with a charge density 2\sigma. Find the electric field.

//|
//|
//|
//|
\sigma |
//|
_ |__________________
//|////// 2\sigma///////////////
//|

Homework Equations

The Attempt at a Solution

I got a question. Can I assume that the planes are infinitly long, specially close to the origin? In such a case, I could apply the Gaus-law.

 

[gneill]

Hi brainslush. By definition a plane is of infinite extent. If you know the result for the field due to an infinite plane of a given charge density, then you're (almost literally) halfway there!