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**1. Homework Statement**

Using direct integration show that the electric field due to an infinite sheet with charge density σ is independent from the distance from the sheet and equals [itex]\frac{σ}{2\epsilon_{0}}[/itex]

**2. Homework Equations**

[itex]\int\int k \frac{Q}{r^{3}}dxdy[/itex]

Which should lead directly to the equation:

[itex]kQ\int\int\frac{z}{(x^{2}+y^{2}+z^{2})^{\frac{3}{2}}}dxdy[/itex]

**3. The Attempt at a Solution**

We had to do the same thing with a line of constant charge and he told us we could use that result in this problem, which is basically the first half of the problem and gives you the result [itex]E=\frac{\lambda}{2\pi\epsilon_{0}z}[/itex]

I don't know if my problem is with the surface integral or the physics but this is just baffling me. I can't get to the "middle" with what I start with and if I start with what he gave us, I can't get to the solution.

Edit: I got the answer the first time by getting rid of the double integral and thinking of it as an infinite number of concentric rings of charge and integrating that but he didn't want it that way. He wants it with the double integral.