Hey, I need help to use the Gauss law in this problem: We have A planar slab of charge with a charge density ρv=ρvosin(2*pi/(2*a)),for -a<x<a the thickness of the stab is 2*a. the horizontal y axis passes through the middle of the stab. the x axis is vertical a) Find the electric field vector in the region -a<x<a. I know I need to use the Gauss law. But I have some problems to establish the integral. What surface should I take? I tried the cylinder as surface of integration. I got: FLUX=2(pi)x*L*Dx=Qenclosed Then I am stuck. The Qenclosed integration give me some problem. Please can someone help me to establish the Gauss law to solve the problem?