More on Charge Density / E fields
Two non-conducting infinite sheets with surface charge densities s1=+3 mC/m2 and s2 = +5 mC/m2 and an uncharged conducting slab
1. Use SUPERPOSITION of Electric Fields.
On Far Left: E = 1/2e0 (-s1 - s2 - sL - sR )
At X: E = 1/2e0 (+s1 - s2 - sL - sR )
In Red: E = 1/2e0 (s1 - s2 + sL - sR ) = 0
On Far Right: E = 1/2e0 (s1 + s2 + sL + sR )
2. Uncharged : sL + sR = 0;
Get sL = (s2 - s1)/2 = 1 mC/m2