# Gaussian Surface for insulated plates have charge Separation

I was wondering the most suitable Gaussian Surface to choose that would allow me solve the electric field easily.

Given 2 insulating infinitely long plates that have charge separation. We need to find the Electric Field Intensity at points 1,2 and 3 respectively.

What would be the most suitable Gaussian Surface to choose for this problem?

The charge separation is of no use, think of it as four big plates and use the formula of infinite plate $$\frac{Q}{2a}\epsilon_0$$ and keep in mind the direction of the field exerted by the plates at the given point . If you want it to solve it by taking a Gaussian surface then take it as a cuboid passing through the plates.