1. The problem statement, all variables and given/known data Three parallel, infinite, insulating planes (sheets) of charge are arranged as shown (see attached image). Note carefully the charge desnitties and distances given. From left to right the charge densities are -3σ, +σ, +σ. How does the magnitude of the electric field at point a compare to the magnitude of the field at point b? 2. Relevant equations E = σ/2ε0 3. The attempt at a solution From what I recall from my lecture, the E field of an infinite sheet of charge does not depend on distance. Second, I believe that the field lines look something like what I've drawn in the second attached image. For that reason, I argued the magnitude of A was larger than B as the charge density of the sheet is larger.