Parallel Plate Capacitors

Consider the three infinite sheets of charge shown in the figure. The first sheet has chage density σ1 = +10μC/m2 and lies on the yz-plane. The second sheet has charge density of σ2 = +10μC/m2 and is parallel to the yz-plane at x = 0.10 m. The third sheet has charge density of σ3 = +10μC/m2 and is parallel to the yz-plane at x = 0.20 m. Determine the  electric field at the point P (0.05 m, 0).

The two infinite, conducting plates of thickness = h and separation = d are oppositely charged. The charge per unit area on the top plate is σ , and the charge on the bottom plate is σ , where σ is a positive number. What is the magnitude of the electric field in each region depicted in the picture? 

Four parallel infinite sheets of charge spaced by 4 cm between adjacent sheets are shown edgewise in the figure. Their charge densities are as indicated with σ = 2.0 μC/m2. What is the magnitude of the electric field at point P midway between two sheets as shown? (1) 4.5 × 105 N/C (2) 2.3 × 105 N/C (3) 1.13 × 105 N/C (4) 9.0 × 105 N/C (5) 0