A square insulating sheet whose sides have length L is held horizontally. The sheet has a charge of Q spread uniformly over its area. Part A

Calculate the electric field at a point located a distance r1 above the center of the sheet. Use the appropriate approximations based on the fact that r1 ? L.

Take the permittivity of free space to be ?0.

Part B

Estimate the electric field at a point located a distance r2 above the center of the sheet. Use the appropriate approximations based on the fact that r2 ? L.