Solve the all parts of given question:
Question: A square insulating sheet 90.0cm on a side is held horizontally. The sheet has 6.15nC of charge spread uniformly over its area.
Part A: Calculate the electric field at a point 0.400mm above the center of the sheet.
Part B: Estimate the electric field at a point located a distance 135m above the center of the sheet.
I need help to solve the above question and would the answers to parts A and B be different if the sheet were made of a conducting material?