A flat square sheet of thin aluminum foil, 25 cm on a side, carries a uniformly distributed -36 nC charge. What is the approximate electric field at the following positions? a.)0.01m above surface? b.) 20m above the sheet? For a.), I used E=chargedensity/(2)epsilon. From my understanding, this can only be used for points far from the edges and close to a surface. So for b.), this formula does not apply. I cannot find anything in my notes or the text that describes this situation. Any suggestions?