A square plate of edge length14.0cm and negligible thickness has a total charge of 7.10x 10-6 C.
(a) Estimate the magnitude E of the electric field just off the center of the plate (at, say, a distance of 0.50 mm from the center) by assuming that the charge is spread uniformly over the two faces of the plate.
(b) EstimateEat a distance of 30m (large relative to the plate size) by assuming that the plate is a point charge.