A square metal plate of edge length 12 cm and negligible thickness has a total charge of 5.6 × 10-6 C. (a) Estimate the magnitude E of the electric field just off the center of the plate (at, say, a distance of 0.49 mm from the center) by assuming that the charge is spread uniformly over the two faces of the plate. (b) Estimate E at a distance of 29 m (large relative to the plate size) by assuming that the plate is a charged particle.