A thin, horizontal 20cm×20cm copper plate is charged with 1.7×10^10 electrons. Consider the electrons are uniformly distributed on the surface.

A. What is the strength of the electric field 0.1 mm above the center of the top surface of the plate?
E=____ N/C
B. What is the strength of the electric field 0.1 mm below the center of the bottom surface of the plate?
E=____ N/C

Please provide answers. Thank you so very much