3*. An electron starts with an exit velocity v0 = 1.6 · 106 m/s and enters a uniform
electric field between the plates in the picture below. Assume that the field between the plates is uniform and that the electron enters the field just in between
the plates.

a) Determine the magnitude of the electric field if the electron just misses the top plate.
b) If the electrons had been replaced by a proton and the other input data are unchanged, had it then went to the wooden plates?
c) Is it reasonable to ignore gravity for the particles? Motivate.