A uniform electric field exists in a region between two oppositely-charged plates. An electron is released from rest at the surface of the negatively-charged plate and strikes the surface of the opposite plate, d = 2 cm away, 20 ns later. a) What is the speed of the electron as it strikes the second plate? b) What is the magnitude of the electric field? c) If instead, a proton is released from rest at the positively charged plate, how long would it take to get to the opposite plate?