A uniform electric field exists in the region between two oppositely charged plane parallel plates. A proton is released from rest at the surface of the positively charged plate and strikes the surface of the opposite plate, 1.60 cm distant from the first, in a time interval of 3.20 \times 10^{-6} s3.20×10
−6s. (a) Find the magnitude of the electric field. (b) Find the speed of the proton when it strikes the negatively charged plate.