3. The diagram below shows a pair of parallel plates 60 mm long and separated by 12 mm to which a power supply (not shown) is connected. An electron beam enters the region between the plates from the left as shown. 12 mm 60 mm a. Assuming that the electric field between the plates is uniform, find the magnitude of the force exerted on any electron by the field given that the potential difference between the plates is 48 V. b. If the speed of the electrons is 5 x10' m/s, find the electron's change of momentum in the y direction that results from passing between the plates. c. Suppose that the beam of electrons is replaced by a beam of negative hydrogen ions of the same speed (a hydrogen ion, H , has the same charge as an electron and a mass equal to 1836 electron masses). Which, if any, of your answers to (a) and (b) above would have to be changed? Why