A beam of electrons of mass me is deflected vertically by the uniform electric field between two oppositely charged, parallel metal plates. The plates are a distance d apart, and the potential difference between the plates is ΔV. 

(a) What is the direction of the electric field between the plates? 

(b) If the y-component of the electrons' velocity as they leave the region between the plates is vy, find an expression for the time it takes each electron to travel through the region between the plates in terms of ΔV, vy, me, d, and e. 

(c) Does the electric potential energy of an electron increase, decrease, or stay constant while it moves between the plates? Explain.