An electron of charge e is moving to the right with velocity v0 when it enters the region between a pair of charged parallel plates, as shown in the figure. Assume that gravitational and edge effects are negligible and that the field between the plates is uniform and has magnitude E. After traveling the length L of the plates, the electron is displaced downward a distance Δy from a straight-line path. Which of the following correctly describes the change, if any, in the total energy of the electron-plates system?