1. The problem statement, all variables and given/known data http://img716.imageshack.us/img716/7692/picture8sj.png [Broken] 2. Relevant equations ΔEp=QV Ek=0.5mv2 3. The attempt at a solution I'm making sure I understand what's going on here. Please bare with me. ΔEp = Ek .5mv2 = Q(1200+V) Solving for V, I get -642V. In a nutshell, is this what is happening?: So electron passes the first plate, and accelerates do to the potential of 1200V. It then becomes near the -642V plate, and stops. Why does it stop because of the plates negative voltage?? Also, since electric field runs from Postive to negative, essentially the field goes form left to right? The answer by the way is A.