1. The problem statement, all variables and given/known data An electron with a speed of 5.0x10^6 m/s is injected into a parallel plate apparatus, in a vacuum, through a hole in the positive plate. The electron collides with the negative plate at 1.0x10^6 m/s. What is the potential difference between the plates? Vi= 5.0x10^6 Vf=1.0x10^6 Me= 9.11x10^-31 q=1.60x10^-19 2. Relevant equations Ke = 1/2 mv^2 Ee =q∆V W=∆E 3. The attempt at a solution I believe I should calculate the change in KE of the electron. Since masses are the same, I can cancel them out and only use velocities. (1.0*10^6)^2 - (5.0x10^6)^2 = -2.4x10^13 -2.4x10^13/(1.60x10^-19) = -1.5x10^32 That is obviously an incredibly high potential difference. The answer in the textbook is 68V. What's the proper ay to solve this?