A proton, initially at rest, is accelerated from plate A to plate B, and aquires 1.92 * 10-17 J of kinetic energy. i. Which plate is positive and which is negative? ii. What is the potential difference? iii. Sketch the correct direction of E between the plates. Does the proton move with or against the field E? Does this agree with the gain (or loss) calculated in ii?? Explain? My Solution: i. Plate A is positive Plate B is negative ii. q * delta V = 1.92 * 10-17 J Delta V = -1.92 * 10-17 / 1.602 * 10-19 C = -1.1985 * 10^2 V The potential difference is -1.1985 * 10^2 V This is a loss in potential iii. The proton moves with the field and this agrees with my previous calculation as an electron moving with a field is like a mass falling downward within Earth's gravitational fieldd. There is no need for an external force so there we witness a loss of potential. Does this make sense to everyone?