1. The problem statement, all variables and given/known data What is the potential difference (in V) between xi = 18.5 cm and xf = 82.2 cm in the uniform electric field Ex = 4920 V/m? 2. Relevant equations Not sure? 3. The attempt at a solution Its simple but I am having problems figuring it out. I have a feeling it has to do with q1 and q2.