1. The problem statement, all variables and given/known data 2. Relevant equations DON'T KNOW 3. The attempt at a solution I can honestly say I've never been this confused by a question. At first my mind automatically went to a=qE/m since I have both charge and mass, but it became apparent that the equation was irrelevant because the velocity is constant. I thought it might be possible that I'm supposed to obtain the electric field by taking the integral of the electric potential, but I don't understand how I can get that using the information I have, and I have no sweet clue why the magnitude of the magnetic field is included.