Voltage required to produce ions.... 1. The problem statement, all variables and given/known data Ions with a charge of +2e travel at a speed v=6.4x10^6 m/s perpendicular to a magnetic field with a strength of 5.4T. What is the voltage required to produce ions with that speed? 2. Relevant equations 1eV=1.6x10^-19 Joules 3. The attempt at a solution This is not all of the question -- the lesson deals mainly with direction changes and forces in magnetic fields. I answered everything related to the magnetic fields with relative ease, but this voltage problem is a curve ball. I was supplied with no prior info. on accelerating protons, but found the above relation between joules and electronVolts. I know the speed and the charge of the particles (3.2x10^-19), but I don't know how to calculate the Joules required to accelerate the protons.