1. The problem statement, all variables and given/known data A proton moves perpendicular to a magnetic field of .005 T. What is the period of the proton's circular orbit? 2. Relevant equations 1. T=2pi/v 2. FB=qv x B 3. The attempt at a solution I know I need to solve for velocity first so I can use the period equation, but I don't understand how I can do that without being given the force. If I knew the force, I could solve for v using equation 2 and then plug that value in to equation 1 to find the period.