1. The problem statement, all variables and given/known data The figure shows the path of a positive ion moving in the xy plane. There is a uniform magnetic field of 6000 gauss in the z direction. Each period of the ion's cycloidal motion is completed in 1 microsecond. What is the magnitude and the direction of the electric field that must be present? Hint: Think about a frame in which the electric field is zero. 2. Relevant equations 3. The attempt at a solution I'll appreciate any help. Thanks!