A doubly charged helium atom (mass = 6.68 x 10-27 kg) is accelerated through a potential difference of 3.00x 103 V. What will be the radius of curvature of the path of the atom if it is in a uniform 0.410 T magnetic field? Part 2: What is the period of revolution for the atom in the previous question? Not sure what formula I should use for either of these questions. I was planning on using r=(mv)/(qB) but i don't have velocity. and the second part i've never seen anything similar to it before.