Physics
posted by Rex .
Singly charged positive ions are kept on a circular orbit in a cyclotron. The magnetic field inside the cyclotron is 0.947 T. The mass of the ions is 3.01×1026 kg, and speed of the ions is 3.45 percent of the speed of the light. What is the diameter of the orbit? (The speed of the light is 3.00×108 m/s. Neglect relativistic effects.)
How many times do the ions complete their orbit in 11.0 s?
Thanks!

consider forces
qvB=m v^2/r
solve for radius 
What do I use for q?

q=e=1.6x10^19 C