A proton is moving in a circular orbit in a uniform magnetic field perpendicular to the orbit plane. The speed of the proton is 1.2 x 107 m/s, and the strength of the magnetic field is 0.12 T.
Find
a) the magnetic force on the proton;
b) the radius of the circular orbit and the period of the circular motion. (The proton mass is 1.67 x 10^-27 kg).