Circular Motion of Charges: an Alpha Particle Is Moving at a Speed

Essay

Circular motion of charges: An alpha particle is moving at a speed of 5.0 × 10⁵ m/s in a direction perpendicular to a uniform magnetic field of strength 0.040 T. The charge on an alpha particle is 3.2 × 10^-19 C and its mass is 6.6 × 10^-27 kg.
(a) What is the radius of the path of the alpha particle?
(b) How long does it take the alpha particle to make one complete revolution around its path?