Cyclotron Frequency: a Charged Particle Is Moving with Speed V

Multiple Choice

Cyclotron frequency: A charged particle is moving with speed v perpendicular to a uniform magnetic field. A second identical charged particle is moving with speed 2v perpendicular to the same magnetic field. If the frequency of revolution of the first particle is f, the frequency of revolution of the second particle is

A) f.
B) 2f.
C) 4f.
D) f/2.
E) f/4.