A Charged Particle of Mass 0

A charged particle of mass 0.0040 kg is subjected to a 4.0 T magnetic field that acts at a right angle to its motion.If the particle moves in a circle of radius 0.10 m at a speed of 2.0 m/s,what is the magnitude of the charge on the particle?

A) 0.020 C
B) 50 C
C) 0.00040 C
D) 2500 C