An Electron Moving Perpendicular to a Uniform Magnetic Field of 0.22

Multiple Choice

An electron moving perpendicular to a uniform magnetic field of 0.22 T moves in a circle with a speed of 1.5 × 10⁷ m/s.What is the radius of the circle? (e = 1.60 × 10^-19 C,m_electron = 9.11 × 10^-31kg)

A) 1.5 mm
B) 0.22 mm
C) 2.2 mm
D) 0.39 mm
E) 3.9 mm