The Magnetic Field of the Earth at a Particular Location

Multiple Choice

The magnetic field of the Earth at a particular location is directed vertically downward with magnitude of 40.0 μT.An electron is moving horizontally toward the west in this field with a speed of 5.2 × 10⁶ m/s.What are the direction and magnitude of the magnetic force the field exerts on the electron? (e = 1.6 × 10^-19 C)

A) 3.33E-17,south
B) 3.33E-17,north
C) 2.08E-20,south
D) 2.08E-20,north