An electron moves in a circle of radius R in a uniform magnetic field B. The field

Question:

An electron moves in a circle of radius R in a uniform magnetic field B. The field is into the page.

(a) Does the electron move clockwise or counterclockwise?
(b) How much time does the electron take to make one complete revolution? Derive an expression for the time, starting with the magnetic force on the electron. Your answer may include R, B, and any fundamental constants.