An electron moves in a circular path perpendicular to a constant magnetic field of magnitude 1.00 mT.

Question:

An electron moves in a circular path perpendicular to a constant magnetic field of magnitude 1.00 mT. The angular momentum of the electron about the center of the circle is 4.00 x 10-25 J s. Determine
(a) The radius of the circular path and
(b) The speed of the electron.