Solving a problem in physics section 33 paragraph 39 el

39. Between the plates of a plane capacitor, located in the vacuum created by a uniform magnetic field of H = 2 kA / m. The electron moves to the capacitor in parallel to the capacitor plates and perpendicular to the direction of the magnetic field with a velocity υ = 2 mm / s. Determine the voltage U, applied to the capacitor, if the distance d between the plates it is 1.99 cm.