10. The electrons in a beam in a cathode ray tube are moving horizontally at 5.0x10^7 m/s and pass through a vertical magnetic field of 3.5x10^-3 T. What size force acts on each of the electrons in the beam?

11. An ion of oxygen having 2 elementary negative electric charges is moving at right angles to a uniform magnetic field for which B=0.30T. If its velocity is 2.0x10^7 m/s, what force is acting on the ion?

Please give m the answer with workings