Worksheet#9 1. ? A uniform magnetic field B, with magnitude 1.2 mT, is directed vertically upward throughout the volume of a labo- ratory chamber. A proton with kinetic energy 5.3 MeV enters the chamber, moving horizontally from south to north. What magnetic deflecting force acts on the proton as it enters the chamber? The proton mass is 1.67 10-27 kg. (Neglect Earth's magnetic field.)