Electron Motion in a Uniform Magnetic Field

The apparatus has a 13 cm diameter helium filled electron tube. This tube is mounted at the center of two 30 cm diameter, 130 turns Helmholtz coils placed about 15 cm apart. The Helmholtz coils provide a highly uniform magnetic field. A beam of electrons is accelerated through the perpendicular magnetic field being deflected to a circular path (initially it is a straight horizontal beam to the side). It is a brightly green colored glowing beam, set against a black background.