E/M of the Electron

Clear Measurements in Classic Study of Electrons

The apparatus consists of a vacuum tube within which a fine electron beam is formed. The tube is surrounded by a pair of Helmholtz coils, providing a transverse magnetic field that bends the electron beam into a circular path. Helium gas at low pressure inside the tube fluoresces, making the beam visible, and the orbit diameter is measured on an internal glass scale with fluorescent scale marks. The mark is lit when struck by the beam, making it simple to determine the exact beam diameter. An included electron gun indirectly heats a cathode with an accelerating anode. Two panel meters monitor the power supplies. The accelerating voltages can be varied from 100 to 500 Vdc, so students can easily study a wide range of electron velocities. The Helmholtz coil current adjusts from 0 to 3A. Size: 11.75 x 15.75 x 15".