Measures the ratio of charge to mass of the electron Internal computer control of voltage and current Unit construction with three power supplies in the base Large Helmholtz coils for uniform magnetic field

This classic experiment consists of a vacuum tube within which the electron beam is formed, mounting inside a pair of Helmholtz Coils providing a transverse magnetic field. The electron gun points downward and the electron beam is bent by the magnetic field into a circular path. The beam is made visible by placing a little helium gas at low pressure in the vacuum tube, which glows when struck by the electrons. The accelerating voltages from 100 to 500 Vdc can be used so that a fairly wide range of electron velocities can be investigated. The Helmholtz Coil current is adjusted to vary the bending force on the electron beam. The orbit diameter itself is measured on an internal glass scale with fluorescent scale marks. The mark glows when the beam strikes it, making it easy to determine the exact beam diameter. The accelerating voltage and coil current are set by two panel knobs. The power supplies are monitored by a pair of three-digit panel meters.

This famous experiment can be repeated by your students in this self-contained apparatus. The visible Helium fluorescent electron beam travels a full circle in the tube, the diameter of which is measured by an internal glass scale. This stability and the single unit design make this apparatus the one you have been waiting for to repeat this seminal experiment.