Experiment set THOMSON Experiment


Ratio of charge to mass of the electron e/m

The compact setup of the THOMSON-Experiment equipment includes the heatable filament, plate capacitors, coil, and tube. This allows for the understanding of the emission of electrons from the heated tungsten wire and the basic principle of the electron beam tube, as well as the behavior of the electron beam in electric and magnetic fields. This arrangement, only slightly modified here, enabled Joseph John Thomson, the later Nobel laureate, to determine the ratio of charge to mass of the electron in 1897. The power supply can be provided by the supplied 12 VAC plug-in power supply or a student low-voltage power supply.

Equipment characteristics:

  • Compact device with visible heating filament, Braun tube, and touchscreen display
  • Clear presentation in a real experiment and very precise measurements
  • Clear control panel with rotary switches for varying the individual parameters
  • Touch-proof shielding of the tube and electronic protection of the high voltage.

73.01.00 Base unit including hood

57.02.00 Plug-in power supply 12 VAC


Topics (for high school and university)

  • Thomson experiment
  • Motion of charge carriers/electrons in a homogeneous E- and B-field
  • Determination of specific charge