• Principal component Franck-Hertz experiment for neon: ..
• The quantization of energy, as well as the generation, registration, and analysis of spectra and the associated experimental confirmation of models, are important components of most curricula around the world. The well-known 1913 experiment by James Franck and Gustav Hertz is fundamental to the detection of discrete energy states in atoms. Because of the importance of these findings into modern physics, 3B Scientific offers three complete experiments compiled for school and university education (see " Recommendation" ).
• Specifications: ..
• Filament voltage: 4 − 12 V
• Control voltage: 9 V
• Accelerating voltage: max. 80 V
• Counter voltage: 1.2 − 10 V
• Tube: 130 mm x 26 mm Ø approx.
• Base with connector sockets: 190 mm x 115 mm x 115 mm approx.
• Weight:  450 g approx.

Product Information: ..
The Franck-Hertz tube is a tetrode with an indirectly heated barium oxide cathode K, a meshtype control grid G, a mesh-type anode A, and a collector electrode E. The electrodes are in a plane-parallel configuration. The distance between the control grid and the anode grid is about 5 mm, and the distances between the cathode and the control grid and between the anode and the collector electrode are both about 2 mm. The tube is supplied already filled with neon gas at a pressure chosen to give an optimum characteristic curve, which is in the region of several hPa.

The connecting sockets for the heater, control grid and anode grid voltages are on the base of the instrument. The collector current is taken off through the BNC socket at the top end of the screening cylinder. An internal 10 kΩ limiting resistor is permanently built in between the connector sockets for the accelerator (control grid) voltage and the anode voltage. This protects the tube in case there is a spark discharge caused by applying too high a voltage. The voltage loss in this resistor when making measurements is negligible, as the anode current in the tube is smaller than 5 pA. (Thus the voltage loss in the protecting resistor is 0.05 V.)