Franck-Hertz-Experiment:
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 with detailed experiment descriptions (see "Recommendation").
The Franck-Hertz experiment on mercury investigates the quantized energy output of free electrons in inelastic collisions with mercury atoms. The excitation energy of the mercury resonance line (61S0 – 63P1) is determined to be 4.9 eV.
Product specifications:
Tube:
The Franck-Hertz tube is a highly evacuated electron tube with mercury filling and plane-parallel electrode system consisting of indirectly heated oxide cathode with pinhole, reticulated anode and a collecting electrode. To obtain a high impact probability, the distance between cathode and anode is chosen to be large (8 mm) compared to the mean free path length in the Hg atmosphere (at approx. 180° C). In contrast, the distance between the anode and the collecting electrode is kept small.
Heating furnace:
In order to achieve the required mercury vapor pressure for a sufficient collision probability of the electrons with the mercury atoms, the electron tube must be heated in the furnace. The Franck-Hertz tube is positioned so that the entire tube, including the connecting wires, comes to a constant, homogeneous temperature. This is necessary because the vapor density of the mercury always follows the coldest part of the tube. The electric heating furnace with continuous temperature control is equipped with a digital temperature display of set and actual temperature. Temperature measurement and control is performed by an integrated microcontroller and Pt100 sensor.
Housing:
The tube and heater are housed in a painted metal enclosure with two viewing windows. The housing is provided with an opening with clamp spring holder for thermometer and a thermally insulated carrying handle.
Technical specifications:
The Franck-Hertz experiment on mercury investigates the quantized energy output of free electrons in inelastic collisions with mercury atoms. The excitation energy of the mercury resonance line (61S0 – 63P1) is determined to be 4.9 eV.
Product specifications:
Tube:
The Franck-Hertz tube is a highly evacuated electron tube with mercury filling and plane-parallel electrode system consisting of indirectly heated oxide cathode with pinhole, reticulated anode and a collecting electrode. To obtain a high impact probability, the distance between cathode and anode is chosen to be large (8 mm) compared to the mean free path length in the Hg atmosphere (at approx. 180° C). In contrast, the distance between the anode and the collecting electrode is kept small.
Heating furnace:
In order to achieve the required mercury vapor pressure for a sufficient collision probability of the electrons with the mercury atoms, the electron tube must be heated in the furnace. The Franck-Hertz tube is positioned so that the entire tube, including the connecting wires, comes to a constant, homogeneous temperature. This is necessary because the vapor density of the mercury always follows the coldest part of the tube. The electric heating furnace with continuous temperature control is equipped with a digital temperature display of set and actual temperature. Temperature measurement and control is performed by an integrated microcontroller and Pt100 sensor.
Housing:
The tube and heater are housed in a painted metal enclosure with two viewing windows. The housing is provided with an opening with clamp spring holder for thermometer and a thermally insulated carrying handle.
Technical specifications:
| Franck-Hertz-Tube | |
| Heating: | 4 to 9 V AC/DC |
| Grid voltage: | 0 to 80 V |
| Counter voltage: | approx. 1,5 V |
| Operating temperature: | approx. 160°C - 200°C |
| Dimensions: | approx.. 130 mm x 26 mm Ø |
| Mass: | approx. 380 g |
| Heater / Housing | |
| Mains supply voltage: | 230 V (50/60 Hz) |
| Opening of the front side: | ca. 230 mm x 160 mm |
| Heating power: | 400 W |
| Maximum temperature: | 300°C |
| Temperature constancy: | approx. ±1°C |
| Dimensions: | approx. 335 mm x 180 mm x 165 mm |
| Mass: | approx. 5,6 kg |
Recommendation:
3B Scientific offers on the topic "Detection of Discrete Energy States in Atoms" three complete experiments compiled for school and university education with detailed experiment description:
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