Physics Lab Equipment

LEAI-31 Apparatus of Franck-Hertz Experiment - Complete Model

LEAI-31 Apparatus of Franck-Hertz Experiment - Complete Model

Note: oscilloscope not included


  • No preheating for Argon gas tube

  • Multiple modes: manual data recording, oscilloscope viewing, or data processing (digital oscilloscope needed)

  • Compact, stable, reliable, and affordable


This LEAI-31 Franck-Hertz experiment apparatus can demonstrate the existence of Bohr atomic energy levels. Experimental results can be acquired by manual data recording, or viewed on an oscilloscope, or processed using a digital storage oscilloscope. It is an ideal teaching apparatus for physics laboratories at colleges and universities.


Using this instrument, the following experiments can be conducted:


1. Observe the relationship curve between plate current and accelerating voltage on an oscilloscope

2. Understand the process of electron-atom collision and energy exchange

3. Calculate the 1st excitation potential of Argon atom from experimental data

4. Using the acquired 1st excitation potential to calculate Planck’s constant


Curve peaks≥ 5
Franck-Hertz tubeArgon gas
Filament voltage VF1 ~ 5 VDC, continuously adjustable 3-1/2 digital display
Accelerating voltage VG2K0 ~ 90 VDC, continuously adjustable 3-1/2 digital display
Micro current measurementrange: 0.1 nA ~10 μA

Parts List

Main unit1 set (incl F-H tube, scanning voltage, current amplifier)
BNC cable2
Power cord1
Instruction manual1

      Franck-Hertz Experiment Apparatus.jpg

Schematic of Franck-Hertz experiment

    Franck-Hertz Experiment Apparatus.png

Experimental results acquired by PC from a digital oscilloscope

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