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 acquisition with software

  • Compact, stable, and reliable

  • Built-in data acquisition card for PC via USB


This LEAI-31 Franck-Hertz experiment apparatus can demonstrate the existence of Bohr atomic energy levels. Experimental results can be recorded by manual data taking, viewed on an oscilloscope, or acquired using a built-in data acquisition (DAQ) card for PC via USB port. No oscilloscope is necessary when using the built-in DAQ card with a PC. It is an ideal teaching apparatus for physics laboratories at colleges and universities.

The instruction manual contains comprehensive materials including experimental configurations, principles and step-by-step instructions. Please click Experiment Theory and Contents to find more information about this apparatus.


Using this instrument, the following experiments can be conducted:


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

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
USB cable1
Software CD1
Power cord1
Instructional manual1

Franck-Hertz Experiment Apparatus.png

Experimental data on oscilloscope

(Click graph to enlarge)


Experimental curve acquired by DAQ

(Click graph to enlarge)

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