Physics Lab Equipment

LEAI-33 Apparatus of Franck-Hertz Experiment - Mercury (Hg)

LEAI-33 Apparatus of Franck-Hertz Experiment - Mercury (Hg)


  • Micro-current measurement accuracy ± 1%

  • Multiple modes: manual data recording, direct observation on screen, data export to PC

  • More than 10 peaks for 1st excitation potential measurement

  • Can measure higher-level excitation potentials of mercury atoms

  • Parameters setting, adjustment and display on a touch screen


The LEAI-33 Franck-Hertz experiment apparatus can demonstrate the existence of Bohr atomic energy levels of mercury atoms. Experimental results can be recorded by manual data taking, viewed on an built-in screen, or exported to a PC for analysis. The most prominent feature is that in addition to measuring the first excitation potential, it can also measure higher-level excitation potentials of mercury atoms. 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. Understand the processes of electron-atom collision and energy exchange

2. Calculate the 1st excitation potential of Mercury atom from experimental data

3. Study the influence of temperature and voltages on F-H curve 

4. Measure high-level excitation potential of mercury atoms


F-H curve peaks (1st potential)≥ 10
Franck-Hertz tubeMercury filled, diameter 18 mm, height 50 mm
Filament voltage VF0 ~6. 5 V, adjustable
1st grid voltage VG1K0 ~ 12 V, adjustable
Accelerating voltage VG2K0 ~ 99 V, adjustable
Retarding voltage VG2P0 ~ 15 V, adjustable
Micro current measurement0.001 nA - 1.999 μA, accuracy +/- 1%
Display7-inch LCD screen, resolution 1024 × 600
Furnacewith temperature controller  
Working modesautomatic scan, manual recording data, exporting to PC

Parts List

Main electric unit1 unit (incl display screen, voltage sources, current amplifier)
Temperature controller1
A set of cables1
Software CD1 (manual and data export software)
Power cord1


F-H curve of 1st excitation potential on screen


F-H curve of high level excitation potential on screen


Parameters display, setting and adjustment on screen

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