P6.2.4.3 Franck-Hertz Experiment with Neon - Recording with the Oscilloscope

The Franck-Hertz experiment with neon is offered in two variations, experiments P6.2.4.3 and P6.2.4.4, which differ only in the means of recording and evaluating the measurement data. In both variations, the neon atoms are enclosed in a glass tube with four electrodes: the cathode K, the grid-type control electrode G₁, the acceleration grid G₂ and the target electrode A. Like the Franck-Hertz experiment with mercury, the acceleration voltage U is continuously increased and the current I of the electrons which are able to overcome the opposing voltage between G₂ and A and reach the target is measured. The target current is always lowest when the kinetic energy directly in front of grid G₂is just sufficient for collision excitation of the neon atoms, and increases again with the acceleration voltage. We can observe clearly separated luminous red layers between grids G₁ and G₂; their number increases with the voltage. These are zones of high excitation density, in which the excited atoms emit light in the visible spectrum.

Components of Experiment:

1	555 870	Ne Franck-Hertz tube
1	555 871	Holder with socket and screen
1	555 872	Connecting cable for Ne Franck-Hertz tube
1	555 880	Franck-Hertz supply unit
1	575 304	Digital storage oscilloscope 70 MHz two-channel
2	575 24	Screened cable, BNC/4 mm

Experiment Instructions Click Here