THE FRANCK-HERTZ EXPERIMENT


LIBRARY RESEARCH. Research the Franck-Hertz experiment. Identify what quantities you would want to measure and what variables there might be to control. Be prepared to explain what differences there would be between a neon Franck-Hertz tube and a mercury one and why.

(a) Franck-Hertz power supply, (b) Neon Franck-Hertz assembly, (c) Mercury Franck-Hertz assembly.
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NEON FRANCK-HERTZ TUBE:

WIRING: EXPERIMENT:
MERCURY FRANCK-HERTZ TUBE:

WIRING: Follow the steps below in order. It is much easier to wire the circuit correctly if you think of it in modular units rather than trying to do it all at once. Call your instructor over to look at each part of the circuit before you plug it in. BEFORE YOU BEGIN, make sure everything is turned off (except the oven) and that all knobs are turned all the way counterclockwise. EXPERIMENT.

ANALYSIS:
Use the voltage values to test whether the voltage peaks are evenly spaced in voltage, and what the spacing is. Compare to the spacing for neon.

Also, describe in your lab writeup what effect temperature has on the amount of current flowing in the tube at various voltages for the mercury tube. Explain what causes this effect. (Hint: think about what role the oven plays.)

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