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Franck–Hertz Experiment

Authors: Ms. Giselle dos Santos Castro - Federal University of Ceara - UFC
Dr. Nildo Loiola Dias - Federal University of Ceara - UFC

CONTROLS:

- Click on one of the three chemical elements to perform the "experiment".
- The MAXIMUM VOLTAGE slider lets you choose the maximum voltage the source will apply between the tube electrodes.
- Click GRAPHIC to view the plot of electrical current versus applied potential as the potential grows to the chosen maximum potential.
- Click on EMPTY to restart.

DESCRIPTION OF THE SIMULATION:

This simulation features an evacuated tube containing mercury (or argon or neon). Inside the tube, electrons are released at the cathode and accelerated by the positive potential of an anode, or of an accelerator grid (located in an intermediate position inside the tube). The grid lets electrons pass towards a retarder plate (positioned to the right inside the tube) connected to a negative potential. Electrons that pass through the grid with enough energy to reach the plate generate an electrical current that is measured as a function of the potential between the anode and the grid. A graph of the electric current as a function of the electron acceleration potential is generated, allowing the determination of the excitation energy of the gas under study.

For an analysis of the data, consult one of the proposed ACTIVITY GUIDE.

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