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In this video, we dive into the details of how the Franck-Hertz experiment provided the first direct evidence of quantized energy levels in atoms, confirming key aspects of Niels Bohr's atomic model.

[Erratum]
04:50: cos(θ) inside the square root should be sin²θ; thanks to ‪@jmmahony‬ for catching this typo.

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[References]

∘ J. Franck and G. Hertz, Über Zusammenstöße zwischen Elektronen und Molekülen des Quecksilberdampfes und die Ionisierungsspannung desselben, Verh. Dtsch. Phys. 16: 457 (1914)
∘ N. Bohr, On the constitution of atoms and molecules, London Edinburgh Philos. Mag. & J. Sci. 26, 151: 1 (1913) https://archive.org/details/londonedi...


[Credits]

Heinrich Hertz, public domain
Heinrich Hertz discovering radio waves, public domain
Phillipp Lenard, public domain
Gustav Herz, public domain
James Franck, public domain
Stanford Linear Accelerator, by P. Kaminski, public domain
Electron-proton deep inelastic scattering, by Ddn2 under CC BY-SA 3.0
Tube for Franck-Hertz experiment, by 3B Scientific https://amzn.to/4fDM6OZ
Hans Geiger, public domain
Ernest Marsden, public domain
Ernest Rutherford, public domain
Arthur H. Compton, public domain
Ping-pong ball, by I. Joseph free use via Pexels https://www.pexels.com/photo/orange-p...
Bowling ball, by A. Shvets, free use via Pexels https://www.pexels.com/photo/close-up...
Franck Hertz experiment, by 老陳 under GNU Free Documentation License V1.2
Franck-Hertz experiment with neon gas, Infoczo/MikeRun as CC BY-SA 4.0
Subway station, by Sosa Films, free use via Pexels https://www.pexels.com/video/a-subway...
Fluorescent lights, by KoolShooters, free use via Pexels https://www.pexels.com/video/video-of...
Tanning lamp, by D. Brown, public domain
Tanning lamp filament, by D. Brown, public domain
Franck-Hertz experiment


CC BY-SA 3.0: https://creativecommons.org/licenses/...
CC BY-SA 4.0: https://creativecommons.org/licenses/...