The Franck–Hertz experiment was the first electrical measurement to clearly show the quantum nature of atoms. It was presented on 24 April 1914, to the German Physical Society in a paper by James Franck and Gustav Hertz. Franck and Hertz had designed a vacuum tube for studying energetic electrons that flew through a thin vapour of mercury atoms. They discovered that when an electron collided with a mercury atom, it could lose only a specific quantity of its kinetic energy before flying away. This energy loss corresponds to decelerating the electron from a speed of about 1.3 million metres per second to zero. A faster electron does not decelerate completely after a collision, but loses precisely the same amount of its kinetic energy. Slower electrons merely bounce off mercury atoms without losing any significant speed or kinetic energy.
The Franck–Hertz experiment, a pillar of quantum mechanics, is presented to the German Physical Society.
On April 24, in the year 1914, The Franck–Hertz experiment, a pillar of quantum mechanics, is presented to the German Physical Society. This event is recorded as a Historical Events event in the history of April 24, one of 380 recorded events on this date across all of history.
Key Facts
- This event took place on April 24, 1914 (AD era).
- It is categorised as a Historical Events event in recorded history.
- Referenced in 3 Wikipedia articles.
- Wikipedia source last updated on 25 March 2026.
On This Date in History 380
This article draws on content from Wikipedia, available under CC BY-SA 4.0.
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