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, the first electrical measurement to clearly demonstrate quantum mechanics, was presented to
The Franck–Hertz experiment, the first electrical measurement to clearly demonstrate quantum mechanics, was presented to the German Physical Society.
On April 24, in the year 1914, The Franck–Hertz experiment, the first electrical measurement to clearly demonstrate quantum mechanics, was presented to the German Physical Society. This event is recorded as a Selected Events event in the history of April 24, a notable event in this corner of history.
Key Facts
- This event took place on April 24, 1914 (AD era).
- It is categorised as a Selected Events event in recorded history.
- Referenced in 3 Wikipedia articles.
- Wikipedia source last updated on 25 March 2026.
On This Date in History
This article draws on content from Wikipedia, available under CC BY-SA 4.0.
More on April 24
A building in the Savar Upazila of Dhaka, Bangladesh, collapsed, killing 1,134 people, making it the deadliest accidenta
A building in the Savar Upazila of Dhaka, Bangladesh, collapsed, killing 1,134 people, making it the deadliest accidental structural failure in modern history.
Secret documents relating to detainees at the United States' Guantanamo Bay detention camp were released on WikiLeaks an
Secret documents relating to detainees at the United States' Guantanamo Bay detention camp were released on WikiLeaks and several independent news organizations.
A backhoe breached a pipeline in Toronto, Canada, which caused a gas explosion that killed seven people
A backhoe breached a pipeline in Toronto, Canada, which caused a gas explosion that killed seven people.
The Provisional Irish Republican Army detonated a truck bomb in London's financial district in Bishopsgate, killing one
The Provisional Irish Republican Army detonated a truck bomb in London's financial district in Bishopsgate, killing one person, injuring forty-four others, and causing damage that…
Gruinard Island in Scotland, the site of biological warfare testing by British scientists, was declared free of anthrax
Gruinard Island in Scotland, the site of biological warfare testing by British scientists, was declared free of anthrax after 48 years of quarantine.
The Hubble Space Telescope was launched aboard STS-31 by Space Shuttle Discovery
The Hubble Space Telescope was launched aboard STS-31 by Space Shuttle Discovery.
Comments 0
Sign in to join the discussion.