Hydrogen line

Rarity: Uncommon

A topic a little better known than average, read and translated beyond its own country.

Rarity follows how well known the article is: its views on the French and English Wikipedia over a year, and the number of languages it exists in.

At a glance

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Notion

Domain

Science and technology

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What Wikipedia says

The hydrogen line, 21 centimeter line, or H I line is a spectral line that is created by a change in the energy state of solitary, electrically neutral hydrogen atoms. It is produced by a spin-flip transition, which means the direction of the electron's spin is reversed relative to the spin of the proton.

Excerpt from the Wikipedia article “Hydrogen line”, under the CC BY-SA 4.0 license. Read the article on Wikipedia

Image: Tiltec, Public domain, via Wikimedia Commons.