Focal length

Rarity: Rare

A topic known well beyond its field, found in many languages.

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 focal length of an optical system is a measure of how strongly the system converges or diverges light; it has units of length, and for an idealized thin lens is equal to the distance between the lens and its focal points.

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

Image: Henrik, CC BY-SA 3.0, via Wikimedia Commons.