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roentgen
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roentgen

unit of radiation
Also known as: R, roentgen unit
Written and fact-checked by
Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
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•History

roentgen, unit of X-radiation or gamma radiation, the amount that will produce, under normal conditions of pressure, temperature, and humidity, in 1 kg (2.2 lbs) of air, an amount of positive or negative ionization equal to 2.58 × 10−4 coulomb. It is named for the German physicist Wilhelm Conrad Röntgen. See also rem.

This article was most recently revised and updated by William L. Hosch.