radiometer
Americannoun
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Also called Crookes radiometer. an instrument for demonstrating the transformation of radiant energy into mechanical work, consisting of an exhausted glass vessel containing vanes that revolve about an axis when exposed to light.
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an instrument for detecting and measuring small amounts of radiant energy.
noun
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A device used to detect or measure radiation. Radiometers generally consist of a glass bulb containing a rarefied gas in which four diamond-shaped paddles are mounted on a central axis. Each paddle is black on one side and silvery on the other. When radiation such as sunlight strikes them, the black side absorbs radiation and the silvery side reflects it, resulting in a temperature difference between the two sides and causing motion of gas molecules around the edges of the paddles. This motion of the surrounding gas molecules causes the paddles to spin. Precision radiometers, which use a complete vacuum rather than a gas, exploit the difference in radiation pressure on either side of the paddles to cause them to spin. Radiometers measure the intensity of radiation by measuring the rate of spin of the paddles.
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Also called light mill
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Origin of radiometer
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Upon closing, Masimo is expected to operate as a standalone company within Danaher’s Diagnostics segment, alongside its other businesses Radiometer, Leica Biosystems, Cepheid and Beckman Coulter Diagnostics.
From The Wall Street Journal • Apr. 21, 2026
After the deal closes, Masimo is expected to operate as a stand-alone company within Danaher’s Diagnostics segment, alongside other businesses Radiometer, Leica Biosystems, Cepheid and Beckman Coulter Diagnostics, the people familiar with the matter said.
From The Wall Street Journal • Feb. 17, 2026
Ditto for the Crookes Radiometer, which MoMA also just began selling.
From New York Times • Feb. 4, 2015
In addition to its ability to measure CO2, the satellite’s Advanced Along Track Scanning Radiometer was, Prata says, the world’s best instrument for measuring sea surface temperatures.
From Nature • Apr. 25, 2012
—The Radiometer 86 V. —Memoir of Thomas Graham 127 VI.
From Scientific Culture, and Other Essays Second Edition; with Additions by Cooke, Josiah Parsons
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
