[ rey-dee-om-i-ter ]
See synonyms for radiometer on
  1. 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.

  2. an instrument for detecting and measuring small amounts of radiant energy.

Origin of radiometer

First recorded in 1870–75; radio- + -meter

Other words from radiometer

  • ra·di·o·met·ric [rey-dee-oh-me-trik], /ˌreɪ di oʊˈmɛ trɪk/, adjective
  • ra·di·om·e·try, noun

Words Nearby radiometer Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use radiometer in a sentence

British Dictionary definitions for radiometer


/ (ˌreɪdɪˈɒmɪtə) /

  1. any instrument for the detection or measurement of radiant energy

Derived forms of radiometer

  • radiometric (ˌreɪdɪəʊˈmɛtrɪk), adjective
  • radiometry, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for radiometer


[ rā′dē-ŏmĭ-tər ]

  1. 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. Also called light mill

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.