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[ak-tuh-nom-i-ter] /ˌæk təˈnɒm ɪ tər/
a device for measuring intensity of radiation, especially that of the sun.
Compare actinograph.
1825-35; actino- + -meter
Related forms
[ak-tin-oh-me-trik, ak-tuh-noh-] /ækˌtɪn oʊˈmɛ trɪk, ˌæk tə noʊ-/ (Show IPA),
actinometrical, adjective
actinometry, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for actinometer
  • The actinometer should be used in an area free of shadows, and with a non-reflecting background.
British Dictionary definitions for actinometer


an instrument for measuring the intensity of radiation, esp of the sun's rays
Derived Forms
actinometric (ˌæktɪnəʊˈmɛtrɪk), actinometrical, adjective
actinometry, 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
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actinometer in Science
Any of several instruments used to measure radiation, such as a pyrheliometer.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for actinometer

in chemistry, a substance or a mixture of substances that reacts through the action of light and that, because of the easily determined quantitative relationship between the extent of the reaction and the energy of the absorbed light, is used as a standard for measurement of light energies involved in photochemical work

Learn more about actinometer with a free trial on
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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