critical angle

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noun

Optics. the minimum angle of incidence beyond which total internal reflection occurs for light traveling from a medium of higher to one of lower index of refraction; the angle of incidence for which refracted rays emerge tangent to the surface separating two media, the light traveling from the medium of higher to the medium of lower index of refraction.

Also called angle of stall, critical angle of attack, stalling angle. Aeronautics. the angle of attack, greater than or equal to the angle of attack for maximum lift, at which there is a sudden change in the airflow around an airfoil with a subsequent decrease in lift and increase in drag.

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Origin of critical angle

First recorded in 1870–75

Words nearby critical angle

criteria, criterion, criterium, critic, critical, critical angle, critical apparatus, critical condition, critical constant, critical constants, critical damping

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use critical angle in a sentence

The heavy line indicates what is commonly known as the critical angle.
Motion Picture Operation, Stage Electrics and Illusions|Henry C. Horstmann
The question is, is the critical angle really as high as Mr. Seller's experiments would show.
The Theory and Practice of Model Aeroplaning|V. E. Johnson
When this condition is reached, the angle of incidence is called the critical angle.
Physics|Willis Eugene Tower
For diamond this critical angle, as it is called, is very nearly 24° from a perpendicular to the surface.
A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public|Frank Bertram Wade

Glass is made in many varieties, each with a special critical angle, never much different from that of water.
Inventors at Work|George Iles

British Dictionary definitions for critical angle

critical angle

noun

the smallest possible angle of incidence for which light rays are totally reflected at an interface between substances of different refractive index

another name for stalling angle

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 critical angle

critical angle

[ krĭt′ĭ-kəl ]

The smallest angle of incidence at which radiation, such as light, is completely reflected from the boundary between two media. At angles smaller than the critical angle, some of the radiation enters the second material and is refracted.