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If A = r2 then solid angle Ω = 1 sr.


n. Abbr. sr
A unit of measure equal to the solid angle subtended at the center of a sphere by an area on the surface of the sphere that is equal to the radius squared. The total solid angle of a sphere is 4π steradians.

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Units) an SI unit of solid angle; the angle that, having its vertex in the centre of a sphere, cuts off an area of the surface of the sphere equal to the square of the length of the radius. Symbol: sr
[C19: from stereo- + radian]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.steradian - the unit of solid angle adopted under the Systeme International d'Unites
angular unit - a unit of measurement for angles
sphere - a three-dimensional closed surface such that every point on the surface is equidistant from the center
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
The independent variables are [??](x, y, z) (in centimeters), E (in megaelectronvolts), and [??]([theta], [phi]) (in steradians).
Objectives Non-uniform ring Non-uniform excitation excitation and non-uniform spacing Beamwidth 0.038 0.177 (Steradians) SLL (dB) -25.58 -18.36
where [[OMEGA].sub.b] is the beam size in steradians. The integrated flux density of a discrete source, in units of Janskys, maybe found by replacing [[OMEGA].sub.b] in (5) by [[OMEGA].sub.s], the source size in steradians.
Irradiance is directional; it includes UV radiation received over 2[pi] steradians; that is, half of the possible directions from which UV rays might originate is included.