Equations · equation
Solid Angle
Vectors & Geometry · 1760
- Equation
- Ω = A/r² (a full sphere subtends 4π steradians)
- Field
- Vectors & Geometry
- Symbols
- Ω solid angle in steradians · A the area cut from a sphere of radius r centred on the vertex
- Year
- 1760
Significance
The radian's three-dimensional cousin: how much of the sky something fills, as the area it covers on a sphere over the radius squared. Gauss's law is the statement that a point charge's flux through any closed surface is the same 4π worth of solid angle; a telescope's field of view, a lamp's output in candela, and the fraction of a star's light a planet intercepts are all solid angles.
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