Symbol Ω. The three-dimensional ‘angle’ formed by the vertex of a cone. When this vertex is the centre of a sphere of radius r and the base of the cone cuts out an area s on the surface of the sphere, the solid angle in steradians is defined as s/r2.
The 3-dimensional analogue of 2-dimensional angle. Just as an angle is bounded by two lines, a solid angle is bounded by the generators of a cone.
A solid angle is measured in steradians: this is defined to be the area of the intersection of the solid angle with a sphere of unit radius. Thus the ‘complete’ solid angle at a point measures 4π steradians, this being the surface area of the unit sphere. The steradian is the SI unit for measuring solid angle.
The shaded region subtends a solid angle at the origin
- z-modulation((of a cathode-ray tube))
- Zoantharia
- zodiac
- Zodiacal Catalogue
- zodiacal dust
- zodiacal light
- Zoeppritz’s equations
- Zog I (1895–1961)
- zoisite
- Zollverein
- zombie
- zombies
- zonal
- zonal flow
- zonal index
- zonal model
- zonal scheme
- zonal soil
- zonal winds
- zona pellucida
- zonation
- Zond
- zone
- zone axis
- zone catalogue