solid angle
Sign in to savemeasure of a subtended portion of a sphere, used to describe the apparent size of items in a three-dimensional field of view
Key facts
- Common symbols
- Ω
- Si unit
- steradian
- Other units
- Square degree , spat
- In si base units
- m /m
- Conserved
- No
- Derivations from other quantities
- Ω = A / r 2 {\displaystyle \Omega =A/r^{2}}
- Dimension
- 1 {\displaystyle 1}
via Wikipedia infobox
Article
In geometry, a solid angle (symbol: Ω) is a measure of the amount of the field of view from some particular point that a given object covers. That is, it is a measure of how large the object appears to an observer looking from that point. The point from which the object is viewed is called the apex of the solid angle, and the object is said to subtend its solid angle at that point.
In the International System of Units (SI), a solid angle is expressed in a dimensionless unit called a steradian (symbol: sr), which is equal to one square radian, sr = rad. One steradian corresponds to one unit of area (of any shape) on the unit sphere surrounding the apex, so an object that blocks all rays from the apex would cover a number of steradians equal to the total surface area of the unit sphere,