solid angle
Definition
- Noun:
- A three-dimensional analog of a plane angle, measured in steradians (sr). It is the angle that, seen from the center of a sphere, includes a given area on the sphere's surface. Formally, it is the angle formed by three or more planes intersecting at a common point (the vertex).
Usage
- The term solid angle is used in geometry, physics, and engineering to describe the amount of the field of view from a particular point that a given object covers. It is a measure of how large an object appears to an observer at that point.
Examples
- Noun:
- The total solid angle surrounding a point in three-dimensional space is 4π steradians.
- A detector's sensitivity depends on the solid angle it subtends at the source.
- Calculating the solid angle of a cone is a common problem in physics.
Advanced Usage
- "To subtend a solid angle": For an area on a sphere's surface, or an object, to form a specific solid angle at a given vertex point.
- The planet Jupiter subtends a very small solid angle when viewed from Earth.
Variants and Related Words
- Steradian (sr) (n): The SI derived unit of measurement for solid angles. One steradian is the solid angle subtended at the center of a sphere by an area on its surface equal to the square of the sphere's radius.
- Plane angle (n): The two-dimensional angle measured in radians or degrees, which is the conceptual counterpart to a solid angle.
Synonyms
- Three-dimensional angle: A descriptive synonym emphasizing its geometric nature.
Related Concepts
- Spatial angle: Another term sometimes used interchangeably with solid angle.
- Angular area: A less common descriptive term highlighting that it measures an area on a unit sphere.
Noun
-
an angle formed by three or more planes intersecting at a common point (the vertex)
