Steradian (Noun)
Meaning
The unit of solid angle adopted under the Systeme International d'Unites.
Classification
Nouns denoting quantities and units of measure.
Examples
- The sphere is the set of all points that are unit distance from the origin, and this solid angle has a measure of exactly four pi steradians.
- This quantity is the number of steradians in a sphere and it is commonly used to express the solid angle of a set of directions from a fixed point.
- Since the surface area of the sphere is spread over four pi steradians, then the radiant energy per steradian is equal to the radiant intensity.
- A conical surface with a vertex angle of ninety-six degrees has a solid angle of about two steradians.
- Radiometry uses as the base unit quantity of a photon one steradian for a source of radiation.