Question

SI unit of solid angle​

Answer 1

• The SI derived unit of angle is the steradian
• which is defined as the solid angle for which the surface area equals the radius squared.

Answer 2

Answer:

Steradian

Steradian, unit of solid-angle measure in the International System of Units (SI), defined as the solid angle of a sphere subtended by a portion of the surface whose area is equal to the square of the sphere’s radius. Since the complete surface area of a sphere is 4π times the square of its radius, the total solid angle about a point is equal to 4π steradians. Derived from the Greek for solid and the English word radian, a steradian is, in effect, a solid radian; the radian is an SI unit of plane-angle measurement defined as the angle of a circle subtended by an arc equal in length to the circle’s radius.