Question

what is one steradian

Answer 1

A steradian can be defined as the solid angle subtended at the center of a unit sphere by a unit area on its surface. For a general sphere of radius r, any portion of its surface with area A = r2 subtends one steradian at its center.

Answer 2

Answer:

Steradian or 1 steradian is the solid angle subtended by a part of the surface of a sphere at the centre of the sphere when the area of the part is equal to the square of the radius of the sphere.  

Explanation:

The area of a spherical surface subtends an angle at the centre of the sphere. This angle is called the solid angle.