Formula for Solid Angle Steradian?

The formula of the solid angle(Ω) is, Ω=Area of part of the spherical surface subtended divided by the radius of the area of the part of the spherical surface subtended. That is, Ω=Ar2. The area is 4πr2 ∴Ω=4πr2r2=4πsteradians.

How do you calculate steradian?

A steradian is defined as the solid angle which, having its vertex at the center of the sphere, cuts off an area equal to the square of its radius. The number of steradians in a beam is equal to the projected area divided by the square of the distance.

What is the formula of plane angle and solid angle?

The dimensionless unit of plane angle is the radian, with 2π radians in a full circle. A solid angle, ω, made up of all the lines from a closed curve meeting at a vertex, is defined by the surface area of a sphere subtended by the lines and by the radius of that sphere, as shown below.