physics
posted by abhi .
what is steradian?

A steradian is a measure of solid angle.
Imagine that you are at the center of a hollow sphere of radius R. Now consider an area A of that sphere. Divide that area by R^2 and you have the solid angle subtended by A, in steradians.
A full sphere subtends a solid angle of 4 pi steradians, from a point inside 
A steradian is a measure of solid angle.
Imagine that you are at the center of a hollow sphere of radius R. Now consider an area A of that sphere. Divide that area by R^2 and you have the solid angle subtended by A, in steradians.
A full sphere subtends a solid angle of 4 pi steradians, from a point inside 
Do I detect an echo?