Question

What is radius of curvature?

Answer 1

The radius of curvature is the radius of the hollow sphere of glass of which the spherical mirror is a part of.

R = 2f

Where R is radius of curvature and f the focal length of spherical mirror

Answer 2

radius of curvature is the radius of the imaginary sphere of which the mirror or lens is a part.

radius of curvature = 2(focal length)