Question

What is the relationship between focal length $\left(f\right)$ and radius of curvature $\left(R\right)$?

Answer 1

Focal length $\left(f\right)$ is the distance from mirror at which the light rays coming parallel from infinity meet.

Radius of Curvature $R$ is the radius of the sphere of which the mirror is a part.

Focal length and radius of curvature are related as:

$f=\frac{R}{2}$