Question

The relation between focal length and radius of curvature of a spherical mirror is \dots

• A. $f = \frac{R}{2}$
• B. $f = 2R$
• C. $R = f$
• D. $R = 3f$

Hint:

The focus of a spherical mirror always lies halfway between the pole and center of curvature.

Answer 1

The Correct Option is A

Concept: For spherical mirrors, the principal focus lies midway between the pole and the center of curvature. Explanation: The distance between the pole and center of curvature is called the radius of curvature ($R$). The distance between the pole and principal focus is called the focal length ($f$). Experimentally and theoretically, it is found that: \[ f = \frac{R}{2} \] or \[ R = 2f \] This relation is valid for both concave and convex spherical mirrors.