Question

The distance between the focus and the center of curvature of a spherical mirror, in terms of the radius of curvature R, is equal to?

• A. 2R
• B. R/2
• C. R/4
• D. R

Answer 1

Answer:

B. R/2

For a spherical mirror, the focal length (f) is R/2. Therefore, the distance between the focus and the center of curvature is R/2. Radius of curvature is observed to be equal to twice the focal length for spherical mirrors with small apertures. Hence R = 2f . We can say clearly that the principal focus of a spherical mirror lies at the centre between the centre of curvature and the pole.