Question

A mirrored-glass gazing globe in a garden is 28.0 cm in diameter. part a what is the focal length of the glob

Answer 1

For a curved mirror, the radius of curvature R is twice the focal length f:

`R=2f` (1)
Since the diameter d is twice the radius R, we can rewrite (1) as

`(d)/(2) = 2f`
From which we can calculate the focal length from the diameter:

`f= (d)/(4)= (28.0 cm)/(4)=7.0 cm`