Question

The radius of curvature of a given spherical mirror is-20 cm. The focal length of the mirror is?

• A. -10 cm
• B. 40 cm
• C. 10 cm
• D. -40 cm

Answer 1

Answer:

A. -10 cm

• The focal length (f) of a spherical mirror is half of its radius of curvature (R).

• The formula is: f = R/2.

• Given R = -20 cm

• therefore f = -20 cm / 2 = -10 cm.