Question

If AB = 10 cm and DB = 40 cm (diameter). What is the radius of curvature and focal length?

• A. 40 cm, 10 cm
• B. 20 cm, 20 cm
• C. 40 cm, 5 cm
• D. 20 cm, 10 cm

Answer 1

The correct option is D

20 cm, 10 cm

The radius of curvature is defined as the radius of the sphere of which the spherical mirror was originally a part of.

Here, the radius of curvature = OB = $\frac{1}{2}\left(40\right)=20cm$

Point A is the focus since parallel rays pass through focus after reflection.

So, AB = focal length = $10cm$