Question

The radius of curvature of a mirror is 20cm. The focal length and the diameter of the mirror is? Pls explain the diameter part with reason

Answer 1

Since we know,

$F = \frac{R}{2} \\ \\ F = \frac{20}{2} = 10$

Hence, the focal length of the mirror is 10 cm.

Radius of curvature = Radius of mirror

2*Radius of curvature = Diameter of mirror

Diameter of mirror =

$2 \times 20 \\ \\ 40 \: cm$

Hence, the diameter of mirror is 40 cm.

Are you also in class 10th ? BTW, I did it myself well. You can recheck.