Question

Define the radius of curvature of a spherical mirror.
If the radius of curvature of a spherical mirror is 20 cm, what is its focal length? [2 Mark]

Answer 1

The radius of the curvature of the mirror is defined by the radius of the sphere from which the mirror was cut from. [1 Mark]

Here,
Radius of curvature (R) = 20 cm
We know that,
Radius of curvature of a spherical mirror, R = 2 x Focal length (f)

$R=2f$

$f=\frac{R}{2}$

$f=\frac{20}{2}$

$f=10cm$

Hence, the focal length of the given spherical mirror is 10 cm [1 Mark]