Question

2.
Focal length of a spherical mirror whose radius of
curvature is 32 cm is
A) 8 cm
B) 16 cm
C) 32 cm
D) 64 cm​

Answer 1

To find:

Focal length of spherical mirror whose Radius of Curvature is 32 cm.

Calculation:

Focus is a point on the principal axis, to which light rays $\rm pa{s}s$ after getting reflected from the mirror surface.

• Distance of the focus from the pole of the mirror is known as the focal length.

Radius of curvature is radius of the sphere from which the spherical mirror has been derived.

For paraxial rays:

$\rm \therefore \: f = \dfrac{r}{2}$

$\rm \implies\: f = \dfrac{32}{2}$

$\rm \implies\: f = 16 \: cm$

So, focal length is 16 cm.