Question

The radius of curvature of a spherical mirror is 20 cm. What is its focal

length?​

Answer 1

Answer:

So, focal length = 21× radius of curvature = 21×20 cm = 10 cm.

Answer 2

Given :-

The radius of curvature of a spherical mirror = 20 cm

To Find :-

The focal length of the mirror.

Solution :-

We know that,

• r = Radius
• f = Focal length

Using the formula,

$\underline{\boxed{\sf Radius \ of \ curvature \ of \ sperical \ mirror=2 \times Focal \ length}}$

Given that,

Radius (r) = 20 cm

Substituting their values,

20 = 2 × f

f = r/2

f = 20/2

f = 10 cm

Therefore, the focal length of the spherical mirror is 10 cm.