Question

radius of curvature of a concave mirror is 25 cm what is its focal length?

Answer 1

the answers is
C=f/2
=25/2
=12.5

Answer 2

Given:

• Radius of curvature, R = 25 cm

To Find:

• Focal length, F = ?

Solution:

As we know,

⇒  $Radius \ of \ curvature = 2\times Focal \ length$

i.e.,

⇒                                 $R=2F$

On substituting the estimated values in the above formula, we get

⇒                                 $25=2F$

⇒                                  $F=\frac{25}{2}$

⇒                                  $F=12.5 \ cm$    

So, the focal length will be "12.5 cm".