Question

If focal lenght is 20cm them what is the radius of curvature of mirror?

Answer 1

Answer:

f=20 cm

r=2f

=2(20)

=40

radius of the curvature is 40cm

Answer 2

Given :-

$\sf{Focal \: length \: (f) = 20 \: cm}$

To Find :-

$\sf{What's \: the \: radius \: of \: curvature \: of \: mirror \: ?}$

Usable relation between f and R :-

$\sf{focal \: length =\dfrac{radius \: of \: curvature}{2}}$

Solution :-

from above relation -

$\sf{f =\dfrac{R}{2}}$

$\sf{R = 2f}$

$\sf{R = 2\times 20}$

$\sf{R = 40 \: cm}$

$\sf{Radius \: of \: the \: curvature \: of \: mirror \: is \: 40 \: cm .}$