Question

CALCULATE THE FOCAL LENGTH IF RADIUS OF CURVATURE OF CONCAVE MIRROR IS 8.4cm​

Answer 1

Answer:

Explanation:

2f=R

the f =R/2

thus f=8.4/2=4.2 cm

Answer 2

Answer:

If the radius of curvature is  8.4cm​, the focal length will be $4.2\ cm$

Explanation:

• For spherical mirrors having a small aperture, the radius of curvature is twice the focal length.

• Let R be the radius of curvature and f be the focal length then,

        $R = 2f$  

       That is,  

       $f= \frac{R}{2}$   ...(1)

In the question, it is given that,

$R = 8.4\ cm = 8.4\times 10^{-2} m$

Substitute  the value of 'R' into equation(1),

We get,

$f = \frac{ 8.4\times 10^{-2}}{2} = 4.2\times 10^{-2}\ m = 4.2\ cm$

• The radius of curvature  = $4.2 \ cm$