A convergent beam of light is incident on a convex mirror so as to converge to a distance 12 cm from the pole of the mirror. An inverted image of the same size is formed coincident with the virtual object. What is the focal length of the mirror?

Question

A convergent beam of light is incident on a convex mirror so as to converge to a distance 12 cm from the pole of the mirror. An inverted image of the same size is formed coincident with the virtual object. What is the focal length of the mirror? (A) 24 cm (B) 12 cm (C) 6 cm (D) 3 cm

Tardigrade Admin · Accepted Answer

Here object and image are at the same position so this position must be centre of curvature ∴ R =12 cm ⇒ f =( R /2)=(12/2)=6 cm <img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/3327381131b1314220e1f52658b15e22-.png" />

Q. A convergent beam of light is incident on a convex mirror so as to converge to a distance $12 c m$ from the pole of the mirror. An inverted image of the same size is formed coincident with the virtual object. What is the focal length of the mirror?

24 cm

12 cm

6 cm

3 cm

Here object and image are at the same position so this position must be centre of curvature
$∴ R = 12 c m$
$\Rightarrow f = \frac{R}{2} = \frac{12}{2} = 6 c m$

Q. A convergent beam of light is incident on a convex mirror so as to converge to a distance 12cm from the pole of the mirror. An inverted image of the same size is formed coincident with the virtual object. What is the focal length of the mirror?