Sun's Rays & Convex Mirrors: What is the Image Size?

[Mr.IITIAN007]

Rays from the sun subtend an angle theta (in radians) at the pole of a convex mirror (in radians) at the pole of a mirror of focal length f. If the diameter of the sun is D ,then diameter of the image of the sun formed by the mirror is:

(a) f theta
(b) 2 f theta
(c) 6 f theta
(d) none of these

Please tell what would be the case if the mirror is plane.

 

[mukundpa]

At the pole of mirror the angle subtended by the object and image will be the same, think...

 

[Mr.IITIAN007]

But , No not always . For a concave mirrror the diameter of the image becomes 2 f theta.Hey friend, perhaps this information would help-'area of the image is pie x r square and is proportional to 2f.'