Question

While performing an experiment on determination of focal length of a convex lens, four students

obtained the image of the same distant tree on the screen as follows Which diagram shows the

formation of image correctly? Support your answer with reason.
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Answer 1

Diagram of Student B is correct.

Reason:

• Irrespective of the position of object , a convex mirror will always form a virtual, diminished and erect image.

• A tree represents an object present at infinity. Hence light rays from the tree, after reflection will meet at the focus.

• Hence , it will help in direct calculation of the focal length of the convex mirror.

Problem with other diagram :

• In student A's diagram , the image has become rotated to the left.

• In student C's diagram, the image has become rotated to the right.

• In student D's diagram, the image is inverted.

Hence , student B is correct.

Answer 2

Answer:

Option D

Explanation:

the above answer would be correct if the question was for convex mirror, but it is for CONVEX LENS, so the image formed will be

Real, Inverted in all cases except one where object is very close to mirror (b/w focus and pole),

here we can assume that object is either at infinity or beyond 2F1, now in both these cases the image formation will be

a) Real

b)Inverted

c)Diminished

So, option D will be correct as the tree given is INVERTED