Question

A student obtained image of same size at 54 cm when

convex lens was placed at 27cm. What is focal length of

lens and nature of the image?
(Is this question even correct I don't know that )

Answer 1

Answer:

answer is 27/2 or 13.5 cm

Explanation:

The distance between the object and the image is 54 cm (given)

Also we know that R= 2f

but here, 2R= 4f (Radius of curvature is double as 54 cm is the total distance between the object and the image)

54= 4f

f= 54/4

⇒ 27/2 or 13.5 cm

Since it is a convex lens, it will be real and inverted.

Hope it helped!