Question

A diminished image of an object is to be obtained on a screen 1.0 m from it. This can be achieved by placing

• A. a plane mirror
• B. a convex mirror of suitable focal length
• C. a convex lens of focal length less than 0.25 m
• D. a concave lens of suitable focal length

Answer 1

Answer: (C)

a convex lens of focal length less than 0.25 m

Answer 2

Image can be formed on the screen if it is real. Real image of
reduced size can be formed by a concave mirror or a convex
lens.
A diminished real image is formed by a convex lens when the
object is placed beyond 2 f and the image of such object is
formed between f and 2 f on other side.
Thus, \hspace20mm d > (2 \, f + 2 \, f)
or \hspace20mm 4 \, f < 0. 1 m
or \hspace20mm f < 0.25 m