Optics Question 684
Question: At what distance from a convex lens of focal length 30 cm, an object should be placed so that the size of the image be 1/2 of the object
[J&K CET 2004]
Options:
A) 30 cm
B) 60 cm
C) 15 cm
D) 90 cm
Show Answer
Answer:
Correct Answer: D
Solution:
$ m=-\frac{1}{2} $
$ \therefore m=\frac{f}{u+f} $
$ \Rightarrow -\frac{1}{2}=\frac{30}{u+30} $
$ \Rightarrow u=-90cm $
