Optics Question 357
Question: The objective lens of a compound microscope produces magnification of 10. In order to get an overall magnification of 100 when image is formed at 25 cm from the eye, the focal length of the eye lens should be
Options:
A) 4 cm
B) 10 cm
C) $ \frac{25}{9} $ cm
D) 9 cm
Show Answer
Answer:
Correct Answer: C
Solution:
$ m=m _{o}\times m _{e} $
$ \Rightarrow m=m _{o}\times ( 1+\frac{D}{f _{e}} ) $
$ \Rightarrow 100=10\times ( 1+\frac{25}{f _{e}} ) $
$ \Rightarrow f _{e}=\frac{25}{9}\ cm $
