Q. Magnification of a compound microscope is 30. Focal length of eye-piece is $5\ cm$ and the image is formed at a distance of distinct vision of $25\ cm$. The magnification of the objective lens is
A) 6
B) 5
C) 7.5
D) 10
Explanation
(b) $m = \frac{v_{o}}{u_{o}}\left( 1 + \frac{D}{f_{e}} \right) = m_{o}\left( 1 + \frac{D}{f_{e}} \right)$
$\Rightarrow 30 = m_{o}\left( 1 + \frac{25}{5} \right) = m_{o} \times 6 \Rightarrow m_{o} = 5$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.