Q. In a compound microscope, the focal lengths of two lenses are $1.5\ cm$ and $6.25\ cm$ An object is placed at $2\ cm$ form objective and the final image is formed is $25\ cm$ from eye lens. The distance between the two lenses is
A) $6.00\ cm$
B) $7.75\ cm$
C) $9.25\ cm$
D) $11.00\ cm$
Explanation
(d) $L = v_{o} + u_{e} = \frac{u_{o}f_{o}}{(u_{o} - f_{o})} + \frac{f_{e}D}{f_{e} + D}$
$\Rightarrow L = \frac{2 \times 1.5}{(2 - 1.5)} + \frac{6.25 \times 25}{(6.25 + 25)} = 11\ cm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.