Q. An astronomical telescope of ten-fold angular magnification has a length of $44\ cm$. The focal length of the objective is
A) $4\ cm$
B) $40\ cm$
C) $44\ cm$
D) $440\ cm$
Explanation
(b) $L = f_{o} + f_{e} = 44$ and $|m| = \frac{f_{o}}{f_{e}} = 10$
This gives $f_{o} = 40\ cm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.