Q. The length of a telescope is $36\ cm$. The focal lengths of its lenses can be
A) 30 $cm,\ 6\ cm$
B) $- 30\ cm,\ - 6\ cm$
C) 30 $cm,\ - 6\ cm$
D) $- 30\ cm,\ 6\ cm$
Explanation
(a) Total length $L = f_{o} + f_{e}$ and both lenses are convex
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.