Question

A planet is observed by an astronomical refracting telescope having an objective of focal length $16m$ and an eyepiece of focal length $2cm$

• A. The distance between the objective and the eyepiece is 16.02 m
• B. The angular magnification of the planet is -800
• C. The image of the planet is inverted
• D. The objective is larger than the eyepiece

Answer 1

Answer: (A), (D)

Tube length $=f_o+f_e$
Angular magnification $=\frac{f_o}{f_e}$
Then, $f_o+f_e=16+0.02=16.02m$
Angular magnification $=\frac{f_o}{f_e}=-\frac{16}{0.02}=-800$
Objective lens is larger than eyepiece in aperture focal length.