Question

A reflecting telescope has a large mirror for its objective with radius of curvature equal to 80 cm. The magnifying power of this telescope if eye piece used has a focal length of 1.6 cm is:

• A. 100
• B. 50
• C. 25
• D. 5

Answer 1

Answer: (C)

25

The focal length of objective mirror $f_0=\frac{R}{2}=\frac{80}{2}=40cm$
and focal length of eye piece = 1.6 cm
$\therefore$ magnifying power, $m=\frac{f_0}{f_e}=\frac{40}{1.6}=25$