A reflecting type telescope has a large concave spherical mirror of radius of curvature `80 cm` as objective. What is the magnifying power of telescope if eye piece used has a focal length of `1.6 cm` ?

Options

A. 100
B. 50
C. 25
D. 5

Answer

C

Explanation

The focal length of objective mirror
`f_(o) = (R)/(2) = 80/2 = 40 cm`
and focal length of eye piece `= 1.6 cm`
`:.` magnifying power, `m = (f_(o))/(f_(e)) = (40)/(1.6) = 25`