An astronomical telescope consists of the thin lenses, `36 cm` apart and has a magnifying power `8`. Calculate the focal length of lenses. Two stars have an actual separation of one minute of arc. Find the angle of separation as seen through the telescope.

Explanation

Here, `L = 36 cm, m = 8, f_0 = ? F_e = ?`
As `m = (f_0)/(f_e) = 8 :. f_0 = 8 f_e`
Now `L = f_0 + f_e = 8 f_e + f_e = 9 f_e = 36`
`f_e = (36)/(9) = 4 cm f_0 = 36 - f_e = 36 - 4 = 32 cm`
Angle of separation as seen through telescope
=`m xx` actual separation
=`8 xx 1' = 8'`.