A telescope has focal length of objective and eye-piece as 200 cm and 5 cm respectively. What is magnification of telescope?

Step-by-step solution

In relaxed eye state of telescope or when final image is formed at infinity, the magnification of telescope is given by |M|= f_o f_e where aligned f_o & = focal length of objective =200 ~cm f_e & = focal length of eye-piece =5 ~cm aligned Hence, |M|= 200 5 =40|M|= 200 5 =40 Note : The aperture of the objective lens is kept large so that more and more rays coming from the heavenly body may enter the telescope and a bright image is formed by the objective lens. The aperture of the eye lens is kept comparatively small