An astronomical telescope has an objective lens with focal length f_o and has an eyepiece with focal length f_e.A second telescope has objective and eyepiece lenses with triple the focal length of the first telescope.Which telescope gives the greater magnification and by what factor? A)The first telescope gives 9 times the magnification of the second. B)The second telescope gives 9 times the magnification of the first. C)Both telescopes give the same magnification. D)The actual focal lengths must be known to answer this question.

Question

Quizplus · Accepted Answer

The magnification of a telescope is given by the ratio of the focal length of the objective lens to the focal length of the eyepiece lens (M = f_o / f_e). Since both telescopes have the same ratio (3f_o / 3f_e = f_o / f_e), they provide the same magnification.

An Astronomical Telescope Has an Objective Lens with Focal Length