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 quadruple the focal length of the first telescope.Which telescope gives the greater magnification and by what factor? A)The first telescope gives 16 times the magnification of the second. B)The second telescope gives 16 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. E)The second telescope gives 4 times the magnification of the first.

Question

Quizplus · Accepted Answer

The magnification of an astronomical telescope is given by the ratio of the focal length of the objective lens to that of the eyepiece lens. Since both telescopes have their objective and eyepiece focal lengths increased by the same factor (quadrupled), the ratio (and thus the magnification) remains the same for both telescopes.

An Astronomical Telescope Has an Objective Lens with Focal Length