An astronomical telescope's eyepiece has a focal length of 10 cm . When the telescope is focussed for normal vision of distant objects, the tube length is 1.0 m . Determine the focal length of the objective and the magnifying power of the telescope.

Step-by-step solution

For normal vision, the final image is formed at infinity. The tube length of the telescope is given by L = f_o + f_e . Given L = 1.0 m = 100 cm and f_e = 10 cm . 100 = f_o + 10 f_o = 90 cm The magnifying power of the telescope for normal vision is given by M = f_o f_e . M = 90 10 = 9