Practice question

**Astronomical telescope** in normal adjustment M = -f_o/f_e, f_o objective focal length (m), f_e eyepiece focal length, length L = f_o+f_e, final image at infinity, angular magnification ratio of angles subtended by image and object. For f_o=100 cm, f_e=5 cm, M=-20, inverted, used for celestial observation. A concave lens diverges light rays, preventing them from converging to a point on the opposite side. The rays appear to diverge from a virtual focal point on the same side as the object, resulting in a virtual image that cannot be projected, regardless of object position. Substituting values gives It diverges light rays, which matches expected image position