question_answer 33)

For the telescope described in the last exercise,in 9.34 (a), what is the separation between theobjective lens and the eye-piece? (b) If this telescope is used to view a 100 m talltower 3 km away, what is the height of image ofthe tower formed by objective lens? (c) What is the height of final image of thetower if it is formed at 25cm ?  

Answer:

(a) Since the final image is formed atinfinity, the distance between the objectlens and the eye-piece is  (b) The angle subtended by the tower is Also, if h is the size of image formed by theobject, then (c) Angular magnification of eye piece is Height of the final image = 6h = 6 x 4.7= 28-2 cm