Question

A lens system consists of the two lenses shown in the diagram below. The focal length of the first lens is 25 cm (you must decide upon the correct sign) and the second lens has a focal length of 8 cm (again you must decide the sign). The lenses are spaced a distance of 45 cm apart and the object is held a distance of 120 cm to the left of the first lens.

Lens #1 Lens #2 ~ Object 120 cm 45 cm

c) If the original object is 10 cm tall, how large would the final image be?

d) Find the angular magnification of the system. Be sure to place your eye at an appropriate spot (your choice).

Answer 1

c) , f = + sem f = +25cn do, = + 120 ma + 120 W di; =+31.579 cm dos = 45 cm - 31.579 cm = + 13.421 cm de do ó - din = +19.806 cm het magnification, m=m, x m2 13-14 m = 31.579 x 19.806 120 13.421 m = 0.388 final image side = mx object size = 0.388 x 10 cm = 3-88 cm

AB' = M, X AB A'B' =-31.579 x 10 = - 2.631 cm 120 tan O2 = A'B' - - A'02 tan. O₂ = 0.1960 2631 13:421 tano i = 10 120tus lova (120+45)cm = 0.0606 angular magnification = dan O2 - Tano = 3.234 -0.1960 0.0606