1. Today 2/10  Multiple Lens Systems 26.9  Lab: Questions?  No HW assigned today  Review in class tomorrow  HW:“2/10 Two Lenses” Due Thursday 2/13  Exam IThursday, Feb 13 5:00 to 7:00pm Witmer 116 Overflow to Witmer 114

2. Example: f = + 6 cm and - 18 cm lenses are 1 cm apart d o = + 12 cm dodo Find the image due to the first lens, ignore the second for now. Now ask what happens to these rays at the second lens. dodo Need another ray-- from the center of the diverging lens along the first image.

3. dodo Math First lens d o = 12, f = 6 d i = ?d i = 12 Second lens d o = -11, f = -18 d i = ? dodo d i = 28.3 didi didi What about Magnification? First image m 1 = -12/12 = -1 Second image m 2 = -28.3/-11 = 2.6 Total m = -1(2.6) = -2.6 Inverted and real Example: f = + 6 cm and - 18 cm lenses are 1 cm apart d o = + 12 cm

4. dodo Math First lens d o = 9, f = 6 d i = ?d i = 18 Second lens d o = -9, f = -18 d i = ? dodo d i = 18 didi didi First image m 1 = -18/9 = -2 Second image m 2 = -18/-9 = +2 Total m = -2(2) = -4 Inverted and real Example: f = + 6 cm and - 18 cm lenses are 1 cm apart d o = + 12 cm