15. Two thin lenses of focal lengths fi = 20 cm and f2 = 60 cm are placed in contact. (a) Find the focal length f' of th
Posted: Mon May 02, 2022 9:08 pm
15. Two thin lenses of focal lengths fi = 20 cm and f2 = 60 cm are placed in contact. (a) Find the focal length f' of the combined lenses system. (b) Find the focal length f3 of a third lens placed in contact with these two that would result in an overall focal length f" = -40 cm. [(a) f'=15.0 cm, (b) f3 = -10.9 cm]