Question

Problem 23.61 Two lenses, one converging with focal length 20.5 cm and one diverging with focal length 11.5 cm , are placed 25.0 cm apart An object is placed 60.0 cm in front of the converging lens. Part A Find the final image distance from second lens. Follow the sign conventions. Express your answer to two significant figures and include the appropriate units. d2 13 cm ubmit Previous Answers Correct Part B Determine the magnification of the final image formed. Follow the sign conventions Express your answer using two significant figures. 63 Previous Answers Request Answer Submit X Incorrect; Try Again; 3 attempts remaining

Answer 1

lens formula  

v = image , u = object , f =focal length

1/v -1/ u =1/f

1/v -1/-60 = 1/20.5  

from here v≈31.1392 cm  

magnification m1 = v/u = 31.1392 /-60 = -0.518986667

now this image work as object for second lens so distance of this image or object from 2nd lens

= 31.1392 -25 =6.1392 cm

now apply lens formula for second image

1/v -1/u = 1/f

1/v -1/6.1392 = 1/-11.5

from here v =13.1698 cm answer for first  

magnification m2 = v/u = 13.1698 /6.1392 =2.14519807

so final megnification M= m1*m2 = -0.518986667 *2.14519807 = -1.1133292 answer

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