A compound lens system consists of two converging lenses one at z -20.0 cm with focal length
fi-+10.0 cm. and the other at z +20.0 cm with focal length f2 +8.00 cm. (Figure 1)An object 1.00
centimeter tall is placed at x 50.0cm What is the location of the final image produced by the
compound lens system? Give the x coordinate of the image. Express your answer in centimeters,
to three significant figures or as a fraction. View Available Hint(s -31.8 cm Previous Answers
Correct Figure 1 of 1 Part How tall is the image? Express your answer in centimeters, to three
significant figures or as a fraction View Available Hint(s) fi f2 cm Submit
Solution
here,
for the first lens
the focal length , f1 = 10 cm
object distance , do1 = 30 cm
let the image distance be di1
using the lens formula
1/f1 = 1/di1 + 1/do1
1/10 = 1/di1 + 1/30
di1 = 15 cm
for the seccond lens
the focal length , f2 = 8 cm
object distance , do2 = 25 cm
let the image distance be di2

using the lens formula
1/f2 = 1/di2 + 1/do2
1/8 = 1/di2 + 1/25
di2 = 11.8 cm
B)
the image height , hi = h0 * ( di1/do1) *(di2/do2)
hi = 1 * ( 15/30) *(11.8/25)
hi = 0.24