Question

Two converging lenses having focal lengths of f₁ = 10.3 cm and f₂ = 20.0 cm are placed d = 50.0 cm apart, as shown in the figure below. The final image is to be located between the lenses, at the position x = 30.7 cm indicated.

Two converging lenses having focal lengths of 1 10.3 cm and 2-20.0 cm are placed d-50.0 cm apart, as shown in the figure below. The final image is to be located between the lenses, at the position x 30.7 cm indicated. 2 fi Object Final image (a) How far (in cm) to the left of the first lens should the object be positioned? 9.82 Your response differs from the correct answer by more than 10%. Double check your calculations. cm b) What is the overall magnification of the system? (c) Is the final image upright or inverted? upright inverted

Answer 1

image distance for lens 2

v' = 50 - 30.7 = 19.3 cm

using lens formula for lens 2

1/f' = 1/v' - 1/u'

1/ 20 = - 1/19.3 + 1/u'

u' = 9.822 cm

now the above object is the resukt of image of lens 1

v = 50 - 9.822 := 40.178 cm

using lens formula for lens 1

1/10. 3 = 1/40.178 + 1/u

u = 13.851 cm

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b)

m = (v/u) (v'/u')

m = (40.178/ 13.851)* ( 19.3 / 9.822)

m = 5.7

imga eis inverted

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