an object is placed 22.0cm to the left of a pair of lenses, with a a converging

Question

an object is placed 22.0cm to the left of a pair of lenses, with a a converging lens of focal length 15cm to the left nngianl 1oP the image formed by this system of lenses. 79. N An object is placed 22.0 cm to the left of a pair of lenses, with a converging lens of focal length +15.0 cm on the left, and a diverging lens of focal length -12.0 cm a distance of 40.0 cm to its right. a. What are the location and magni of the final image formed by the two lenses? b. Is the final image formed by the two lenses upright or inverted roblems 80 and 81 are paired

Explanation / Answer

here, focal length of Converging lens = +15 cm

focal length of Diverging lens fd = -12 cm

distance between these lenses = 40 cm

object distance from fd = u1 = 22 cm

now use lens equation to find image distance for Converging lens

1/fc = 1/u1 + 1/v

1/v = 1/+15 - 1/22

v = 47.14 cm

Now for Diverging lens

object disatnce u2 = 40 - 47.14 = -7.14 cm

image distance V2 = ?

so again from 1/u2 +1/v2 = 1/fd

1/-7.14 + 1/V2    = 1/-12

1/V2 = -1/12 + 1/7.14

v2 = 17.62 cm is the final image distance

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magnification of first image m = -v/u = -V1/u1

m1 = -47.14/22 = -214

magnification of secod image = m2 = -V2/U2

m2 = -17.62/-7.14 = 2.46

total magnification M = m1 * m2

M = -2.14 * 2.46   = -5.27

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as m1 is -ve, image between the lenses in inverted.

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