Image of an object at infinity is formed by a convex lens of focal length 30cm such that the size of the image is 2cm. If a concave lens of focal length 20cm is placed in between the convex lens and the image, at a distance 26cm from the convex lens, size of the new image is:
A
2.5cm
B
2.0cm
C
1.025cm
D
1.05cm
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Updated on : 2022-09-05
Solution
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Correct option is A)
Without the concave lens, image is formed at a distance 30 cm from the convex lens. When concave lens is placed, it serves as the object for the concave lens.
Hence, for concave lens, u=4cm
Given, f=−20cm
From lens formula,
v1−u1=f1
v1=41+−201=204
v=5cm
Magnification of lens, m=uv=45
Magnification of lens, m=hohI
⟹hI=2×1.25=2.5cm
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