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A convex lens of focal length 10 cm is i...

A convex lens of focal length 10 cm is in contact with a concave lens. The focal length of the combination is numerically equal to that of the concave lens. The focal length of the concave lens is

A

10 cm

B

15 cm

C

5 cm

D

20 cm

Text Solution

Verified by Experts

The correct Answer is:
D
`(1)/(10)+(1)/(-f)=(1)/(f) rArr (1)/(10)=(2)/(f)`
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  • A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is

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