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Two concave lenses each of focal length ...

Two concave lenses each of focal length `30 cm` are placed in contact. What is focal of the compound lens ?

Text Solution

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`-15 cm`, from `1//f = 1//f_(1) + 1//f_(2)`
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Knowledge Check

  • A concave lens of focal length 20 cm placed in contact with a plane mirror acts as a

    A
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    B
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    D
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  • A convex lens of focal length A and a concave lens of focal length B are placed in contact. The focal length of the combination is

    A
    (A+B)
    B
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    D
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