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JEE Main & Advanced Physics Ray Optics Question Bank Refraction at Curved Surface

  • question_answer
    The focal length of a combination of lenses formed with lenses having powers of + 2.50 D and - 3.75 D will be [RPMT 1997]

    A) - 20 cm                                   

    B) - 40 cm

    C) - 60 cm                                   

    D) - 80 cm

    Correct Answer: D

    Solution :

    \[P={{P}_{1}}+{{P}_{2}}=2.50-3.75=-1.25D\]            So \[f=\frac{100}{1.25}=-80\]\[cm\]


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