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JEE Main & Advanced Physics Question Bank Human Eye and Lens Camera

  • question_answer
    A man suffering from myopia can read a book placed at 10 cm distance. For reading the book at a distance of 60 cm with relaxed vision, focal length of the lens required will be    [MP PMT 1989]

    A)            45 cm                                      

    B)            ? 20 cm  

    C)            ? 12 cm                                   

    D)            30 cm  

    Correct Answer: C

    Solution :

                       For lens u = want?s to see \[=-\,60\,cm\] v = can see \[=-\,10\,cm\] \[\therefore \frac{1}{f}=\frac{1}{v}-\frac{1}{u}\]\[\Rightarrow \frac{1}{f}=\frac{1}{-10}-\frac{1}{(-60)}\]\[\Rightarrow f=-\,12\,cm\]


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