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  5. Light - Reflection and Refraction

10th Class Science Light - Reflection and Refraction Question Bank Light

  • question_answer
    An object 10 cm from lens, has a virtual image at 10 cm from the object. The power of the lens is

    A)  10 diopters      

    B)         \[-10\]diopters

    C)  5 diopters         

    D)         \[-\] diopters

    Correct Answer: C

    Solution :

     Here, \[u=-20\,\,cm=-0.2\,\,m\] \[\therefore \]  \[P=\frac{1}{f}=\frac{1}{v}-\frac{1}{u}=\frac{1}{-0.2}-\frac{1}{0.1}\]                    \[=-5+10=5\] Note that since power in diopters is to be calculated, all distance were kept in metres.


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