BHU PMT BHU PMT (Screening) Solved Paper-2011

  • question_answer
    A square of side 3 cm is located at a distance 25 cm from a concave of square is at the axis of the mirror and the plane is normal to axis of mirror. The area enclosed by the image of the square is

    A)  \[4c{{m}^{2}}\]

    B)  \[6c{{m}^{2}}\]

    C)  \[16c{{m}^{2}}\]                             

    D)  \[36c{{m}^{2}}\]

    Correct Answer: A

    Solution :

                     Linear magnification, \[m=\frac{I}{O}=\frac{f}{u-f}\] \[=\frac{10}{25-10}\] \[m=\frac{10}{15}=\frac{2}{3}\] Areal magnification \[={{m}^{2}}=\frac{4}{9}\] Area of image\[=\frac{4}{9}\times \]area of object                                 \[=\frac{4}{9}\times {{(3)}^{2}}=4c{{m}^{2}}\]


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