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NEET Sample Paper NEET Sample Test Paper-82

  • question_answer
    A lens is placed between a source of light and a wall. It forms images of area \[{{\operatorname{A}}_{1}}and\,\,{{A}_{2}}\] on the wall, for its two different positions. The area of the source of light is

    A)  \[\frac{1}{{{A}_{1}}}+\frac{1}{{{A}_{2}}}\]             

    B)  \[\frac{{{A}_{1}}-{{A}_{2}}}{2}\]

    C)  \[\sqrt{{{A}_{1}}{{A}_{2}}}\]            

    D)  \[\frac{{{A}_{1}}+{{A}_{2}}}{2}\]

    Correct Answer: C

    Solution :

    By displacement method, size of \[\operatorname{object} \left( O \right) =\,\,\sqrt{{{l}_{1}}\,{{l}_{2}}}\] \[\therefore \,\,\,Area\,\,of\,\,source\,\,light\,\,=\,\,\sqrt{{{A}_{1}}{{A}_{2}}}\]


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