JEE Main & Advanced Physics Ray Optics Sample Paper Topic Test - Refraction of Light Through Curved Surfaces

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

    A) \[\sqrt{\left( {{A}_{1}}{{A}_{2}} \right)}\]

    B) \[\left( {{A}_{1}}{{A}_{2}} \right)/2\]

    C) \[\frac{{{\left( \sqrt{{{A}_{1}}}+\sqrt{{{A}_{2}}} \right)}^{2}}}{2}\]

    D) \[{{\left[ \frac{l}{{{A}_{1}}}+\frac{l}{{{A}_{2}}} \right]}^{-1}}\]

    Correct Answer: A

    Solution :

    [a] By displacement method, the size of object is given by \[O=\sqrt{{{I}_{1}}\times {{I}_{2}}};\] \[\therefore \]      \[A\sqrt{{{A}_{1}}\times {{A}_{2}}}\]

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