JEE Main & Advanced Physics Ray Optics Sample Paper Topic Test - Reflection of Light

  • question_answer
    In the figure shown, a thick plano convex lens is silvered at both the surfaces. A point source of light 'S' is inside the lens. The radius of curvature of the spherical curved surface is (8/3) cm and the distance 'S' from the curved surface is 2 cm. If the images formed due to direct reflections from the plane and curved surface coincide, then find the thickness of the lens in cm.

    A) 5

    B) 7

    C) 3

    D) 8

    Correct Answer: C

    Solution :

    [c]
    For mirror \[\frac{1}{v}+\frac{1}{-2}=\frac{3}{-4}\]\[\Rightarrow \]\[v=-\,4\]. This is at \[{{I}_{1}}\].
    Image \[{{I}_{2}}\] is formed by plane mirror which coincides with \[{{I}_{1}}\]
    From the figure it is \[2x=2\]
     
    \[\sqrt{\frac{h}{g}-\frac{{{P}_{0}}}{\rho {{g}^{2}}}}\] \[x=1\,cm\]
    \[{{P}_{0}}\]    thickness \[=\,3\,cm\]


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