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JEE Main & Advanced Physics Ray Optics Question Bank Self Evaluation Test - Ray Optics and Optical Instruments

  • question_answer
    A hemispherical glass body of radius 10 cm and refractive index 1.5 is silvered on its curved surface. A small air bubble is 6 cm below the flat surface inside it along the axis. The position of the image of the air bubble made by the mirror is seen:

    A) 14 cm below flat surface

    B) 20 cm below flat surface

    C) 16 cm below flat surface

    D) 30 cm below flat surface

    Correct Answer: B

    Solution :

    [b] Given, radius of hemispherical glass R=10cm \[\therefore \]Focal length \[f=\frac{10}{2}=-5cm\] \[u=\left( 10-6 \right)=-\,4cm.\] By using mirror formula, \[\frac{1}{v}+\frac{1}{u}=\frac{1}{f}\Rightarrow \frac{1}{v}+\frac{1}{-4}=\frac{1}{-5}\Rightarrow v=20cm.\] Apparent height, \[{{h}_{a}}={{h}_{r}}\frac{{{\mu }_{1}}}{{{\mu }_{2}}}=30\times \frac{1}{1.5}=20cm\] below flat surface.


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