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BHU PMT BHU PMT (Screening) Solved Paper-2008

  • question_answer
    A ray of light is incident on the surface of separation of a medium with the velocity of light at an angle\[45{}^\circ \]and is refracted in the medium at an angle\[30{}^\circ \]. What will be the velocity of light in the -medium?

    A)  \[1.96\times {{10}^{8}}m/s\]    

    B)  \[2.12\times {{10}^{8}}m/s\]

    C)  \[3.18\times {{10}^{8}}m/s\]    

    D)  \[3.33\times {{10}^{8}}m/s\]

    Correct Answer: B

    Solution :

                     \[\frac{{{c}_{1}}}{{{c}_{2}}}=\frac{\sin i}{\sin r}\] \[\therefore \]  \[\frac{3\times {{10}^{8}}}{{{c}_{2}}}=\frac{\sin {{45}^{o}}}{\sin {{30}^{o}}}=\frac{0.707}{0.5}\] So,          \[{{c}_{2}}=\frac{3\times {{10}^{8}}\times 0.5}{0.707}\]                 \[=2.12\times {{10}^{8}}m/s\]


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