Manipal Medical Manipal Medical Solved Paper-2001

  • question_answer
    Light takes\[{{t}_{1}}\]sec to travel a distance\[x\,cm\]in vacuum and the same light takes\[{{t}_{2}}\]sec to travel \[10x\,cm\]in the medium, critical angle for the corresponding medium is:

    A)  \[{{\sin }^{-1}}\left( \frac{10{{t}_{1}}}{{{t}_{2}}} \right)\]

    B)  \[{{\sin }^{-1}}\left( \frac{{{t}_{1}}}{10{{t}_{2}}} \right)\]

    C)  \[{{\sin }^{-1}}\left( \frac{{{t}_{2}}}{10{{t}_{1}}} \right)\]

    D)  \[{{\sin }^{-1}}\left( \frac{10{{t}_{2}}}{{{t}_{1}}} \right)\]

    Correct Answer: A

    Solution :

     Here, Initial time\[={{t}_{1}}\]sec Initial distance\[{{x}_{1}}=x\,cm\] Final time\[={{t}_{2}}\]sec Final distance\[{{x}_{2}}=10x\,cm\] The velocity of light in vacuum is \[{{\upsilon }_{0}}=\frac{x}{{{t}_{1}}}\] The velocity of light in medium is \[\upsilon =\frac{10x}{{{t}_{2}}}\] Now, the relation for critical angle is given by, \[\sin C=\frac{1}{\mu }\] So,         \[C={{\sin }^{-1}}\frac{1}{\mu }\] and refractive index\[\mu \]is given by, \[=\frac{{{\upsilon }_{0}}}{\upsilon }=\frac{x}{{{t}_{1}}}\times \frac{{{t}_{2}}}{10x}=\frac{{{t}_{2}}}{10{{t}_{1}}}\] Hence, \[C={{\sin }^{-1}}\frac{1}{\mu }={{\sin }^{-1}}\left( \frac{10{{t}_{1}}}{{{t}_{2}}} \right)\]


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