CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2006

  • question_answer
    A ray of light passes from vacuum into a medium of refractive index p, the angle of incidence is found to be twice the angle of refraction. Then the angle of incidence is:

    A)  \[{{\cos }^{-1}}\left( \frac{\mu }{2} \right)\]      

    B)         \[2{{\cos }^{-1}}\left( \frac{\mu }{2} \right)\]

    C)  \[2{{\sin }^{-1}}(\mu )\]              

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

    E)  none of these

    Correct Answer: B

    Solution :

    Given, \[i=2r,\mu =\frac{\sin i}{\sin r}\frac{\sin 2r}{\sin r}=\frac{2\sin r\cos r}{\sin r}\] \[\cos r=\frac{\mu }{2}\]or \[r={{\cos }^{-1}}\left( \frac{\mu }{2} \right)\]                 \[i=2r=2{{\cos }^{-1}}\left( \frac{\mu }{2} \right)\]


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