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CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2000

  • question_answer
    Light is incident on a glass plate at an angle \[{{60}^{o}},\] the reflected and refracted rays arc mutually perpendicular to each other, then the refractive index of plate will be:

    A)  1.732                   

    B)  1.5

    C)  1.4                                        

    D)  1.5

    Correct Answer: A

    Solution :

     Angle of incidence \[i={{60}^{o}}\]is given As it is clear that the angle of reflection = angle of incidence Angle of reflection \[={{60}^{o}}\] As the reflected and refracted rays are mutually perpendicular. Hence, angle of refraction \[r=[{{180}^{o}}-({{90}^{o}}+{{60}^{o}})]={{30}^{o}}\] Now, the refractive index of plate is                                 \[\mu =\frac{\sin i}{\sin r}=\frac{\sin {{60}^{o}}}{\sin {{30}^{o}}}\]                                 \[=\frac{0.866}{0.6}\]                                 \[=1.732\]


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