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JEE Main & Advanced JEE Main Paper (Held On 09-Jan-2019 Morning)

  • question_answer
    Consider a tank made of glass (refractive index 1.5) with s. thick bottom. It is filled with a liquid of refractive index \[\mu \]. A student finds that, irrespective of what the incident angle I (see figure) is for a beam of light entering the liquid, the light reflected from the liquid glass interface is never completely polarized. For this to happen, the minimum value of \[\mu \] is: [JEE Main Online Paper (Held On 09-Jan-2019 Morning]

    A) \[\sqrt{\frac{5}{3}}\]

    B) \[\frac{4}{3}\]

    C) \[\frac{5}{\sqrt{3}}\]

    D) \[\frac{3}{\sqrt{5}}\]

    Correct Answer: D

    Solution :

    \[\tan \,\theta \,\,\,=\,\,\frac{1.5}{\mu }\,;\,\,\,Sin\,\theta \,\,=\,\,\frac{1}{\mu }\] \[\frac{1}{\sqrt{{{\mu }^{2}}-1}}\,\,=\,\,\,\frac{3}{2\mu }\] \[4{{\mu }^{2}}\,\,=\,\,\,9({{\mu }^{2}}-1)\] \[5{{\mu }^{2}}\,=\,\,9\] \[\mu \,\,=\,\,\frac{3}{\sqrt{5}}\]


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