JEE Main & Advanced Physics Question Bank Prism Theory and Dispersion of Light

  • question_answer
    The minimum deviation produced by a hollow prism filled with a certain liquid is found to be 30°. The light ray is also found to be refracted at angle of 30°. The refractive index of the liquid is                                           [MP PET 1991]

    A)            \[\sqrt{2}\]                           

    B)            \[\sqrt{3}\]

    C)            \[\sqrt{\frac{3}{2}}\]        

    D)            \[\frac{3}{2}\]

    Correct Answer: A

    Solution :

                       For minimum angle of deviation for a prism                    \[A=2r\],  \[\therefore \] \[A={{60}^{o}}\]            Now \[\mu =\frac{\sin \frac{60+30}{2}}{\sin \frac{60}{2}}=\frac{\sin {{45}^{o}}}{\sin {{30}^{o}}}=\frac{1}{\sqrt{2}}\times \frac{2}{1}=\sqrt{2}\]


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