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

  • question_answer
    A triangular prism of glass is shown in the figure. A ray incident normally to one face is totally reflected, if \[\theta ={{45}^{o}}\]. The index of refraction of glass is                                 [AIEEE 2004]

    A)            Less than 1.41

    B)            Equal to 1.41

    C)            Greater than 1.41

    D)            None of the above

    Correct Answer: C

    Solution :

                       For total internal reflection \[\theta >C\]                    \[\Rightarrow \] \[\sin \theta >\sin C\Rightarrow \sin \theta >\frac{1}{\mu }\]            or \[\mu >\frac{1}{\sin \theta }\Rightarrow \mu >\frac{1}{\sin {{45}^{o}}}\Rightarrow \mu >\sqrt{2}\]\[\Rightarrow \]\[\mu >1.41\]


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