Punjab Medical Punjab - MET Solved Paper-2004

  • question_answer
    If the refractive index of material of equilateral prism is \[\sqrt{3}\] then angle of minimum deviation of the prism will be:

    A) \[{{25}^{o}}\]                                    

    B) \[{{60}^{o}}\]

    C) \[{{45}^{o}}\]                                    

    D) \[{{30}^{o}}\]

    Correct Answer: B

    Solution :

    Refractive index of the material\[\mu =\sqrt{3}\] The relation for refractive index is                 \[\mu =\frac{\sin i}{\sin r}\]                 \[\sqrt{3}=\frac{\sin i}{\sin r}\]                 \[\sqrt{3}=\frac{\sin \frac{A+{{\delta }_{m}}}{2}}{\sin \frac{A}{2}}=\frac{\sin \frac{A+{{\delta }_{m}}}{2}}{\sin \frac{{{60}^{o}}}{2}}\]                 \[{{v}_{3}}=\frac{\sin \frac{A+{{\delta }_{m}}}{2}}{\frac{1}{2}}\] or            \[\sin \frac{A+{{\delta }_{m}}}{2}=\frac{\sqrt{3}}{2}\]                 \[=\sin {{60}^{o}}\] (where \[A\] is the angle of equilateral prism) Hence,  \[\frac{A+{{\delta }_{m}}}{2}={{60}^{o}}\] Thus,     \[A+{{\delta }_{m}}=120\]                 \[{{\delta }_{m}}={{120}^{o}}-{{60}^{o}}\]                 \[{{\delta }_{m}}={{60}^{o}}\]


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