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

  • question_answer
    When light rays are incident on a prism at an angle of 45°, the minimum deviation is obtained. If refractive index of the material of prism is \[\sqrt{2}\], then the angle of prism will be [MP PMT 1986]

    A)            30°

    B)            40°

    C)            50°

    D)            60°

    Correct Answer: D

    Solution :

                       \[\frac{\sin \frac{A+\delta \,m}{2}}{\sin \frac{A}{2}}=\mu ,\] But \[\frac{A+{{\delta }_{m}}}{2}=i={{45}^{o}}\]            So \[\frac{\sin {{45}^{o}}}{\sin (A/2)}=\sqrt{2}\Rightarrow \frac{1}{2}=\sin \frac{A}{2}\Rightarrow A={{60}^{o}}\]


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