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

  • question_answer
    A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to 3/4 of the angle of the prism. The angle of deviation is          [MNR 1988; MP PMT 1999; Roorkee 2000; UPSEAT 2000; MP PET 2005]

    A)            45°

    B)            39°

    C)            20°

    D)            30°

    Correct Answer: D

    Solution :

                       Given \[i=e=\frac{3}{4}A=\frac{3}{4}\times 60={{45}^{o}}\]                    In the position of minimum deviation            \[2i=A+{{\delta }_{m}}\] or \[{{\delta }_{m}}=2i-A=90-60={{30}^{o}}\]


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