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

  • question_answer
    A ray of light is incident at an angle of 60° on one face of a prism of angle 30°. The ray emerging out of the prism makes an angle of 30° with the incident ray. The emergent ray is  [EAMCET 1990; MP PMT 1990]

    A)            Normal to the face through which it emerges

    B)            Inclined at 30° to the face through which it emerges

    C)            Inclined at 60° to the face through which it emerges

    D)            None of these

    Correct Answer: A

    Solution :

                       We know that \[\delta =i+e-A\Rightarrow e=\delta +A-i\]                    = \[{{30}^{o}}+{{30}^{o}}-{{60}^{o}}={{0}^{o}}\]                    \[\therefore \] Emergent ray will be perpendicular to the face.            Therefore it will make an angle of 90° with the face through which it emerges.


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