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Uttarakhand PMT Uttarakhand PMT Solved Paper-2008

  • question_answer
    The ratio of intensity at the centre of a bright fringe to the intensity at a point distant or one fourth of the distance between two successive bright fringes will be

    A)  4               

    B)  3

    C)  2               

    D)  1

    Correct Answer: C

    Solution :

     Intensity at the centre of bright fringe, \[{{I}_{0}}=I+I+2\sqrt{I\,I}\cos 0{}^\circ \] \[{{I}_{0}}=2I+2I\] \[{{I}_{0}}=4I\] Intensity at a point distant\[\beta /4\](with a phase difference\[=2\pi /4=\pi /2)\]is \[I=I+I+2\sqrt{I\,I}\cos \frac{\pi }{2}\] \[I=2I+2\sqrt{I\,I}\times 0\] \[I=2I\] \[\therefore \] \[\frac{{{I}_{0}}}{I}=\frac{4I}{2I}=2\]


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