CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2005

  • question_answer
    Two coherent light beams of intensity \[I\]and \[4I\] are superposed. The maximum and minimum possible intensities in the resulting beam are:

    A)  \[9I\] and \[I\]                

    B)  \[9I\] and \[3I\]

    C)  \[5I\] and \[I\]                 

    D)  \[5I\] and \[3I\]

    Correct Answer: A

    Solution :

    As \[I\propto {{a}^{2}}\] or \[a\propto \sqrt{I}\] \[\therefore \]  \[\frac{{{a}_{1}}}{{{a}_{2}}}=\frac{1}{2}\]                 \[\frac{{{I}_{\max }}}{{{I}_{\max }}}={{\left( \frac{{{a}_{1}}+{{a}_{2}}}{{{a}_{1}}-{{a}_{2}}} \right)}^{2}}\]                                 \[={{\left( \frac{1+2}{1-2} \right)}^{2}}\]                                 \[=\frac{9}{1}\] \[\therefore \]  \[{{I}_{\max }}=9I,\,{{I}_{\min }}=I\]


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