RAJASTHAN ­ PET Rajasthan PET Solved Paper-2008

  • question_answer
    The ratio of intensities of two beams of light in interference is 9 : 1. The ratio of maximum and minimum intensities

    A)  10 : 8            

    B)  9 : 1

    C)  4 : 1             

    D)  2 : 1

    Correct Answer: C

    Solution :

     \[\frac{{{I}_{1}}}{{{I}_{2}}}=\frac{a_{1}^{2}}{a_{2}^{2}}=\frac{9}{1}\] \[\Rightarrow \] \[\frac{{{a}_{1}}}{{{a}_{2}}}=\frac{\sqrt{9}}{1}\] \[\Rightarrow \] \[\frac{{{a}_{1}}}{{{a}_{2}}}=\frac{3}{1}\] Then, \[\frac{{{I}_{\max }}}{{{I}_{\min }}}=\frac{{{({{a}_{1}}+{{a}_{2}})}^{2}}}{{{({{a}_{1}}-{{a}_{2}})}^{2}}}\] \[=\frac{{{(3+1)}^{2}}}{{{(3-1)}^{2}}}\] \[=\frac{{{(4)}^{2}}}{{{(2)}^{2}}}=\frac{16}{4}=\frac{4}{1}\] Here, \[{{I}_{\max }}:{{I}_{\min }}=4:1\]


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