KVPY Sample Paper KVPY Stream-SX Model Paper-15

  • question_answer
    Two coherent source- produce waves of different intensities which interfere. After interference, the ratio of to the minimum intensity is of the waves are in the ratio:

    A) \[4:1\]   

    B) \[25:9\]

    C) \[16:9\]

    D) \[5:3\]

    Correct Answer: B

    Solution :

    \[\frac{{{\text{I}}_{\text{max}}}}{{{\text{I}}_{\text{min}}}}\,=\,16\]\[\Rightarrow \] \[\frac{{{\text{A}}_{\text{max}}}}{{{\text{A}}_{\text{min}}}}\,\text{=}\,\text{4}\]
    \[\Rightarrow \]   \[\frac{{{\text{A}}_{1}}+{{\text{A}}_{2}}}{{{\text{A}}_{1}}-{{\text{A}}_{2}}}=\,\frac{4}{1}\]
    Using componendo and dividendo
                \[\frac{{{\text{A}}_{1}}}{{{\text{A}}_{2}}}\,=\,\frac{5}{3}\]
    \[\Rightarrow \]   \[\frac{{{\text{I}}_{\text{1}}}}{{{\text{I}}_{\text{2}}}}\,\text{=}\,{{\left( \frac{\text{5}}{\text{3}} \right)}^{\text{2}}}\text{=}\frac{\text{25}}{\text{9}}\text{.}\]


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