J & K CET Engineering J and K - CET Engineering Solved Paper-2004

  • question_answer
    Two coherent sources of intensity ratio \[1:4\] produce an interference pattern. The fringe visibility will be

    A)  \[1\]               

    B)  \[0.8\]           

    C)  \[0.4\]            

    D)  \[0.6\]

    Correct Answer: B

    Solution :

    Fringe visibility \[V=\frac{2\sqrt{{{I}_{1}}{{I}_{2}}}}{{{I}_{1}}+{{I}_{2}}}\] where \[{{I}_{1}}\] and \[{{I}_{2}}\] are intensities of coherent sources. Given,          \[\frac{{{I}_{1}}}{{{I}_{2}}}=\frac{1}{4}\] \[\therefore \] \[{{I}_{2}}=4{{I}_{1}}\] \[\therefore \] Fringe visibility  \[=\frac{2\sqrt{{{I}_{1}}\times 4{{I}_{1}}}}{({{I}_{1}}\times 4{{I}_{1}})}\] \[=\frac{2\times 2{{I}_{1}}}{5{{I}_{1}}}=\frac{4}{5}\] \[\Rightarrow \] \[V=0.8\]


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