NEET NEET SOLVED PAPER 2015 (Re)

  • question_answer
    Two slits in Young?s experiment have widths in the ratio 1 : 25. The ratio of intensity at the maxima and minima in the interference pattern \[\frac{{{I}_{\max }}}{{{I}_{\min }}}\] is                                                                      

    A)  \[\frac{9}{4}\]                  

    B)  \[\frac{121}{49}\]                           

    C)  \[\frac{49}{121}\]                           

    D)  \[\frac{4}{9}\]

    Correct Answer: A

    Solution :

                    Given, In YDSE experiment, having two slits of width in the ratio of                 1 : 25 So, ratio of intensity, \[\frac{{{I}_{1}}}{{{I}_{2}}}=\frac{{{W}_{1}}}{{{W}_{2}}}=\frac{1}{25}\Rightarrow \frac{{{I}_{2}}}{{{I}_{1}}}=\frac{25}{1}\] \[\therefore \]       \[\frac{{{I}_{\max }}}{{{I}_{\max }}}=\frac{{{(\sqrt{{{I}_{2}}}+\sqrt{{{I}_{1}}})}^{2}}}{{{(\sqrt{{{I}_{2}}}-\sqrt{{{I}_{1}}})}^{2}}}={{\left[ \frac{\sqrt{\frac{{{I}_{2}}}{{{I}_{1}}}}+1}{\sqrt{\frac{{{I}_{2}}}{{{I}_{1}}}}-1} \right]}^{2}}\] \[\Rightarrow \,\,\,\,\,\,{{\left[ \frac{5+1}{5-1} \right]}^{2}}={{\left( \frac{6}{4} \right)}^{2}}=\frac{36}{16}=\frac{9}{4}\] Thus,    \[\frac{{{I}_{\max }}}{{{I}_{\min }}}=\frac{9}{4}\]


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