AMU Medical AMU Solved Paper-2000

  • question_answer
    If the two interfering beams have intensities in the ratio of 9 : 4. The ratio of intensities of maxima and minima in the interference pattern will be

    A)  4 : 9                                      

    B)  3 : 4

    C)  1 : 25                                    

    D)  25 : 1

    Correct Answer: D

    Solution :

                     The intensity of interfering beam is given by                 \[I=k{{a}^{2}}\]where a is amplitude. \[\therefore \]  \[\frac{{{l}_{1}}}{{{l}_{2}}}=\frac{{{a}_{1}}^{2}}{{{a}_{2}}^{2}}\] Given,   \[\frac{{{I}_{1}}}{{{I}_{2}}}=\frac{9}{4}\] \[\therefore \]  \[\frac{{{a}_{1}}}{{{a}_{2}}}=\frac{3}{2}\]                 \[\frac{{{I}_{\max }}}{{{I}_{\min }}}=\frac{{{({{a}_{1}}+{{a}_{2}})}^{2}}}{{{({{a}_{1}}-{{a}_{2}})}^{2}}}\]                 \[=\frac{{{\left( \frac{3}{2}{{a}_{2}}+{{a}_{2}} \right)}^{2}}}{{{\left( \frac{3}{2}{{a}_{2}}-{{a}_{2}} \right)}^{2}}}=\frac{25}{1}\]


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