Two coherent sources of intensity ratio $9: 4$ produce interference. The intensity ratio of maxima and…

Two coherent sources of intensity ratio $9: 4$ produce interference. The intensity ratio of maxima and minima of the interference pattern is
  1. $13:6$
  2. $5:1$
  3. $25:1$
  4. $3:2$

Solution

$\begin{aligned} & \text { } \frac{I_{\max }}{I_{\min }}=\left(\frac{\sqrt{I_1}+\sqrt{I_2}}{\sqrt{I_1}-\sqrt{I_2}}\right)^2=\left(\frac{\sqrt{9}+\sqrt{4}}{\sqrt{9}-\sqrt{4}}\right)^2 \\ & =\left(\frac{3+2}{3-2}\right)^2=25\end{aligned}$

Asked in: AP EAMCET 2015

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