Question

The ratio of the maximum and minimum intensities in the interference pattern is pattern produced by two coherent sources of light is 9:1.the intensity of used light?

• A. $4:1$
• B. $25:1$
• C. $36:1$
• D. $49:1$

Answer 1

The correct option is A $4:1$

$\begin{array}{c}\frac{I_{max}}{I_{min}}=\frac{{\left(a_1+a_2\right)}^2}{{\left(a_1-a_2\right)}^2}\\ \frac{9}{1}=\frac{{\left(a_1+a_2\right)}^2}{{\left(a_1-a_2\right)}^2}\\ \frac{a_1}{a_2}=\frac{2}{1}\\ \frac{a_1^2}{a_2^2}=\frac{l_1}{l_2}=\frac{4}{1}\end{array}$

Hence, Option $A$ is correct.