Question

Two coherent sources have intensity ratio of $100:1$, and are used for obtaining the phenomenon of interference. Then the ratio of maximum and minimum intensity will be -

• A. $100:1$
• B. $121:81$
• C. $1:1$
• D. $5:1$

Answer 1

The correct option is B $121:81$

Given, $I_1:I_2=100:1$

$\frac{\sqrt{I_1}}{\sqrt{I_2}}=10:1$

The maximum intensity obtained in the interference is,

$I_{max}=(\sqrt{I_1}+\sqrt{I_2}{)}^2=(10+1{)}^2=121$

The minimum intensity obtained in the interference is,

$I_{min}=(\sqrt{I_1}-\sqrt{I_2}{)}^2=(10-1{)}^2=81$

The ratio of maximum and minimum intensities is,

$\frac{I_{max}}{I_{min}}=121:81$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(B\right)$ is the correct answer.