Question

Two coherent sources produce waves of different intensities which interfere. After interference, the ratio of the maximum intensity to the minimum intensity is $16$. The intensity of the waves are in the ratio:

• A. $4:1$
• B. $25:9$
• C. $6:9$
• D. $5:3$

Answer 1

Answer: (B)

$25:9$

$\frac{I_{max}}{I_{min}}=16$
$\Rightarrow \frac{A_{max}}{A_{min}}=4$
$\Rightarrow \frac{A_1+A_2}{A_1-A_2}=\frac{4}{1}$
Using componendo & diviendo.
$\frac{A_1}{A_2}=\frac{5}{3}\Rightarrow \frac{I_1}{I_3}={\left(\frac{5}{3}\right)}^2=\frac{25}{9}$