Q. Two waves coming from two coherent sources, having different intensities interfere their ratio of maximum intensity to the minimum intensity is 25$.$ The intensities of the sources are in the ratio
A) 25 : 1
B) 25 : 16
C) 9 : 4
D) 5 : 1
Explanation
(c) Given $:\frac{I_{\max}}{I_{\min}} = 25$
$\frac{I_{\max}}{I_{\min}} = \frac{(a + b)^{2}}{(a - b)^{2}}$
where $a,b$ are amplitudes of two waves
$\Rightarrow \frac{a + b}{a - b} = \frac{5}{1} \Rightarrow a + b = 5a - 5b$
$\Rightarrow \frac{a}{b} = \frac{3}{2}\ \ \therefore\frac{I_{1}}{I_{2}} = \frac{a^{2}}{b^{2}} = \left( \frac{3}{2} \right)^{2} = \frac{9}{4}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.