Question

$S_1,S_2$ are two coherent sources of sound located along x-axis separated by $4\lambda$ where $\lambda$ is wavelength of sound emitted by them. Number of maxima located on the elliptical boundary around it will be :

• A. $16$
• B. $12$
• C. $8$
• D. $4$

Answer 1

The correct option is A $16$

At the end of major axis the path difference between the two waves are $4\lambda$ and at the end of minor axis the path difference is $0$

So there will be 3 points of maxima with path differences $3\lambda ,2\lambda ,\lambda$

So there will be total $12$ points on the four arcs

On the ends of both major and minor axis it forms maxima because path differences are $4\lambda$ and $0$

So there are total of $12+4=16points$