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Waves — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysicsWaves3 Marks
Question
Two sound waves originating from the same source, travel along different paths in air and then meet at a point. If the source vibrates at a frequency of 1kHz and one path is 83cm longer than the other, what will be the nature of interference? The speed of sound in air is 332m/s.
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Answer

Wavelength of sound wave is
$\lambda=\frac{v}{\text{v}}=\frac{332}{1\times10^3}=0.332\text{m}$
Phase difference between the waves arriving at point of observation is
$\phi=\frac{2\pi}{\lambda}\Delta\text{x}$
$=\frac{2\pi\times0.83}{0.332}=5\pi$
Since phase difference is an odd multiple of $\pi,$ the interference is destructive.

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