Question

For a sound wave travelling towards +x direction, sinusoidal longitudinal displacement $\xi$ at a certain time is given as a function of x(Figure). If bulk modulus of air is $B=5\times {10}^{5}N/m^2$, the variation of pressure excess will be

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

$\xi =Asin(kx-\omega t)P_{e}x=-B\frac{d\xi }{dx}=-BAkcos(kx-\omega t)Amplitudeof{P}_{ex}isBAk=(5\times {10}^5)\left({10}^{-4}\right)\left(\frac{2\pi }{0.2}\right)=5\pi \times {10}^{2}Pa$