# Intensity of sound wave

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Find the intensity(I) of sound wave whose frequency is 250 Hz. The displacement amplitude of particles of the medium at this position is 1 × 10$^{–8 }$m. The density of the medium is 1 kg/m$^3$ , bulk modulus (B) of elasticity of the medium is 400 N/m$^2$ .

I know I=2$(\pi f A)^2 \rho v$
And v $=\sqrt {B/\mu}$
Where $\mu =$ mass per unit length .

But I could not understand how to use them .

You seem to have all the equations and data which you need. Put in the values and calculate the answer. I don't understand the difficulty.

$\mu$ should be density, not mass per unit length.
Here what is amplitude ?
*The displacement amplitude of particles of the medium at this position is 1 × 10^–8 m. *

I=2$(\pi f A)^2 \rho v$
And v $=\sqrt {B/\mu}$
Where $\mu =$ mass per unit volume .
And I =2$\pi ^2 (250)^2(10^{-8})^2 20$
I =$2.46$ x$10^{-9}W/m^2$