Due to point isotropic sound source, theintensity at a point is observed as 40 dB. The density of air is `rho=((15)/(11))(kg)/(m^3)` and velocity of sound in air is `330(m)/(s)`. Based on this information answer the following questions.
Q. The pressure amplitude at the observation point is

Options

A. `3(N)/(m^2)`
B. `3xx10^3(N)/(m^2)`
C. `3xx10^-3(N)/(m^2)`
D. `6xx10^-2(N)/(m^2)`

Answer

C

Explanation

In the propagation of sound waves, let pressure amplitude be `trianglep_0` and displacement amplitude be `A`, then,
`trianglep_0=BAK`
where symbols have their usual meanings. We have
`FL=10log((I)/(I_0))`
`implies40=10log((I)/(10^(-12)))`
`impliesI=10^-8(W)/(m^2)`
`I=(trianglep_0^2)/(2rhov)`
`impliestrianglep_0=sqrt(Ixx2rhov)`
`=sqrt(10^-8xx2xx(15)/(11)xx330)(N)/(m^2)`
`=3xx10^-3(N)/(m^2)`