A point `A` is located at a distance `r = 1.5 m` from a point source of sound of frequency `600 H_(Z)`. The power of the source is `0.8 W`. Speed of sound in air is `340 m//s` and density of air is `1.29 kg//m^(3)`. Find at the point `A`, (a) the pressure oscillation amplitude`(Deltap)_(m)` (b) the displacement oscillation amplitude `A`.

Answer

(a) `5Nm^(-2)` , (b) `3 mum`

Explanation

`P_(0) = sqrt(2l_(rho)V)`
`= sqrt(2((P)/(4pir^(2)))rhoV)` , `(":' I = (P)/(4pir^(2))) = sqrt((2 xxa .8 xx 225pi xx 340)/(544 xx 4pi xx 1.5 xx 1.45)) = 5N//m^(2)`
`S_(0) = (P_(0))/(Bk) = (P_(0))/(rhoV^(2)((w)/(V))) = (P_(0))/(2pirhoVn)` (`:' B = rhov^(2)` or `k = (omega)/(v)`)
`= (5 xx 44)/(2pi xx 225pi xx 340 xx 600) = (5 xx 544 xx 3 xx 3.375)/(2 xx 225 xx 340 xx 600 xx 100) = 3 xx 10^(-6)m = 3 mum`