For a person with normal hearing, the faintest sound that can be heard at a frequency of `400 Hz` has a pressure amplitude of about `6.0 xx 10^(-5)` Pa . Calculate the corresponding intensity and sound intensity lavel at `20^(@) C`. (Assume `upsilon = 330 m//s` and `rho _(air) = 1.29 kg //m^(3)`).

Answer

A, B, C, D

Explanation

`I = (nu(Delta p)^(2)max)/(2B) rArr nu = sqrt((B)/(rho))`
:.`B = rho nu^(2)`
:. `I = ((Delta p)^(2)max)/(2rho nu)`
`= (6 xx 10^(-5))^(2)/(2 xx 1.29 xx 330)`
`= 4.2 xx 10^(-12) W//m^(2)`
`L= log^(10) ((I)/(I_(o)))`
`= 10 log^((10) ((4.2 xx 10^(-12))/(10^(-12)))`
`= 6.23 dB`