(a) What is the intensity of a `60 dB` sound ? (b) If the sound level is `60 dB` close to a speaker that has an area of `120 cm ^(2)` . What is the acoustic power output of the speaker?

Answer

A, B

Explanation

(a) `L = 10 log_(10) ((I)/(I_(o)))`
`60 = 10 log_(10) ((I)/(10^(-12)))`
Solving we get,
`I = 10^(-6) W//m^(2)` (b) `I = (P)/(S)`
:. `P = (I) (S)`
= `(10^(-6)) (120 xx10^(-4))`
`= 1.2 xx 10^(-8) W`