IIT JEE , AIEEE Forum - Physics , Mechanics

sachin_gupta1991

Q. A certain loudspeaker(ssumed to be a point source) emits 30 W of sound power. A small microphone of effective cross-sectional area 0.75 cm² is located 200 m from the loudspeaker such that surface of microphone is in normal direction to wave propagation.Calculate:

(a)the sound intensity at microphone,

(b)the power received by the microphone.

Decoder

look i will give u some hints..

amplitude of waves from a pt. source changes with distance as

A = k/ r ...where r is the distance and k is proportionality const..

so from here u get Amplitude..

tht is earlier amplitude * r..

u have got the area of crossection as well..now calculate..

sachin_gupta1991

Come on goiitians, try it!!!!!!!!

SALUTES ASSURED.

harsha_27

(a) I = 5.97 x 10^-5 W/m².

(b) P = I.A = 4.47 x 10^-9W.

sachin_gupta1991

how did u get the answer to the first part?

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