Question

Chapter 17, Problem 035 A po int source emits 79.3 w o sound isotropically. A small microphone intercepts the sound n an area o 0.122 ст 570 m rom ie source. Ca u ate a esu intensity there an e power tercepte the microphone. (a) Number (b) Number Units Units

Answer 1

Intensity = Power/Area = 79.3/4 pi r^2 = 79.3/4 pi (570)^2 I = 1.942 times 10^-5 W/m^2 (b) A = 0.122 cm^2 = 0.122 times 10^-4 = 1.22 times 10^-5 m^2 Then the power interpted by the microphone is P'1 = IA = (1.22 times 10^-5) times [1.942 times 10^-5) p'1 = 2.37 times 10^-10 w