Login

Search the forums now!

Welcome, Guest. Please login or register.

October 21, 2025, 04:22:29 pm
Pages: [1]   Go Down

Author Topic: sound: finding power of source  (Read 796 times)  Share 

0 Members and 1 Guest are viewing this topic.

Thelimz

  • Victorian
  • Forum Regular
  • **
  • Posts: 81
  • Respect: 0
sound: finding power of source
« on: August 24, 2011, 03:46:43 pm »
0
3 m away from a speaker, the intensity is 0.71 Wm^-2. What is the power of the source?
Logged
Methods cas 43 --->~47 (2010)
Specialist 39--->~50
English 41--->~40.4
German 38--->~46.7
Chemistry 36--->~40.5
Physics 42--->~44.5       Aggregate 192.8

mardat

  • Victorian
  • Adventurer
  • *
  • Posts: 16
  • Respect: 0
  • School: Melbourne High School
Re: sound: finding power of source
« Reply #1 on: August 24, 2011, 04:32:56 pm »
0
The formula to use is I=P/A where I is intensity, P is power, and A is area. Given you want to find power, you can re-arrange that equation to P the subject -> P=I*A. Then sub in values. I is 0.71, and A is 4*pi*r^2 (The surface area of a sphere) where r is the distance from the speaker, i.e. 3. That formula will give you P=0.71*4*pi*3^2 = 80.30W
Logged

Lasercookie

  • Honorary Moderator
  • ATAR Notes Legend
  • *******
  • Posts: 3167
  • Respect: +326
Re: sound: finding power of source
« Reply #2 on: August 24, 2011, 04:34:04 pm »
0
intensity = power/area
Sound intensity is the ratio of the sound power to the surface area of a sphere of radius r. (think about the shape of a wave)





Surface area of sphere:





Let me know if this is correct.

edit: damn, beaten :(
Logged
Pages: [1]   Go Up