Physlet Illustration: Intensity as a Function of Position

 

 

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The speaker projects 100 Watts of sound isotropically into the room shown.  How do the intensity (I, in Watts/m2) and sound level (b, in dB) depend upon the position of the microphone? Horizontal and vertical distances from the speaker can be "measured" by clicking the mouse and are shown in meters.

Hints

  1. Move the microphone to various positions and observe the Intensity.  Does it vary with horizontal position? Vertical position?  Distance from the speaker?
  2. Measure the intensity at several positions and determine if it varies like 1/r2.
  3. Measure the sound level at several positions and determine if it is calculated properly. (Remember that I0 = 10-12 W/m2.)

Reference

See Walker, Section 14-5

Illustration written by Chuck Niederriter