12/15/09
Post date: Dec 15, 2009 2:18:50 PM
Bell Ringer: Why does the laser (reflecting off a speaker) bounce around so much?
Sound as vibration
Speaker vibrates, causes air molecules to vibrate
Vibration of speaker causes vibration of laser (reflecting off a vibrating mirror)
Sound as a pressure wave
As speaker moves forward and backward, it compresses and expands the air
Compressions and expansions (rarefactions) move outward from the source
Ear is a very sensitive pressure sensor (can detect pressure change when going in an airplane, driving up or down a big hill, or even changes in the weather)
Ruben's Tube demonstration - flame height indicates amount of pressure
Finish 16.1 Notes
16.1 Review due tomorrow