Week 6: Waves II
Chapter 18
Facts you may need for the Quiz:
Do the homework and think about the concepts
they are trying to illustrate,
i.e Doppler shift, how and WHY intensity
varies with amplitude and distance,
interference phenomena, etc..
Concept-tests:
6.1 Foghorns
6.2 Booming Bass
6.3 Measuring decibels.
6.4 Beats
Answers to
Concept Tests
Demos:
RIPPLE TANK--showed how waves spread out from source, with
two sources an interference pattern can be seen.
Chlandni Plates--used to demonstrate how a stereo speaker works.
SOUND SOURCE MEASURED BY dB METER--demonstrated dependence of intensity on
amplitude and distance. Demo was used in conjunction with concept test 6.3
Interference Slides--demonstrates interference between circular waves.
TWO SPEAKERS OUT OF PHASE--demonstrated destructive interference of sounds waves
by wiring the speakers such that they are out of phase with each other.
Hoot Tube--demonstrated a resonant cavity "wind" instrument.
ACOUSTICE BEATS--two speakers are driven at slightly different frequencies. They
combine to form a sound that oscillates in amplitude. This osciallation is called
a beating phenomena, and the rate at which it occurs is the beat frequency.
Links: