A tuning fork is struck to activate the "clang tone" and whirled about the instructor's head on a string. The Doppler effect can easily be heard in a small classroom or a reasonably quiet lecture hall.
• Encourage students to listen closely to how the pitch changes, and compare it to other similar sounds. Where else do they experience this effect?
As the source of the sound waves moves through the air, the wavefronts in the direction of motion are compressed, while the wavefronts in the opposite direction are extended, changing the pitch we hear. Because the fork is rotating, this causes a repeating pattern as the pitch is first higher, then lower, than the natural pitch of the tuning fork.
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Last modified on Monday, 22 March 2021 16:56