3B40.20 • Doppler Effect: Rotating Speaker Bar

Location: Cabinet 6

Pictures show demonstration used at the University of Texas at Austin

Instructions:

• Start by selecting a desired frequency for hearing while the speaker bar is stationary.
• Then, manually rotate or oscillate the speaker bar at a constant rate.
• Compare the sound to the stationary orientation. Notice how inference patterns are generated when the bar is set to oscillate.

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Concept Conveyed:

• The rotating speaker bar allows students to hear the effect of sound interference and demonstrates the Doppler effect.
• When the bar is set to oscillate and students are stationary, they will perceive different interference patterns.

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Demo Staff:

• Connect the digital function generator to the speaker bar.

Last updated on April 27, 2026