Seebeck's Disk

Ensure compressed air pressure does not exceed equipment ratings (typically 30-60 PSI). Do not direct air jet toward people. Secure all hose connections to prevent whipping if disconnected under pressure.

This demonstration can produce loud tones, especially at high rotation speeds. Warn the class before starting and limit exposure time. Consider ear protection for extended use or when demonstrating high frequencies.

Purpose

Demonstrates that periodic air disturbances produce musical tones while aperiodic ones produce noise. Evenly spaced holes on the outer rings create chords; randomly spaced inner holes create noise. Changing rotation speed changes pitch, showing $f \propto f_{rotation}$ .

Large metal siren disk with multiple concentric rings of holes, mounted on a white motor base. A yellow air hose with nozzle is positioned near the disk, and a yellow bar clamp secures the apparatus to the table.

Figure 1: The Seebeck disk apparatus showing the perforated disk mounted on a motor with air jet positioned to interrupt airflow through the holes. The outer rings have evenly-spaced holes for producing musical tones, while inner holes are randomly spaced to produce noise.

Siren Disk on Rotator

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Warning: Compressed Air Safety

Warning: Loud Sound Warning

Purpose

Safety Warnings

Warning: Compressed Air Safety

Warning: Loud Sound Warning

Purpose