When a PVC pipe is placed over a propane torch flame, the heated air resonates within the tube, producing a tone. The pitch depends on the length of the pipe, with longer tubes producing lower tones.

1. Light a propane torch and set it to its hottest setting.
2. Position the flame so that it points horizontally.
3. Lower a PVC pipe vertically over the flame, adjusting its height until a resonant tone is heard.

How Heat Sings (Thermoacoustic Resonance) - Walter Lewin:

📄 A Hot Tone - Lucas Owens (Page 11 - A Hot Tone): https://www.unco.edu/nhs/science/pdf/demos/2013_LongsPeak.pdf

• Use pipes of varying diameters to observe changes in resonance.

• Always wear heat-resistant gloves and safety glasses when working with open flames.
• Keep flammable materials away from the flame.
• Hold the torch securely and never point it toward yourself or others.
• Ensure the work area is well-ventilated to avoid buildup of combustion gases.
• Allow pipes to cool before handling after use.

• Why does heated air create a standing wave in the tube?
• How does the length of the tube affect the frequency of the sound produced?