SUBJECT AREA: (Physics, General Science, Sound)

MATERIALS:

1. PVC drain pipe, 1.5 to 2 inches diameter, several lengths from two to five feet long.

2. Propane torch

PROCEDURE:

1. Light propane torch and turn on to largest (hottest) setting.

2. Hold the torch in a position so that the flame is perpendicular.

3. Lower the pipe over the flame. Adjust height until tone develops.

4. Repeat with each pipe length.

QUESTIONS:

1. How is the tone produced?

2. Is there a difference with different lengths of pipe?

RATIONALE:

The heat of the flame causes the air in the tube to suddenly expand. The hot air begins to oscillate up the tube, resulting in a resonating tone. A standing wave is created in a tube with open ends. The longer the tube, the longer the wavelengths produced in the standing wave and thus the lower the tone.

APPLICATION:

Steam whistles, upward air draft on a chimney

PREPARED BY: Annette Hynes

TAKEN FROM: Ron Bonnstetter