3D30.70 - Hoot Tubes
Demonstrate standing sound waves in air which are caused by convection currents.
InstructionsA metal/cardboard tube has a 'block' of metal screen placed inside it a short distance from one end (~1/5 L). The tube dimension ratios must fall near: Diameter = L/9. Place the tube over a burner to heat up the screen, allow the screen to become cherry red, then remove the tube from the burner. With the tube in a vertical position the cooling screen sets up a sound vibration. Turn the tube horizontally and the sound stops. Turn the tube vertically again and the sound continues.