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General Thermodynamics

  • H3-12: ROARING TUBE - 4 FT

    H3-12
    Demonstrate standing sound waves in air excited by convection currents.
    A switch is held closed, activating a nichrome wire coil in a vertical glass tube, leading to a very loud roar at about 130 Hz, the fundamental frequency of a four-foot air tube. This is the classic Rijke tube demonstration with an electrical heater replacing a gas burner and screen as the source of the convection currents.

    Consider combing this with H3-13, and invite students to make predictions about the differences in pitch and volume.
    FS1

  • H3-13: ROARING TUBE - 8 FT

    H3-13
    Demonstrate standing sound waves in air excited by convection currents.
    A switch is held closed, heating a nichrome wire coil in a vertical four-inch diameter galvanized steel downspout tube, leading to a very loud roar at about 65 Hz, the fundamental frequency of an eight-foot air tube. This is the classic Rijke tube demonstration with an electrical heater replacing a gas burner and screen as the source of the convection currents.

    Consider combing this with H3-12, and invite students to make predictions about the differences in pitch and volume.

    h3-13coilh3-13drawing

  • H3-16: SINGING PIPES

    H3-16
    Show sound resonance created by convection currents in a tube.
    A gas flame is inserted into one end of the tube, heating the wire mesh which has been pre-positioned in the lower half of the tube using the plunger. Holding the tube vertical after the mesh has been heated red hot creates convection currents which enable the tube to resonate. Tilting the tube nearly horizontal limits the convection currents and the sound ceases.

    This can be an exciting demonstration, but requires careful handling for safety. Also consider H3-12 and H3-13.