3D40.20 Singing Rod


Longitudinal standing waves in an aluminum rod, resonance


An aluminum rod is held at various nodal points and stroked with rosined fingers or gloves, producing a loud sound that lasts a long time. The sound can be amplified by touching the end of the rod to a styrofoam cup.



  • [1] Aluminum rod
  • [1] Rosined gloves
  • [1] Bag of rosin powder
  • [1] Solid resin
  • [1] Styrofoam cup

Important Notes

  • This demonstration requires a lot of advance practice.


  1. Wear rosined gloves and add more rosin powder as necessary.
  2. Pinch the rod between two fingers at the L/2 location.
  3. Stroke the rod firmly starting at L/2 all the way to the rod's end. The rod produces the first harmonic.
  4. Press the end of the rod to a styrofoam cup after it has been excited to amplify the sound.
  5. Repeat step 2 to 4 while pinching the rod at the L/4 and then L/6 positions to produce the second and third harmonic respectively.


Additional Resources


  • PIRA 3D40.20


  • Don't attempt this at home!

Last revised

  • 2018


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If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.