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Travelling Waves [UBC PHAS Demonstration Room Catalog]

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Travelling Waves


A clear rubber rope filled with barium sulphate (a high density powder). It's about 9.5m long (~31 feet). One end is capped with a piece of acrylic rod, the other end is tied to a large brass lobster clasp.


This is a highly versatile demonstration. It can be used to demonstrate a number of concepts relating to waves and their propagation through media. It can be used to:

  • Demonstrate how transverse waves can propagate through a string,
  • Demonstrate the reflection of a pulse from a rigid-non-rigid boundary,
  • Demonstrate reflection and transmission of waves at a boundary,
  • Demonstrate standing waves,
  • Demonstrate different modes of standing waves.


  • 'Yak's milk'1) rope


The tubing is stretched across the lecture theatre with one end fixed to a hook on the wall while the other end is free to be manipulated by hand to show the various demonstrations. If no hook is available, attaching it to a door handle or a volunteer student may also work. For the non-rigid reflection and for the partial reflection and transmission at a boundary the far end is attached to a piece of cord and the other end manipulated.

The rope may also be laid flat on the floor and viewed with a camera from above. This is another way that travelling waves may be viewed. This definitely works better with the rope under tension and off the ground, though.

Finally, with a TA or volunteer, standing waves can be produced in the Yak's milk rope. Higher-order standing waves can be obtained with sufficiently great effort.


Demo room information

Location S4
Maker Unknown
Current State Working
It was apparently named that by a previous professor who taught here some years ago. He was supposed to have an affinity for very colorful and interesting language- hence the name of this rope.
demonstrations/3_oscillations_and_waves/mechanical_waves/travelling_waves/start.txt · Last modified: 2020/03/13 21:03 by demoroom