Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds
 

Standing waves

Demonstration

Generating standing waves from transverse waves on a rope and from longitudinal waves on a slinky spring.

Apparatus and materials

Slinky spring

Rope, 6 m, soft and flexible

Tank, large rectangular transparent

Health & Safety and Technical notes


Read our standard health & safety guidance

 

Procedure


a Tie one end of the rope securely to a fixture on a wall. Pull the other end taut. Move that end up and down, to excite transverse waves. Build up a pattern of standing waves, by feeling for the right resonant frequency, and adjusting the tension. 

wavesA more effective method is to drive the motion at a node. Secure the rope firmly at both ends. Mark off the rope into equal segments, such as fifths. Make a loose ring with a finger and thumb round the rope at the nearest marked point. Move your hand up and down, and change the frequency until the 5-loop motion builds up. Different resonances can be produced, of course, by changing the frequency or the tension. 

 
b Build up a longitudinal standing wave on a Slinky. Clamp both ends of the well-stretched spring, support it on a trolley runway, and excite it by hand near a node. 

 


Teaching notes


Be clear about the purpose of your demonstration. Depending on the course level and students’ abilities, your purposes in demonstrating standing waves may be any or all of the following: 

  • to demonstrate standing wave patterns as a form of vibration. 
  • to discuss energies associated with different patterns. 
  • to consider the two trains of waves necessary to the production of standing waves.  

 

This experiment was safety-checked in February 2006

 

Relating experiment


Water waves seen in section