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

Standing waves and resonance

Demonstration and class experiments of standing waves provide a key link to musical instruments and to an important principle of engineering design. 
Use a selection from these experiments to illustrate that standing waves are to be found in many situations. The waves are in general more complex than those on a cord, but certain features remain the same:

  • There are definite modes of oscillation, at each of which the response is large (resonance).
  • The patterns depend on the frequency, there being more nodes or nodal lines for high frequencies (short wavelengths).
  • Standing waves have to 'fit' into the system, whether it has one or more dimensions. They are the result of superposition of reflected waves from the boundaries and waves travelling towards the boundaries. As a general rule, wave-carrying systems with edges exhibit standing waves.

Experiments

Standing waves

Ring of standing waves

Vibrations in a rubber sheet

Standing waves on a rubber cord

Standing waves along trolleys

Melde's experiment

Musical instruments

Music from standing waves: monochord

Sound waves

Vibrations of a loudspeaker cone

Centimetre waves

Stationary waves in an air column

Longitudinal standing waves

Longitudinal standing waves in rods

Standing waves with a variable wavelength

 

Related Guidance

Demonstration or class experiment?

Why experiment with waves?

Using wave simulations

The usefulness of the standing wave idea

Standing waves and resonance

Some ideas for home experiments: waves