Standing Waves, beats and the Doppler effect

Demonstrations, experiments and resources for teaching Phys  3.3

Doppler Effect

The Doppler effect: video, practical and virtual demonstrations.

Doppler Ball
A Doppler ball shows the Doppler effect qualitatively.

Doppler Ball Frequency Shift Quantitative
Video and audio analysis software are used to study the Doppler effect quantitatively.

Beats and superposition

Includes virtual and physical demonstrations of beats.  Video and audio files are provided.

Combining Sounds
Add two sine waves. Display the signal versus time, the Fourier Power Spectrum, and play the resulting sounds on computer speaker.

Tuning Fork Beats
Two tuning forks with slightly different frequencies give beats.

Square Wave Simulation
Add sine waves to make a square wave.

Standing Waves and resonance

Tuning Fork Resonance
A tuning fork can easily transfer energy to another matching tuning fork, but not to one that resonates at a different frequency.

Standing Waves on a Slinky
A slinky mounted on a frame is used to demonstrate transverse and longitudinal standing waves. Markers on the slinky make the oscillatory motion of the medium visible.

Rubens Tube: Sound Flames
The heights of flames from holes in a tube shows sound nodes and antinodes.

Standing Waves on a Wire
An AC electric current is used to excite standing waves in a wire passed over a magnet.

Videos and simulations for teaching standing waves

This Physics Classroom interactive simulation helps you to see how the two travelling waves make one standing wave by interference 

For people interested in music watch Minute Physics’ “Why it is impossible to tune a piano”

Curious videos made with cameras inside a guitar: “No Iphone Guitar – Better guitar oscillations With a Webcam Inside” (note that these don’t show the standing waves – the ‘waves’ that are shown are artefacts of the rolling shutter.