Physics Demo Videos: Waves and Oscillations

Videos of demonstrations illustrating concepts related to oscillations, waves, sound, and interference.

For other videos from our demonstration collection, please visit Physics Demo Videos. You may also wish to view our Video Lecture Series for short tutorials on topics from first year physics.

[Note: if you get an error message on playing a video, try clearing your browser’s cache and cookies, or try viewing in an incognito window.]

Oscillations
Spring and Rotating Wheel.  The y-component of a point on a rotating wheel matches the motion of an oscillating mass on a spring.
Chladni Plates. When a two dimensional object is vibrated, patterns of waves can be seen. The sand on the plate collects in the nodes, or areas of no motion, of the waves.
Wave propagation on a wave machine
Shive Wave Machine; wide section, single wave, free end. A wave propagates down the machine. At the free end it is reflected with the same amplitude and without inversion.
Shive Wave Machine; wide section, single wave, fixed end. A wave propagates down the machine. At the fixed end it is reflected with the same, but negative amplitude.
Shive Wave Machine; narrow section, single wave, free end. A wave propagates down the machine. At the free end it is reflected with the same amplitude. The wave on this section moves faster than the wave on the wider section.
Shive Wave Machine; narrow section, single wave, fixed end. A wave propagates down the machine. At the fixed end it is reflected with the same, but negative amplitude. The wave on this section with narrow rods moves faster than the wave on the wider section.
Shive Wave Machine; all sections, single wave, free end. A wave propagates down the machine, going from a wide section to a narrow section via a connecting section. As the sections get narrower, the wave travels faster.
Shive Wave Machine; two sections, single wave, free end. When a wave hits the abrupt transition, as represented by going from the narrow to the wide section without the connecting section, most of the wave is reflected at the barrier. Compare to what happens when light travels from a medium with one index of refraction to another.
Sound
Pasco Synthesizer: Pure Tones. A synthesizer is able to produce ‘pure’ tones, each being a single sine wave.
Waves on strings
Guitar strings: overtones. Touching a string kills all overtones except those having a node where touched.
Guitar strings: mass per unit length. Strings of different mass per unit length yield different pitches.
Guitar strings: tuning a string. Increasing tension increases the pitch.
Guitar strings: changing length. Pressing strings down onto frets shortens the string, increasing the pitch.
Guitar strings: tone. The relative intensity of different overtones changes the tone of the guitar. Strumming closer to the bridge results in more intensity in higher frequency overtones.
Waves in air columns
Pipe, closed end.   As the piston is moved out, the standing wave that is set up inside the instrument lengthens, producing a lower pitch. When the slide comes out, this changes from a closed end to an open end, and the pitch increases substantially. How much does the frequency increase?
Organ pipes. Different lengths of pipe yield different pitches. Blowing harder can excite higher frequency modes.
The Doppler Effect
Moving a tuning fork. Swinging a tuning fork toward the observer increases the frequency of the sound. Swing it away lowers the frequency.
Twirling a tuning fork. When the tuning fork moves toward you, the frequency of the sound you hear is higher. As it moves away …
Doppler shift, sidewalk observer. The Doppler shift created by a passing car: The frequency of the car’s horn is higher when the car is moving towards you and us lower as it is moving away.
Doppler shift, observer traveling with source. Car horn as heard by a passenger in the car.
Doppler shift, observer in a car meeting another car whose horn is blowing. The pitch change is even greater as the cars pass each other.
Interference
Beats from two tuning forks. Tuning forks at slightly different frequency produce “beats,” that is, sound whose volume varies periodically.