Science with Rina. Longitudinal and Transverse Waves

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Video illustration to TranslatorsCafe.com Sound Wavelength Calculator.

In this video, Rina and I will show you the longitudinal and transverse waves using a slinky spring.

Sound is transmitted through various media as different kinds of waves. It is transmitted through gases and liquids as longitudinal waves. When sound is propagated through solids, it can be transmitted as both longitudinal waves and transverse waves.

To understand both kinds of waves, it is convenient to use a stretched Slinky spring, which will represent the medium (liquid or gas). When you compress and then release the Slinky spring’s coils at one end, the squeezed coils move forward thus transferring energy from one end of the spring to another.

When a sound is propagating through liquid or gas, it travels away from the source as periodic compressions of the gas or liquid moving from the source. We can compare the spring coils to air or water molecules bumping against each other.

Because the direction of these compressions is parallel to the direction of wave propagation, this wave is called longitudinal.
If you move one end of the Slinky spring representing the medium perpendicular to it, a transverse wave is created. It is called transverse because the motion of the spring coils is perpendicular to the wave motion along the Slinky. The energy is transferred along the spring while its coils move in the direction, which is perpendicular to the direction of energy transfer.

Using the Slinky, we can also observe vertical, horizontal and circular polarization of waves.

Note that the spring represents the medium in which a wave is propagating and this medium does not travel with the sound wave. It only vibrates. We can easily observe this in a solid and the same is true for any liquid or gas. That is, the molecules of liquid or gas transport the vibration while the average position of the molecules does not change over time for any kind of waves.

Music from YouTube Free Audio Library

“Les Toreadors” from Carmen by Georges Bizet
Ersatz Bossa by John Deley and the 41 Player