Animation 1: Longitudinal Waves

Sound waves move energy using longitudinal waves. As each sound wave passes through a medium on its way to your ear, the particles of that medium move in the same direction as the wave itself, which is side to side.

Watch this animation to find out more about:

1) How the particles move in a sound wave; and

2) Which properties of sound waves can be measured.

As you watch the segment, you may want to check the definition of specific terms. In addition to the glossary words listed above, the terms wavelength, frequency and amplitude will be described.

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Longitudinal Waves: Transcript

All waves transfer energy, but the way they do it varies. A longitudinal wave can carry energy through air, water and solids, and it does it by compression and expanding the medium in the same direction it transfers the energy.

This compression and expansion can be measured in different ways:

1) Compression and Rarefaction: A compression is a point where the medium is at its most squished--or maximum density. A rarefaction is a point where the medium is most spread out--or least dense.

2) Amplification: Amplification is the measurement of how far the particles are pushed from their resting state (equilibrium).

3) Wavelength: The wavelength is the length of one wave cycle (compression to compression, or rarefaction to rarefaction.

Longitudinal waves need particles to push the energy. That means they can travel through gas, liquids and solids, but not through a vacuum. Sound is a longitudinal wave, for instance, and there is no sound in space.

Feel that beat? That's the longitudinal wave.

Take Notes

In the space below, write one sentence describing how particles move in a longitudinal wave. Then, write two more sentences describing how wavelength and amplitude are measured.