# Physics Lesson 11.5.2 - Things You Need To Know About Sound Waves

Welcome to our Physics lesson on Things You Need To Know About Sound Waves, this is the second lesson of our suite of physics lessons covering the topic of Sound Waves. Intensity and Sound Level, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.

## Things You Need To Know About Sound Waves Before Entering Into Details

• Being a longitudinal wave, sound source causes the medium's particles vibrate back and forth. Therefore, denser the material, easier for the sound to propagates as it is easier for medium particles to find other particles to collide with. Look at the figure.

In the first figure, the material is less dense, so it is more difficult for a particle to find other particles to collide with, while in the second figure the material is denser, so particles collide more easily with each other. Hence, sound waves propagate at a higher speed in denser media such as metals, concrete, etc. Now, you can understand why sound cannot propagate in vacuum, i.e. because there are no particles in the medium through which sound can propagate.

• The typical speeds of sound in some media are shown in the table below.
• Sound waves can be modelled as transverse waves on a screen to ease their study, i.e. to make visible the distinction between wavelength and amplitude. A typical example of a sound wave modelling is shown in the figure below.

It is easy to see that wavelength has not changed during the sound wave modelling. Compressions are represented by wave crests while rarefactions by troughs.

• Sound waves can easily penetrate through solid objects as they propagate in a longitudinal way. Yet, the speed of sound changes when it changes medium. We will explain this phenomenon when discussing about a phenomenon called the "refraction of waves".

You have reached the end of Physics lesson 11.5.2 Things You Need To Know About Sound Waves. There are 7 lessons in this physics tutorial covering Sound Waves. Intensity and Sound Level, you can access all the lessons from this tutorial below.

## More Sound Waves. Intensity and Sound Level Lessons and Learning Resources

Waves Learning Material
Tutorial IDPhysics Tutorial TitleTutorialVideo
Tutorial
Revision
Notes
Revision
Questions
11.5Sound Waves. Intensity and Sound Level
Lesson IDPhysics Lesson TitleLessonVideo
Lesson
11.5.2Things You Need To Know About Sound Waves
11.5.3Limits of Audibility. Audible Sound. Infra and Ultrasound<
11.5.4Echo
11.5.5Intensity of Sound Waves
11.5.6Sound Level
11.5.7Loudness and Pitch

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