# Physics Lesson 11.5.1 - Things You Already Know About Sound Waves

Welcome to our Physics lesson on Things You Already Know About Sound Waves, this is the first 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.

So far in this tutorial we have covered sebveral lessons which discussed waves in general and occasionally we mentioned sound waves to describe them. Thus, in the previous tutorials of this section, you have learned that:

• Sound is a mechanical wave as it needs a material medium to propagate. No sound waves exist in vacuum.
• Sound is a longitudinal wave as its amplitude is in the same direction to the wavelength.
• Sound (as all the other types of waves) propagates at the same speed within the same medium. The equation of sound is the same as the equation of all waves, i.e.
v = λ × f

where λ is the wavelength and f is the sound frequency.

• Other equivalent equations we can use for sound waves are:
v = λ/T

where T is the period of sound waves;

v = s/t

where s = N × λ is the total distance travelled by the sound, t = N × T is the total time needed for this process and N is the total number of cycles made by the wave during the time t.

• Sound waves cause compressions and rarefactions in the medium in which they propagate. Thus, in regions containing compression, the medium's particles are denser than usual while in the regions where there is rarefaction, the medium is less dense than in normal conditions as shown in the figure.

We will extend further the discussion about sound waves based on the above information.

You have reached the end of Physics lesson 11.5.1 Things You Already 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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