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The information below is intended to provide introductory material for elementary students and further material for high school students.

Please keep in mind that not all demonstrations are presented at each show, and each topic may not be covered.


SOUND

Introduction

  • Sound is caused by air particles vibrating back and forth very rapidly. These air particles collide with their neighboring air particles and spread throughout space.

    Although you may not know it, when you talk, you are using your vocal cords to vibrate the air. These vibrations travel through the air until they reach your friend's ears. The vibrating air particles in your friend's ears collide with his/her ear drums, vibrating his/her ear drums at the same frequency and loudnesss that your vocal cords uttered them. To see this, simply place your fingers on your throat and talk normally, you will feel your vocal cords vibrating. Sounds may be produced by more than just your vocal cords, however. Stereos use a cone-shaped material that vibrates. Other objects may also be vibrated by sound. You can probably recall "feeling" a loud noise because the noise caused your chair to vibrate a little.


  • More Specifically

  • Sound is longitudinal waves through air.

    Longitudinal waves are waves which travel in the same direction as their disturbance. For sound, this means that air particles bounce back and forth and collide with their neighboring air particles, thus propogating the wave. Thus sound can be created by any vibrating object (your vocal cords, a stereo, a book falling on the floor, etc.). If a material is flexible enough, it will also register sound (your ear drums, a microphone, etc.).


  • Related Demos

    The following demonstrations illustrate this physics topic:

    Sponsored by the Physics Department and the Center for Science, Mathematics, and Engineering Education -- University of Virginia