Sound+wave

Sound wave is caused by something that vibrates. People are using sound wave to create telephone, televisions, video tape recorders, speakers and so on. Also, echoes are sound waves too.

http://phet.colorado.edu/simulations/sims.php?sim=Sound

If you go this link, you can see the applet of the sound wave. This link shows how the wave changes by replace the frequency and amplitudes. You can move the person and you can hear what person listens. Higher frequency causes bigger number of hertz which means more sound waves occurred in one second. Higher amplitudes create stronger compressions and rarefactions. As long as the speaker continues to vibrate back and forth, compressions and rarefactions are formed because sound waves are compressional waves. As the speaker vibrates, it bump with the air molecules, and then transfer some of its energy to the molecules. Then, the molecules continues to pass the energy to one to another. This process of energy transfer causes a sound wave.

http://phet.colorado.edu/index.php

The internet site is made by the scientist team of the University of Colorado. The scientist group is consist of software engineers and scientist educators. Those people established this useful internet site to support student with visually comprehend science concepts.