How are sound and light waves different?

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Sound and light both travel in waves, which are caused by vibrations.  The vibrations begin when an object at rest is set in motion (e.g. a guitar string or electrons).  This vibrating motion can begin (initial displacement) in two ways, longitudinal or transverse.  Light waves are transverse.  This is when...

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Sound and light both travel in waves, which are caused by vibrations.  The vibrations begin when an object at rest is set in motion (e.g. a guitar string or electrons).  This vibrating motion can begin (initial displacement) in two ways, longitudinal or transverse.  Light waves are transverse.  This is when the movement of electrons is perpendicular to the motion of the wave.  An example is a football stadium wave.  Everyone is waiting for their turn, and when it comes, they sit and stand in an up and down motion, and the wave continues forward.  Light waves, therefore, move faster than sound waves, which are longitudinal.  Light waves can also travel through space.   

In the case of sound waves, which are longitudinal, the vibrations begin when a movement is made that is parallel to the wave path (a push instead of a rise).  This is sort of like a slinky being pushed, the wave that comes from it moves away from it in a parallel direction, without moving up and down.  Sound waves, being longitudinal, are slower than light waves, and do not travel through a vacuum (e.g. space).

  Finally, and again, because of their initial displacement and type of motion, sound waves travel faster through denser mediums (solids), while light waves travel faster through less dense mediums (gases).

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