Question

How does a sound wave differ from an electromagnetic wave

Answer 1

A sound wave is very low frequency as it starts off on the Wave spectrum, You can tell if the frequency is low or high by the wavelength.

the wavelength is how wide the wave is from crest to crest (crest: the top of the wave)

If the wavelength is very long, it means that there is low frequency, the closer the crests are the higher frequency there is throughout the wave!

So sound waves are much less frequent or concentrated, than Electromagnetic waves.

If you don't understand this, go look at some pictures of the wave spectrum. It should help a bit!

http://hyperphysics.phy-astr.gsu.edu/hbase/ems1.html

Answer 2

A sound wave is a mechanical wave and cannot travel through empty space. It needs to travel through a medium of some kind. To remember this, the saying "no one can hear you scream in space" is somewhat helpful considering sound waves cannot travel through an empty vacuum like such. An electromagnetic wave ( EM wave ) does not need a medium to travel and can travel freely through empty space.