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How does energy travel in space?
Electromagnetic radiation is one form,
and it acts like a wave as it moves at the speed of light.
It's how energy from the sun reaches Earth.
This type of energy oscillates as it propagates.
See--waves?
So why do we care about electromagnetic waves that travel through space?
Well, electromagnetism is one of the four fundamental forces in nature.
That means that it affects just about everything.
Without it, we wouldn't have electricity or magnets,
two aspects of this force.
And then, there's this:
electromagnetic radiation is classified by the frequency--
how many times the wave oscillates in a given amount of time.
Waves with different frequences are useful in different ways.
This includes high frequency waves like gamma or X-rays,
and low frequency radio waves, too.
And, in between, are all these other kinds, including visible light.
The electromagnetic spectrum is the range of all possible wave frequencies.
