is the Electromagnetic Spectrum?
have found that many types of wave can be arranged together
like the notes on a piano keyboard, to form a scale.
notes' have a low frequency and a long wavelength.
notes' have a high frequency and a short wavelength.
say "wave", you might think of a wave on the sea.
There, it's nice and obvious what's going on - the surface
of the sea is vibrating up and down.
With a sound wave, it's the air particles that are vibrating.
vibrating when an electromagnetic wave passes by?
That's not so easy.
Electromagnetic waves are vibrations of magnetic and electric
don't need air in order to travel. They don't need anything
to be there at all.