- A SKEPTICs GUIDE - A SKEPTICs GUIDE 
We have special names for electromagnetic (EM) waves of different
wavelengths and frequencies.14.15
We call EM waves with
m ``radio waves,''
which are subdivided into various ranges or ``bands''
like ``short wave'' (same thing as high frequency),
VHF (very high frequency),
UHF (ultra high frequency)
and so on.14.16
The dividing line between ``radar'' and ``microwave'' bands
(for example)
is determined by arbitrary convention, if at all, but the rule
of thumb is that if the wavelength fits inside a very small appliance
it is ``microwave.'' Somewhere towards the short end of the
microwave spectrum is the beginning of ``far infrared,''
which of course becomes ``near infrared'' as the wavelength
gets still shorter. The name ``infrared'' is meant to suggest
frequencies below those of the red end of
the visible light spectrum of EM waves, which extends
(depending on the individual eye) from a wavelength
of roughly 500 nm (5000 Å) for red light
through orange, yellow, green and blue
to roughly 200 nm (2000 Å) for violet light.
Beyond that we lost sight of the shorter wavelengths
(so to speak) and the next range is called ``near ultraviolet,''
the etymology of which is obvious. Next comes ``far ultraviolet''
which fades into ``soft x-rays'' and in turn ``hard x-rays''
and finally ``gamma rays'' as the frequency increases and the
wavelength gets shorter. Note all the different kinds of ``rays''
that are all just other forms of light - i.e.
EM waves - with different wavelengths!
