PROFESSOR:
Electromagnetic radiation
is composed of wavelengths
from very, very
long to very, very short.
We've talked about
the relationship
between the wavelength, the
frequency, and the speed
of electromagnetic radiation.
In fact, the product of the
wavelength and the frequency
is the speed.
For electromagnetic
radiation, light,
speed is fixed at
the speed of light.
So if the wavelength increases
the frequency has to decrease.
They're inversely proportional.
And you can see I have
wavelength increasing here
and frequency increasing here.
The visible region,
in particular,
we're going to talk a
lot about because we
can perceive the length of
the radiation by the color.
So we can make that
easy connection
between a wave and its length
by the color that we see.
Long wavelengths in the
visible region are red.
Intermediate wavelengths
going down from yellow
to orange, to green, to
blue, indigo, and violet
from long to short wavelengths.
In fact, this kind of
spells a guy's name--
ROY G BIV from long
to short wavelengths.
I often write that
down, and I can remember
the colors of the rainbow.
Now there's more properties
to electromagnetic radiation
and waves in general.
For instance, the intensity--
we haven't touched on that yet.
You can think of the
intensity of waves
in the ocean as their height
as they come in to the shore.
A big wave would be
an intense wave--
a tall wave an intense wave.
How do we do that for our
electromagnetic radiation?
Well, let's talk
about intensity more
as we go through this talk.
