wrote in message
...
On Jan 15, 7:50 pm, Tim wrote:
OK, I picked this up on another board,a nd seeing that Eisboch, Tom,
Gene and Larry have had dealings with this stuff. I thought I'd
present it here. It has my curiosity up as well.

I'm not up on physics, concerning this so here goes:

"I searched the web but couldn't find an answer to a simple question
which for my purposes is really a matter of curiosity. Of course,
sometimes these
kinds of questions end up teaching me the most.

Most defintions of wavelength are along the lines of the distance
between points of corresponding phase of two consecutive cycles of a
wave. I'm not
an idiot , so I understand what is a pretty
straightforward definition.

What I don't get is why the term length? I mean, they don't call the
amplitude the waveheight. I kind of think of it as a wavegap. If you
painted a big sine wave on the street and asked me how long it was,
I'd get one
of those little rolling doohickies for measuring and trace the line
through its curve. Without knowing the definition in advance, I
wouldn't think you would
be asking me the straight distance between two points of
corresponding
phase.

I ask this question because I don't understand why it's called what
it's called, not because I want to tell the experts they got it
wrong. It's bugged me for a while, so I've finally decided to take the
plunge and risk looking stupid.

Thanks in advance for any responses or links to read..."

--
Jim Carr

It is called "length" because it truly is a length. Amplitude is not
a length but has other units, for example with sound, amplitude has
units of pressure. With light, radio waves or other electromagnetic
radiation, the amplitude is electric or magnetic field. Consider the
wavelength of your VHF which is roughly about the length of your 8'
antenna. The wavelength of the microwaves in your microwave oven is
roughly 3 cm (just over an inch). The wavelength of your cell phone
waves is somewhat longer than those in a microwave, about 3X.
Infrared light has a a wavelength as small as .5 micron or about .
00002". Visible light has length between .5 micron (red) and .3
micron (violet). Vacuum Ultraviolet goes from there down to about 120
angstroms (1 angstrom =1 X10-10 m), soft x-rays from there down to
roughly 6 angstroms and the x-rays your dentist uses down to about .6
angstroms. Gamma rays can be very short.
At the other end of the spectrum, Extremely Low Frequency waves have
lengths comparable to the diameter of the earth. Remember the old AM
radio towers, they were about the length of the AM radio waves. Your
AM radio had a long antenna cuz the AM waves were long whereas the FM
waves are much shorter hence the smaller FM antenna.
I am sure this is MUCH more than you wanted to know but AT LAST, I get
to expound on something I know something about (I make x-ray mirrors
for waves that have lengths of anywhere from 120 angstroms to 1.2
angstroms).
Now, about boats......

Can you shave in those mirrors? 8-)

BTW, good explanation.