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Old July 5th 09, 01:24 PM posted to rec.radio.amateur.antenna
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Default Obtaining electromagnetic radiation from accelerating electrons

Is it not true that if I were able to accelerate my cup of coffee at light
speeds at a frequency of 14Mhz my cup of coffee would radiate a 14Mhz
carrier?

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Old July 5th 09, 02:46 PM posted to rec.radio.amateur.antenna
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Default Obtaining electromagnetic radiation from accelerating electrons

On Sun, 05 Jul 2009 13:24:20 +0100, Richard wrote:

Is it not true that if I were able to accelerate my cup of coffee at
light speeds


non sequitur. acceleration = rate of change of speed.

at a frequency of 14Mhz


non sequitur. frequency is not a measure of speed or acceleration.

my cup of coffee would radiate a 14Mhz carrier?


No.

--
Rich

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Old July 5th 09, 05:36 PM posted to rec.radio.amateur.antenna
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Default Obtaining electromagnetic radiation from accelerating electrons

On Jul 5, 5:24*am, "Richard" wrote:
Is it not true that if I were able to accelerate my cup of coffee at light
speeds at a frequency of 14Mhz my cup of coffee would radiate a 14Mhz
carrier?



No.
You don't have to go the speed of light . Bigger the acceleration,
bigger the amplitude of the radiated signal.

And, it's the vibrating your cup of coffee back and forth at 14MHz
that would do it.

Another problem.. there's no net charge on your coffee.. so no
radiated field when you move it back and forth.


Consider a balloon which you've charged up by rubbing it on your hair
(or that fuzzy sweater...) If you move it back and forth, and have an
electric field meter some small distance away, you'll see the field
changing. Move the meter farther away, and the field is still
changing, but the amplitude is smaller.

Now look at the time delay between your moving the balloon and when
you see the field change. That delay is the time it takes for the
changed field to "propagate" to the meter.. aka the speed of light.
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Old July 5th 09, 07:36 PM posted to rec.radio.amateur.antenna
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Default Obtaining electromagnetic radiation from accelerating electrons

Jim Lux wrote:
Another problem.. there's no net charge on your coffee.. so no
radiated field when you move it back and forth.


How many free electrons in coffee? How about salt water?
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com
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Old July 6th 09, 04:19 AM posted to rec.radio.amateur.antenna
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Default Obtaining electromagnetic radiation from accelerating electrons

I don't care if it works or not, YOU are the one that's gonna have
to clean up that @#$ coffee mess!
- 'Doc


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Old July 6th 09, 09:46 AM posted to rec.radio.amateur.antenna
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Default Obtaining electromagnetic radiation from accelerating electrons


"Rich Griffiths" wrote in message
communications...
On Sun, 05 Jul 2009 13:24:20 +0100, Richard wrote:

Is it not true that if I were able to accelerate my cup of coffee at
light speeds


non sequitur. acceleration = rate of change of speed.

at a frequency of 14Mhz


non sequitur. frequency is not a measure of speed or acceleration.

my cup of coffee would radiate a 14Mhz carrier?


No.

--
Rich


If the cup was to move 5 meters left, then 10 meters right, then ten meter
left again that would be one cylcle. There are 14 million cycles in one
second. So, net speed of cup is speed of light.
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Old July 6th 09, 09:51 AM posted to rec.radio.amateur.antenna
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Default Obtaining electromagnetic radiation from accelerating electrons


"Richard" wrote in message
...

"Rich Griffiths" wrote in message
communications...
On Sun, 05 Jul 2009 13:24:20 +0100, Richard wrote:

Is it not true that if I were able to accelerate my cup of coffee at
light speeds


non sequitur. acceleration = rate of change of speed.

at a frequency of 14Mhz


non sequitur. frequency is not a measure of speed or acceleration.

my cup of coffee would radiate a 14Mhz carrier?


No.

--
Rich


If the cup was to move 5 meters left, then 10 meters right, then ten meter
left again that would be one cylcle. There are 14 million cycles in one
second. So, net speed of cup is speed of light.


Actually the frequency ought to be 15 Mhz.

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Old July 6th 09, 01:46 PM posted to rec.radio.amateur.antenna
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Default Obtaining electromagnetic radiation from accelerating electrons

On Mon, 06 Jul 2009 09:51:12 +0100, Richard wrote:

"Richard" wrote in message
...

"Rich Griffiths" wrote in message
communications...
On Sun, 05 Jul 2009 13:24:20 +0100, Richard wrote:

Is it not true that if I were able to accelerate my cup of coffee at
light speeds

non sequitur. acceleration = rate of change of speed.

at a frequency of 14Mhz

non sequitur. frequency is not a measure of speed or acceleration.

my cup of coffee would radiate a 14Mhz carrier?

No.

--
Rich


If the cup was to move 5 meters left, then 10 meters right, then ten
meter left again that would be one cylcle. There are 14 million cycles
in one second. So, net speed of cup is speed of light.


Actually the frequency ought to be 15 Mhz.


Nonetheless, you still have acceleration, speed, and frequency seriously
confused. If you want to do a "thought experiment" (or any experiment,
for that matter), you must formulate it properly if you want to draw
sound conclusions from it.

And the "clarification" about frequency also makes no sense.

Either the cup has infinite acceleration at each end of its motion, or it
accelerates steadily from zero speed to a maximum at the middle and then
decelerates to zero again. The first implies an infinite change in
momentum and kinetic energy. The second implies a speed higher than the
speed of light at the middle of the motion.

You can't postulate conditions that defy the laws of physics and then ask
what physics implies anyway.

This is all WAY off topic, so we should end it.

--
73
Rich
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Old July 6th 09, 04:22 PM posted to rec.radio.amateur.antenna
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Default Obtaining electromagnetic radiation from accelerating electrons

Cecil Moore wrote:
Jim Lux wrote:
Another problem.. there's no net charge on your coffee.. so no
radiated field when you move it back and forth.


How many free electrons in coffee? How about salt water?


pH = -log hydrogen ion concentration

the pH is about 7, so hydrogen ion concentration is 1E-7. It's
neutral, so there's an equal number of negative ions. How many of them
are free electrons is another question.


But the important thing is that there's an equal number of positive and
negative charges floating around there, so there's zero net charge. An
possible radiated field from a negatively charged electron will be
exactly matched by the opposite field from a positively charged
something else.

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Old July 6th 09, 06:37 PM posted to rec.radio.amateur.antenna
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Default Obtaining electromagnetic radiation from accelerating electrons

On Mon, 06 Jul 2009 08:22:19 -0700, Jim Lux wrote:

Cecil Moore wrote:
Jim Lux wrote:
Another problem.. there's no net charge on your coffee.. so no
radiated field when you move it back and forth.


How many free electrons in coffee? How about salt water?


pH = -log hydrogen ion concentration

the pH is about 7, so hydrogen ion concentration is 1E-7. It's
neutral, so there's an equal number of negative ions. How many of them
are free electrons is another question.


But the important thing is that there's an equal number of positive and
negative charges floating around there, so there's zero net charge. An
possible radiated field from a negatively charged electron will be
exactly matched by the opposite field from a positively charged
something else.


The pH of water in contact with the atmosphere tends to be about 6.5, due
to CO2 dissolving in the water and forming carbonic acid. Other commonly-
occurring ions that "match" the H+ are sulfate and nitrate. Of course in
salt water, most of the ions are sodium (Na+) and chloride (Cl-). Not
many free electrons. The motion of any ions could create electromagnetic
radiation, but as you note, the net charge is zero, so no radiation,
regardless how the cup is accelerated or what speed it travels at ;-)

--
Rich

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