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