This link is for Harry;
Physicists Measure Elusive 'Persistent Current' That Flows Forever
<http://www.sciencedaily.com/releases/2009/10/091011071349.htm>
Doesn't sound like anything is ever going to be powered by it.
Ron
--On Wednesday, October 14, 2009 8:28 AM +1100 mix...@bigpond.com wrote:
In reply to Harry Veeder's message of Mon, 12 Oct 2009 02:35:43 -0400:
Hi,
Ok, I guess it is necessary to distinguish between a capacitor, a
battery and an EMF. Both a battery and a capacitor can produce a
current for a _limited_ period of time, whereas an EMF can produce a
current for an _unlimited_ period of time.
There ain't no sich animal. Nothing runs forever. The universe is a big battery,
and it's running down. You can only maintain an EMF at a "constant" level, when
current is flowing in a resistive circuit, by supplying energy. IOW you have to
"pump" the electrons from the low voltage side back to the high voltage side.
This is usually done with a changing magnetic field (i.e. a generator or
dynamo), which once again introduces a step in the voltage going around the
circuit. You can picture the voltage at each point as single rotation of a helix
with a vertical axis with the begin and end points joined by a straight vertical
line. That vertical line is where the energy is added. Energy is lost to
resistance as the current runs around the helix.
With that in mind, let me refine the question. Can a current which runs
indefinitely (and does not occur in a superconductor) be explained
consistently only with the concept of an electric field?
[snip]
Regards,
Robin van Spaandonk
http://rvanspaa.freehostia.com/Project.html
