If you are going to snip, ******, I will too.
Now behave or **** off, a field rotates with a magnet

Since you have resorted to ad hominem name calling, I
decline to further engage you in discourse.

On May 14, 5:42 am, Benj wrote:
On May 13, 12:03 am, " wrote:

So yes, a (conductive) Beanstalk will definitely carry a current.

Didn't they launch a "beanstalk" satellite a while back but the thing
failed because the rope (conductive) broke?

Weighted tether hanging off a shuttle burned through because of all
the current. Consider shuttle orbital velocity...

Benj may feel cheated; I suggest he research the Homopolar Generator
and variants.

Tell it to Faraday! It was data and questions that came from Faraday
studying (and inventing) the Homopolar generator that started this
whole thing. My feeling was that by now in the 21 century answering
his questions should at least be possible if not "easy".

Seen this?

http://depalma.pair.com/Absurdity/Ab...enceWrong.html

I'm not recommending it either yea or nay, only presenting it as
maybe pertinent.

Bottom line though is as usual; build it and see. Not as difficult
as you might think either:

http://dangerouslyfun.com/homopolar-motor

http://www.metacafe.com/watch/971400...lectric_motor/

Variations are limited only by your imagination and ability to
visualize what you want to happen.

And yes, the question of does the earth's field rotate with the planet
(or maybe its core) is the same one.

Yep!


Mark L. Fergerson

"Kevin G. Rhoads" wrote in message
...
| If you are going to snip, ******, I will too.
| Now behave or **** off, a field rotates with a magnet
|
| Since you have resorted to ad hominem name calling, I
| decline to further engage you in discourse.

Good!
*plonk*

----------------------------
" wrote in message
...
On May 14, 5:42 am, Benj wrote:
On May 13, 12:03 am, " wrote:

So yes, a (conductive) Beanstalk will definitely carry a current.

Didn't they launch a "beanstalk" satellite a while back but the thing
failed because the rope (conductive) broke?

Weighted tether hanging off a shuttle burned through because of all
the current. Consider shuttle orbital velocity...

Benj may feel cheated; I suggest he research the Homopolar Generator
and variants.

Tell it to Faraday! It was data and questions that came from Faraday
studying (and inventing) the Homopolar generator that started this
whole thing. My feeling was that by now in the 21 century answering
his questions should at least be possible if not "easy".

Seen this?

http://depalma.pair.com/Absurdity/Ab...enceWrong.html

I'm not recommending it either yea or nay, only presenting it as
maybe pertinent.

Bottom line though is as usual; build it and see. Not as difficult
as you might think either:

http://dangerouslyfun.com/homopolar-motor

http://www.metacafe.com/watch/971400...lectric_motor/

Variations are limited only by your imagination and ability to
visualize what you want to happen.

And yes, the question of does the earth's field rotate with the planet
(or maybe its core) is the same one.

Yep!


Mark L. Fergerson
---------------
Unfortunately there is nothing in your references (except DePalma's lack of
basic understanding) that violate any basic principles. The spiral hides the
operating part (for more pizazz) of the device in one display but the
alternative construction in another doesn't. If you don't like Faraday,
Coulomb's force law is quite applicable. There is no mystery or unexplained
phenomena in a homopolar machine. Note also that "flux cutting" is somewhat
of a misleading and antiquated concept as is the idea of "lines of flux".

--

Don Kelly
remove the X to answer

On May 14, 8:35 pm, "Don Kelly" wrote:
" wrote in message

...

On May 14, 5:42 am, Benj wrote:
On May 13, 12:03 am, " wrote:

So yes, a (conductive) Beanstalk will definitely carry a current.

Didn't they launch a "beanstalk" satellite a while back but the thing
failed because the rope (conductive) broke?

Weighted tether hanging off a shuttle burned through because of all
the current. Consider shuttle orbital velocity...

Benj may feel cheated; I suggest he research the Homopolar Generator
and variants.

Tell it to Faraday! It was data and questions that came from Faraday
studying (and inventing) the Homopolar generator that started this
whole thing. My feeling was that by now in the 21 century answering
his questions should at least be possible if not "easy".

Seen this?

http://depalma.pair.com/Absurdity/Ab...alScienceWrong....

I'm not recommending it either yea or nay, only presenting it as
maybe pertinent.

Bottom line though is as usual; build it and see. Not as difficult
as you might think either:

http://dangerouslyfun.com/homopolar-motor

http://www.metacafe.com/watch/971400...enon_simplest_...

Variations are limited only by your imagination and ability to
visualize what you want to happen.

And yes, the question of does the earth's field rotate with the planet
(or maybe its core) is the same one.

Yep!

Mark L. Fergerson

---------------
Unfortunately there is nothing in your references (except DePalma's lack of
basic understanding) that violate any basic principles.

I'm not saying there is. I brought DePalma up to illustrate that
some people are indeed investigating the OP's "mystery" with no
concrete "mysterious" results. I suppose I could have been clearer
about that but I wanted the OP to convince himself without any bias
from me.

The spiral hides the
operating part (for more pizazz) of the device in one display but the
alternative construction in another doesn't. If you don't like Faraday,
Coulomb's force law is quite applicable. There is no mystery or unexplained
phenomena in a homopolar machine. Note also that "flux cutting" is somewhat
of a misleading and antiquated concept as is the idea of "lines of flux".

No complaints. My whole point is that the OP need not be put off by
the possible difficulty of building a "full-blown" homopolar device
but can get started with some really simple hands-on stuff like a
battery, a magnet, and a bit of wire (that doesn't _have_ to be wound
into a spiral).

With some imagination (and maybe the use of an old-fashioned record
turntable) the OP can do his own investigating of magnets, fields, and
their rotational relationships. He need believe nothing but evidence
he himself collects.


Mark L. Fergerson

Don Kelly wrote:

There is no mystery or unexplained
phenomena in a homopolar machine. Note also that "flux cutting" is somewhat
of a misleading and antiquated concept as is the idea of "lines of flux".

Don,
Actually there IS a mystery in a homopolar machine. Or at least a
question. Faraday noted that in his machine you get an ouput. Then he
just had the machine sit there while he rotated the magnet. No
output. So the question arose: Is the field rotating with the magent
or not? Since a rotating magnet produced no output, many concluded
that the field of a magnet did NOT rotate with it. But then some
other people looked closely at the problem and noticed that you got
the SAME answer (no output) no matter if you assumed the field rotated
or if it did not! Obviously only ONE of these assumptions can be
true. Which one? Well, the problem is to find a way to do the
experiment. It's clear that if you use closed loops to try to do this
you can't prove a thing. I"ve done this and it's true. No output, no
conclusions. So people proposed doing it electrostatically. OK fine.
But these measurements seem pretty delicate (homopolar voltages are
low) to work. As far as I know nobody has sucessfully proved anything
so far. Hence my idea of a "superconducting shield". Apparently that
idea is bogus as well. So the "mystery" remains.

As for "flux rules". They actually don't work with homopolar deviced
because the flux is not "cut" nor changing. It only shows that "flux
rules" are just a handy thing for certain calculations because they
often work, but are not the fundamental goings on electrically
speaking.

On May 14, 8:56*am, Benj wrote:
On May 11, 3:03 pm, Edward Green wrote:

On May 5, 10:57 pm, Benj wrote:

OK. Let me pick your brains. *I'm working on the age-old question does
a magnetic field rotate with the magnet if you spin it.

Assuming you are spinning the magnet around an axis of cylindrical
symmetry: no. *There is no concept of a rotating geometrically
invariant field.

What in the world do you mean "there is no concept"? *Of course the is
a "Concept"!!! * Faraday *himself raised the "concept" in examining
his homopolar generator. I take it you mean that one does not speak of
the problem in polite physics company because they are still trying to
sweep the problem under the physic rug.

I should have said, there is no concept of a rotating but otherwise
geometrically invariant magnetic field under maxwell's equations.
That's what I meant to say, and that's my assertion.

Maybe it is even correct.

I say "geometrically invariant" because a bar magnet rotated about one
of its minor axes generates would could plausibly be called a
"rotating magnetic field".

Which doesn't mean the field as described in normal
terms will not change. *That's a different question --

Agreed.

Good.

and you are
free to think of the new field as a "rotating magnetic field" if you
like -- nobody can stop you. ;-)

Spoken like a true physicist! *Of course I can imagine a field doing
anything I wish! *That doesn't make my idea real! *Who do you think I
am? Aut? *My world, apparently unlike yours is determined by
experiment and data rather than my own thoughts on how I think it
should work. You must be a cosmologist....

You are making some very extensive assumptions about who I am and what
I think based on insufficient data, and you missed my point.

I asserted -- and again, maybe I am even correct -- that while
conventionally we would not describe the magetic field of a bar magnet
rotating about its major axis a "rotating magnetic field", we seem to
agree that even in conventional terms the field would still be
modified from that of the non-rotating bar magnetic, and you could, I
say, consider the resulting field configuration as a rotating version
of the first one, if that floats your boat.

I don't think you will succeed in adding anything to the conventional
EM treatment of fields by adding in terms for "rate of rotation" -- as
opposed to merely adding in words to the effect that this field
configuration is a rotating version of that one -- though I could be
wrong.

... right

Much ado about nothing.

Faraday didn't think so and I don't either. The answer has a lot to do
with the understanding of several things including the Faraday
generator and the "beanstalk" device.

It's possible that Faraday's understanding has been overtaken by more
modern notation and concepts.

Magnetic fields have a great deal to do with rotation already, I will
grant you that. We might notice the coriolis equivalent description
of the Lorentz force law -- it _looks_ as if a magnetic field is a
local rotation seen by charged particles.

Edward Green wrote:

I say "geometrically invariant" because a bar magnet rotated about one
of its minor axes generates would could plausibly be called a
"rotating magnetic field".

Which the Andro figure is. But that isn't the case we are talking
about.

You are making some very extensive assumptions about who I am and what
I think based on insufficient data, and you missed my point.

Probably, on both counts. But that is what makes this place
interesting!

I asserted -- and again, maybe I am even correct -- that while
conventionally we would not describe the magetic field of a bar magnet
rotating about its major axis a "rotating magnetic field", we seem to
agree that even in conventional terms the field would still be
modified from that of the non-rotating bar magnetic, and you could, I
say, consider the resulting field configuration as a rotating version
of the first one, if that floats your boat.

Actually I agreed it COULD be modified not that it WOULD be so. I see
no point in defining all dogs top be cats to make a neat theory.
Words have meanings. We all know what a rotating field is. It means
that the field generated by a non-rotating bar magnet is attached to
the reference frame of the magnet. Therefore, like the field rotates
when the magnet rotates like the bristles on a cylindrical hair brush.
If you want to say that all this and that is just a "changed" field.
Ok. You can say that. But the question is HOW does it change?

Supposedly, relativity requires the magnetic field to be attached to
its generating source. Hence two traveling electrons do NOT attract
each other as do two current-carrying wires. In the case of the
electrons. In their own reference frames they see each other as
stationary! Hence the conclusion that their magnetic fields are
attached to them and therefore no qVxB forces are seen as V is zero
(relative to each other).

So say we have a bar magnet. Suppose we rotate it about the major
axis. Suppose we have a plasma cloud off the end of the magnet. What
happens? If the magnetic field is referenced to some frame other than
the material of the magnet, say the plasma frame...nothing happens!
But if the field is referenced to the frame of the magnetic material
then clearly the negative ions will all move radially one way (say to
the center) and the positive ones the other (say to the edge). Two
totally different things. Which one is what really happens? Damned if
I know. Which is why we ask the question.

I don't think you will succeed in adding anything to the conventional
EM treatment of fields by adding in terms for "rate of rotation" -- as
opposed to merely adding in words to the effect that this field
configuration is a rotating version of that one -- though I could be
wrong.

I would point out while you are stressing Maxwell's equations, they do
NOT include the Lorentz relation even though there is a connection
there. Hence Maxwell is ill suited to "explain" these matters.

It's possible that Faraday's understanding has been overtaken by more
modern notation and concepts.

Now that was my feeling as well! Which is why I raise the issue of a
re-visit to these old questions.

Magnetic fields have a great deal to do with rotation already, I will
grant you that. We might notice the coriolis equivalent description
of the Lorentz force law -- it _looks_ as if a magnetic field is a
local rotation seen by charged particles.

Rotational dynamics was never one of my favorite subjects, but I can
see your point, but I can't help feel there is more needed here than
merely a choice of reference frames needed to convert magnetic to
electric fields and back. So the question remains: What exactly DO the
charged particles in the plasma "see" off the face of a rotating bar
magnet?

On Thu, 15 May 2008, Edward Green wrote:

I should have said, there is no concept of a rotating but otherwise
geometrically invariant magnetic field under maxwell's equations.
That's what I meant to say, and that's my assertion.

Maybe it is even correct.
[cut]
I asserted -- and again, maybe I am even correct -- that while
conventionally we would not describe the magetic field of a bar magnet
rotating about its major axis a "rotating magnetic field", we seem to
agree that even in conventional terms the field would still be
modified from that of the non-rotating bar magnetic, and you could, I
say, consider the resulting field configuration as a rotating version
of the first one, if that floats your boat.

If the magnetisation of the magnet, M, is unaffected by the rotation, then
the magnetic field will be unaffected by the rotation. For
non-relativistic rotation speeds, this will be the case (the relativistic
change is 2nd order).

Spin the wire about the stationary magnet, there's an emf. Spin the wire
with a moving magnet, there's an emf. Stationary wire, spinning magnet, no
emf. There's no mystery in the "lab" frame, the Lorentz force on the
electrons in the wire covers it all.

In the rotating frame, the relativistic transformation of the fields tells
us there is an electric field. Wire in electric field - emf. What about
when the wire is stationary in the lab frame? Now it's rotating in the
opposite direction in the rotating frame, and the emf produced by the
rotation is reversed. This cancels the emf produced by the electric field.
So there's no mystery in the rotating frame either, since the Lorentz
force on the electrons in the wire covers it all.

Which suggests an interesting exercise: what electric field should we
observe due to the Earth's magnetic field and rotation? Is this a
significant component of typical atmospheric electric fields? If I have
time, I'll do the numbers.

[1] Van Bladel covers all of this thoroughly in Relativity and
engineering, a neat book indeed.

--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://eprint.uq.edu.au/view/person/...,_Timo_A..html
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html

"Benj" wrote in message
...
OK. Let me pick your brains. I'm working on the age-old question does
a magnetic field rotate with the magnet if you spin it. People have
established that if you put a loop near a Faraday generator and spin
the magnet you get no voltage. Some have taken this as proof that the
magnetic field does not rotate with the magnet. But others have shown
that the voltage induced in a loop this way is zero because the
voltage in the front side of the loop is exactly canceled by the back
side of the loop. Hence one person has even formulated a "law" that
says you cannot ever determine if the field rotates IF you only use
CLOSED loops!
The following link is not on this subject, however, I do believe it relates
well to the overall question, and some others posted over the last couple of
months.
Is there really a "motional E field", and is it closely related to gravity?
A non shieldable field that resembles gravity to such an extent that it is
basically indistinguishable from it? If so, then Floyd Sweets VTA, or
Searle's device may well be the real deal.
http://jnaudin.free.fr/html/hpmoncrt.htm
Some things in the crankarama can at times be very interesting.
Regards,
Vince