"Kevin G. Rhoads" wrote in message
...
| If we ever build a Beanstalk (tethered mass in geosynchronous
| equatorial orbit) will the stalk carry a current from "cutting" the
| Earth's field as it orbits?
|
| If conductive, perhaps -- remember B fields, like motion, are expressed
| in vectors, so the cross product can be zero even if both terms are not
| (they only need be parallel).


No, the Earth's magnetic field moves with the Earth - the magnetic pole
doesn't travel in a circle every day, yet it is offset from the Earth's
axis.
Therefore it rotates with the Earth.
Nobody will build a "beanstalk" anyway, the engineering and safety
requirements are too excessive and the uses too few. 23,500 miles of
steel cable (or even titanium or carbon fibre) won't be lightweight.

On May 12, 8:43 am, "Kevin G. Rhoads" wrote:
If we ever build a Beanstalk (tethered mass in geosynchronous
equatorial orbit) will the stalk carry a current from "cutting" the
Earth's field as it orbits?

If conductive, perhaps -- remember B fields, like motion, are expressed
in vectors, so the cross product can be zero even if both terms are not
(they only need be parallel).

It was a "trick" question. The Earth's field is generated somewhat
differently from that of an ordinary magnet; the angular velocity of
the conductive fluid within the Earth that generates its field is not
directly tied to the angular velocity of the surface (note that the
spin and magnetic poles of the Earth are not co-located and their
relationship changes over time).

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

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


Mark L. Fergerson

| If we ever build a Beanstalk (tethered mass in geosynchronous
| equatorial orbit) will the stalk carry a current from "cutting" the
| Earth's field as it orbits?
|
| If conductive, perhaps -- remember B fields, like motion, are expressed
| in vectors, so the cross product can be zero even if both terms are not
| (they only need be parallel).

No, the Earth's magnetic field moves with the Earth - the magnetic pole
doesn't travel in a circle every day, yet it is offset from the Earth's
axis.

The Earth's magnetic field does not move with the Earth out to arbitrary
distances. In the ionosphere the field gets shaped by the interaction
of the solar wind with the internal generator of the Earth (among other
lesser influences). Your analysis is oversimplified to the point of
being flat out wrong. With all due respect: Please, try again.

"Kevin G. Rhoads" wrote in message
...
|| If we ever build a Beanstalk (tethered mass in geosynchronous
| | equatorial orbit) will the stalk carry a current from "cutting" the
| | Earth's field as it orbits?
| |
| | If conductive, perhaps -- remember B fields, like motion, are expressed
| | in vectors, so the cross product can be zero even if both terms are not
| | (they only need be parallel).
|
| No, the Earth's magnetic field moves with the Earth - the magnetic pole
| doesn't travel in a circle every day, yet it is offset from the Earth's
| axis.
|
| The Earth's magnetic field does not move with the Earth out to arbitrary
| distances.


Yes it does, we are only concerned here with 24,000 miles.
See thread title, the field rotates with the magnet.
http://www.androcles01.pwp.blueyonder.co.uk/AC/spin.gif



| In the ionosphere the field gets shaped by the interaction
| of the solar wind with the internal generator of the Earth (among other
| lesser influences).

The path of the solar wind is shaped by the field, you have the cart
before the horse.


| Your analysis is oversimplified to the point of
| being flat out wrong. With all due respect: Please, try again.

With all due disrespect you are flat out wrong.

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?

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".

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

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.

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

Agreed.

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, 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.

On May 13, 3:26 pm, "Androcles" wrote:
"Kevin G. Rhoads" wrote in ...

| The Earth's magnetic field does not move with the Earth out to arbitrary
| distances.

Yes it does, we are only concerned here with 24,000 miles.
See thread title, the field rotates with the magnet.

http://www.androcles01.pwp.blueyonder.co.uk/AC/spin.gif

Nice animation, Andro! Only the question has to do with rotation of
the magnetic field when the rotation is about the central axis of
symmetry of the cylindrical magent rather than one perpendicular to
it. "Bristle theory".

| The Earth's magnetic field does not move with the Earth out to arbitrary
| distances.

Yes it does, we are only concerned here with 24,000 miles.

There are significant variations in the Earth's magnetic field
due to solar wind effects at less than 24,000 miles. Assuming
pure rotation with the earth out to 24,000 miles is severe
oversimplification.

If you sincerely believe otherwise, then we have nothing more
to say to one another. Because in that case it is a matter of
(your) faith, not science. You have made claims, you have provided
no support for those claims. If you don't want to believe me,
check out any of the space weather web-sites.

With all due disrespect you are flat out wrong.
Got evidence? Try disproving all the data shown on various
sites monitoring real time near-Earth space weather.
http://spaceweather.com/
http://www.swpc.noaa.gov/
http://sohowww.nascom.nasa.gov/
http://sohowww.nascom.nasa.gov/data/data.html
http://www.dartmouth.edu/~aurora/spaceweather.html

Please provide support for contrary assertions if you choose
to continue. You may consider the effect of the solar wind
upon the Earth's B field out beyond 100km to be negligible,
but I do not.

On May 6, 8:27*pm, Uncle Al wrote:
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. *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!

[snip crap]

Given an axially symmetric dipole magnetic field, what does "rotate"
mean when the symmetry axis is the rotation axis? *Are you implying
that lines of force are physical entities that can flow through a coil
and entrain charge?
----------------------
yes crackparroter
do you really know what is charge anyway??
---------

Benj
(who notes that answering the rotating magnet question is a "good
first step" toward finding that precise arrangement of magnets that
will produce "free energy"!)


Idiot.

not my paragraph
anyhow :
it is not free energy
it is conserved energy
inner energy




* *1) Time is homogeneous.

idiot

* *2) Noether's theorem
* *3) Mass-energy is locally conserved.

do you mean that energy has mass ??

if yes welcome to sane physics

ATB
Y.Porat
-----------------------------

"Kevin G. Rhoads" wrote in message
...
|| The Earth's magnetic field does not move with the Earth out to arbitrary
| | distances.
|
| Yes it does, we are only concerned here with 24,000 miles.
|
| There are

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

--
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http://www.androcles01.pwp.blueyonder.co.uk/