Re: Young minded experimentalists

On Jun 11, 2:43 am, Benj <bjac...@xxxxxxxxxxx> wrote:
xray4abc wrote:
OK
The first experiment I would suggest is :
Measuring the induced voltage in a horizontal metallic bar
rotating in a uniform vertical magnetic field .
Rotation would be about a vertical axis passing
through the middle of the bar.
Above and under the rotating bar should be 2 horizontal
metallic contact-rings, connected to an electrometer/voltmeter
to measure the induced voltage.
Other ideas would be : -2 ring-sectors only, connected to
an electrometer.
- no contact measurement, using the
electrically induced voltage when the 2 ends are passing near
2 given electrodes connected to the voltmeter/electrometer
This experiment is designed to - kind of - reproduce the
well known situation of a metallic bar moving in a magnetic field
as described in the classical textbooks.
I was unable to find any description of a practical experiment
of this sort in the available sources, that is why I started to think
of one myself.

IF you think about this, you find that if you measure the voltage at
the ends of the bar the emf induced in one half of the bar is balanced
by that in the other half. You really need to measure the voltage
between the center of the bar (driving rod) and the ends (circular
ring).
You are right! I got lost for a moment between the many
ideas!:-)
The described setup is still usable to double the intensity of the
current
supplied by this generator.
Actually, the idea I had was, using unequal bars , connected to the
same
non-conductive vertical shaft. The leads would go along the shaft
(for example,
one wire could go up and the other down, inside the shaft and through
the
middle of the magnets or solenoid).Sure, it could be just one bar,
with one end
on the shaft.
That it could be a disc ,or that the disc itself could be
the
magnet itself I did not think until now. One more thing to think about
for me,
which is fine because I think that one needs to analyse different
situations
to get a better picture of things.

Of course, what you've just invented is the Faraday generator,
somewhat reduced to a simple segmented form! The bar insures that the
charges rotate with the bar which might be questioned in the disk
case. These results are well known and do indeed show the effect of a
metallic bar moving in a magnetic field.

Of course the rotating magnet situation could be an alternative
to this experiment.

Which is also of great interest to those pondering whether the
magnetic field rotates with a magnet. Here you have the cases of
rotating the magnet and keeping the bar fixed or rotating magnet and
bar together. The problem is that there is no way to distinguish the
two theories. In one case it is said that the flux does not move with
the magnet so there is no induction in the wiring. In the other case
the flux is assumed to move with the magnet but it ALSO therefore
induces a balancing emf in the wiring. As it turns out BOTH
assumptions give the same result! The question is to find a
configuration that separates the two!
Well, actually your reference to Kelly, helped me to find the
description of experiments done in Ireland in 1998 to clarify this
issue.
Apparently they did answer the question: Yes, the magnetic field
does rotate with the magnet, as it supposed to do.
I am still studying their experiment, which should be repeated .

==========================

Your "zero field" question below is a VERY interesting one! The
question is do two equal and opposite fields cancel and produce NO
field or do they REMAIN separate in space and by superposition
therefore produce ACTIONS that cancel even though both fields are
present.

Here is a VERY important point with regard to the difference between
physics and mathematics. Today physicists are so enamored with math
that they accept the rules of math as reality. Zero field is the
PERFECT example. In the mathematics of vectors, two equal and opposite
vectors sum to zero. Therefore physicists conclude that when you have
equal and opposite vectors that the Field is zero. And Lo! It measures
zero on a gauss meter for example! So God is in his heaven and all's
right with the world!

But is it? Take the case of a long solenoid. If you think about it a
bit, you can convince yourself that the magnetic field contributions
from the top half of the turns is one direction while that from the
bottom half is in the other. The switching point is at the tangent
from the measurement point to the side of the coil. So do these fields
really "cancel" or do they coexist and only MEASURE zero on a
gaussmeter? The question is: Can we measure the so-called "zero
field" with some OTHER device that might show that two opposite fields
do NOT sum to a zero field? The fact that induction and quantum
effects can take place in this so-called "zero field" region may just
be the big hint that the fields are just equal and opposite and not
actually ZERO!
I picture this for myself like the
electric current
issue, in a metal for example. The charge carriers are there,
they are moving, there are then lots of simultaneous currents there
cancelling each other's effect. An action that favors one of the
movements creates the macroscopic current.
One could say that it existed from before, together with
an opposite current . Did it exist or not? Yes and no, and it really
does not matter, does it?
But, here we got into the subject of the nature of magnetic
field.
Another experiment which I would like to be done is one
that should check if the magnetic field of a conductor does have
mechanic effect on the conductor itself
( a kind of self-magneto-constriction) which I suspect it should
happen.

This is really fundamental stuff that I'll talk more about later.

Benj
==============



There is then the interesting idea of the zero field.
According to this idea (I am not the author of the idea) a zero field
can
behave like the sum of 2 opposite fields. I would like to design some
experiments to test it, as I came to ideas not far from it, pondering
over the phenomenon of auto-induction.
The thing comes like with electrical charges ;one can not create
negative charges without creating corresponding positive charges.
Translated : one can not create one kind of electric field without
creating a second kind of it. This situation may apply for magnetic
fields
too.

Best regards, LL- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

All the best, LL

.

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