Jerry wrote:
> On Jul 27, 9:28 am, jim <j...@[EMAIL PROTECTED]
> wrote:
>> I need some help in locating ceramic disc magnets that measure 120mm in
>> diameter with no hole in the center. The thickness can be as much as
13 mm
>> 25.4mm.
>>
>> The strrength is not as im****tant as the dimensions and that it be a
solid
>> disc (no hole in center).
>>
>> I have found neo magnets that are up to 8" in diameter, but their
strength
>> will actually make it more difficult to perform the initial experiment.
>>
>> If anyone knows where I may purchase ceramic desci magnets that are at
least
>> 120mm in diameter and up to 25.4mm in thickness, with no holes in them,
>> please let me know.
>>
>> Thank you for your help.
>>
>> (I have Googled, Ask'd, Yahoo'd, etc. - all to no avail. The magnets
that I
>> have found generally top out at 76mm in diameter. If I have missed
>> something in these searches, I would appreciate someone pointing it
out.)
>
> I suspect that you are asking the wrong question. I suspect that
> your REAL question is, how can you create a close approximation
> to a uniform magnetic field over an area of many square
> centimeters.
>
> The answer WON'T be by using a large monolithic hunk of ceramic.
> Inevitable nonuniformities in manufacturing that arise during
> the magetization step mean that the strength of field will vary
> considerably between center and edge of the disc.
>
> Instead, consider a large array of carefully matched magnets
> faced off by pole pieces.
>
> Why don't you share your actual requirements with us, rather
> than trying to be so secretive about the experiment that you
> intend to perform?
>
> Jerry
>
Didn't mean to sound so secretive....just didn't think it really
mattered. I'm just interested in how magnets behave in a monopolar
situation as opposed to the usual 2 poles that they are found in.
In particular, I wondered (not being big in physics) what would happen
if I mounted a small magnet on a horizontal arm in the center of a
larger disc magnet that kept the smaller magnet within the diameter of
the disc magnet and kept the smaller magnet close to the larger disc
magnet's surface while allowing horizontal movement and not allowing
vertical movement.
I actually wondered if the smaller magnet, turned slightly so that it's
opposing pole faced the surface of the disc magnet at an angle, would be
propelled around the arm in a circular motion due to the force created
between the opposing magnetic flux lines.
My tests are not very scientific and my tools are not exact in their
manufacture, but I have determined that it will not move at all unless
acted on by outside forces.
The magnetic force exerted by the face of the disc magnet against the
angled, same pole of the smaller magnet does produce a force. But, it
is not a force in the sense of wind acting on a windmill's propellers or
of water falling on the blades of a turbine or even photons hitting the
vanes of a radiometer.
It seems that magnetic force is a force, but is not a moving force (as
wind, photons or water droplets) which is needed to produce movement in
another object.
My interest was aroused when I watched some youtube videos of people
attempting to build motors using only permanent magnets for power.
I can see the attraction of such an idea, and how it deludes many into
thinking it is possible. Alas, it is not possible to build a motor
using only permanent magnets as the power source.
I knew that going in. And, although I suspected it, I had seen no
experiments that used a single disc magnet (as opposed to many
exotically arranged magnets) as the stator and I was curious as to
whether the opposing magnetic fields in such an arrangement would act as
a "high pressure" area and produce movement in the arm holding the
smaller magnet.
In my very unscientific testing it resulted in no movement of the
smaller magnet or the arm holding it.
I suspect it is because the magnet's flux field must compress the disc's
flux field lines in order to move in any direction. Therefore, there is
no "low pressure" area for the smaller magnet to move towards. The
"pressure" (or magnetic flux field) of the disc is the same all around.
Thus, there is no potential difference to take advantage of.
I had thought that the compression of the 2 opposing fields may result
in a higher pressure area that may move the arm holding the smaller
magnet forward. It did not.
I was just curious.
Now I know.
Thanks for your help!
jim
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