A question on magnets
xray4abc
Let�s end the year 2009 pondering over a thought-stimulating question!
Consider an interesting observation on magnets:
Brake a magnet in 2 halves, let say, along its longitudinal symmetry
axis!
Then try to glue the 2 halves back or at least to bring them back to
their
initial position. I bet that that you will hardly be able to do that,
due to the strong
repelling of the 2 parts (if you use a neodymium magnet!).
Now, a question arises:
Is this radial repelling action between the parts of a
magnet, suggested by this experiment, a permanent phenomenon which
produces
a permanent internal tension in the magnet, or not?
My opinion is that : It well may be!
It could be checked experimentally by measuring the diameter of a disc-
magnet
before and after demagnetization, as the demagnetized disc is expected
to have
a smaller diameter than the initial disc-magnet!
(I intend to do this experiment.
I have no idea if in the literature the above raised issue was already
discussed or not.
A quick google search turned up nothing, but it may not be relevant. )
All the bests for everybody in this group in the new year!
Laszlo Lemhenyi
X-Phy
> Hi, everybody!
> Let�s end the year 2009 pondering over a thought-stimulating question!
> Consider an interesting observation on magnets:
> Brake a magnet in 2 halves, let say, along its longitudinal symmetry
> axis!
> Then try to glue the 2 halves back or at least to bring them back to
> their initial position. I bet that that you will hardly be able to do
> that, due to the strong repelling of the 2 parts (if you use a neodymium
> magnet!).
The distance between the centers of the two parts can't made zero, so
the repelling force isn't infinite, it is difficult but not
impossible.
> Now, a question arises:
>
> Is this radial repelling action between the parts of a
> magnet, suggested by this experiment, a permanent phenomenon which
> produces a permanent internal tension in the magnet, or not?
>
> My opinion is that : It well may be!
> It could be checked experimentally by measuring the diameter of a disc-
> magnet before and after demagnetization, as the demagnetized disc is
> expected to have a smaller diameter than the initial disc-magnet!
> (I intend to do this experiment.
> I have no idea if in the literature the above raised issue was already
> discussed or not.
> A quick google search turned up nothing, but it may not be relevant. )
> All the bests for everybody in this group in the new year!
The natural state of a magnetic metal is demagnetized, so there is a
potential energy in a magnet, that demagnetize slowly naturally. A
motor can be constructed using that energy.
--
X-Phy
Khrapko
> Is this radial repelling action between the parts of a
> magnet, suggested by this experiment, a permanent phenomenon which
> produces
> a permanent internal tension in the magnet, or not?
>
> My opinion is that : It well may be!
> It could be checked experimentally by measuring the diameter of a disc-
> magnet
> before and after demagnetization, as the demagnetized disc is expected
> to have
> a smaller diameter than the initial disc-magnet!
It is interesting, but what is a disc-magnet? A simple magnet is
rectangular.
Radi Khrapko
xray4abc
Disc-magnets.....they look like, let say, a 1$ coin.
They are selling ring-shaped and cylindrical rod-shaped ones as well.
(And, yes, rectangular ones too.)
You can't say that they are not ...."simple magnets" ! :-)
On "youtube" you can see very nice experiments done with them.
For example, you can watch some interesting homopolar motors,
constructed with such magnets.
Explaining how they work is ...not that simple.
Best regards, Laszlo Lemhenyi