Inertial Forces in Magnets
Bill McMurtry ( weber@powerup.com.au )
Fri, 30 Jan 1998 20:41:14 +1000
Hi all, something I've been curious about for too long now is the
mechanical stresses within permenant magnets. Perhaps some new lines of
thought may lead in interesting directions:
Take two permenant bar magnets and place them side by side, both north
poles at one end - both souths at the other. Press them together and let
them go. As you would expect they are each thrown away from the other. Like
poles repel. If you imagine a single bar magnet as being made up of lots of
little magnets (afterall you can make a large magnet by stacking smaller
magnets), then it follows that there exists, within the magnet, mechanical
stresses which tend to make it want to explode perpendicular to the side of
the magnet. The adhesion of the particals that make up a magnet prevents
this from happening. If it were possible to magically make the particle
adhesion dissapear, the magnet would explode outwards.
If you examine the "field lines" at the pole ends of any magnet you will
observe the familiar expansion of the field with distance from the pole
face. This expansion can be imagined as the result of mechanical stress
potential, locked within the magnetic field, being allowed to express
itself in the absence of the confining effects of the body of the magnet
(or the energetic confining effects of a coil). A magnetic flux will tend
to want to decrease in intensity if it can. The point here is that there
exists an inertial potential force within a magnetic flux acting outwards
from the region of maximum intensity towards the region of minimun
intensity. OK, sort of hard to explain without diagrams, but I'll press on.
If two magnets of the same dimensions and strenght are placed north pole to
south pole (attracting) so that a gap exists between the poles, there
occurs what is called magnetic fringing across the pole gap. The field will
bow out (expand) across the gap. By my previous reasoning, this is the
result of inertial locked in field stresses being partially released and
absorbed across the pole gap.
Question: is it possible to inject an applied inertial stress around the
pole gap flux so that radial compression is applied to the field? If so,
then if this applied inertial stress is quickly removed will the field
density of the pole gap flux oscillate to rest?
There are indications that this may be possible but I've not been able to
find any reference research on this matter. Any pointers?
Bill.