Magnet Myths and Misconceptions

[verpies]

I would agree and the logic here is very interesting because if a machine can impart a permanent magnetic field in a material then another machine may remove this permanent magnetic field.

Yes, but in case of magnets (hard ferromagnetics) this "imparting" and "removing" is very lossy and the magnet heats up.
However in case of soft ferromagnetics and ferrites this this "imparting" and "removing" can be done with very little losses.

Now if the energy contained in a permanent magnetic field within a volume is a reversible process then it should apply to any magnetic field anywhere.

Yes, efficient reversible magnetization happens everyday in all ferrite cored coils. (in iron/steel cored, too).

That's why discharging a ferrite cored coil takes longer with the ferrite inside it than without it, when other parameter are the same. 
When the ferrite demagnetizes, it returns the energy that was used to initially align its domains parallel to the coil's MMF.

[sparks]

   I finally found the copper that is missing today from Ed's less than permanent magnet holder called a generator.   Looks like a variable reluctance generator.  His armature completes a magnetic circuit just like a set of contacts completes an electrical circuit.  The core is that iron pipe the output windings are wrapped around.  This pipe must be polarized by the Earth's magnetic field.  He then sends a wave of magnetism of varying intensity and polarization through the IRON as the armature aligns with the iron magnets placed around the circumference of the stator.   This is interesting in that there must be a delay between current flow in the output windings and alignment of the armature with the stator flux.  You could transmit power this way using steel cables instead of copper wire.  The load current would not increase the rotor drag like it does in a typical alternator. 
  In this famous demonstration there appears to be no electrical load.  He does however have a piece of iron balanced on what appears to be a transformer core.   I wonder if it started jumping around. 
  If you placed a shorted copper coil at the end of a long steel cable I wonder if it would reflect a magnetic wave.   A small amount of input over a long time could accumulate until there is alot of energy in the magnetic resonance thingy.   A few hours of cranking that deal stored up and let loose all at once could move some rocks around or power a jackhammer etc.

[poynt99]

Yes.  In an ideal solenoid all of the input energy is used to create the magnetic field around that solenoid

If the inductor is ideal, then no energy input to that inductor is required, in order to maintain its field.

A bit of a brain teaser

If zero energy is required to maintain the field, why would energy be required to build it?

An ideal inductor implies DC resistance is 0 Ohms. There can be no power dissipation in an element that is purely inductive, and energy is simply power x time.

Of course an ideal inductor is purely hypothetical, but it does mess with our concepts of energy and limits  . And of course it takes energy to energize the ideal inductor , but it also gives back all of that energy when the source is removed.

[minnie]

   Sounds like Super conducting magnetic energy storage.
            John.

[NoBull]

Of course an ideal inductor is purely hypothetical, but it does mess with our concepts of energy and limits  .

Not really.  I once conducted an experiment with a superconducting tube (which cost only $60) and once I froze the magnetic flux in it, the magnetic field persisted for hours and showed no indication of diminishing.  Eventually I run out of LN and it thawed.
See below:
http://tinyurl.com/n3udeg3