Magnet Myths and Misconceptions

[MileHigh]

Tinman is comparing different weight iron samples that he can lift with one or the other of his electromagnets.  He is measuring force.  Force on a soft iron piece goes with the gradient of the flux density, which is much higher for the iron wire coil.

Okay, so I can suggest a follow-up test for Tinman.

You line up the axis of your copper-wire coll on magnetic east-west.   Then you put a compass say 10 inches away from the end of the coil on the line of the coil's axis.   Then you can energize the coil and note the amount of compass needle deflection for a certain amount of power dissipated in the coil, and also for a certain amount of current flowing through the coil.  You can obviously tweak the distances and amount of current flowing through the coil to give you a "nice" deflection of the compass needle, say somewhere between 30 and 45 degrees.

Then repeat the whole thing again for the iron-wire coil and compare results.

This test should give you a nice indication of the relative magnetic field strengths for both types of coils.  (This is not to be confused with the magnetic attraction force measurement.)  You basically have the compass needle aligning itself with the net magnetic field as supplied by the Earth and the coil under test (the two magnetic field sources will be at right angles to each other.)

MileHigh

[tinman]

Okay, so I can suggest a follow-up test for Tinman.

You line up the axis of your copper-wire coll on magnetic east-west.   Then you put a compass say 10 inches away from the end of the coil on the line of the coil's axis.   Then you can energize the coil and note the amount of compass needle deflection for a certain amount of power dissipated in the coil, and also for a certain amount of current flowing through the coil.  You can obviously tweak the distances and amount of current flowing through the coil to give you a "nice" deflection of the compass needle, say somewhere between 30 and 45 degrees.

Then repeat the whole thing again for the iron-wire coil and compare results.

This test should give you a nice indication of the relative magnetic field strengths for both types of coils.  (This is not to be confused with the magnetic attraction force measurement.)  You basically have the compass needle aligning itself with the net magnetic field as supplied by the Earth and the coil under test (the two magnetic field sources will be at right angles to each other.)

MileHigh

I was editing my post above when you were posting this one MH.
As i said,i would suspect the copper coil would have a far larger magnetic field than that of the iron wire coil-->i think this go's without saying,as the iron wire itself would be pulling in the magnetic field-attraction.

[Cap-Z-ro]

"I made a lot more electricity with my generator than I ever made with urine soaked cloth."
--Ned Leedskalnin

[MileHigh]

There is no conundrum to contemplate MH. If the P/in is the same in both coils,then the disipated energy in both coils must be the same,as energy can neither be created nor destroyed only transformed. I would suspect that the coil that uses the soft iron wire would be acting or represent a permanent magnet,where as the copper coil would not,as the copper itself is not magnetised.

EDIT: - i forgot to add this in.
As i said before,i would suspect that the copper coil would have a far larger field to that of the iron wire coil,as not only is the iron wire making the field,it becoms part of the field-much the same as having a core.

Now in saying that MH,here is a thought experiment(brain fart).
Lets take two cores that are identical in every way-lets say they are 1/2 inch round x 2 inches long,and well use solid ferrite for this thought experiment. We wind 100 turns of .55mm copper wire on one,and 100 turns of .55 soft iron wire on the other-both enameled coated for insulation.
We apply a P/in of say 5 watts to both(now) electromagnets.
Which do you suppose will have the strongest and largest magnetic field for the same P/in?.
An interesting thought experiment i think,as the one useing the iron wire now has a larger core,but uses the same amount of wire,where as the one useing the copper wire has a smaller core,but still has the same size outside diameter

For the first part, I would suggest that the iron wire coil more of less "hides" some of the magnetic field inside the wire itself.  It's kind of like a variation on a leedskalnin PMH.  The magnetic field buried inside the wire will not affect the outside world.

For the thought experiment, the copper wire coil around the ferrite core would have the strongest magnetic field because you can pump more current through the coil for the same power dissipation.  If you go to the limit and the cooper wire resistance is zero, then it takes no continuous power to produce the magnetic field.  However, it still takes a certain finite amount of energy to get the current flowing because it's just a ferrite-core inductor that happens to have a coil wrapped around the ferrite that has zero resistance.

MileHigh

[MileHigh]

Here is a final thought for you to contemplate Tinman:

You have a rectangular block of ferrite on a wooden table.  There is no latent magnetic field in the ferrite.

You have a small magnet in your hand.   You approach the ferrite block and you feel the magnet tugging on your hand as the magnet goes and sticks to the ferrite block.

So, in the "before" case there was no magnetic field, and no magnetic energy inside the ferrite block.

In the "after" case now there is a magnetic field inside the ferrite block.  That means there is measurable magnetic energy inside the ferrite block.

So where did that energy come from?  Does a magnet act like some kind of "bottomless cup of coffee" with an infinite capacity to transfer energy into neutral blocks of ferrite?

Well, obviously that's impossible.  (Although just suggesting it makes me worry that someone is going to get all excited by the concept.)

The answer is that there is good old Lenz drag.  Even though the magnet is attracted to the neutral ferrite block, there is just a tiny tiny smidgen of Lenz drag as the magnet approaches the ferrite block.  There has to be, energy can't just appear in the ferrite block like magic.

That means that mechanical energy (force x displacement) is expended by a variation on "Mr. Hand" to pay the price to fill up the ferrite block with magnetic energy.

MileHigh