iron cores; how important is iron vs other magnetic ore

[solinear]

Most people here aren't looking for an explanation of magnetic realms and how the electron shells work into this, it's useless for their purposes.  They want to find a good magnet core and basically once you get to a certain point, it doesn't really make a difference.

I gave them a basic understanding of how the core affects an electromagnet.  If you follow the logic (reduction and impact upon the magnetic field strength by the air gap), you will easily understand why most industrial magnets for lifting have the poles on the same face (which is done by wrapping a ferrous material from one side to the other - so the magnetism can travel through it) - because it reduces air gap and increases the strength of the magnet by reducing total coercivity (which you somehow don't mention at all) and why those magnets far exceed twice the strength of magnets with their poles on opposite sides.  I also never stated that it conducts magnetism, I said to *think* of it as conductance then continued to explain in terms that are easily understood by someone who basically understands an electrical circuit but doesn't understand the physics of magnetism.

What I stated was relatively accurate, while you gave very little detail (in your other article) as to the shape of your electromagnet, leading one to come to the conclusion that it was a straight rod.  Which means that, even with the cobalt-based alloy 2714A (1,000,000 permeability at high frequency), a 2cm magnet (or any magnet, regardless of length) would not be 5000 times as strong as one with an air core.  Because of the way magnetism travels through mediums and the low permeability of air, you would have to basically wrap the poles around to where they were 1/5000th of the distance (actually less, because of the permeability of the material you're using as a core).  No.... if you had a magnet that was 5000cm long and wrapped the 2714A back around from one pole to the other and made it so that the poles (ends of the core) were less than 1cm apart, then you could make a magnet that was 5000 times as strong as it would be with an air core.

But just think about it for a second... 1 amp turn (1 coil of wire with 1 amp going through it), figuring for a reluctance of 1 (permeability of 1000) and 1cm core surface area, will generate 1 gauss (pulling this off the top of my head).  Now throw enough turns to fill up 1cm - what, 15-20 of 26 gauge wire (just an offhand guess)?  So now we're up to 15 gauss.  Drop it down to .2 amps and when you multiply that by 5,000 and all of a sudden we would all be running around making 15k gauss magnets in 10 minutes, no more of these electromagnets with thousands of windings.  Of course, you still have to deal with the saturation point of the material, so we couldn't really make many 15k gauss magnets anyway.

BTW, I'm not sure why, but you seem to have not seen the nearly dozen times I used the word permeability.

My biggest issue here is that so few people talk about watts and joules.  I can't count the number of times I've seen quotes like: "I'm putting 12 volts in and getting 36 volts out!!!" without any mention of the watts in or out.

[Paul-R]

Try coat hangers for a cheap source of iron.

I'm not sure this is so. I think they are steel. Check out this:
http://www.publicbookshelf.com/public_html/The_Household_Cyclopedia_of_General_Information/steeliron_cej.html

[The Observer]

Hey Sol,

A very interesting response.

An industrial lifting magnet that has both poles on the same end. A U if you will.

    The reason is two poles are twice as powerful as one because iron will attract to
    both north and south poles.

You mention what I assume is Magnetic Coercivity.
   
    Magnetic Coercivity can be likened to the "Stickyness" of the dipoles with respect to
    spinning freely about it's center.

      - Ferromagnetic Materials which have low coercivity like iron and super malloy
        have dipoles that are very susceptible to turning in the presense
        of external magnetic fields. "Not very Sticky"

       -Ferromagnitic Materials that have high coercivity are magnets like neodynium and
         its dipoles are not susceptible to turning in the presense of an external magnetic
         field. "Very Sticky"

So you might see that I am a little confused when you say "reduce the coercivity'.
This can only be done by changing the atomic makeup of said material.

Yes the formula mentioned above is for a straight rod wrapped with wire.

It is important to realize that Magnetic Permeability is represented by the μr in the
aforementioned formula.

B = (μ0 * μr * N * i) / l

If you were to stick a material that has a Magnetic Permeability of 1 Million into a coil.
the resultant magnetic field would (1 Million) x (the magnetic field of an empty coil).

I've said it quite a few times without many people seeming to understand.

It is so important to realize that whether magnet or magnetic material, the magnetism
comes from dipoles.

     When a magnet that has 1 Million dipoles comes near a piece of iron that has
     1 Million dipoles... the total number of dipoles now pointed in a single direction is
     2 Million. !

Sol. I'm sure you know this, but I would really like others here to realize what is going on.

If go down this road, you will come to a strange form of energy not mentioned by many.

                Anisotropic Energy.

I claim we are already reaping the benifits of this energy with out acknowledging it.
I think we will reap huge benefits from this energy once understood.

(if you are wondering what we already use.. a simple example is a speaker)
If you tried to make a speaker work without a Magnet or a Ferromagnetic Coil Core,
it would take 100's perhaps 1000's times the energy to make it work.

Well, thanks for your response Sol, I am looking for anyone who wants to have a dialog
about this.

Walk Lightly and Carry a Big Stick,
                                                        The Observer

[solinear]

I think that this is a futile argument.  You're using calculations based upon closed circuit magnets (no air gap) and likely don't realize it.

My recommendation: Go get a bunch of magnet wire, a nice variety of cores and a gaussmeter.  Until you actually do it yourself, you're going to hold onto your current understanding of how electromagnets work in relation to their cores.

Here is a good article on how to calculate magnetic strength of an electromagnet: http://sci-toys.com/scitoys/scitoys/magnets/calculating/calculating.html

[The Observer]

Hey Sol,

As far as the formula goes...it was garnered from Wiki as well as numerous college Physics text books.

As far as me needing to build my own coils.
                                                                      You are right.

However, could you be the one person who says they understand that a piece of iron
turns into a magnet in the presence of a magnetic field or another magnet's magnetic field?

I will be clear.
    2 items are placed next to each other

                                      - 1 magnet with 1 million dipoles  =  -->
                                      - 1 piece of iron with 1 million dipoles =  -> <-
   
                                                          (-->) + (-> <-) = (---->)

Translation... 1 million organized dipoles + 1 million disorganized dipoles = 2 million organized dipoles.
(ALL POINTED IN THE SAME DIRECTION)

Anyone else that's with me, I would really like to hear from you.

Be Grand,
                The Observer