Wow, this 2006 thread has been revived.

Nobody brought up the fact that, unlike gravity, a magnet is bipolar in nature. Ferromagnetic meterials are attracted to the GAP between the poles. The ferromagnetic material can more easily contain lines of force (field density) than free space or air. As the field shrinks it becomes a lower energy level, thus attracting the material.
Diamagnetic materials (eg: a common grape is an example) can absorb less lines of force than free space, so these materials increase the energy level as they approach a magnetic gap, so are repelled by the magnet.

You can't get away from mentioning the magnetic field and the lines of force to explain magnet behaviour and understand it intuitively.

 

So in essence, you are saying that a magnet is precisely a .................. (please fill in the blank space)

 

THe physical phenomena that causes the generation of magnetic fields is associated with terms like "quantum spin", "electron spin" "magnetic moment", or variations of it like "magnetic dipole moment" or "spin magnetic moment". It's really strange ultra-physicsy mathy stuff. I won't explain it here because I don't know it well enough. You are best off if you Google and Wiki those terms to find out what they actually are.

To get you started...
http://en.wikipedia.org/wiki/Spin_(physics)

 

What always confuses me about this dicussion is how the Lorentz force equation is some how an insufficient definition of a magnetic field. A field is defined to be magnetic field such that when an electric charge moving with some vector velocity v is crossed with that field it produces a force.

That is the definition of a magnetic field. Magnetic field - Wikipedia, the free encyclopedia Certainly there are other equivalent definitions as the author notes, but this is a viable definition.

The Lorentz force equation is one of the fundamental definitions of electromagnetics, it seems like a reasonable place to start.

 

you guys haven't exactly answered my question

 

A magnet is something that has a magnetic field. You might think it's using a word in it's own definition (well it kind of is, but not as blatant because we are dealing with physics instead of pure language and things in physics overrules language). It's different because this definition is not asking what something MEANS, it's asking what something IS.

What you have to end up realizing is the word magnetic field is actually a label for a large chunk of text of some intense physics, so the label itself doesn't tell us anything.

A better definition would replace what this label with the description it actually represents and get into what a magnetic field actually is, but then it's anything but simple. THat definition would go like this:

"A magnet is a single piece of homogenous substance or compound that produces a [insert full length explanation of a quantum physics and how magnetic field are produced here] with or without the presence of an electrical current running through it."

It reminds me when I asked what electric flux actually is...still haven't gotten an answer...the prof has never gotten an answer either.

 

Does that mean that there is no straight answer for the definition of a magnet?(besides the one you gave me earlier on)

 

If you are really interested in this then I assume that you have spent some time looking in other places, possibly even reading a textbook. Some things can't be explained in "..................".

I'll give you two areas you could investigate. I see no inconsistency in defining the magnetic field as something that produces the velocity dependent part of the Lorentz force on moving charged particles. This then enables you to define a magnet as something that produces a magnetic field. You can even work out the attraction / repulsion between electromagnets using this approach.

Alternatively, if you dig deeper, you will discover that the magnetic field is actually not a new field but a distortion of the electric field. If you take a metallic conductor, this consists of a large number of fixed positive charges and a large number of free electrons. As there is no net charge the enormous electric field of the positive charges exactly balances the enormous electric field of the negative charges and so there is no external electric field. When a current flows the negative charges move and the positive ones stay still. Relativity requires that the fields from the moving charges are distorted in a special way and as a result the electric fields no longer exactly cancel, and the resultant (small) field appears as the magnetic field. Moving charges 'see' this distortion in different ways (according to relativity) so the force they see depends on their velocity.

So another definition of the magnetic field is that it is simply the electric field in the rest frame of the moving charges that cause it. there, that doesn't fit into "............." either.

 

How do we measure the magnetic field, is there a piece of equipment that can measure or see the movement of flux around the poles,when influenced by movement or a copper coil.

 

A multimeter will pick up the induced voltage from a magnet being passed through a coil of wire.

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Very Funny

 

Is it possible to create a magnet (electromagnetism) that can attract a piece of metal from 38m away using only one pole (heating the sides to remove magnetism) ?

 

You'll need a pretty big magnet and a very small target.

__________________
Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com/

 

I'm sorry, did you say 38 meters? Not a freegin chance. You'd have difficulty affecting something as small as a compass needle at that distance.

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But I thought using the principle of mmf=in, i, being current and n, number of turns. Increasing the current for example, 1000volts and the turns being 500 turns (although it might take months to complete), 1000 X 500 = 500,000. Shouldn't this work? And please give me a straight answer anything other than a yes or a no with explanation may no be helpful. No "I be cat" answer