How does a magnet work? Where is the force generated?

Question

Never was any good with Physics. :(

Do the N and S poles affect a magnet?

of the Earth? If the poles were to 'disappear' would a magnet fail also?

Answer 1

This is really more than one question, but you're lucky I'm in such a good mood tonight.

Okay, first, let's think about what a magnet is made of. It is made of alloys containing one or more of the ferromagnetic metals, iron, nickel, or cobalt.

Second, how do you magnetize something? A weak magnet can be made by rubbing it against another magnet, or by banging it and allowing the vibrations to settle out in a magneitic field, like the Earth's magneitc field.

(Try it. Take a mild steel bar, and a hammer. Hold the bar at about eye leve, horizontal, lined up with the magnetic poles. Then hit it hard with the hammer, the long way, as if trying to drive a nail. Then use something like a compass needle to test the steel bar. it should now be weakly magnetic.)

So, how do they make powerful magents...? They use a really, really big hammer, right? no.

To make strong magnets, they heat the metal until it almost softens and gets ready to flow. Then they place it in a big coil with a strong current running through it. The current makes a strong magnetic field, and as the metal cools and hardens, it becomes a strong magnet.

Why does this work? When you hit the steel bar, you shake up the domains, the alignment of the atoms within the bar. If there is nothing else to line them up, they will go back to their random directions, like a crowd of people milling about. But if there is a mild magnetic field, some of the atoms will line up to pay attention to it, like some people in the crowd noticing something interesting. Some of the people will go back to their random directions, but some stand and stare.

When you HEAT the bar until it almost melts, you really get the atoms moving around! and by subjecting them to the powerful magnetic field provided by the electromagnet coil, a lot more of them will line up the same way. It is like a drill seargeant yelling at a bunch of guys just out of basic training. Now that they have gone through the heat, they will snap to attention and line up in formation. Now they are ready to work.

When the vibrations die down, or the bar cools off, some of the atoms stay lined up in the direction provided by the magnetizing force. Obviously, if more of them were lined up, more of them are likely to stay lined up.

There are all kinds of different alloys with the ferromagnetic metals. Some are better at holding a magnetic field than others. The name of the quality that allows them to be magnetized it permeability. The name of the quality that allows them to stay magentized is retentivity, if I recall correctly. But they are two different things.

Each atom of iron, nickel or cobalt is like a tiny magnet. Alone, they are of no value. When they are facing in random directions, they are opposing each other, and their magnetic field cannot be felt beyond the piece of material. It is only by getting a lot of the atoms to cooperate together that we can make a 'magnet'.

Man made magents (and pieces of naturally occurring magnetic iron ore) do not depend on the Earth's magnetic field to stay magnetic. It could vanish and they would remain magnetized. We just couldn't use compasses to find North and South any more.any more

I hope this help you out... I probably just gave you a hundred new questions! But try looking up any of the words I used that you didn't understand: field, ferromagnetic, permittivity, permeability, domain, electromagnet. Try those for starters. You are about to enter a fascinating world of electromagnetism!

Answer 2

An electro-magnetic field is present around an electric current - and that includes the electrons orbiting an atom's nucleus. In a piece of iron, these electrons are randomly dispersed through out the material and the north and south poles of the magnetic field pretty much cancel each other out. If these electrons are aligned, however, the poles ot the electro magnetic field will be concetrated at each end of the alignment. It is this alignment that is disturbed (which weakens the magnet) if they are heated or struck.

Answer 3

in metallic networks, electrons in the outer orbitals, can be displaced easily. therefor, when a piece of metal is in electromagnetic field, all those electrons(which were in the last orbit) will gather in one said of metal. so that side will be negative. thereby, the other side will be positive. and we call that"magnet".
but I think the main question is: what is that electromagnetic force, which cause the positive and negative poles or particles(like electron and proton) attract each other?
the essence of the electromagnetic force, is "virtual photon" (but it some times appear as a real photon). that means the positive or negative particles, project photon and that cause the attraction between the positive and negative particles.
so the electromagnetic field, around the magnet, is projection of photons.
I hope I help could help

Answer 4

cdf-Rom just pipped me there. I was going to say the same thing.