When a bar magnet is being manufactured, how does one end become N and the other S.?

Answer 1

Some of those are close, but there is no other magnet needed to make the new one. It doesn't take the properties of any other magnet. A current is run through it, however. A magnet works by magnetic domains. Each domain in a regular piece of metal is randomly faced. When the current is run through the bar, it (the current) will force the domains to face the same way. As the domains align, the bar acquires a magnetic field. This picture should explain what i mean by aligning them,
http://www.mcdl.net/i/magnetic_domains.gif
To the left of the picture you're about to (or have already) see, is the south, the north is to the right, where the arrows are pointing towards.


Also, so you know, I read in an earlier answer that heat was used in the making of the magnets. It may be, but I'm pretty sure it's not. Either way, afterword, excess heat or dropping the newly made magnet can randomize the domains again. This would cause the magnetic field to be lost.

Answer 2

Really the ends are North Seeking and South Seeking. That means that if you allow the magnet to move freely (ie by hanging or floating) the ends point to the North or South poles of the earth. A magnet is made by subjecting iron or other magnetisable metal rod to an electromagnetic field and fixing all it molecules so they line up in the same direction. Each individual molecule acts like it has a n and s. When they are lined up, all the ns are looking one way, and all the s's are looking the other. This determines the n or s of the whole magnet. Magnets can be made in various ways. Even by hitting it. First you have to set the rod up so that it is lined in a north south direction. Then the end pointing to the north will become the n. (It's not a very good method).

Mostly kids are taught to make it by winding wire around a rod and passing an electric current through the wire. The more coils the stronger the magnet. If you follow the coils of wire around with the fingers of your hand, your thumb will indicate the north seeking end.

Answer 3

Well, likely the materials are heated, then exposed to an existing magnetic field. A current may also be run through or around the magnet-to-be. During the cooling process, the electrons get aligned to the magnetic field of the existing magnet, so that the north of the new magnet matches the north of the old magnet. Once it's all cooled, everything should mostly be locked in, I think?

That's my understanding anyway...

Answer 4

I believe the metal is placed within an electric coil which generates a magnetic field. It is possible to make (weak) magnets this way at home, all you need is a battery, some wire and some nails to magnetise.
1. Take some insulated wire and wrap it around a pencil (to make a coil).
2. Place a nail within the coil.
3. Connect the ends of the wire to the terminals of a battery (a PP9 like fitted in smoke alarms should be suffieient).
4. Disconnect the wire, your nail should now be magnetised (test with a compass).
NB. To demagnetise the nail, withdraw it from the coil whilst the battery is connected. (Edit:- Sorry, this needs an AC Current)
Incidentally ships become magnets during the process of being built. This is because of the prolonged periods of being bashed whilst in the same position with respect to earths magnetic field.

Answer 5

I wonder if you're familar with electromagnets. What it is is a big coil of wire with DC current passing through it. When the coil is being energized, what you have then is a strong magnetic field with the poles already existed which is depedent on the direction of current flow. you see, you can pass DC current through a coil of wire from either direction. (I have to elaborate on this so you can make sense of how magnets are made.) With this being said, the way magnets established the 2 poles is how the electrons in the object being magnetized. So what I'm saying is this, the metal piece you put in the core of the coil when energized by the electromagnetic field causes the electrons in that metal piece to align themselves accordingly.

Answer 6

Good Question :).

By induction. During manufacturing each end is possibly exposed to a different polarity. So, the end which is exposed to a existing south polarity, becomes north, and vice-versa.

Answer 7

Neodymium Magnets, also known as NdFeB, NIB, or Neo magnets, are the most widely-used type of rare earth magnets. It is the strongest type of permanent magnet made from an alloy of Neodymium, Iron, and Boron with the Nd2Fe14B tetragonal crystalline structure. It has replaced other types of magnets in many applications in modern products that require strong permanent magnets, such as motors in cordless tools, hard disk drives, and magnetic fasteners. Use of sintered Neodymium magnets, either as an individual magnet or in an assembly, without license is prohibited by the Patent Law of the United States of America.

Answer 8

they hang the magnet freely on a thread... the pole which directs toward the north gets the N sign and the other one South..!!!