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We know that a piece of ferromagnet, such as iron, can be magnetized by putting in a strong magnetic field to get domains parallel to the field grow.

I also remember from pop. culture and MacGyver old tv series that you can magnetize a piece of iron by hitting it hard, with a hammer say, along the same direction.

1-Is this way of magnetizing iron scientific? or is it pseudoscience?

and if it is scientific then:

2-what is the physical principle that will allow iron to get magnetized by hitting? and

3-how about nonferromagnetic materials?

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What is meant by asking whether a way of magnetizing a piece of iron is scientific? Is 'scientific' just a stand-in here when the OP really wants to know whether it actually works? Just curious. –  LarsH Mar 19 at 18:13

1 Answer 1

up vote 25 down vote accepted

Seems that it can be done, and here are instructions

copying from link:

Strike an iron nail squarely and sharply several times with a hammer while keeping the nail positioned in a north-south orientation. The impact of the hammer with the iron nail causes the magnetic domains within the nail to break loose from their current orientation. The Earth's magnetic field will then reposition the domains into a new orientation parallel with the Earth's magnetic field.

It is evident that this can be done only with materials that have small domains with magnetization, which are randomly oriented, so the material has to be ferromagnetic.

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This method also requires external magnetic field. So the domains are oriented by the field not mechanical influence itself. There are multiple metastable domain configurations that are almost equivalent without external field. When you hit the piece of metal with hammer the system jumps randomly from one state to another. The states with lower energy (oriented along external field) are a little bit more probable (it depends on the field strength). –  Maksim Zholudev Dec 16 '11 at 10:54
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@MaksimZholudev Yes, without an external field the randomness cannot be defeated. –  anna v Dec 16 '11 at 11:18

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