How do you magnetize and demagnetize things?

Factual Questions
1

I have seen devices that do this for small tools, how do they work? How would you build a machine to impart a very intense magnetic field into an object? How would you build such a machine for a large object or for an object that is as much as a foot away?

2

You can magnetize steel tools by aligning them with the magnetic field of the earth and hammering them.

Generally though, things are magnetized by putting them in a strong magnetic field and then turning the field off. The field must be strong enough to place the material being magnetized well up on its magnetization curve. If you google magnetization curve you will see what that is.

You demagnetize by putting the object in an alternating magnetic field and gradually reducing the field strength to zero.

3
      • The screwdriver magnetizers I have seen were just a strong bar magnet, and you stroked the screwdriver across one end of the bar a few times to magnetize it slowly.
        ~
4

Large permanent magnets are magnetized by wrapping heavy cable around the body and poles of the magnet. A bank of large capacitors are charged in parallel and discharged in series to send a large current through the cable creating a magnetic field to magnetized the magnet material. :slight_smile: