Magnetism experiments

How to make a permanent magnet with iron filings

We know that a magnet can attract ferromagnetic objects, or attract or repel the poles of another magnet. Today we will see a very simple home experiment, where we will learn a little more about magnetism and how we can magnetize other objects that are not permanent magnets.

Materials:

* Permanent magnet.

* Iron filings.

* Small plastic bag.

* Clip or bra.

Process:

I will explain in detail how to do the experiment. I recommend that you read well first and then watch the video, since it shows other things that do not interest us and may confuse you.

First we are going to place filings inside the plastic bag, we remove a little air and close it (you can stick it with adhesive tape if you want).

Draw the bag to the clip or bra and you will notice that it does not attract it.

Now you place the bag with the filings on one of the poles of the magnet. If you do not know where the poles are, you can use another magnet, and bring them together to see where they attract and where they repel. Hit the bag a little so that the filings line up. Bring the bag back to the clip, and you will see how it now attracts it.

To finish, stick a little to the bag so that the iron filings are mixed. If you bring the bag closer to the holder, it will appear that the magnetism has disappeared.

In the following video you can see how to make this simple home experiment:

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¿How does it work?

Initially iron filings do not have their own magnetic field. When we place them on the magnet, they magnetize and align a bit with the magnetic field lines. When removing it from there, there remains a remaining magnetism, which is more than enough to attract other ferromagnetic objects.

But when we hit and shake the filings, we are messing up all those little magnets, and since the magnetic field of each one is very small, without an order "they do not add up" their fields, rather they "cancel".

Something similar happens in larger ferromagnetic objects. For example, if we have an iron or steel nail, initially it will not have its own magnetic field. If now we approach a magnet, it will have a small field since the "small magnets" inside it all align in the same direction. To remove the magnetism from the nail, we have to redirect the small magnets inside, and for that we can hit it hard with a hammer. Another option is to heat it above a tempera known as the Curie point, where the agitation of matter is so high that it ends up doing the same work and demagnetizes the material.