How to demagnetize a magnetic material

Magnetize / demagnetize

We will deal with magnetizing and demagnetizing in this article. Summary of the content:

  • A Explanationwhat magnetizing and demagnetizing means.
  • Some Examples to this topic.
  • tasks / Exercises on the subject of magnetism.
  • A Video, which deals with magnetizing and demagnetizing.
  • A Question and answer area around this topic
Note:

This article is part of our electrical engineering course "From the basics of electrical engineering in 5th grade to becoming an engineer".

Explanation of magnetizing / demagnetizing

Magnets can only be made from ferromagnetic materials. Ferromagnetic substances? So what is that? Well, that includes the elements iron, nickel and cobalt. These have very specific properties. There are many "mini magnets" in these, which are also called Elementary magnets designated.

Now it depends on how these elementary magnets are aligned. If the elementary magnets are disordered, there is no external magnetic effect (demagnetized). If we align the elementary magnets, we have an outward magnetic effect (magnetized). Let's see how to magnetize and demagnetize.

Magnetize:

How can one - for example iron - magnetize? The elementary magnets must be aligned. This can be achieved by:

  • The elementary magnets can be aligned with another magnet.
  • In other words: the elementary magnets can be aligned by an external magnetic field.

Demagnetize:

How can one now perform a demagnetization? To do this, the alignment of the elementary particles must be reversed, i.e. they must get out of order.

  • This is possible by heating.
  • The elementary particles are also disordered by shaking - letting them fall down (several times) is often enough.
  • Materials are also demagnetized by a strong alternating magnetic field, which then gradually fades away. This results in a reversal of magnetization, with the strength of the magnetization decreasing further and further.

We have now got to know magnetization and demagnetization. In the next section we will look at typical tasks on this topic.

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Examples of magnetization / demagnetization

In this area we look at typical tasks and exercises for magnetizing and demagnetizing, as they are often done in school.

example 1:

An iron nail is brought near a permanent magnet. Why does it then behave as if it were a magnet itself?

Solution: The magnetic field of the permanent magnet ensures that the elementary magnets align in the iron nail. Now that these "mini magnets" are aligned, the iron nail itself becomes a magnet.

Example 2:

How can I magnetize a nail made of iron? Describe the process.

Solution: In addition to the iron nail, you also need a magnet. With this you stroke several times in the same Direction over the nail. This aligns the elementary particles.

Example 3:

A student drops a magnet in a physics class. The magnet hits the floor. What happens to the magnet?

Solution: The magnet has probably lost strength. The reason for this is that at least some of the elementary magnets have lost their order due to the shock. If this happens several times, the magnet continues to lose strength. Of course, this depends on the strength of the shock.

Tasks / exercises magnetism

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Video magnetize / demagnetize

Explanation of magnetism

In this video we will cover how to magnetize and how to demagnetize. Corresponding possibilities for this are presented and explained. The basics of magnetism can be learned with it.


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Questions with answers about magnetizing

This section deals with typical questions with answers about magnetizing and demagnetizing.

Q: What topics are there to learn about magnets / magnetism?

A: We've covered magnetizing and demagnetizing here. Here is a list of the absolute basic articles we still have around this topic: