How to Demagnetize a Magnet

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Magnets are useful for all kinds of things, whether we’re using them to stick things on the fridge or as an internal component of our phones. But have you ever been curious about how to demagnetize a magnet? As it turns out, there are a few ways to make a magnet less strong, and we’re here to walk you through all of them. We’ll give you the full rundown on how demagnetization works, and all the ways to demagnetize metal in this complete guide.

Section 1 of 4:

What is demagnetization?

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  1. Magnet fields are formed when the electrons (small particles that contain electric charges) in a substance are oriented towards a north and a south pole. By changing how the electrons align, magnets can become less strong or almost demagnetized altogether. This process is called degaussing. [1]
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Section 2 of 4:

What can demagnetize a magnet?

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  1. Hitting a magnet with a hammer can shake up its electron alignment. With enough blunt force, especially force applied to the poles of the magnet, you can shake up its atoms enough to weaken or demagnetize the metal. [2]
    • You may not even need to reach into your toolbox to weaken a magnet. Simply dropping one might be enough to weaken some magnets.
  2. Exposure to another strong magnetic field can weaken a magnet. This method is usually carried out by devices that produce an alternating electrical current. These devices make a strong magnetic field in the opposite direction of the magnet that you’re trying to demagnetize, thus changing the orientation of the electrons in the weaker magnet. As the weaker magnet’s electrons realign to match the stronger magnetic field, it loses its original magnetism. [3]
    • This technique was originally developed by navies during World War II to deal with the threat of magnetically activated mines destroying ships made of metal. [4]
  3. All magnets have a maximum temperature, after which they’ll lose their magnetism. This is due to heat causing the atoms of the substance to move around and realign. The temperature at which permanent magnets, also called ferromagnets, permanently lose their magnetic properties is called the Curie temperature. Keep in mind, however, that all magnets will become weaker when heated, even if you can’t reach their very high Curie temperatures. The Curie temperatures for some common types of permanent magnets are: [5]
    • Iron: 1043 Kelvin (770 degrees Celsius, or 1418 degrees Fahrenheit)
    • Cobalt: 1388 Kelvin (1115 degrees Celsius, or 2039 degrees Fahrenheit)
    • Nickel: 627 Kelvin (354 degrees Celsius, or 667 degrees Fahrenheit)
  4. With enough time, magnets will lose their magnetic properties. This is because, just like all substances, magnets are exposed to heat and other magnetic fields constantly. For some very weak temporary magnets, demagnetization can happen really quickly, within a few minutes. For permanent magnets, it could take a lot longer—a samarium-cobalt magnet, which is a common alloy used for a variety of different applications, would lose its strength in about 700 years. [6]
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Section 3 of 4:

Why would you want to demagnetize a magnet?

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  1. Since hard drives, and other data storage devices have magnets as an integral part of how they work, demagnetizing these devices is a good way of destroying their data. [7]
    • If you are really concerned about someone accessing your hard drive data, the best way to destroy any information on it is to use a hammer and smash it.
  2. Over time, magnetic fields can cause your watch to lose track of time. To fix this, it’s necessary to demagnetize it regularly. While you can always go to a watch store to have them demagnetize your watch, you can also do it at home with a degausser machine.
  3. Magnetized screwdrivers and other tools are popular because they make working with small screws even more convenient. However, when dealing with sensitive electronics, it’s a good idea to demagnetize your tools before touching hard drives or other storage devices—the magnetism could damage the data. [8]
    • For demagnetizing a screwdriver or other tool, blunt force should be sufficient. Hit the tools really hard, then test them on non-magnet metals to check their strength.
    • There are also handy and affordable devices that can demagnetize your tools easily. As a bonus, these tools can also remagnetize magnets as well.
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Section 4 of 4:

How does magnetism work?

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  1. All substances are made up of tiny particles known as atoms, which have even smaller particles that carry electrical charges, called electrons. In some substances—like iron, cobalt, and nickel—these electrons are mostly spinning in the same direction in relation to their atoms. This makes these kinds of substances possible magnets, although they won’t be able to attract other magnets yet. [9]
    • Iron, cobalt, and nickel are ferromagnetic substances. Ferromagnetism is the strongest type of magnetism, and the one you’re most likely to encounter when you’re dealing with magnets. [10]
  2. If a magnetic substance comes into contact with a strong magnet, its electrons will align along two poles—the north pole which is attracted to south poles, and the south pole, which is attracted to north poles. Substances like iron, cobalt, or nickel then become permanent magnets. [11]
    • A magnetized substance needs to be exposed to a strong magnet to become a magnet itself because of how its electrons are oriented.
    • Although the electrons in a magnetic substance are spinning in the same direction in relation to their atoms, these electrons need to spin in the same direction in relation to the other atoms in the substance too.
    • Magnetic fields are also produced by electric currents, which means that you don’t necessarily need another magnet to magnetize a substance.
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Expert Q&A

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  • Question
    How do you demagnetize a watch?
    Himesh Patel
    Metallurgical Engineer & Manager
    Himesh Patel is a Metallurgical Engineer at Mcclelland Laboratories in Reno, Nevada. With over five years of industry and graduate research experience in the raw materials industry, Himesh has extensive knowledge of mining and mineral extraction and recovery methods, mine financing, and the environmental impacts of mining. He received his MS in Metallurgical Engineering from the University of Nevada, Reno, and a Dual Degree in Mineral Engineering from the Indian Institute of Technology (Indian School of Mines), Dhanbad. Himesh is passionate about educating the public about the minerals industry.
    Himesh Patel
    Metallurgical Engineer & Manager
    Expert Answer
    The short answer is using a magnet—there are specific devices available on the market that you can use.
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      References

      1. ↑ https://www.simply.science/images/content/physics/Electricity_magnetism/Magnetism/Concept_map/Demagnetization.html
      2. ↑ https://www.simply.science/images/content/physics/Electricity_magnetism/Magnetism/Concept_map/Demagnetization.html
      3. ↑ https://www.scienceabc.com/humans/movies/breaking-bad-magnet-scene-can-you-really-destroy-a-hard-drive-using-magnets.html
      4. ↑ ​​ https://navymuseum.co.nz/explore/by-themes/technology-and-weapons/degaussing-2/
      5. ↑ http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/Curie.html#c1
      6. ↑ https://www.sciencefocus.com/science/do-magnets-wear-out/
      7. ↑ https://www.scientificamerican.com/article/how-to-destroy-a-hard-drive-permanently/
      8. ↑ https://www.popularmechanics.com/home/tools/tips/a18372/magnetize-any-screwdriver-with-this-simple-trick/
      9. ↑ https://www.nationalgeographic.org/encyclopedia/magnetism/
      1. ↑ http://hyperphysics.phy-astr.gsu.edu/hbase/Solids/ferro.html
      2. ↑ https://www.nationalgeographic.org/encyclopedia/magnetism/

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