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What Are Neodymium Magnets?

A neodymium magnet cube.
The term “rare earth elements” is used to describe sixteen elements on the periodic table.
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Neodymium magnets are a type of permanent magnets also known as rare earth magnets, due to the fact that they contain one or more of the rare earth elements of the periodic table. Most are made of a metal alloy containing neodymium, iron, and boron. They are much stronger than most of the magnets people are accustomed to using, like refrigerator magnets. Because of the forces they generate, they can be dangerous or even cause fatal injury if not handled properly.

These magnets are the strongest permanent magnets available, and are able, in some cases, to hold up more than 1,000 times their own weight. They are manufactured in many different shapes and sizes, such as cubes, discs, spheres, plates, and rings, among others. Small ones are used in certain electronic devices, such as computer hard drives and headphones. They have also been found to be useful in the construction of engines for remote-controlled model aircraft.

The strength of neodymium magnets is noted as the letter "N" followed by a number, with a range from N24 to N55. In theory, it is possible to make one that is as strong as N64, but this remains a mostly theoretical possibility. These magnets have some odd properties when they interact with certain other materials because of their impressive strength-to-size ratio.

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One of these properties is known as magnetic braking, and it can be observed by dropping a neodymium magnet through a copper pipe. The magnet's fall will be very slow, because of the way that the magnet and the nonmagnetic copper interact with each other. Immersing the copper pipe in liquid nitrogen is said to enhance this effect. A row of sufficiently strong neodymium magnets is powerful enough to affect the speed and angle of a steel bullet in flight.

Most of the neodymium magnets in use are small, and even these can be dangerous if improperly handled. For example, if a child is left unattended and swallows two small magnets, they can pinch together internal organs and cause fatal injuries or infections. Even more care must be taken with larger magnets, such as those that are as large as the palm of a person's hand. These magnets are strong enough to affect everything magnetic or electronic in a room, often with unpleasant results.

Manufacturers are unable to ship these larger magnets on aircraft, because they are so strong that they can interfere with a plane's navigation system, especially its compass. The websites of many neodymium magnet retailers are replete with safety warnings regarding their handling. Despite these warnings, the magnets can prove very useful in scientific applications, both for demonstration and experimentation.

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stl156
Post 7

@JimmyT - The magnets on the cranes at junkyards are called electromagnets. Basically, they work by running an electric current through coiled metal. I don't know a lot about different types of magnets, but I think electromagnets would have the potential to be stronger than neodymium rare earth magnets. Electromagnets might not be as strong per square inch or however they are measured, but I don't think you can get a neodymium magnet that big.

I do know, though, that the rare earth magnets are strong enough to re-magnetize regular magnets that have lot their pull. If you just hold the neodymium magnet next to a regular refrigerator magnet, it will realign the molecules and make it start working again.

JimmyT
Post 6

@kentuckycat - That is kind of interesting. I'm sure the magnets would quickly ruin any credit cards or things with a magnetic strip, though.

I never thought about the dangers some of these magnets could have. Swallowing two of the pieces and having them get stuck inside you would be terrible. The doctors wouldn't have any idea what was going on, either, until they took an X-ray.

Since these magnets are so powerful, would they be the kind of thing that is used for big things like the magnets at junk yards?

kentuckycat
Post 5

@titans62 - I have a few small neodymium magnets that I have found a lot of different uses for. I always say to people that they are the kind of thing that you don't know you need until you need it.

I do a lot of woodworking, so I am constantly using nails and screws. The magnets are perfect for picking up things that I have dropped on the floor. I just have a magnet attacked to a stick and can use that to pick up things that I have dropped. This little tool is especially useful if I spill a bunch of nails on the floor.

I have a friend who uses the magnets as a money clip. If he is going out and doesn't want to carry a wallet, he will just fold up some bills and hold them together with a couple of the magnets. Of course, a money clip could do the same thing, but the magnets are a conversation starter.

titans62
Post 4

@anon284627 - They are very fun. You can actually buy little construction kits that use a bunch of different types of magnets. Most of the magnets in the set are regular magnets, but a few of them are neodymium magnets that you can use for special purposes. I bought a kit like this for my brother's birthday a couple of years ago, and he really liked it.

Outside of being able to use these magnets for scientific purposes and in manufacturing is there any common use for them? I know that you can buy them at stores, but why would you need them?

anon284627
Post 3

These magnets sound fun.

anon82909
Post 2

how much stronger is an N55 than an N35 (of same size).

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