What is a magnet? Easy readable explanation!
From compasses and cellphones, to trains and MRI machines, magnets are crucial components of our everyday lives. Without them, some of our most important objects would not be able to function properly. However, not many people can say the they know exactly what magnets are and how they work.
What is a magnet? A magnet is any object that creates an invisible magnetic field around itself, such that it applies force on other magnets within its range. There are several types of magnets that exist in the world, from permanent to temporary and everything in between.
Magnets are typically made of iron, and thus, will attract other iron-containing materials; however, virtually any material can function as a magnet so long as it exerts (or can be made to exert) a magnetic field.
Permanent magnets are materials that retain their magnetic properties when they’ve been magnetized - refrigerator magnets, for example. Temporary magnets are objects that become magnetized when introduced to a magnetic field, but lose their magnetic properties when removed from it, such as paper clips.
Today, we will be looking at how magnets work, what makes something magnetic, and the various, dangerous ways a magnet can lose its field. Keep reading to find out everything that you’ve always wanted to know about these unique objects.
What is a Magnet - And how do they work?
Take a paperclip and a refrigerator magnet, rub the paperclip on the magnet for a while, and then stick the paperclip on your refrigerator. You will find that the paperclip sticks to your fridge, but it doesn’t last very long, unlike the real magnet you used to magnetize it with.
It’s an experiment you probably did as a child anyways, but it illustrates the idea of magnetism very well.
Interestingly enough, science has been trying to understand how magnets work in the first place, and there are still aspects of magnetism that physicists do not understand yet.
One of the biggest questions in magnetism is why these objects exert this kind of force in the first place. However, the general idea of magnets will be explained throughout the rest of this section.
Take a look at the table down below to enlighten yourself on what we do know about magnets, before we get into some of the smaller details and unanswered questions.
|Types Of Magnets||Examples||How They Work||What They Are Made Of|
|Permanent Magnet||Refrigerator Magnet, Magnets found in MRI machines||Produce a magnetic field to attract objects using electrons||Rare Earth Materials, Neodymium|
|Temporary Magnet||Paper Clip, Iron Nail||Produce a temporary magnetic field to attract objects using electrons (in the presence of stronger permanent magnet)||Iron, Steel|
|Electromagnet||Magnets found in automobiles and audio recording equipment||Use an electric current through coiled wires inside of magnet to produce a magnetic field and attract objects using electrons||Iron, Steel, Nickel, Cobalt|
Atoms are the smallest unit of an element, and they have protons, neutrons and electrons.
Protons have a positive charge, while electrons have a negative charge. Neutrons are neutral and thus, have no charge. Protons and neutrons bunch together in the center, or nucleus, of an atom, while the electrons orbit around the nucleus.
The key component here are the electrons. Magnetism is thought to occur because, when you take a sample of any matter, the electrons of the atoms making up that material have magnetic fields that point in different directions, thus cancelling each other out.
However, when these field align in the same direction, they exert a net magnetic field on the object, turning the material itself into a magnet.
So, how do we make these fields align in the same direction? The answer is by introducing the material to a magnet!
For reasons we still do not fully understand, metallic objects are most susceptible to becoming magnetized iron, cobalt, and nickel, for instance.
These metals are known as ferromagnetic materials, meaning that they can become magnetized when introduced to a magnetic field; it’s why your doctor will make sure you are not wearing rings, jewelry or bracelets that contain these metals when undergoing an MRI, which exerts an enormously strong magnetic field.
These materials can be easily magnetized, and can pose dangers for removing you from the scanner.
Like I said, there’s still quite a bit we do not understand about magnets. The following list below states some of the more interesting confusions surrounding magnetism.
What Science Does Not Understand About Magnets:
- North and south poles: all magnets have them, but science can’t explain why. When you magnetize a metal, it will generate a north and south pole orientation for no explainable reason.
- We are unsure if magnetic fields function as clouds, or if they function as wavelengths that communicate with other objects at a quantum level.
- Why do magnets prefer to exert their field on like metals, rather than other materials in our world? (ie wood)
- We do not know why electrons have a magnetic field in the first place -- it is simply a property of our universe that cannot be explained, yet.
Thankfully, understanding the nuanced mysteries behind magnetism is not necessary to see it in action. Now, let us examine magnets more closely.
In an atom of an element, their electrons occupy shells that circle the nucleus, or the center, and these shells have letters associated with them.
Going from innermost to outermost shell, they’re labeled K,L,M,N,O,P and Q. Within these shells are smaller shells called orbitals, which are labelled s, p, d and f.
These orbitals also have suborbitals, but I’m not going to name them since that’s not really the point; the take-home here is that only two electrons can occupy a suborbital, and they have their own discrete spin, which move in an up or down direction.
Due to the Pauli exclusion principle, electron pairs can not occupy the same suborbital if they have the same spin direction. Each orbital has a certain amount of suborbitals associated with them: s has none, p has 3, d has 5, and f has 7.
Not every atom will have all of its orbitals and suborbitals filled, which means that there will be unpaired electrons in some elements.
It is theorized that these unpaired electrons are what generate strong magnetic fields. It’s why iron, cobalt, and nickel - which have unpaired electrons in their outer orbitals - are so easily magnetized.
Furthermore, there’s evidence that factors like the structure of a material, the alloy composition, and the softness of the object influence the strength of the magnetic field in various ways.
These are only some of the ideas generated by physicists as to why magnets behave the way they do, and their function is still being studied to this day.
Finally, because magnets are for the most part, pretty predictable we can use magnets for a variety of purposes.
To further explain this theory, take this for an example: a magnet will never start behaving in a way that goes against the laws of physics like suddenly switching polarity, becoming demagnetized for no reason, or increasing/decreasing their field without external cause.
With that being said, we can shape them into all kinds of orientations, and it’s part of why they’re so critical to our way of life.
What is the Polarity of a Magnet?
So we understand how a magnet functions, generally speaking. But there is one aspect of magnetism I glossed over that I will expand upon in this section: namely, I want to talk about polarity.
If you’ve ever stuck a magnet on your refrigerator, or tried to push two repelling ones together, you’ve already experienced this polarity firsthand.
Magnetic polarity is simply the orientation of any magnet where one end points North, and the other points South. It’s why we hear the phrase “opposites attract,” because the North and South poles of different magnets will attract each other.
Time for another science experiment. Find a compass that you don’t mind potentially ruining, any kind will work so long as it isn’t on your phone.
Get a small magnet with a clearly labelled North and South polarity and move them closely to one another.
Since a compass uses the same logic of North and South in relationship to our globe, the red arrow will always point North.
If you put one end of your magnet against the compass, the North needle will be attracted to the South side of your magnet. This is a common way to determine the polarity of one’s magnet, and it’s so simple, a child can do it.
Understanding magnet polarity is key to applying their force to our modern technologies. Without general knowledge of polarity, it would be impossible to make a compass point North, a credit card to swipe, or a refrigerator magnet to stick.
There are plenty of alternative ways to determine magnet polarity:
Using the compass method, as already described.
Tie a string around your magnet and let it freely hang; the North and South poles will orient themselves North and South to our globe.
Float your magnet: if your magnet has no clear markings, place a piece of styrofoam on water, and put your magnet on top -- the magnet will turn the styrofoam so the North pole of your magnet will point North.
Get two magnets, one where you know the polarity, and one where you do not. Attempt to place the ends of them together; the North and South poles will attract, while the like poles will repel.
When you are using a magnet, it is important to be aware of what side is pointing north and south.
Otherwise, common applications of magnets can fail, and they will inevitably stop many of our modern technologies from working properly. This again, is a fact of our universe, as even the globe has North and South poles, and polarity is crucial to navigation.
Some magnets polarities are difficult to decipher, and this is mainly due to their discrete shape. Spherical magnets suffer from this problem, as it’s almost impossible to determine their polarity through conventional means.
Usually cut from a cube of metal, the cube’s poles will be preserved in the sphere, but its structure will make our home tests useless. They typically will be labeled by the manufacturer for this very reason, but unless you have a very specific need for one, it’s unlikely you will ever use a sphere magnet for anything useful.
Of course, the best kinds of experiments are those done by hand: see for yourself how magnetic polarity can be determined!
Luckily, you do not have to be a physicist to run your own polarity experiment in the comfort of your home, so long as your magnet is convenient and decipherable.
Can Magnets Ever Stop Working?
We’ve talked a lot about how magnets work, their polarity, and common applications of magnets in our everyday lives. However, the big question we should be asking is one of permanence.
More specifically, can a magnet ever stop working? The answer to this particular question is that it really depends.
For example, a permanent magnet can keep its magnetic properties for centuries with little loss in strength, so long as you store it properly. Only under very specific circumstances can a permanent magnet lose its field.
Magnets by their very nature are consistent, but admittedly, it is a little scary to think that these cornerstone devices can suddenly stop. The good news is, it takes quite a bit of work to demagnetize a magnet, intentionally.
Demagnetizing a temporary magnet is a matter of waiting until the field dissipates -- temporary magnets are notorious for their short lives, and you do not have to do much of anything to change it.
You can see this firsthand by looking at how quickly a nail, paperclip, or other soft metal lose their magnetic properties.
But when you demagnetize a permanent magnet, you are changing the material itself on an atomic level, which is already a huge task to accomplish.
By that I mean, you essentially have to change the material such that the magnetic domain, or the orientation of the electron fields, scrambles again from its forced, fixed orientation.
Along with understanding how to create a magnetic material, it is important to learn how materials are demagnetized.
This is doubly true in the medical field, where there are tons of protocols in place to make sure MRI’s can cease their strong magnetic field at the drop of a hat.
Let’s look a bit more closely at how magnets lose their magnetism, and the methods in place for demagnetizing them intentionally.
Here is how magnets can lose their magnetic field:
- Extreme heat, also known as quenching
- Being placed in a demagnetizing magnetic field
- By hitting it hard enough.
Magnets, like many materials, function at an optimal temperature, mainly ambient, room temperature. When you raise the heat of a magnet, not only do you risk changing the shape, but you also weaken its magnetic pull.
This isn’t to say that putting your magnet in the microwave will ruin the magnet, though it’s not a good idea to do so, but extreme heat can fundamentally alter its function.
This is due to something called the Curie point, or Curie temperature. The Curie point is the minimum point where a magnet can be heated and start to lose its magnetic properties.
It is very difficult to reach the Curie temperature accidentally, and you would essentially have to apply constant, intense heat to your magnet to get anywhere close to reaching it.
Since I doubt any of you reading this are in the business of creating molten iron, I will not go into detail about the dangers than can arise from extreme heat applied to metals.
This heating process, however, is especially important for stopping MRI’s from happening. If a metal gets lodged in the scanning bore, it isn’t possible to simply turn off the magnet with a switch.
You can shut down the electricity and stop power from entering the machine, but it does not change the strength of the main magnet system.
You have to raise the temperature of the conducting coil in the machine, a process known as quenching. Quenching is one of the only methods for stopping a magnet as powerful as an MRI.
Secondly, magnets can be demagnetized by being introduced to an opposing magnetic field over time.
Magnets have an inherent property of conduction known as coercivity, which refers to a magnet’s ability to withstand being demagnetized. Think of it akin to torque, which is a material’s ability to resist a force being applied.
Materials with high coercivity are resistant to opposing forces, but with materials with a low coercivity, it is possible to weaken the field over time.
Constant, gradual exposure to an opposing field will eventually kill your magnet, so beware if you store your magnets together in close proximity to one another.
Finally, a material can be demagnetized by accident! This really only applies to steel and old materials that have a high chance of accidental damage.
When you change the orientation of a magnet by hitting it or dropping it, you essentially affect its magnetic integrity as a whole.
This is not much of a risk with powerful, tough magnets, but toy magnets can stop working if they’re handled improperly.
This is due to the fact that a magnet functions as a result of its north and south poles’ orientations -- if you break the magnet and shift its structure, you compromise this alignment and the magnetic field can be dissipated.
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In conclusion, we’ve explored what magnets are, how they work, how their polarity plays a role, how they can lose their function.
Like all great scientific topics, it is key to see this kind of phenomenon first hand. Go to a hobby store, pick up a few magnets for yourself, and see the presented explanations in play.
At the heart of it, there are thousands of technologies that utilize magnets, and their versatile role has changed the face of modern life forever.