If you have questions about magnets, you’re not alone.+
They’re kind of mysterious, right?
It’s a thing that isn’t sticky, but it sticks to stuff?
And we can use them to see inside our bodies?
And somehow they make our phones work?
The more time you spend thinking about magnets,
the more questions that seem to pop up.
And you’re in luck, because today we’re diving into
the most frequently searched questions on the Internet about magnets.
Including why we sometimes feed them to cattle.
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Alright, we’re gonna start at the very beginning here.
What are magnets made of?
So, magnets are made of metals, either solo or combined with other metals,
which are called alloys.
The key here is that they have to be what’s called ferromagnetic.
Ferro for iron, and magnetic for… magnets.
I love when the names for things are so straightforward!
The naturally occurring ones contain iron, but cobalt and nickel
can also be magnetized, along with some synthetic alloys.
Now, what do magnets stick to?
Like we said, the big one is iron,
but you can make magnets out of nickel, cobalt, gadolinium, and neodymium,
meaning that magnets will also stick to all of those things, too.
And you might think there’d be more ferromagnetic things out there,
but those really are the only five elements that can be permanently magnetized,
at least at room temperature.
Anything else needs to be manipulated
in all kinds of weird ways to become a magnet,
which is why these guys are so special.
Why are magnets called magnets?
So they got their name based on where humans
first discovered magnetic stuff out in nature.
There’s a type of natural magnet called a lodestone,
which is made of a mineral called magnetite.
And those lodestones were originally mined in a part of Greece called Magnesia.
So… Magnesia, magnet…
The rest is history.
How do magnets work?
So, this whole thing comes down to electrons,
the negatively-charged particles around an atom.
Very basically, electrons have a property called spin,
and that spin gives each one a teeny magnetic field.
And in general, electrons are more stable when they’re in pairs.
But when they’re paired off, they always have opposite directionalities.
That’s called the Pauli Exclusion Principle.
The spin dictates the direction of the magnetic field, so two electrons with opposite
directions will create two opposing magnetic fields and cancel each other out.
And that’s why the vast majority of things are not magnets.
Each electron might have a tiny little magnetic field of its own,
but the net magnetic field gets canceled out by the paired-off particles.
But ferromagnetic materials don’t have their electrons in pairs,
their electrons are single and ready to mingle, baby.
No electron pair means no Pauli Exclusion Principle, and no canceling.
And no canceling means that you, my friend, have a net magnetic field.
The net magnetic field in that atom can influence the others around it
to line up their unpaired electrons in the same direction,
which means all those tiny magnetic fields combine their forces, and Voila!
There’s your magnet.
All right, next question.
So, how do you make a magnet?
Well, we have a few ways.
And a lot of them sound like straight-up lies.
First, you can literally just rub a rock on a thing.
That feels like a prank, but it’s true!
At least, if it’s the right rock, and right thing.
If you rub a lodestone along a piece of ferromagnetic material
over and over in the same direction, you will turn that material into a magnet.
This works because the ferromagnetic material
has those solo electrons I was talking about earlier.
But they aren’t lined up right,
so they’re not able to act like a whole magnet.
At least, not yet.
In their natural state, those charged atoms are pointing in all different directions
inside the material, so the net charge cancels itself out.
Remember, the electrons all need to be pointing in the same direction
to get that magnetic field going.
But rubbing the lodestone on that material reorients the atoms to put the negative
sides all in one direction, which lets them make a net magnetic field.
Now, there’s another way to make your own magnet,
and it also sounds like a prank.
You can orient a ferromagnetic thing along the north-south axis
of the Earth’s magnetic field, and then…
just, like, smash it with a hammer a bunch of times.
The idea here is that instead of coaxing the electrons into alignment
with the lodestone, the pull of Earth’s magnetic field will do it for you.
The hammer temporarily loosens their bonds to each other,
and the force of the Earth’s magnetic field can pull the magnetic bits around
until they eventually end up in weak alignment.
It’s kind of like tapping a shuffled deck of cards on the table
until they’re all lined up with each other.
You can also expose a ferromagnetic material to a magnetic field, and it’ll make that
material magnetic too—for as long as it’s in contact with that field, anyway.
For example, electromagnets.
To make a super-basic electromagnet, you can wrap something ferromagnetic,
like an iron nail, in wire.
And then connect the ends of the wire to both ends of a battery - very carefully!
Once it’s hooked up and powered on,
electrons will flow out of the power source and through the wire.
The electric current is just electrons all moving in one direction,
and they pull the electrons in your nail in that same direction, too.
This creates a net magnetic field in the nail,
turning it into a magnet, at least while the power is on.
Now, what are the types of magnets?
And, there are three basic kinds.
You can have permanent magnets,
which constantly generate their own magnetic field, like a fridge magnet.
And you can also have temporary magnets, which need to be in the presence
of an existing magnetic field to stay magnetized.
Electromagnets are an example of these,
they only get to be magnets while the power’s on.
And temporary magnets are useful because we’re able to make them a lot more
powerful than the permanent kind.
They just can’t be magnets all the time.
And then you have hybrids.
Now, technically, hybrids are also temporary magnets.
But they get their own category because they have a unique set of properties.
For instance, some hybrid magnets are made using a
superconducting temporary magnet and a resistive temporary magnet.
This combo lets them produce a much more sustained magnetic field
than a lot of other temporary magnets can, while using as little energy as possible.
They still use a lot of energy though.
And they have to be kept VERY cold, or things can get kind of nasty.
Like, runaway voltage nasty.
These are the don’t try this at home category of magnets.
What magnets are the strongest?
Well, that depends on what you mean by strongest.
Lodestones are the strongest naturally occurring magnets.
But human-made neodymium magnets
are the strongest you can buy at, like, a magnet store.
And hybrid magnets are the most powerful that also stay around for a long time.
But for raw attractive power, nothing beats a type of magnet called a pulsed magnet.
They are the opposite of permanent, but they are SO strong.
They do have a tendency to explode, but before they do, they pack a punch.
When we’re talking about how strong a magnet is,
our unit of measurement is either a tesla or a gauss.
So for comparing exactly how strong magnets are, let’s start with a baseline
of Earth’s magnetic field, which clocks in at between .25 and .65 gauss.
A standard fridge magnet is more than 100x stronger
than the Earth’s magnetic field, clocking in at .01 tesla, or one hundred gauss.
And an MRI magnet can be anywhere from 0.5 tesla up to three tesla.
The world’s strongest pulsed magnet is a whopping 100 tesla,
making it 66x stronger than an average MRI magnet.
There have been stronger magnets,
but those are the ones that exploded, so this one is special because it didn’t.
Why do magnets lose their magnetism?
If your magnet went kaput,
there’s a few things that could have caused it to demagnetize.
For starters, it might have ended up
in an oppositely-aligned magnetic field, which cancels it out.
It also could have just gotten too hot.
If magnets reach a high enough temperature, all the magnetic properties
just kind of fall out of orientation as the substance gets warmer.
Pretty relatable, if you ask me,
since I also get a bit discombobulated if I’m overheated.
But fortunately, it’s not all that easy to de-magnet your magnet.
In general, the harder it was to magnetize something,
the longer it will stay magnetized.
Easy come, easy go.
And difficult come, difficult go.
Why do magnets in a compass point north?
Well for starters, they kind of don’t.
Or at least, it depends on what you mean by north.
Allow me to explain.
So, the north point of your compass
is attracted to the south magnetic pole of the Earth, because opposites attract.
But the Earth’s magnetic south pole is actually the one at the top of the map,
near the geographic north pole.
So the north point of your compass is attracted to the south,
but the south is actually in the north, which is how the compass points north.
It makes total sense, right?
And the weird thing is, the whole geographic south is magnetic north thing
isn’t always true, because Earth’s magnetic poles can switch places!
But you don’t have to worry, it only happens every 300,000 years or so,
so you won’t need to rush out and buy a new compass anytime soon.
You might have wondered: Why are magnets U-shaped?
Well, obviously, not all of them are.
But the ones that are are called horseshoe magnets, for obvious reasons.
The horseshoe shape lets them create stronger magnetic fields.
When a magnet’s two poles are close together and pointing in the same direction,
they can make a stronger, denser magnetic field.
So bending a magnet brings its poles together, and therefore ups its magnetic ante.
Why are magnets bad for computers?
Now, this question is a little misleading.
And here’s why: Your computer’s hard drive
is a disk that works by getting magnetized in small sections.
And these sections indicate the 1s and 0s
that make your computer go beep beep boop boop.
So, it is true that demagnetizing a hard drive
will definitely make it lose those ones and zeroes,
but if it wasn’t magnetized in the first place, there’s no information to wipe.
Also, it would take a very strong magnet to be able to wipe a hard drive at all.
So if someone puts a fridge magnet near your laptop, you’ll probably be fine.
Just maybe don’t send your computer into an MRI scanner.
Can you produce electricity from magnets at home?
Well, absolutely!
If you’ve got a wire and a magnet ready to go, you can do this without much trouble.
You just take a magnet and move it around a wire coil,
or take a coil and move it around a magnet.
Either way will work.
This gets the electrons in the system moving
and that movement creates an electrical current.
And it works especially well in metals like copper, where electrons are kinda
malleable and ready to be moved out of their orbits at a moment’s notice.
So, this next question was a surprising one to find, but:
Why are magnets administered to cattle?
It’s a thing!
See, cows are not quite as discerning as most of us are when they eat stuff.
They just kind of graze along in pastures and eat whatever they find.
And unfortunately for them, this can mean that if there happens to be
metal out in the field, like say, loose nails, or something,
they can end up swallowing that metal too.
And that’s bad, because those sharp metal bits can puncture their organs.
It even has a name – hardware disease.
So to keep metal from going rogue and causing damage, farmers will feed cows a
sort of magnet pill, which grabs any unwanted metal and just holds onto it forever.
Yeah, apparently they don’t poop it out, so they end up
with a big blob of metal in their stomachs, just kind of hanging out there.
I guess, take that, iron deficiency.
So, we can use magnets to help cows,
but how can we use them to help us in medicine?
The most well-known medical magnet is probably the MRI machine,
which stands for magnetic resonance imaging.
The machine creates a large magnetic field around your body, and that field
makes all the hydrogen in your body’s water magnetize in the same direction.
Then, radio pulses from the machine make the hydrogen
jump out of alignment and rapidly demagnetize.
Different frequencies of radio pulses affect different tissues,
so doctors can fine tune what they’re looking at.
But that overarching magnetic field is still there, so all the newly disrupted
hydrogen atoms want to realign with the field and magnetize again.
And the energy those atoms release when re-magnetize
is recorded as a pretty picture of at least part of your insides.
But MRIs aren’t the only magnets used in medicine.
Magnet therapy is also a thing.
Now, data on this stuff is extremely limited and somewhat inconclusive.
We don’t have a lot of concrete evidence
that it has much in the way of real, measurable effects.
But that hasn’t stopped researchers from trying.
For example, there are certain magnet therapies
that are FDA approved to help heal fractures.
One study from 2007 even found that just placing magnets into the patient’s cast
resulted in their wrist or hand fractures healing up to 35% faster.
They only looked at 40 people though, so, take it with a grain of salt.
And there’s also a procedure called transcranial magnetic stimulation.
It uses a magnetic field to stimulate nerve cells in the brain,
and it’s FDA approved to treat things like depression, OCD, and migraines.
But there’s still a long way to go before your doctor
is going to prescribe you some magnets.
Why are magnets still a mystery to scientists?
So based on how long this video is,
I can’t say we’re totally in the dark about magnets.
But there are questions that scientists still can’t answer,
such as where this entire phenomenon came from in the first place.
Like, we know how magnets do what they do,
but we still aren’t sure why magnetism happens in the first place.
We know it’s all about the electron spin that we talked about earlier, but there’s still
a lot that researchers don’t understand about that phenomenon, either.
They don’t even all agree if the spin phenomenon equates to
literal spinning movement at the subatomic level or not.
Which made researching parts of this video challenging, to say the least!
And on top of that, there’s a bit of a chicken-or-egg situation
with Earth’s magnetic field.
We’re pretty sure that the Earth’s magnetic field is only able to exist
because the molten core of the planet is slowly cooling and solidifying.
But the thing is, that core only started solidifying
after our magnetic field first popped up.
There’s also a bit of unreliable info in our record thanks to something called zircons,
which are really old magnetic mineral deposits,
but we can’t tell if they were magnetic back when they formed.
And unfortunately, since humans weren’t around when Earth’s magnetism started,
we just… might never know how it happened.
And finally: Why are magnets so important and useful?
Well, besides all the stuff that we’ve already talked about…
How much time do you have?
Because magnets are crazy useful!
For starters, the Earth’s magnetic field is pretty awesome
because it protects us from solar radiation.
But we can also use magnets to make stuff like low-friction Maglev trains
and even our phones.
And while researching this video we found out that some doorbells
use a tiny electromagnet to make the bell clapper move!
So, magnets are everywhere, and they’re versatile enough
that I could probably spend all day listing the places they’re useful.
But, for now, that does it for our rapid-fire answers about magnets!
Hopefully you can appreciate how important they are in our lives,
even if you mostly just use them to hang macaroni art on your fridge.
Let us know in the comments if you had other questions
about magnets that we missed!
And if you like a smorgasbord of science knowledge on subjects like magnets,
you should listen to our podcast, SciShow Tangents!
It’s a lightly-competitive, highly-entertaining spinoff of our regular SciShow content.
You can check it out on YouTube or at the link below.
They even did an episode on magnets way back in 2020
(I’m on that episode, by the way)
so, if you’re still craving more magnet facts, check it out.
And besides, who doesn’t love a good vintage podcast episode?
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