So, although everyone makes jokes about magnets, how do they work?
Most people genuinely don't know and there aren't that many comprehensive resources to find out.
Which is kinda surprising considering magnets have been a critical component in modern technology
and are directly responsible for many extremely important inventions that you use every day.
Like VHS tapes. Think about it.
If we didn't have VHS tapes, that means we wouldn't have Jurassic Park on VHS.
And if we didn't have Jurassic Park on VHS, we wouldn't have dinosaurs.
And if we didn't have dinosaurs, booking my trip to Australia next month
would've been a complete waste of money.
With that said, in order to understand magnets, we have to understand electromagnetism.
And electromagnetic force is one of the four fundamental forces of nature, which is,
as the name would imply, the phenomena associated with electric and magnetic fields.
In our case, imagine a coil of wire with electric current running through it.
And much like how mass will inherently generate a gravitational field, by nature the electric current
produces a perpendicular magnetic moment, which follows the direction of the right hand rule.
In this instance, if your fingers follow the coil, the induced moment is in the direction
of your thumb.
The right hand rule itself is often accredited to André Ampère, who was the first person
to use the right-hand rule to selectively domesticate wild magnets.
The selectivity eventually wiped out all the non-conforming magnets
and led to the current population of predictable right-handed ones
that we're able to use in everyday applications.
So, I just wanted to show you guys a quick experiment that you can do at home
if you want to investigate electromagnetism yourself.
So, all you need is a microwave, which operates of course using electromagnets,
and something with a lot of simple carbohydrates or sugar.
I'm just using a piece of brownie and what you can do is just put it in there
and then set your microwave to high
and go for ten seconds and then watch really closely.
Hopefully, I can get the focus right and you can see it.
[Microwave beeping]
Okay.
Oh yup. That's really good.
Your brain runs pretty much exclusively off of glucose, so it's really important to have a brownie break
every half hour if you're doing a lot of thinking.
Okay, so now that we know the basics of electromagnetism,
imagine an atom, or if you're like me and have great eyesight,
you can just look at something reeeally closely.
In this case we're making it simple by just considering one electron that's orbiting around a nucleus.
The orbit of the electron itself is like a current travelling through a coil,
so a small magnetic moment is generated,
and the electron itself also has its own up or down spin.
Now, it's called spin, but it's not actually spinning, or at least we can't see it doing anything on the outside.
But, it is trying as hard as it can on the inside.
And this slightly sadder, relatable force is what physicists call intrinsic angular momentum.
And, uhhh, this creates a magnetic moment as well.
So, then you just take the resultant by adding all the moments together,
and now you have the net magnetic moment for the whole atom.
It's important to remember in reality orbitals are filled up by pairs of electrons with opposite spins
that sort of "cancel out", so in practice only some of the transitional metals which have partially filled
3d orbitals are really magnetic and the rare earth metals have some interesting magnetic properties
but generally have to be put in alloys to function at room temperature.
Okay, so there's a lot that just went on, so I'm gonna give you a second to pause the video and get a brownie.
Okay, we're back.
So, the last thing is, in a large piece of the material, collections of similarly oriented atoms are grouped
in domains, but the domains themselves are essentially randomly oriented.
So, the magnetic forces also kind of "cancel out".
But if you can get all the magnetic domains to align by putting them in another magnetic field for example,
you can get all the forces acting together which creates a very powerful magnet.
The magnet itself generates a magnetic field that runs from its north to south pole,
and that magnetic field can align the domains of certain materials, which causes attraction or repulsion.
And that's really all there is to it.
A fun project that you can do to occupy your kids is asking them to prove the Earth is a big magnet
by getting them to dig until they hit the Earth's iron core.
And yeah, thanks for watching, and please consider hitting the subscribe button,
because next time, I'm gonna show you how to avoid another lonely Valentine's Day
by building a forty-five Tesla bitter magnet to help you pick up girls.