Kind: captions
Language: en
this is the world's strongest magnet
capable of sucking objects in generating
electric current can you see that yep
and levitating non-magnetic objects it
even WS havoc on camera equipment wies
magnetic so if it's a semas sensor the
electrons just can't find their way well
they get redirected so yeah if you
notice bad video or audio know that it's
incredibly hard to shoot in these
magnetic fields a portion of this video
was sponsored by
Google I came to the National High
magnetic field laboratory in Tallahassee
Florida where since the year 2000 they
have held the Guinness World Record for
the strongest continuous magnetic field
somebody left a chair where it wasn't
supposed to be it then got accelerated
across the cell completely pulled the
guts out of the chair now we all have
those nice super uncomfortable wooden
chairs for reference the magnetic field
of the earth is
0.00005 Tesla a fre magnet is around 01
Tesla MRI machines can get up to three
Tesla but this electromagnet creates a
magnetic field of 45 Tesla so nearly a
million times Earth's magnetic
field to achieve this field the magnet
consists of an outer superconducting
magnet and an inner resistive magnet
I'll explain why you need both types in
a moment the apparatus is two stories
tall but the the maximum field or Field
Center only occurs in the center of a
narrow cylinder that runs through the
middle right now it's off is it there's
no M can I can I put my finger in the
boore is that a bad idea no it's fine
you can totally do that let me
see so that's where there's 45 Tesla
further down a meter away from that a
meter down and so that just drops down
for it's clear all the way all the way
through to the bottom oh wow the maximum
field is basically a cenim tall here we
have very small samples think something
like a chip in a computer or a cell
phone that's what users will come in
with so that's plenty big for what we
want to do with Material Science or
conects matter research since we can't
see or film in the center of the magnet
we're going to experiment with the
magnetic field that extends above and
around the magnet on this platform so
the magnet's over there yes but the
magnetic field extends all the way out
here yes and pass this is known as The
Fringe field and it's much weaker than
45 Tesla it is still plenty dangerous
for a super inducting magnet it depends
on the size of that bore so the bigger
the bore the larger The Fringe field
because the magnetic flux does not
penetrate the windings and you have to
form a complete Loop so those Loops just
move further and further and further out
to make that feel so this is the 100 G
line for The Fringe field so what
happens to objects around the 100 G line
things with shapes will start orienting
themselves to the field so if you have
it sitting on a
tabletop say over here it will start
pivoting on its own and if you get it
too much closer it will just go and by
the time you notice it's moving it's
already too late meaning if no
ferromagnetic objects within the 100 gal
line if you have anything ferromagnetic
on you any implants that are metallic
pacemaker anybody anybody anybody
okay ramping up this magnet to full
power takes around an hour and a half
that's because they have to put
47,000 amps of current into the outer
superconducting electromagnet 47,000
amps 47,000 amps 500 volts that it is so
insane all right so let's take it all
the way up to full
field one thing that happens in a strong
magnetic field obviously is that
magnetic materials are attracted to it
we cut open a Nerf football and put in a
couple steel washers being careful to
tape it up so the washers can't get out
we also covered the opening to the
magnet so the ball won't get sucked down
into it I got an unmodified Nerf
football and sure enough it's easy to
tell which ball contains the
washers I tried to throw the football
and hit the side of the
magnet okay after a few misses no are
you kidding me
no it bounced around and stuck it should
have looked looked more like
this another thing to do if you have a
strong magnet is get ferrofluid
ferrofluid contains nanoscale pieces of
magnetite that's an iron containing
mineral and they're suspended in
solution coated in surfactant so they
don't all Clump together but in an
external magnetic field they all line up
like iron filings around a bar magnet
this ferrofluid started to develop
parallel ridges even meters away from
the magnet and as we got closer spikes
formed on the surface aligning the
magnetite particles with the field
closer still and the ferrofluid climbed
up the side of the vessel so it's not
much but it's just kind of a a little
bit of a tug yeah and then try and tilt
it away and then you'll feel the
difference oh yeah it it it definitely
preferentially wants to come this way
magnetite is actually the mineral that
led people to discover the phenomenon of
magnetism in the first place at least
3,000 years ago naturally magnetized
pieces of magnetite were found in a part
of Greece called magnesia that's
actually where the word magnet comes
from in Greek they were called stones
from magnesia but they were also
referred to as load stones and it was
discovered that load Stones could
attract each other or pieces of iron and
by the 11th century in China it was
realized that magnets could be used to
make a compass needle that would always
point in the same direction the side
that pointed to the north of the Earth
was referred to as a North seeking pole
and the other side the South seeking
pole though these days we often just say
North Pole and South Pole of the magnet
but why are only some materials magnetic
electrons are essentially tiny magnets
but in most atoms they are paired up one
pointing one way and the other pointing
the opposite way so their fields cancel
out in elements with half full outer
shells of electrons well then they can't
pair up so atoms have magnetic fields
but if neighboring atoms aren't aligned
well then the magnetic fields of all the
atoms cancel out and the bulk material
is non-magnetic but even if you get all
these atoms aligning in one part of the
material known as a domain they may be
aligned opposite atoms in other domains
and cancel out so you need all the
domains to be aligned normally when you
see these they are really strong magnets
but not here not yet and this can be
done by applying a strong external
magnetic field so right now these are
not
magnetic they do not stick to each other
but he is loading them in there into the
Hem holds
coil here who and then you get a
permanent magnet materials that meet
these criteria are called ferromagnetic
after iron the most common magnetic
element but nickel and Cobalt are also
pherom magnetic in the powerful magnetic
field around the world's strongest
magnet what is even more surprising to
see is the behavior of nonferromagnetic
materials
here we have four sheets of different
materials two different types of plastic
copper and aluminum when they are
stationary in the field there's no
difference between them but when they
move 2 1 drop materials that conduct
electricity fall a lot
slower I'll get into that but first this
portion of the video was sponsored by
Google and they were interested in this
video because it's all about magnets
which are core to our future electric
vehicles for example use electric motors
which need magnets to work and US search
interest for electric vehicle reached an
all-time high in the last 12 months that
is according to Google Trends a tool
that allows you to see what people are
searching for the thing that connects
these trending searches and many others
is that people are trying to find ways
of doing things that are less
destructive to the planet and Google is
like we live on this planet too we also
want to do that in fact Google has has
matched 100% of their electricity use
with renewable energy since 2017 they
also run project sunroof which helps
people decide if solar is right for
their home by providing Google Maps data
to create a 3D model of your roof and
estimate Energy savings from rooftop
solar personally I'm just happy to learn
that people are searching for things
related to sustainability and that
Google has made a real commitment to
sustainability too you can learn more
about sustainability and Google's
efforts at sustainability. gooogle so
thanks to Google for sponsoring that
part of my video and now back to
magnets what's happening is that as the
metal plate is falling through the field
the number of magnetic field lines
passing through it is changing this
change in magnetic flux induces electric
currents called Eddie currents in the
plate which create their own magnetic
field that opposes the change in flux
this is known as lens's law so if the
plate is Falling Towards a north
magnetic pole the induced currents
create a north magnetic pole themselves
so that the plate is repelled and so it
falls much
slower so as that big Plate Falls there
are Eddy currents
generated in the metal which should
dissipate some energy as heat so I want
to see if we can see that it's actually
slowing down
now cuz it's in a much higher field now
it is slight but I think you can see
that the plate is warming up a bit as it
falls previously I visited an
electromagnetic levitator at the palace
of Discovery in
Paris it uses an alternating current to
levitate a plate but the Edie currents
in that plate generates so much heat
that water actually boils on its surface
check out how hot this plate
is I like to think of lens's law as the
no you don't law because whatever you
try to do nature acts to oppose you
there you
go if the plate is falling any currents
are induced to slow its
descent but if you try to pick up the
plate come on nature also says no you
don't in this case a South magnetic pole
is induced under the plate attracting it
back to the magnet they don't know if
I'm weak or if this is actually
insanely
difficult there you go oh my goodness
you're strong like
bull no matter how hard I tried to push
the plate down it just wouldn't go very
fast because even if I could speed it up
a little bit that would increase the
rate of change of flux and hence the
induced currents and their Associated
magnetic
field that is
ridiculous so weird we tried a number of
other conductive but non-ferromagnetic
objects around the magnet like this
thick cylinder of aluminum drop it
straight on the magnet and nature says
no you don't try to roll it across the
top no you don't it just refuses to
roll we wrapped up a volleyball in
aluminum foil and passed it across the
magnet that's or dropped it straight
in again the changing magnetic flux
induces Eddy currents that produce their
own magnetic field to oppose the
original change in flux we wanted to see
just how much deceleration The Fringe
field of the 45 Tesla magnet could
achieve so we decided to fire
projectiles from a potato cannon across
the top ready all right
ready 2
[Music]
1 this is what the projector looked like
with the magnetic field off and this is
what it looked like with the magnetic
field
on if we compare the two shots you can
see that as the projectile enters the
magnetic field the induced Eddy currents
rotate the projectile so it remains
oriented along the magnetic field lines
and this minimizes the change in flux
that's experienced by the projectile 3 2
1 now some of the projectiles contained
coils of wire that were connected to
LEDs as LEDs are actually biased of
opposite polarity so no matter which
direction the field is coming in one of
them will be lit and we're we're hoping
that as it crosses through a field
you'll see the change in color of LED of
the nose G and sure enough these
projectiles light up showing how the
induced currents are changing in the
coil you know in all these cases the
induced electric energy is dissipated
either as light or heat but what if you
had a material that didn't dissipate
energy like a superconductor below its
critical temperature there are two
important things to know about the high
temperature superconductor we're using
here first below its critical
temperature most of the material has
zero electrical resistance which means
if you bring a magnet close to it
currents will be induced to oppose the
change in flux and since it's a
superconductor those currents can
persist indefinitely and expel all of
the magnetic field second there are some
filaments through the material that are
not superconducting there's defects that
are engineered into the superconductors
a second phase that traps those magnetic
field lines and keeps them from moving
it can no longer rise or fall because
it's kind of locked in that magnetic
configuration this is the human
levitator it consists of a 90 lb or 40
kg magnet hovering above a ring of
superconductors so it's I'm standing on
the magnet and underneath is a
superconductor that's right when I stand
on the magnet it is pressed down into
the superconductors but the increase in
magnetic flux is opposed by currents in
the superconductors creating a magnetic
field that repels the magnetic field
from the magnet I'm standing on I'm
maintain my angular moment oh
yeah so I remain levitating above the
superconductors I also brought a leaf
blower if you just want to hold on that
and turn it on for
real it's up to
[Music]
you
[Music]
okay now there's another way to levitate
in a magnetic field that has nothing to
do with induced Eddy currents and it's
all because all materials actually have
magnetic properties they're just hard to
see unless a strong magnetic field is
present some materials are always
attracted to magnetic fields they
display what's called
paramagnetism oxygen is like this we
have a liquid oxygen dripping off the
bottom
here and it gets attracted to the magnet
it doesn't matter if it's a North or
South magnetic pole the presence of the
external field causes the magnetic field
of the material to strengthen the
overall magnetic field and that causes
attraction other materials in fact most
materials are repelled by a strong
enough magnetic field either north or
south and this is known as
diamagnetism water is a good example of
this in the presence of the external
field the water molecules become
opposing magnets effectively and so they
are
repelled so here you can see how
bringing a magnet close to the surface
of water creates an indent you can use
this repulsion in a strong enough
magnetic field to levitate objects you
ordinarily wouldn't think of as magnetic
here we're using a slightly weaker 31
Tesla magnet so that we can use a
periscope setup to actually see into the
boore and our camera as soon as you are
on this Optical way you you should be
able to re everything down wonderful
this strawberry will be magnetic in a
strong enough field well it's di
magnetic right now it's just we're not
in a strong enough field right for us to
see anything mhm correct because of the
water water is di magnetic and there's a
lot of water in
strawberries oh that's nice oh that's
beautiful
that's beautiful and the same occurs
with a raspberry or a little piece of
plastic
Pizza living organisms contain enough
water that they too can be levitated
they wouldn't do it here at the mag lab
but people have levitated
[Music]
frogs and
grasshoppers even mice and experiments
meant to help understand the effects of
weightlessness without having to go into
to space so are very strong magnetic
fields safe for living things there are
no lasting effects there are no
long-term effects but we have notice
that there is the possibility of
actually polarizing the stones that are
in the inner ear and the effect that
that has on the rodent is that the
rodent actually
spins um so they go in circles they go
in circles it doesn't last for very long
it's only a few minutes after the animal
comes out of the
magnet so how do you actually make the
world strong longest magnet contrary to
what I expected you can't do it just
with superconducting magnets alone the
highest magnetic field you could
generate with superc conducting wire was
nominally 20 Tesla that's because
superconductors have a limit to the
amount of magnetic field they can
withstand before they're no longer
superconducting so the solution is to
combine an outer superconducting
electromagnet with an inner
electromagnet made of ordinary wire so
the blue green and salmon colored bits
that's the superconducting outsert that
produces 11.5 Tesla inside of that we
put a uh resistive magnet that produces
33 and2 Tesla Maxwell's equations Fields
add we get 45 Tesla but making Highfield
magnets with ordinary resistive wire is
really hard for a wire wound magnet like
a junkyard magnet a traditional
electromagnet the highest magnetic field
you can get is about two Tesla and the
reason is
that you cannot get the heat out of the
innermost windings so back in the 1950s
Francis bidder up at MIT he realize that
physics doesn't care what shape the
conductor is you can take your round
wire and smash it into a very thin plate
if you then stack those plates with
alternating insulators you make a helix
that electrically looks just like that
but now I can push cooling water axially
through the stack of conductor so that
means that innermost part I can now pull
all that heat away which means I can go
to much much much much much higher
currents through these coils up to
57,000 amps than what you can do with a
traditional wire wound electromagnet
that gives you like 34 Tesla that that
gives you 33.5 but it's stacked up so we
stack all of these up in a stacking jig
they're aligned up with tie rods we then
put about 20 tons of force on it and
then lock those tie rods down and that
holds the coil together and gives us our
electrical connection between each turn
and we're pushing you know several
thousand gallons per minute of deionized
water through those coils to keep them
cold cuz otherwise it melts and you're
done occasionally you get material
failure that happens when the material
goes past its plastic limit and starts
flexing either into the coil next to it
or maybe even shorting to ground and
this is what happened here the coil
plastically failed meaning the metal
went beyond its springy characteristics
where it would come back and it just
completely deformed which drove it into
the coil next to
it burned through the insulator and then
vaporized all of this metal you can see
more on the inside it killed this coil
which is the B coil but because it
failed on the inner Edge it killed the a
coil failed on the Outer Edge it also
killed the C
coil so that was an expensive failure
yeah
yeah the record is the highest
continuous magnetic field in the world
period China recently commissioned their
45 Tesla hybrid very similar in concept
to ours so now there's two of them in
the world running this strongest magnets
on the planet takes a lot of energy the
mag lab uses a significant fraction of
tallahassee's electricity so we can
consume with all four power supplies at
full blast about 8% of their total
generating capacity what's the
electricity budget of this place so
nominal $250 to $300,000 a month holy
yeah that's a lot so we operate in their
federally mandated Reserve which every
utility has to have they have to have
that available to push into the grid if
there's a problem we have a deal set up
with the city so that they can actually
make money off that power that they have
to produce but which they can't sell the
flip side is when they need it we ramp
down and we can go down much faster than
they can spin up a Jenny why do you need
45 PS there are a couple things that
drive material Discovery one of them is
just growing a new material the other
one is putting it in an extreme
environment like high magnetic field
high electric field high pressure ultra
low temperature another axis is taking
an existing material and improving its
funl so getting all the impurities out
so as you drop the impurities in the
material
you're reducing where the electrons
scatter from in there and that improves
the properties enables you to see things
that you were never able to see before
we've only just barely scratched the
surface on what can be done with this
people are going to look back about 25
years from now and this will be the
inflection point this 5year period