Oxygen is MAGNETIC?!
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Liquid oxygen has unusual magnetic properties. This demonstration with the MIT Technical Services Group and a crazy blowtorch demonstration on the curie point of iron share a glimpse into how different kinds of magnetism work.
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Creator: Dianna Cowern
Editor: Jabril Ashe
Thanks to: Josh Wolfe, Andy Neely and MIT TSG
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That Curie Point is quite an interesting one for blacksmiths and knifemakers. They use that loss of magnetism as an indicator for tempering/hardening steel. Either they use their eyes and check the colour, or they use a magnet. When it doesn't stick to the metal, they know it's time for a good temper !
Jarastlad ...
and it’s important for blacksmiths and knifemakers to have a good temper, with all that hot metal n knives to hand 😆
That's how Weller TCP soldering iron tips work too.
The science of heating, treating, and colling metals in specific ways to alter its properties is so fascinating to me. I know just enough chemistry to get why something like that would work, but enough of it is still a mystery to me that people who do that are absolute geniuses.
@@Pablo360able i always like to think that our forefathers who did these treatments were kinda like alchemists. They didn't know anything about phase diagrams and curie points ... yet they managed to forge, mint and treat metals toesuch an extent that we still have good examples that we can hold in our hands !
I have had advanced physics and engineering classes, and yet I get just as excited as Dianna (who has had way more Physics training than me) when I see simple science experiments like this. It is so cool to see all this science in action!
There are some things in life that make you feel the wonder of a child, and for me they're often physics demonstration.
Or rocket engines and such, (applied physics) :p
@@physicsgirl you’re amazing but please be wary of the sponsors. Allegedly this sponsor has been shown to give back false data after an Iguana was tested. I believe there is a pending class action suit being prepared.
100%
Scraping ferrofluid off of a super strong magnet is the worst job ever. Imagine you need a job, go to MIT, and that's what you earn money with! That must be horrible!
The ferrofluid poured on a magnet was done in my bathroom. It's still soaking up in a sacrificial washcloth.
Physics Girl But what if you got an even _stronger_ electro-magnet and put that sort of like a shell around the magnet with ferrofluid on it, with a bit of a gap between the two and powered that up? Just theoretically, that'd be possible, right?
Physics Girl you could of covered the magnet in plastic wrap then you could avoid the cleaning of the magnet, I'm guessing that would work
Just add heat! MIT has all kinds of cools ways of making heat, I think you'd just need ~1700°F. You'd have to re-magnetize the neodymium when you're done, but hey.
I think you can try to solidify the liquid, for example by cooling, so it could be easier to scrape off. The magnet could crack from thermal shock, so you may want to cool it gradually (e.g. fridge, and not in liquid gas). Please make a video of that also :)
Hypothesis: Gaseous oxygen is also paramagnetic. Experiment: Using the same or similar electromagnets, turn them on and wait a while for oxygen from the surrounding air to accumulate between the poles, and nitrogen to be excluded by its presence. Introduce a flame to the space between the poles, i.e. a lit match or candle. If the flame brightens noticeably, the hypothesis is confirmed.
It would also be interesting to note how the ionized gases of the flame would be deflected by the magnetic field.
When can I expect to see the video?
In 48 yrs as an electronics tech you are still teaching me. And, you are way prettier than any of my Army instructors!
Careful with all that oxygen and electric sparks! That's what happened inside Apollo 1! Back around 1980 I was working with a group of people looking at medical technology that could be used in the future. The magnetic properties of oxygen were intriguing on paper and to get a better feel for it we made a small amount of liquid oxygen and everyone was amazed at how the stream would bend when we poured it past a giant magnetron magnet. Of course, that magnet could not be turned off and we had to take other precautions in the lab when we took it out of it's big drum holder - you didn't want to be wearing your mechanical watch or other ferrous jewelry anywhere near it. We were looking to see if oxygen concentrations could be measured using oxygen's response to pulsed magnetic fields inside a tuned cavity and even what it would take to make a device to extract oxygen from the air magnetically. It was going to take a lot of power to extract usable amounts of oxygen from the air magnetically but experiments building prototype sensors were very promising. Unfortunately the company wanted to move in other directions and the work was abandoned. Love how you make science concepts concrete and relatable! Looking at basic concepts in new ways is how breakthroughs happen!
All right, I just found another role model for my grand daughter!
amen
Thats awesome
Suggestion for another good role model for your grand daughter: the guy from practical engineering. He's fantastic at visuals and explaining the science that drives our world.
This comment is so pure
Great video! As a side note blade smiths use the Curie point in tempering steel. Heat until non-magnetic then quench.
If I remember my welding classes right, the reason the iron loses it's magnetic properties has to do with the shape of the iron crystals. As the iron heats up these crystal shapes change (way before it melts) which is why you can arc weld iron using DC current. The magnetic field doesn't effect the shape of the weld joint. It dose effect the shape of the arc however, but it can be manipulated to be beneficial.
You'd think the arc would be lightning bolt shaped, but it's not. Usually it's cone shaped.
Those are awesome demos for magnetism which tends to be pretty hard to understand/wrap your head around.
"Oh my gosh, i can't believe this demo"
"it's really cool."
I see what you did there, MIT guy.... I SEE IT.
ahhhh!!! love physics...love magnets even more,and nothing beats a smart lady!!!(that loves both) this made me smile!!! cant wait for more!!!
Jesus, running a channel like this is admirable. So many smarties in the comment section correcting everything you do. Lots of a cool knowledge you can get from the comments, but a bit taxing. Keep on doing cool stuff, Dianna!
Fine work on that logo. I know the physics behind the paramagnetism, yet it was cool to watch liquid oxygen doing that for the first time...:)
i was aware of paramagnetism but never knew liquid oxygen had the property! it was fascinating to see how the liquid pooled over thin air because of magnetism. also the iron being heated past the curie point was really interesting to watch - knowing it happens and seeing it does are very different experiences.
i think this means the entire oxygen family [ O, S, Se, Te, Po] must be attracted to magnets cuz they all have the paragamgentic configuration in their valence shell?
Very cool demonstration! And .. phrases like "where your spit freezes WAY before it hits the ground" are just another reason why Dianna is so beloved. ;)
the "emf" at the end was actually an inductive spark. they happen when contacts are separated that were supplying power to a coil. A capacitor or lamp load spark happens at the beginning when contacts are closed. Very important to know in electronics!
Correct! All they have to do it look at this...., *Simple Equation: H2O = H+ O- H+ - Now pay attention to the " O- "*
Dianna- a huge compliment - I was watching "The Princess Bride" when i saw you had posted a new video today. I turned off the movie and immediately cast your video to my TV.. Thanks for doing this awesome show.
Dioxygen has 2 unpaired electrons. Unpaired electrons make it a paramagnetic substance which is weakly attracted by magnets.
Yea, I was really surprised when I learned this in Molecular Orbital Theory. Before that I knew, only substances like iron and cobalt showed magnetism
Very cool demonstration! Fantastic job Diana!
Hoping for the freezing preschoolers in a future episode.
It was a joke. A JOKE!!!!! My god, what have you done!?
Oh come on. Do it for science.
+Chip Matthews
Okay, sure. Children are a rapidly renewable resource anyways.
S C I E N C E !
They also cook better from frozen.
Chip Matthews that’s pretty *cold*
Jabril seems like a very competent video editor! Love the animations. :D
"wanna hangout?" said magnets to the liquid oxygen...
I remember doing the experiment with heating iron to it's Curie point back in school, but I haven't seen the liquid oxygen effect before. Very cool!
"I feel nervous don't know why" - holds one of most dangerous liquids.
Near the sparking on/off switch...
@@mattjohns3394 Liquid Oxygen isn't flammable. Neither is it in a gaseous state. Oxygen will not burn on its own. Remember the fire triangle.Heat-Oxygen-Fuel. Take one away, fire goes out, or is unable to start. In this case there is oxygen, and that's it. There is no fuel or heat. That means no fire. Once a fire is started, adding oxygen will make the fire burn more energetically. An example would be Oxy-Acetylene welding torch. Acetylene burns fairly hot. Adding oxygen makes the flame hotter.
@@Cline3911 That never would have occured to me. Thanks for the learning.
@@Cline3911 great reminder! Ngl, I puckered a bit when I watched that switch spark.
That look of disappointment 2:26 😂
"The physics here is really cool!" −297.33 °F, to be precise. Why no gloves or goggles?
burn easier
I don't suppose you've ever ridden a bicycle without a helmet.
For gloves, in this case, gloves are more dangerous. If you get liquid oxygen on your bare skin, the leidenfrost effect will keep you totally safe momentarily as the liquid flows away. Gloves may capture that liquid and hold it against your skin, causing more serious injury.
Same question. I really wanted to show this in my class but my students would never be allowed to do this without both of us wearing lab coats and goggles. Please follow the same safety rules that are in effect in any classroom.
As per the Molecular Orbital Theory oxygen is paraamagnetic in nature as it contains unpaired electrons hence it is attracted by opposite poles
100% !!! All they have to do it look at this...., *Simple Equation: H2O = H+ O- H+ - Now pay attention to the " O- "*
Hi Dianna.
What if you submerge a neodymium magnet in the liquid oxygen then pull the magnet out, will the oxygen stick to the magnet?
Patricio Diaz yes, lots and lots of "tiny magnets"(dipoles) will stick to your magnet...
don't get confused, they're using an electromagnet here only to show the behavior of liquid oxygen in no magnetic field...
thanks
"... in fahrenheit that's when ur spit freezes way before it hits the ground" made my day😂😂😂
I love you , Physics girl 😀
I know it's beyond the scope of this channel, but if anyone is curious, it's not the magnetic field, but the magnetic field's gradient that holds the LOX. I.e. it's not where the magnetic field is strong that hold is, it's where the field is rapidly changing from strong to weak.
Happy physicsing!
Why do scientists say the Earth’s core is molten iron and that’s why we have magnetic poles but molten iron is way above the curie point!??? I am having difficulty understanding how that can work. But maybe it’s something I just have not heard a good explanation of yet.
Well you know the answer to that, the earth's magnetic core is science-fiction. The deepest hole on earth is only 8 miles deep so who knows what is deeper than that? Lots of today's science is theoretical story telling.
The circulating liquid outer core is a self-exciting dynamo. Some electrical generators use the same principle and don't have permanent magnets.
@@karhukivi there is no circulating liquid outer core of the earth.
@@jamezbond78 And how do you know that?
@@karhukivi there is no scientific proof for it.
I've always been fascinated with science and I figured this was another one of those videos were knowledge, not laughter is gained. That is until you mentioned freezing children. I hit the floor laughing so hard at that.
correct me if im wrong, but these "mini magnets" are unpaired electrons that align.
Leo Steinmetzer yep you are right its their spins that align up
i think it would help people to understand more if she used the MO theory to prove this, other than that its was a good video
"The electrons in the Lewis structure are all paired, but there are two unpaired electrons in the molecular orbital description of the molecule. [...] The molecular orbital model of O2 is therefore superior to the valence-bond model, which cannot explain this property of oxygen." Bodner Research Web, General Chemistry Help
Can´t it be a resonance, where one oxygen atom pulls the bond to itself getting negative charge while leaving the second one with positive?
Gejmrz Bradrz magnetism doesn't have to do with charge. Its all about the spin of electron and how they align
I would like to suggest a topic!
- Searl Effect Generator -
1. Does it really work?
2. Is it possible for it to make anti-gravity
3. What are the effects explanation allegations? (Glow, Levitation, Energy conversion)
Where are the safety glasses?!?
Jose Hoyos to show good example
And where is the ear protection!
;)
There is always one person that insists that you need to be as safe as they like to be. They will tell you that their way of safer is better. Or the good example point. How about if you don't care about being a good example, is that allowed?
I think safety glasses wouldn't be so bad. that woman is kinda dangerously gorgeous don't you think?
#YOLO
Very Nice, and I like the way you explain the calculation from Kelvin to Fahrenheit!
*Found the answer to #2 on my homework*
That's awesome. I didn't know liquid oxygen did that. I never saw that experiment done. I did know that Iron won't stick to a magnet if heated up. Great video though. Can't wait for the next one
*Not back EMF. It's inductive kickback that causes the spark.
Back EMF occurs in motors (and other things, but mostly motors). Due to the spinning motor (and copper elements moving through magnetic fields) the motor itself produces a voltage. This opposes the voltage applied by your energy source.
Inductive kickback is when somebody, for example, disconnects an inductor from a power source. The inductor will not allow the current to change instantaneously, so the voltage skyrockets, and if it's not clamped by a diode or capacitor it'll usually cause an arc in the air (which will in effect clamp the voltage).
Very different effects.
Joel Sullivan sry, what EMF stands for?
Electro-motive force. Here's the Wikipedia page describing Back-EMF. en.wikipedia.org/wiki/Counter-electromotive_force
Here's a Maxim Semiconductor page about inductive kickback (which is what's causing the spark in the video - NOT back EMF). www.maximintegrated.com/en/glossary/definitions.mvp/term/Inductive%20Kickback/gpk/175
My view on it is that any voltage that is induced by a changing magnetic flux is a back emf. And that is the same, whether it is the voltage induced in a stator of an electric machine with a rotating rotor field, or a a coil with decreasing current.
Inductive kickback is just a more precise wording for this certain appllication of back emf.
I disagree Samuel. For one, kickback causes a huge spike in voltage of the OPPOSITE sign. It's a constant current based event, and that generates wild negative voltage swings. These can be destructive and usually have to be clamped with diodes. Back EMF by comparison is relatively harmless, causes voltage of the SAME sign, and is a constant voltage based event.
Kickback is constant current, and back EMF is constant voltage. If those are the same thing, then that's like saying a capacitor and an inductor are the same. A capacitor will maintain a constant voltage and an inductor will maintain a constant current. Same thing, right? Not quite.
This channel is secretly a big how to take over the world as a mad scientist I LIKE IT
If iron is not magnetic when it is hot, then where does the Earth's magnetic field come from?
We were taught at skool that it is from the molten nickel-iron core.
Keith Kennaugh The earth's core is mostly iron and it spins because the earth spins. So do iron's electrons. When electrons move...magnetism.
I think magnetism is induced by the movement of *charge* and the electrons there are balanced by the protons.
hairyloon Electrons and protons carry a charge. Charge is not separate from them
Yes, but if there is an equal number then there is no net movement of charge.
If there is not an equal number, then why is that so?
Surface effects. There's irregularities at surfaces of materials, which breaks the balance.
You should be in EVERY classroom in the world. I just love you. GREAT role model.
I've watched this channel since 100K subs, yet I never subscribed. I don't know why? I'm going to sub now.
+FLAMINGMOH(Mohawesome) that's awesome. Thanks for sticking around and welcome! Sort of..
Physics Girl lol!
Physics Girl yoo makeup girl , do experiments on red mercury magnetism or else I unsub , by the way do u wanna know about gravity secrets and secret metals , if you did your masters in physics , answer me
What?
Dude WTF
This is a nice little trail of videos I’ve been following. One after another. And since I just found them I’ve got plenty of healthy TH-cam watch time and something to learn everyday
Do they find the Curie point by calculation or experiment?
Both, always...... (at least today....)
louisng114 both can be done, as of today experiment is probably more accurate.
This was one of the reasons why VBT was rejected in favor of MOT. You read it in chem class but actually seeing it is so cool!
If you breathe liquid oxygen, do you drown ?
Naej you would get energetic
Your lungs would freeze and possibly shatter/explode when you try to breathe or as the oxygen boils it will expand your frozen lungs. You would probably die from asphyxiation... It'd probably be much more painful than drowning.
Naej Now i need to know!!!
I would imagine that it would not be a smart idea as CO2 would not be able to diffuse across the affected alveoli, causing a ventilation/perfusion mismatch and increased partial pressure of CO2 in the blood, therefore making it more acidotic. However, you would simply cough up any liquid that has been aspirated in the first place before that could happen.
Either it is so cold that you would freeze your lungs and die from asphyxiation like specter0420 said or you would be under so much pressure to allow oxygen to be a liquid at ambient temperatures in which case your lungs would collapse and be unable to inflate them. Its a lose-lose, but it is my understanding that there are special solutions you can have for deep sea diving which allow you to breath oxygen from a liquid, though it is not liquid oxygen.
Awww Physics Girl.... i really hope you're doing ok and recovering! Much Love! Please get better! The world needs you! All the best and all the love to you Physics Girl!!! ❤️❤️❤️
"But if you freeze the preschoolers..."
I instantly like you more
The Curie Point was really cool to learn about. I had no idea that heat would have such a direct result over magnetism, even though it makes a lot of sense.
Oxygen is paramagnetic!?
Yes! The paramagnetic oxygen analyzer uses this principle to measure the amount of oxygen in a gas.
There’s this thing called molecular orbital theory and basically it’s because oxygen has an unpaired electron pair
th-cam.com/video/dVWtvG9ztMQ/w-d-xo.html
Akram Faiza Rabbit Piet, your “unpaired electron pair”... isn’t that an oxymoron? (Or should that be oxygenmoron?).
@@rolandeauten8798 A pair of unpaired electrons lol
+Physics Girl DIANA!!! I have done some research into the bit about guitar pickups, and my hunch is correct. SO, YOU HAVE TO DO AN EPISODE ON HOW ELECTRIC GUITAR PICKUPS WORK!!! (Trust me, folks, it's real cool. Not going to spoil it here.)
why are you supporting you own video? 23 wasn't enough?
hah. i get it. It took me 23 seconds though.
consider this comment as a like on your 's. It's 23, and I get situational OCD!
Gábor Králik Not anymore, I liked her comment so now it’s 24.
Looks like you upped your graphics. Keep the great work coming! You're videos always put a smile on my face
So so HOT......
...and then it de-magnetizes
Ramped Upp did you even bother to read the full comment?
Ramped Upp your assumptions and stupidity are hopefully going to trigger a natural selection event at somepoint in your life.
Nick Rickhoff pretty sure the individual concerned doesn't have the intelligence to pull that off as they can't even read a full comment before making assumptions. I knew someone would go for the bait, they always do. have a great day 😎
Double Troll!! You guys just rolled each other. It was a troll collision, a troll-ception.
CanadaBud23 no, it wasn't.
What a treasure this channel is!!! Thanks for the awesome demos!!!
Why no explosion with so much oxygen and that huge spark ????
What would be the fuel source?
It would still need something to burn like carbon or something else, I think the spark didn't actually burn anything since it was an electric spark.
Thing is: With pure oxygen nearly everything can burn. Its actually really dangerous stuff. But the only pure oxygen wasn't close to the spark. It probably had dispersed before it got close.
too cold?
Oxygen atoms make a race for space plus there's no fuel to explode..
Hi Diana, I saw that demo almost forty years ago in San Francisco. I hope that some day you'll get a chance to go the science museum there. Keep up the good work :)
I am glad you use Kelvin, but at least translate it to both Fahrenheit AND CELCIUS. I am very triggered.
Since you put Celsius in caps I assume it's the unit you want. The Wikipedia article on Kelvin (which in itself is interesting) has this simple formula for converting K to degrees Celsius: [°C] = [K] − 273.15. For Fahrenheit it's [°F] = [K] × 9⁄5 − 459.67.
Though, she did entered it for the temperature of liquid oxygen. However, there is no excuse for the Curie point of iron...
She put both F and C in figures on the screen. Also, she said "In Fahrenheit it's when your spit freezes way before it hits the ground"... that'll be the same in Celsius. Thanks PG, cool video as always.
Just add 273...
Instead of saying '9/5', it's simpler to use '1.8' for a calculator.
°C = (°F - 32) ÷ 1.8
°F = °C x 1.8 + 32
Very cool. Pls do one on hysteresis in magnetism (you mentioned it briefly), and the implications for electric motors?
Hey, that's why our oxygen don't float and leave us for space.
・ロイドマークマ・ロイドマ Wow, I'm just realizing now how important the magnetic field is
Maybe to some degree... but more so because the magnetic field prevents particles and radiation from the sun to slowly "blow" away the atmosphere (which mostly is Nitrogen anyways)
earth is like a magnet, we don't know how they work!
Atmospheric oxygen is not liquid.
Oxygen only becomes magnetic as a liquid, otherwise magnetic fields have no effect on it.
This is very interesting! I've always been fascinated with the magnetic field. Thanks for sharing this.
arent you suppose to do it wearing only a leather bikini?
Wow! You really knocked it out of the park with this video!
That blew my mind, and then it was 'why not?'.
Magnetism is an awesome property/force, its characteristics are rather random, but they turn up, like pi, in some pretty interesting applications.
Nice visual of the curie point of a magnet and paramagnetic liquid oxygen between unlike poles of an electromagnet. THANKS
I have seen this effect when I was in highschool. Our physics teacher has condensed the oxygen from air with liquid nitrogen and a teapot :D It was pretty neat
That thing with the iron is really cool
I've seen something simmilar that was like a perpetual motion system with a candle heating something and a magnet
Hey Dianna, I'm from Brazil. Another very good video!
I was wondering if the opposite can also occur. Can a extremely low temperature also prevent the little atoms magnetic fields to align and make the magnetic properties of the material inactive?
Very nice! It would be interesting if you also gave an idea of the magnitude of the magnetic field and the current you needed to produce this effect.
Great demo! Looking forward to the video on inductive kickback.
Those big double knife switches are SOO FUN!
Fun fact blacksmiths will heat steel to the "curie point" then quench it to harden it. Experienced ones learn the color of the steel, but some do use magnets to test the steel.
Pure liquid oxygen has a slightly blue color, that's also the reason, why oxygen pressure cylinders are painted blue (I think).
The cryogenic liquid in your video seemed to be clear. So I assume, that you poured liquid air over the magnets poles, and the oxygen inside the mixture was attracted to the magnet only. Low Temperature lectures and demos are really cool!
AMAZING demo, Dianna.
Thank you Diana, for bringing us those fancy experiments. :)
Hi Dianna! I recently saw one of your videos about a zero gravity skyscraper, and I also read an article about how architects want to build a building hanging from an ASTEROID. Could you make a video explaining the physics behind that building?
how have I not found this channel until this week
I love how interesting this concept is I've never seen it before does it have any real-world applications?? I would love to see more interesting stuff like this
Easy Answer... Because of this, we get WATER !!!
Your demonstrations are the Best!
I don't want to wait... I need more physics girl
At the starting i always feel like "yeah this too advance for me"
But then you make it very simple and easy to understand " 😄
This video is one of the many that makes the internet worthwhile :) Nicely done
Very neat demos!
That said I definitely got a little anxious about the lack of PPE - especially when handling the liquid oxygen. =P
I could not believe what I was watching. When I handled liquid nitrogen and oxygen in chem lab the instructors were very definite I wore safety googles, lab coat, and gloves. In this video we watch someone in street clothes handle very dangerous materials as if they were cans of Coke-ignorance in full display. She may get an A in video productions but she sure gets an F when it comes to safety.
Cool! I never seen liquid oxygen (it's mostly liquid nitrogen that you hear about) too and yea, they usually never show this kind of experiments in physics classes in uni... which is a shame.
Thanks Physics Girl. Informative and entertaining as usual.
I wonder how it would look if you pour in a bunch of complex ions with the correct electron configuration....it would look cool with all the different colours
Thank you assistant! People really say which type of current, but you did. Cheers.
Hey Dianna I have a question to ask, you mentioned that the liquid oxygen is magnetic electrons, so does that mean that the metals that is attracting the liquid is made up with positive charges so that the electrons and protons will attract?
*has
Nice!!! Physics and math were/are two subjects since my school years that I was never good at. And it was painful because I found them very fascinating! Your videos bridge that gap Diana :) They are brilliant yet easy to understand.
Lots of love from India. Happy physicing and sciencing :)
It would be interesting to hear your thoughts on induction heating. I wonder how liquid oxygen would react to a very rapidly changing, high strength magnetic field?
Kudos, to the best Physics Teacher in the world!💓 Go Diana!🔥👊
I don't think the alignment without the magnets is as random as we think it is. But thanks for the video it adds up to what my mind says :)
Hello Dianna. I have seen this demo and it's pretty cool. Oxygen can only do that because it is in its triplet ground-state. If you can get your hands on compounds called sensitizers (like rose bengal) and shine UV light on the oxygen in the presence of said compounds, you can get it to go to a singlet state and make it lose its paramagnetism. I can't get my hands on this stuff, but maybe you can :)
Very good demonstration of something I have read about but never seen.
Those electromagnets look like they have thousands of windings.
The science teacher in me says "Gloves and goggles, please".
Magnetism in steel can be quite a pain to work around when your trying to weld it. Its called arc blow when it happens and it literally blows the welding arc around as one would blow a candle flame. it would be kinda fun except that it usually causes molten drops to fly about and land on you...
I'm, as we may measure this attitude in electronics: "very-very" glad that you've decided to demonstrate something as fundamental as this little truth!!
"... because the physics here is really cool!" as you are working with liquid oxygen! LOL!
It's not only liquid oxygen that is magnetic, but gaseous oxygen as well. In fact, there exist meters that measure the oxygen in the air by using this principle. I used one back in 1973. If you find such a meter, open it and be fascinated. It's a very delicate and sensitive simple movement.