Steel wool in a microwave

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Super fine steel wool looks beautiful in a microwave. Tough to film but I'm really happy with the shots that I got! Along the way we get into how mirrors work.
More videos of things in microwaves (including CDs): • Filmed inside a microwave
Self siphoning liquid video: • The liquid that pours ...
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[@SteveMould]

This one was tough to film but I'm really happy with the shots. Steel wool looks beautiful in a microwave!

[@wierdalien1]

Steve Mould The PEO is just boiling off the trapped water though it does look pretty cool Did it still self siphon?

[@TheCaveD]

I'm still very interested in how you managed to film inside the microwave... looks amazing!

[@wierdalien1]

TheCaveD yeah i am still wondering that

[@Ace-ro2do]

Steve Mould hello, I came to your talk on how to be a badass scientist at the Cambridge Science Festival and it was very interesting, i brought both of your books and have done most the experiments inside. Thank you and keep up the goood work

[@paullight4186]

Admiral Percy I hadn’t realized it had been that long ago, but he certainly did. I believe he said something about being concerned about someone trying it them-self. Somewhere on youtube I managed to find some old videos someone else who had done this by cutting a “peep hole” in the sheet metal back that was smaller in diameter than the wavelength of the radio waves.

[@PyrodynamicGuy]

The wool looks like Tom Scott's hair.

[@OutOfNamesToChoose]

It's steve's headhunting trophy

[@PaulPaulPaulson]

Tom Scott wasn't the first victim of Steve. Ever asked yourself how Scott Manley and Matt Parker got their efficient hairstyle?

[@OutOfNamesToChoose]

Paul Paulson I think theirs is more to do with stopping their heads from overheating, with all the thinking they have to do

[@Dorumin]

I love how much overlapping is between Steve's subscribers and Tom's!

[@krishnastarz]

Matt Cummings And Scott Manley's!

[@brekkoh]

Steve's house must be a battlefield having a a baby running around and steve is constantly sticking random things in the microwave.

[@wierdalien1]

Stu Dunn 2 babies

[@peacedustinc.7108]

Imagine how his wife feels.

[@Commandelicious]

Basically the sims.

[@DanteYewToob]

"How's life? The kids, the husband..." "Oh, it's great. A bit of a mad house, he keeps sticking things in the microwave, pouring shampoo on the floor, sniffing money, and last week he was running around the flat in his ice skates!" "Oh, kid's are so silly!" "Kids? No. I meant Steve! The kids great, a real treasure. I just need to find a husband sitter while I spend time with the baby.."

[@christianheichel]

At least the kids not being stuck in a microwave....😮

[@danjger]

Fantastic. The best part of this video is buried. How a mirror reflects! Why have I not seen this so elegantly explained as you have done here?

[@schwarzarne]

Dan Gervais propably because that is not the whole story. At least not for visible light, as he implies there. Surfaces can be reflective without being a metal or conductive and can be conductive without being reflective.

[@danjger]

Arne Schwarz can a material reflect without any free electrons? I think there is a bigger lesson in here that I would love to see a video on

[@schwarzarne]

daniel355273 In both cases you describe the reemitted light is in a random direction. And I think what you are talking about is actually fluorescence and hasn't much to do with reflection.

[@schwarzarne]

Dan Gervais Well just think about it. Does glass have free electrons? It actually is an excellent insulator. And still a noticeable part of the light that hits it is reflected.

[@garetr]

+

[@coyotedomino]

There are just, like, ten seconds in this video where you _really_ describe reflection, and that explanation was so intuitive and logical... I just paused the video, sat back, and kinda thought “holy shit” to myself a few times.

[@Hypercube9]

When I was a kid, I touched a 9 volt battery to a flash bulb from an old fashioned camera. The bulb had I think 20 flashes and 20 strands of filament inside this bulb that normally would have gone one at a time. I triggered all 20 at the same time! The flash was blinding! The bulb melted and bubbled under the heat! When I was in Boy Scouts, they taught us to use a 9 volt and steel wool as a basic fire starter! I'm glad you included that in your demo. :) Hot pockets and some french bread microwave pizzas also come with a cardboard sleeve that has a metal inner layer. I think it's to give a crispier crust.

[@akshat9282]

The reflection part blew my mind. I have physics as my major and I've never thought about reflection that way. Well we never questioned why reflection happens so yea I'm glad you enlightened us, you beast.

[@beachboardfan9544]

Not trying to stomp on your sponsor here, but the best way to learn is by wonderful people like yourself sharing your knowledge for free!

[@IbakonFerba]

Oh my god. That explanation how reflection works just blew my mind... I never even thought about how it works because it is such an everyday thing! But this explanation is so fascinating and makes so much sense!

[@moiquiregardevideo]

Another way to explain why electromagnetic waves are reflected by metal is impedance mismatch. The impedance of free space being 377 ohm suddenly encounter a piece of metal with DC resistance below 0.1 ohm. Any wave that encounter a sudden change of impedance is reflected.

[@SirM0linarius]

a more generalized way to think about reflection and transmission of waves, thank you. Alltough the more specific explanation shown in this video is a lot more intuitiv to understand

[@martinconrad9260]

2:52 "Well, you know this...." I love the conversational tone of that! Thanks!

[@BobSmith-pl6sm]

Sometimes I just have his videos as background noise, his voice is sooo calming. Not to say I don't pay attention though. Love ya Steve!

[@ElectraFlarefire]

A number of cookbooks advise and show using metal foil to shield things like the ends of bones to prevent burning in the microwaves. One other danger is people putting things like metal saucepans with metal lids in the microwave, completely shielding the food and thus running the microwave with no 'load', burning it out. (Short duration are fine like these sort of tests, but longer can cause damage.) Also really need to upload some high speed microwave footage.. SO MANY THINGS TO DO!

[@thewolfin]

There are also certain soup brands that have metal tins with plastic lids, and have microwave instructions on them. You open the tin, replace the vented plastic lid, and heat it in a microwave. Seems to work fine, but I can't speak about the health effects of heating plastic adjacent to liquids.

[@daniel355273]

There are some really tough plastics that are stable even at the temperature the microwave raises it to. A random soft plastic would probably start to fall apart in higher temperatures though.

[@vertigo220]

It's not an issue of the plastic melting or "falling apart," but rather that plastics leech chemicals when heated, which is why it's not a good idea to heat, or even store, food in plastic, especially acidic foods. When I eat these types of soups, I always pour them into a bowl to microwave them or a pan to heat them on the stove.

[@ofiasdfnosdf]

Tons of respect for this channel showing the video highlights right at the beginning!

[@UnknowableHobo]

That first shot looks absolutely fantastic. I want a wallpaper of that!

[@radunicoara8057]

Thank you so much for explaining reflection at an atomic level. Asked my Nuclear Professor and I did not really get an answer, so the question stuck around me until today. So thank you for fixing that! :)

[@brandonmack111]

I was thinking about just this yesterday! Thanks for the video!

[@fireandcopper]

This is fantastic footage. It's so sharp and crisp

[@jefferyjoslin4549]

I have to say that the microwaving of the Polyethylene Oxide at the end might be the best real world visual of convection I have ever seen (beginning at around 12:25). You can easily see the bubbles internally being forced up while all of the ones on the outside are falling very reminiscent of the textbook diagrams. This would be a cool teaching aid for that subject I believe.

[@Kal_43]

The steel wool looks so amazing.

[@km5405]

I love it when a detailed scientific description linking multiple experiments come together.

[@uhmarcel7417]

The explanation of mirror reflection as the opposing electric field blow my mind, makes so much sense

[@dickjohnson4447]

Looks super fun and also well explained

[@fanjapanischermusik]

Very good video. got me thinking about electric fields in the (outer)space that surrounds us. i still got a lot to learn when it comes to electricity i guess.

[@DeclanMBrennan]

Great video - both demos and explanations are very thought provoking. I think the sparks moving on the wire wool at 9:05 look very like a cellular automata (such as Conway's Game of Live) and I think it probably approximates to one in actuality albeit without perfectly regular square cells. I've seen a similar effect in the soot on the inside of my fireplace. In this case extinct cells appear to come alive again so perhaps a cell temporarily runs out of oxygen having already ignited some neighbour cells but can reignite later because it still contains some fuel once the local oxygen recovers. It's only a theory of course until proper experiments are done.

[@rokronroff]

Where can I buy this beautiful robot hair?

[@zhengqunkoo]

Great explanation!

[@erikhendrych190]

I use metallic grilling grid in microwave - no problem. (There is microwave program, grill program and combination, everything works fine with the grid)

[@kevinndayishimiye934]

i never noticed how many times he looks at his script when he's talking i cant unsee it

[@fredrik.larsen]

You should put a tray of grated cheese in the microwave to show the wavelength. That's why most ovens utilise a revolving plate.

[@TheAechBomb]

thermal paper works good too

[@PromptedHawk]

I've never thought about reflections like that! It almost feels like I should have thought of it myself. That actually raises a question for me, Aluminium is like a mirror in infra-red, even with its oxide layer, while other metals don't seem to be as reflective or not at all. The same thing seems to happen in reverse in the visible light spectrum. Does this mean that the level of reflection (like how you get completely matte, slightly reflective shimmer (like a book cover), and so on until a mirror surface finish) depends on the material and the frequency of light?

[@Dolkarr]

All materials are reflective to some extent. Most non-metals reflect around 4% of the light that hits them at a right angle to the surface. It just doesn't seem that way because most surfaces are very rough and scatter the reflected light in all directions. But even stuff like cardboard or a tire reflect about the same amount of light as the surface of water. If you somehow managed to polish a rubber tire, it would look just as reflective. Things get a lot more interesting with metals. Those reflect more than 50% of the light, with some, like aluminium, reflecting more than 90%. Metals like gold and copper reflect different amounts of light at different frequencies, giving them their colored appearance.

[@schwarzarne]

Makes you think of that explanation of reflection is even true, at least for visible light. I don't think it is at all.

[@Orionrobots]

Red dye instead of blue and you have Ghostbusters 2? The reflection explanation was awesome. Great footage too.

[@dbayboyds409]

Wonderful video. Thank you

[@Pfaeff]

It looks so CG. Amazing,

[@astbrnrd]

🤔 The best theoretical and factual explanation of tig welding, just the way you phrase it, makes one imagine it visually 🤯 Awesome job Steve 😉 🤔 I might make a screen saver of this video 🙄😁 Loved the sparks crumbling the metal structure.

[@astbrnrd]

🤔 What if the steel wool is in an argon / vacuum container... Would the metal still burn the same way?

[@iury0545]

I'm so in love with this guy

[@fiveoneecho]

I want to try to make a render of something like that burning steel wool... That was awesome looking!

[@kaveh8425]

To be rigorous, only the tangential (to the metallic surface) component of electric field must be zero (PEC boundary condition). This means the total electric filed (indict wave from the oven + scattered wave from the metallic object) with always will be perpendicular to the surface of the meta, hence no tangential field. Wherever the surface curvature is sharp the divergence of electric filed increases (try to imagine perpendicular electric field around a sharp edge; it looks like the E fields vectors are diverging away from a the center of the curvature). Higher E divergence >> higher electric charge concentration (Gauss law). The E field near those charges can become so high that it exceeds the breakdown voltage of the air around the sharp edges >> spark

[@WyattCayer]

I looks so much like a simulation made in c4d, beautiful image.

[@jamesleehunter]

Awesome, thanks Steve. My daughter and I want to know what tree sap would do in a microwave? What even is tree sap all about?

[@Craznar]

Veritasium sent me ...and I think I'm staying. Amazing channel.

[@scottalbertine3601]

The bokeh effect on the regular steel wool reveals how you're filming inside a microwave ;) Very clever, well done.

[@PopeGoliath]

Watching the final video made me wonder if a fume hood was prudent. Was the substance boiling off water, or chemically decomposing?

[@rahulrajani6071]

Based on your explanation of how metal interacts with microwaves, or EMR in general, might it be interesting to see how a superconductor (closest to an ideal metal) behaves inside a microwave oven? Future video idea!

[@ericmurillo1526]

Hey Steve, I've been pondering how exactly electrons flow through a circuit. From my understanding electron flow is compressible, and when a voltage is applied to a system, a wave propagates at the speed of light. So that would mean that anytime electron flow meets a resistance there is likely some type reflecting wave. This sort of reflecting wave would be very simple to consider in a DC circuit, but much more complicated in an AC circuit with many waves propagating and reflecting off of various resistances in the circuit. If this is how electron flow works in a circuit, is there some type of significant occurrence caused by this phenomenon? Great video by the way!

[@moiquiregardevideo]

Two years later, I watch again your video. Here is my interpretation of mirror: Because metal are good electrical conductor (because of the cloud of electrons the move so easily), they present a very low resistance. They are a short circuit. The electromagnetic wave which encounter the impedance of free space of 377 ohm suddenly encounter 0.1 ohm. Such an impedance mismatch force a wave to reflect like the wave on a string when reaching the end of a bond wire will immediately reverse direction. The electron are moving in the direction of the wave in an antenna. But any antenna need to present an impedance of 377 ohm. That is why your FM radio have a 300 ohm input with an antenna at 75 ohm. In case of transparent material, like Silicium oxyde, glass, the electron shared between the atom of oxygen and the atom of silicium, which form the chemical bond, is not free to wander around, like in metal. This is why transparent material are electrical insulators. When a wave at 500 THz reach the surface of glass, the electrons near the surface are attracted toward the peak of the wave. But, like a dog on a short leash, the electron stop following the wave and returns to its usual location, in between the silicium and oxygen atom. Because electrons have mass, about 1/1836 that of a proton, they take time to move in one direction, then slow down to halt, then revert direction. It is similar to a spring/mass system where the mass is the electron and the spring is the electrostatic force. It is the mass of the electron that slow down an electromagnetic wave travelling thru a transparent material. It am a software engineer who worked on the firmware of the femtosecond laser MaiTai. The lab experience with this laser helped to get a strong classical view of the electromagnetic waves.

[@Archiekunst]

I like the wave explanation of reflection. Reflection angles seem intuitive if you think the light is a stream of particles bouncing off. But as a wave emanating from the mirror, if the induced oscillating electric field is trying to cancel out the incident wave of light, why is it not in the same direction as the incident, given the source is held at an angle to the mirror? In other words, why doesn't the mirror send back a ray of light back in the direction of the source in order to cancel it out? Could you follow up on Snell's law with this explanation?

[@MHWGamer]

it's explained by /Bragg`s reflection law/ (WRONG), google it ;) (it is basically the atom structure/grid)

[@schwarzarne]

MHWGamer this has nothing to do with X-ray diffraction. Stop spreading bs

[@MHWGamer]

ok I was wrong with Bragg, sorry. I forgot that it only works under specific bragg angles and that it has to be xrays (I think we did an experiment with a laser at school and our teacher said that atom structure with the bragg equation is the reason for it, so I don't know that exactly) Funny that I've always thought that reflection is explained by Bragg on Atom level p.s Instead of being so toxic you can explain me and the original commentator how it actually works on atom level

[@schwarzarne]

MHWGamer I have no idea :-D I just know that it is not bragg

[@whuzzzup]

Oh yes I had this question also years ago but never got a real answer. Like you could think of the incoming E (or B) field creating Hertz oscillation in the metal but then this oscillation would also emit in the same direction the original field came from.

[@mistertheguy3073]

I like how you sped it up

[@joeycook6526]

I haven't read all 287 previous comments, so forgive me.if this has been brought up, but when you mentioned smooth edges being OK in microwaves, it reminded me of how Skunkworks at Lockheed solved the primary radar cross-section problem by removing all right angles from stealth aircraft. No reflection back to the source, no problem.

[@karatekickz]

This was a great video

[@ossiebird0]

I'm sure someone has probably already said this but you can also get the same effect by passing a current through the steel wool, in fact just touching it with a 9v pp3 battery will do the same.

[@jakemcmillian]

Great explanation. Now I want to see a mirror in the microwave. Or a parabolic mirror focused on something. Can you supercharge your microwave by focusing on a small spot?

[@lank_asif]

Steve Mould If you put a thin layer of magnetite in a microwave would it convert all the energy into heat and survive or would it reach a point of failure and then combust. Or survive but become less magnetic? Thanks for another informative and well presented video.

[@nikkiofthevalley]

Would get very, very hot, possibly melt and hit its Curie temperature, then wouldn't be magnetic. You'd either end up with a bunch of very hot magnetite, and a broken microwave, or a mess of non-magnetic molten magnetite and an even more broken microwave.

[@Yossus]

Despite knowing a lot about optics, I didn't understand why reflections caused a half wavelength phase shift until now. Thanks!

[@whtiequillBj]

sorry for the late comment, but I've never heard such a clear explanation for why reflection happens and then relate it to a mirror and viable light.

[@AbeDillon]

This is a great explanation of reflection! It got me thinking: In a non-ideal metal, there is some resistance which dampens the response of the electrons, so they can't exactly cancel out the wave, so the metal just behind the outer surface sees a slightly canceled out wave and the electrons deeper in will oscillate slightly less vigorously and so on until the wave diminishes as it penetrates the block. For this reason, it seems like superconductors should be super-reflective too, but they never look that way. Is that because the outside surface of a superconductor is usually non-superconducting impurities or something? Or maybe the surface geometry is super jagged on a very small scale? What role do the crystal boundaries in metals play in all this?

[@uhmarcel7417]

Good question. I have no idea.

[@Dolkarr]

It's pretty hard to notice the difference between something being 92% reflective like aluminium and 100% reflective. The only way you can notice it with mirrors is if you let them reflect off of each other, creating this infinitely repeating space. Then you can see that the copies that look farther away and undergo through more reflection seem a bit faded and somewhat green. That is both because aluminium reflects slightly more green and blue than red (92% vs 90%) and because glass in front of the mirror is often a bit green-ish as well.

[@schwarzarne]

I guess it is because the explanation he gave is misleading if not plainly wrong, at least for visible light. Surfaces can be reflective without being metal or conductive and can be conductive and still not reflective.

[@Dolkarr]

Well, all surfaces are reflective to some degree, conductive or not.

[@schwarzarne]

Dolkarr exactly. You would think that steve knew better.

[@anacierdem]

There is also the effect of wavelength and shape. e.g microwave oven's cavity size.

[@shiddy.]

does it do the same thing if the steel wool is submerged in water? ... very good video +sub

[@slpk]

I was told that some metal shapes, like a fork, can create a spark and electric field strong enough to damage the magnetron It seems to make sense since the spark would be a huge one, given the space between each finger and the finger thickness

[@goombie8962]

amazing video

[@adrianflo6481]

You just blew my mind by telling me how mirrors worked.

[@deano43]

11:47 when the ghostbusters ooze gets charged with anger.

[@samuelprice538]

I found that Psyllium Husk goo also self siphons and is probably cheaper to make than PEO

[@KevimationYT]

Great video, wish there was sound or music over the fluid in microwave bit. But great video. That steel wool looks so amazing I need some of that thinness.

[@maxximumb]

Play Yakety Sax over that bit of the video, it kinda fits. kzbin.info/www/bejne/kJ-rnqahrNZ2ebM

[@kirkelicious]

kzbin.info/www/bejne/n6uqqHepp7Zkm7M should work well for all the beaker enthusiasts out there.

[@NachitenRemix]

The wool burning looks like a cool 3D particle animation

[@crazyliclay]

Where and how do you get such fine steel wool?

[@PierreThierryKPH]

Is it something similar that makes still water a reflective surface?

[@davegtar]

NOOOOOOOOOOO, MY GRANDMOTHERS WIG!

[@them4309]

forget the wool, this guy's profession is sharpening sandpaper with his bare hands, apparently.

[@idlewildwind]

I cannot touch soapy steel wool (the one you use for cleaning burnt pots) because it gives me meltdowns, but _this looks so cool!_ How does it feel to touch it? Is it soft? slippery? bristly? static? So curious!!!

[@thechandan136]

this explains reflection at 90° angle but what about incident rays which get reflected forming same angle. how does it cancels the incidence rays effect

[@superj1e2z6]

That seems good for metal but what about other shiny non metal things? Do they make an opposing EM wave or is this just wave mechanics all over again.

[@wierdalien1]

superj1e2z6 both

[@venkya2790]

Spectacular!

[@matendie9586]

What about liquid metal in microwave? Like mercury from old type of thermometer? What would happen to it?

[@anthonypistocchi60]

Where can I buy this kind of steel wool, I can’t find it

[@viveksoley]

The thin wire has more resistance. But how does that link to heating up of such wire (steel wool) in a microwave? I think it has more to do with the dull, large and random surface area which it has.

[@coryman125]

How does that steel wool feel? Is it soft, or still somewhat wiry? As someone who's worked with metals and jewellery before, I can only imagine how shiny you could get a surface using it...

[@lostplshelp]

coryman125 I would love to know as well... I tried to find some online, but I cant find anything that fine.

[@TheBertjeT]

So what happens to the energy when nothing is placed in a microwave. And does the steel wool also "burn" when something else is placed in the microwave (bowl of water for example)?

[@vonshango6311]

want to see before/after! i want to know if it melts into a puddle or disintegrates into vapor. if you microwave the steel wool 10x longer than the initial burn will you consume the wool fully?

[@donreid358]

Thinner wire has a higher ratio of surface area to volume so it heats up more.

[@jayeshdeshmukhe6167]

The metal grill is provided for the conventional setting of the microwave. That is when you use it as an oven.

[@Kyrazlan]

Wouldnt the electrons feel a violent oscillation instead of reaching an equilibrium causing it to rapidly rise in heat?

[@schelsullivan]

What a coincidence, I just made a macro video of steel wool burning. There's a lot of beauty in that very tiny fire.

[@simondancer]

I notice the liquid will boil vigorously in the beaker but is much less inclined to do so on the floor of the microwave. I'm guessing this is because that is a node in the standing wave of microwaves inside the oven or is it because the liquid there has lost some volatile component or perhaps it's just dumping heat into the floor of the oven? The liquid running down the side of the glass is interesting as well. It does not appear to be boiling either. Is that because it is losing heat through evaporation fast enough to prevent it boiling?

[@Framdir]

Concerning the behavior of the electrons reacting to the magnetic field: You say they bunch together and spread out again, but isn't the movement you make with your hands more the way the electrons would behave if the wave was longitudinal?

[@EmanueleVedovati]

Are you filming with a long and wide lens from outside the microwave oven?

[@larok875]

If the reflection is created to cancel out with the incident field, why am I able to look into my eyes in a mirror? Shouldn’t the reflection cancel out and not reach me? Or is there some sort of phase shift between the field affecting the electrons, and the electrons creating an inverse field?

[@Maninawig]

Would rust effect this micron steel wool in a microwave?

[@GabrielKnightz]

Wonder what it looks like in long exposure.

[@romanlopez9485]

Where can I get some of that steel wool

[@loreleihillard5078]

What happens when you have a flame (say from a matchstick) inside a microwave?

[@foxnyl4141]

Nice Video :) But I don't quite see how the explanation of reflection given at about 5:20 would give you the correct angle that light reflection would occur in. Maybe I am missing something here ...

[@louisandreas2034]

Why is electrons tends to spike up on edges though?

[@lowercase18]

So then how do you get a reflection on water? I'm assuming you're specifically talking about metal mirrors, and not reflections as a whole.?

[@anotherguy9402]

Where can that steel wool be purchased?

[@mikeypeters7003]

Where did you buy the steel wool? What grade would I ask for? Thank you.

[@moiquiregardevideo]

Start steel wool fire with lighter or torch and use a fan; the heat is so intense to feel burn many centimeters away. Make sure that flying sparks can not start fire, for example making this test inside two metal boxes. First time i understand how mirrors reflect electromagnetic waves. At visible light frequency, the skin effect is probably on the first atom layers even if the size of the wave is much bigger. The free electrons on the outmost layer of metal can oscillate at any frequency instead of the narrow bandwidth of, for example, hydrogen atoms. Most liquids are transparents at visible light frequency because there is no matching resonnant frequency to excite any electron to higher orbital. Photons just zip by those "rusted" hydrogen, even easily crossing thru the middle of the nucleus.

[@gecc7774]

It looks like an After Effects animation. Cool!

[@oldcowbb]

how do you keep them without rusting

[@thechandan136]

Thanks for clarifying my one of the childhood conundrum but why angle between incident rays and reflected rays is equal and 90° apart.. if they wanna cancel the field from incident rays it should be in the same direction not 90° apart.. ur explaination i guess works if incident rays is at 90°... Can You explain if i missed something?

[@AttilaAsztalos]

Kinda late and surely a stupid reply, but if you imagine a "ray" coming from the left and hitting a mirror, the "bottom" edge of the ray will hit it first, and will get reflected first. The "top" edge arrives at the mirror later, and gets reflected later - so by now it is the new "bottom" edge of the reflected ray - and it's exactly as late as it took longer to arrive...