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Exploding Wires
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- čas přidán 15. 08. 2024
- Putting electrical current through wires made from different metals.
More links and info in full description ↓↓↓
Featuring Senior Technician Neil Barnes and Professor Martyn Poliakoff
A video on every element: bit.ly/118elements
Discuss this video on Brady's subreddit: redd.it/br91u9
Some papers on exploding wires...
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From the School of Chemistry at The University of Nottingham: bit.ly/NottChem
With thanks to the Garfield Weston Foundation.
Periodic Videos films are by video journalist Brady Haran: www.bradyharan....
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“Anything that makes us think is really good, and anything that makes us think differently is brilliant.”
that was the perfect segway into a brilliant add
What else would you expect from a bunch of brilliant bastards
I think torturing people is bad.
@@thiskal I thought that's exactly where he was going with that lol.
Reminds me Andre Geim and Konstantin Novoselov who got the Nobel prize using a pencil and scotch tape.
In every video, I like to imagine the professor begging neil to do stuff cuz in every video hes like "I managed to convince neil"
He so rarely talks I'd imagine Neil agreeing with a facial expression.
Bilb Ono Neil can make facial.... expressions?!? ;p
Neil doesn't even make facial expressions it's probably a grunt in the professors general direction
Bilb Ono
Neil just doesn’t like hearing his own recorded voice.
@@ragnkja haha
"The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, 'hmm... that's funny...'"
- Isaac Asimov
that is usually said before something explodes or otherwise causes lots of damage :)
Proceeded by the phrase "hold my beer"...
I like the way the smoke trails off the molybdenum.
I know right? Hypnotic
10:17 that must be one of the smoothest winks I have ever seen, but amazing experiment nonetheless :)
Benjamin Lum Neil, man of mystery.
Don't look too much. He might get you pregnant.
I can wink like that with my right eye, but not my left... lol
Evan Devries oof, looks like you need some practice then.
yeah... it's cancer, thanks tho
6:40 So that is how those Bathroom Drain Plug-Chains are made! :D
XD
sure, "bathroom drain plugs"
Dickhole beads
The molybdenum wire probably liquified on the surface and underwent a Plateau-Rayleigh instability, which favours a particular wavelength (here spacing between drops) depending on the surface tension and wire thickness.
Woo...that's lot for me to digest.
Probably why Neil wants to use DC.
@@jerril42Plateau-Rayleigh instability has nothing to do with the frequency of electric current. Its what makes a stream of water break up into droplets.
misium ah but dc has no skin effect meaning that the wire would melt evenly
@@charliemallindine8164 moly just had the right properties to blob together. Skin efect melted the outer most material inwards. Atomspheric pressure and surface tention made it form up. I dont think it had to do with 50Hz mains frequency.
One does not start down the path of Photonicinduction without eventually becoming a full-fledged, carpet-torching electropyromaniac.
😄
+Crimson Halo
Yeah, also why are there a half of dozen arrows sticking in my chest?
"We've popped the f*cker"
He's coming back soon, so he says.
He was coming back soon 6 months ago :(
what happens if you do the Molly wire vertically do you still get the nodules
This is what I was really hoping to see
I was thinking that running a current through molly created a magnetic field, and the bulbs are created perpendicular to the current at regular intervals.
@@11u510n15t it would be interesting to see the effect of differing the frequency on the formation, maybe they could borrow a VF drive from the engineering dept and do the test
@@11u510n15t I also thought that. But molybdenum is only very slightly magnetic. And I would assume it gets less magnetic as it gets hotter.
_unduloids_
Try it with a titanium wire; I bet your little clamps will fail first. ;)
Well hello Cody! First time seeing you on Periodic Videos, though not a surprise at all
Why would it fail
Why
I'm 33 and if you will notice, the Profesor's explanations and the way he explains reactions and theories have a heavy smack of what I would call "Traditional Trivia of the Foundation of Applied Sciences":. Like explaining why Mg ribbon burned slightly differently than the wire of the same. It shows expertise that is understood from the micro to the macro level and is rare these days. Whether it's testing combined with younger professors, I appreciate ANY professional that obviously can imagine and perfectly understand the most remote in the chain of causation that leads to a result. The Scouting organization strives for this in putting youth through studies and applications of myriad disciplines just for the sake of learning correlation. I'd like to see more. Choose Older Professors if you Can!! Maybe the class is early, but their style of cool will often leave you far ahead of the pack when you're in the field. Bravo!
What a quote at the end from the Professor!
10:19 this kind of stuff is why I will always love science. On the surface, the concept of zapping wires until they melt seems rather mundane, but by changing the materials and observing how they react, you end up demonstrating the chemical and physical properties of different metals, and then stumble upon an unexpected phenomenon that leads to further research and ideas for future experiments. great video :D
As an electrician it’s nice to see under the right circumstances.
I was always wondering why copper beyond the conductivity. Less fires. Could you imagine us wiring with magnesium lol! Fires galore
@@joshuamudd8216 Copper is the second best conductor at room temperature. Its also cheap compared with the best conductor (silver).
True, but nerve wracking to see a Fluke so close to fire.
@@Shenron557 It wasn't imposed towards silver. I meant to impose against cheaper amalgamations. After seeing this demonstration it looked as if a cheaper conductor wouldn't be possible without raising fire potential. Counter productive towards safety.
My guess would be that the size and spacing of the "unduloids" probably has more to do with surface tension and viscosity. Wire diameter too.
But I find it quite amazing how the metal is able to melt to form these shapes, yet a wire connecting them still remains!
As an electrician I would love to see the molybdenum via DC as I feel strongly that the unduloids were a result of the wires resonant frequency interacting with AC current and the voltage frequency. If your in europe take the length of the wire between your two electrodes and divide by 50. Then measure the distance between each bead center to center to see if you will have a multiple of the number. Love the coil demo, though I think it could be improved by interweaving three separate coils and only attaching 1 to the electrodes to see how the magnetic field adjusts the results, or three coils wired in delta interwoven with a isolated pipe in the middle.
The frequency of the AC was exactly what I was thinking, curious to see what happens with DC
"Anything that makes a scientist think is good; anything that makes us think differently is brilliant." -- Martin Poliakoff PhD 2019
Somebody put that on a shirt now!
masterimbecile
I would buy several in a heart beat! Is the Chemistry Department allowed to make a profit? I hope so!
Roy Lewis
Buffalo, NY USA
"Neil was a bit disappointed. Nothing burned!"
Very interesting video! One thing to bear in mind - it looks to me like that article about exploding wires was about "exploding bridgewire" which is used as a detonator for some types of shock-sensitive explosive (like PETN). A big difference from your experiment is that the current in an exploding bridgewire is thousands of amps for just microseconds. The wire is also usually thinner than you used. The majority of the energy is dissipated not in melting the wire but rather in the arc which happens right after the wire breaks. This causes a mini shockwave to form which is enough to initiate the explosive. They are much more predictable in how long they take to set off the explosive (compared to an electric match which is just a heating wire) and they are also much safer because they only have enough energy to set off the explosive if the current is delivered very rapidly. A lower, longer duration current will melt the tiny wire but not deliver enough energy to set off the charge. An electrostatic discharge will also not be able to set it off because it won't have enough energy to melt the wire so no spark will happen within the detonator.
You put Neil in this video's thumbnail. That's all I need to know to click and watch this video.
So did it still happen with dc? What if you change the frequency of the ac?
I was thinking the same thing. I'm guessing this happened because of the AC current. They should also repeat the experiment with different lengths of wire to test if this happened because of standing waves. The blobs might have accumulated in the anti-nodes. I did a quick calculation and got a wavelength comparable to the whats seen in the video.
c_Mo = 1/sqrt(μ_0*μ_r * ε_0*ε_r)
λ = c_Mo/f
Here f = 50 Hz, μ_r ≈ 1, ε_r ≈ 10^18 (it is ideally infinity for perfect conductors), and c_Mo is the speed of electromagnetic waves in Molybdenum. Substituting, we get a result of approximately 0.6 cm. This result seems to comply with the distance between the beads in the video.
@@Shenron557 what if it depends on the distance between the terminals (ie. wire length), wire thickness, whether or not you sacrificed a goat beforehand (/s)
@@Shenron557 Well I'm sorry, but you must be some orders of magnitude off. Mains AC in the UK has 50 Hz. The wavelength of that is about the size of Europe. 300 MHz for example, has a wavelength of about a metre, so since those nodules are about a centimeter appart, we are talking about wavelength of about 30 GHz. At least when we consider the wavelength of any electromagnetic wave.
There is of course the hypothesis that it might somehow be a mechanical wave or sound wave. The speed of sound in Molybdenum is around 6200 m/s, so a wavelength of a centimeter would be around 620kHz which is still to high to have something to do with the AC current.
that will be resolved in the upcoming sequel: Exploding Wires Endgame, starring Unduloids
@@altebander2767 You may be wrong, because electrons do not move at the speed of light in a metal; the current does though. It is a common misconception, and a quick calculation shows that they may be moving at around a milliter or so per second.
Just an idea, but it could explain the phenomenon they observed...
Molybdenum is paramagnetic. Paramagnetic materials will attract other magnetic materials, and naturally itself, when an external electromagnetic field is applied. In this case the AC power from the variac provides all forms of electromagnetic energy (E, B, H fields), kinetic and potential - and the effect is marvelous and spectacular :-)
THANK YOU!!! Periodic Videos. Very informative.
As the video states the outer layer of the wire most likely becomes molten and fluidic. My reply to why this happens is that the molten material will collect in spheres due to energy conservation, causing the even spacing between the solidified drops. The wire breaks in/around the middle due to gravity pulling the wire down, and the wire tearing itself apart due to the magnetic forces the Mo atoms creatres themselves. The droplets ought to arrange themselves evenly in a N-S (space) N-S (space) N-S (space) configuration, as the wire is relatively thin + friction forces between the solid wire and the molten outer skin.
It would be VERY interesting to see similar materials (paramagnetic, and around same melting point) - such as Niobium wire, which is a bit more paramagnetic than Mo but a little lower melting temperature.
Thanks again - to ALL of you (I know there are much more involved than just the stars we see here on the scren) at Periodic Videos
Sooo... nobody's talking about neills badass boots? 3:03
Neil is just so boss he can wear New Rocks in the lab XD
I was starting to think I was the only one that noticed this robot legs.
yes wondering if he likes to visit the leather clubs at night
Motorcycle leathers a
Hes probably just way cooler than we already think he is.
Yay! Periodic Videos channel is alive!
I am not a qualified scientist, but that even spacing seems to have some sort of buisness with magnetic fields coursing around wire. You're putting high current throughn it anyway.
Like water in ultrasonic standing waves, the droplets of molten metal may congregate in the nodes of electromagnetic waves.
Current going through a wire produces a magnetic field that wraps around the wire (it's basically disks or planes that cut directly across the wire). The magnetic fields would do very little to no work since the direction of movement in the wire is perpendicular to the magnetic fields generated by the wire.
@@GhostyOcean But the field itself exerts a pressure on the wire, so will affect any melt.
Should have tried Silver, the most conductive metal.
I have a special fondness of silver. I love the way it feels and sounds when dropped.
Should've tried industrial diamons
Graphene! No graphene, no fun!
I've tried this experiment with thin graphite rod, it start glowing, then burned for short time and finally broke.
And for silver - the result should be similar to gold. It is in the same group as gold and copper, so it should act alike :)
@@Erksah68 Are Diamonds conductive? No because they have a tetrahedron structure made by covalent bonds between carbon atoms. The crystal structure has no free electrons that can flow or travel between potential differences. Hence, no electricity (or little electricity) passes through diamond crystals which makes them poor conductors of electricity.
today i randomly remembered that i used to watch these vids frequently a couple years back and i am so so glad this man in still alive it brought tears to me eyes
A similar effect to the undulations seen with the molybdenum wire can be seen in Gas Metal Arc Welding (MIG welding) when using the welding process in globular transfer method with a high CO2/low Argon concentration. It is related to the interaction of the near plasma shielding atmosphere and the electromagnetic field when a consumable filament is present and part of the circuit.
"anything that makes us think differently is brilliant" -Sir Martin. true for everyone really
Fantastic video! If you placed a camera very close to the molybdenum wire, with a #10 welding shade between the camera and wire, you may have been able to see much more as it happened.
A few ideas to increase visual satisfaction during this experiment.
1. Set up oscilloscope, the obvious implication being waveform's impact on size shape and spacing
2. Use the most feature rich AC/DC welder with pulse and adjustable frequency
3. Regarding Molybdenum, grab cordless drill and braid multiple strands in parallel.
4. Set up artificial atmosphere such as argon, helium, etc
5. Since commenters are mentioning speed of sound, perhaps a subwoofer or full range speaker could be utilized
6. Epic edit, posted on CZcams
7. Realize you went down the rabbit hole
Words can not describe my appreciation for you all and what you do. You bring science to life, and explain it better than any television program or internet video I have seen. There is no question that you make the world a better place. I honestly did not think it was possible for my tablet to bring me this much joy, especially from some free videos. 👏👍💯👽⚡💥♥️♥️♥️
Thanks Professor & the whole team. NEAL YOU ROCK.!!!! ... All of your videos are so illustrative and educating. Greetings from Venezuela. Still struggling in our way to freedom.
03:02 Are those boots lab equipment, or is it just Neil having a strange dressing style?
I'd guess Neil comes to work on a motorcycle :)
@@UltimatePwnageNL be neil
packs lunch
packs pencil case
doesn't pack shoes
rides to work to get filmed
is totally OK with that
Yes, the motorcycle transport may explain the leather pants too!
As an electrical engineer, I agree with the professor. I doubt the AC current has anything to do with the beading. The current would change at the same rate throughout the entire wire. There will never be a time when one part of the wire experiences a different current than any other part of the wire. Both beading sections and non-beading sections would see the same current. You will probably see the same beading with DC current. Therefore, the reason for the beading is likely mechanical than electrical.
This type of wire burning/exploding is known as "Fusing Current" in electrical engineering. If you search the wiki page on "American wire gauge" you'll see a nice table with the fusing current of copper. Fuses are essentially just pieces of metal which melt at high currents.
My co-worker built a similar device to the one shown in the video a couple of years ago using the transformer of a broken microwave.
Fun video!
Wife: he must be thinking about other girls.
Professor: *molybdenum wires*
The University should bring the in the SlowmoGuys to do experiments with their specialized high speed cameras.
Or simply something better than a potato. At least it was a high speed potato.
I think we all have further questions. About Neil's boots.
Motorcycle boots
Wonderful experiments!
I use your experiments in my work as a chemistry formulator, working in product development and material science.
There's The Professor on the Drum Kit, & The Professor at The Table. Both are amazeballs.
Neil casually snipping up one of Pat Butcher's gold earrings.
neil is just awesome
So am i 😎
sure(not)
Not sure about Neil's theory. The mains frequency is 50 Hz. The nodules seem to be about 3mm appart and there should only be one or two per wavelenght in a standing wave, depending on if the nodule forms at the nodes or antinodes. This means the wavelenght is either 1.5 or 3. Multiply that with the frequency and you get a maximum travelling speed of about 15 cm/s, which is really slow for any kind of wave. I'm with Professor Poliakoff here. Turning the wire vertical might gives some more insight.
This definitely deserves a part 2
Neil could make any video awesome .
Thumbs up for Neil!
Watching this video reminded me of an incident a few years ago. I had a ~300 yard radio fence (solid core, 14 AWG) on my property, which traveled next to some trees. Lightning struck one of the trees, and it must have traveled into the fence. It sounded like an explosion, and the whole yard erupted into a thick brown smoke. When I checked the next day, 90% of the line had been vaporized - just completely gone, and left ruts in the ground where it had burst. Just wanted to share my own "exploding wire" story!
Beautiful message from the Professor at the end.
Looks like a standing wave on the moly wire.
I'm in a chemical college and we have quantum mechanics as a lesson and I'm quite interested in it (my Organics teacher gave me a book he had '84 when at Uni). And - i have only seen this in movies or cartoons so far, but - as I read this whilst eating, my face literally froze for like 8 seconds straight. Super wierd moment. But I really like the idea that this experiment could actually be quantum-mechanic related.
@@obst3085 I think he means standing waves of the electrical current, which has nothing to do with quantum mechanics.
@@NPEvM - Everything hast to do with quantum mechanics... ultimately. Everything except gravity.
@@LuisAldamiz well, only until we know better
@@Henrix1998 - Another quantum gravity fanatic? It's relativistic mechanics, get real!
"A very quick flash of green light" So.. Voldemorte wasn't using death magic, he was using copper. My childhood... it's ruined.
Maybe he’s secretly using copper as a spell component
The tungsten in a light bulb is hotter than in Neil's experiment (at least until the very end). Tungsten oxidizes in air a fairly low temperatures. As someone who makes homebrew pirani vacuum gages, you learn that pretty quick.
The water in air catalyzes the reaction...it's in all the vacuum materials books - check say, Kohl for analysis.
For any of you guys who are interested, the drooping effect is a process called creep, the Tungsten is a really cool example (creep is also the way most light bulbs fail!!). When a metal gets to about 60% of it's absolute melting temperature, diffusion starts to become really quick and that means that even really small stresses in the material can cause the material to stretch and fail. The way engineers can slow it down in industry and science is by making single crystal materials, like in jet engine turbine blades!
Dude combs his hair with 50 Kv of electricity.
I think you mean 1.21GW of power.
I was thinking about the 50Hz being a possibility when the molybdenum was done, I would like to know what different frequencies and DC would produce. I hope they do a video for it.
WHAT'S THE FREQUENCY KENNETH????????🤭
Current flows along the surface of the wire, so the heat is generated on the very surface of the wire. Since the metal transfers the heat relatively quickly, this effect is not very apparent, but the results you saw with the molybdenum wire are fascinating.
My initial hypothesis was that the thermal conductivity of molybdenum is relatively low compared to the other metals, and this allowed the inner core of the wire to remain relatively solid while the surface melted and droplets begin to form. As surface tension pulled the molten molybdenum into regularly spaced droplets, the circumference of the wire increased where each droplet caused a bulge, and narrowed at the constriction between the droplets. The same amount of current generates a larger amount of heat in a thin wire than it does in a thick wire, again because it flows along the surface, and the surface area per unit of length is lower for a thin wire, which causes a higher concentration of current per unit area. Because the thin parts between the droplets was heated more, this furthered the effect as that molten metal was pulled into the droplets, until the wire got too thin somewhere and it failed.
After searching for the thermal properties of molybdenum, I discovered that its thermal conductivity is actually very high, but its melting temperature is also extremely high. So, although my hypothesis about the thermal conductivity being low appears to have been wrong, I think that the combination of its thermal conductivity relative to its melting point was still probably what caused the overall effect, and that I believe would have still occurred approximately as I described it.
In fact, the high melting point of molybdenum may have been the primary factor in getting that result, as I think the other wires probably would have experienced the same effect to a very slight degree but they also melted and thus the experiment ended before the surface effects were pronounced enough to see. The exception, of course, being the very ends of the broken wires, where most of the wires (except the ones which burned away too quickly) could be seen to collect into a bubbles at each end of the broken wire.
Any video that starts with "Neil, our technician" has got my attention, even at 10:10 on a Wednesday morning.
I saw Neil in the thumbnail and immediately thought "oh no what're they making poor Neil clean up now?"
I miss you're videos. I hope you make more soon. You guys are the reason i love science.
Commenting in hopes of CZcams actually showing me your videos in my subs in the future, despite the fact that I watch every one of them, listen to all your podcasts, and am subscribed to all your channels
This is a fabulous video, perfectly summarised by PMP at the end.
You can see how accident investigators (like plane crashes) can tell if a light was on or off when the bulb was broken. On and the filament stretches out a lot before breaking. Off and it's still coiled tightly and cracked without stretching. :)
Can't do that with LEDs
@@sashimanu totally true, but now aircraft have FDRs and CVRs so we at least know what the lights should have read assuming they were working.
The most interesting man in the world. Right here. Love this guy!
I must be really tired after work. I almost fell asleep watching this exciting, dramatic episode. My goodness.
Yes, thank you so much for your work and time...I was hoping you could make a video explaining to all of us who are laymen, explaining the importance of colors in chemistry and explosive reactions...I ask for this because you talk about and demonstrate such things and I perceive there is great gravity to such things but I don't quite fully understand why, thank you again for your time and work and this channel
Who knew that heating up metals could be this enjoyable to watch
Every welder ever knows what joy comes from heating metals.
Try others
Lanthanum is superconductive and high melting point
Vanadium is electro-conductive AND thermal insulating
Lanthanum is not superconductive at room temp. It would be interesting to see the experiment done with superconductive wire at low temp. If I remember correctly, a too-high current flux (or is it too-high magnetic field?) will suddenly stop the superconductivity, leading to potential fireworks.
@@fordsfords Superconductors have both a maximum current (current density really) and a maximum magnetic field, above which they stop being superconductors.
Lanthanum would most likely ignite in air, like magnesium. I was thinking some of the lanthanoid metals might be fun to try out.
And how about rhenium, osmium or iridium? Rhenium has a volatile oxide; osmium tetroxide is also surprisingly readily formed and very volatile - besides being highly toxic.
Iridium would be fun simply for the bling factor. :D
I am not pursuing a scientific education, but I find these videos very fascinating. Thank you for making the wonders of chemistry accessible even to people like me :)
This phenomenon is called "Rayleigh Instability." You can actually use the math to determine the minimum size of wire/fluid jet that is required to form the droplets and what the final size of the droplets will be.
Were you measuring the failure voltage of the wires? That would be cool to know. Also, what happens to the molybdenum if you increase the voltage slowly vs rapidly?
Great video!
Repeat this in an oxygen rich environment? Anyway, lovely video as usual!
Agreed. Run aluminum and for in oxygen enriched environment. I wonder if aluminum would react more like magnesium.
Run aluminum and copper in oxygen enriched environment. Typod on previous message.
I think Cody's Lab has some videos about burning metals in an oxygen chamber. It ended with the oxigen hose catching fire.
Would also be interesting to see what happens in a deoxygenated atmosphere.
do it in a vacuum
"...but Brady was satisfied" He wont settle for less than the respect he deserves (or a bit more). :D
You're correct, professor, it is the surface tension of molten molybdenum that caused it to condense into droplets on the wire. I'm not sure if it was the frequency of the induced electricity, that is more probably due to the inherent surface tension of the liquid metal pulling itself into evenly spaced deposits.
Para or di-magnetism in the molybdenum wire? I know that molybdenum has very interesting magnetic properties... perhaps that contributes to the unduloid formation in the liquid high temp electrically charged molybdenum
How was the wire made? Maybe it's an artifact of the manufacturing process?
The wires are drawn through a die.
Both platinum and gold < Au> wire and foil are used in exploding bridge wire detonators in nuclear bombs.
As for Molybdenum, I think the wire starts to melt which causes a droplet effect like you said. However, if you were to imagine water covering the wire, it would flow until it dripped at it's lowest point instead of forming droplets all along the wire. I think the difference is that once the droplet begins to flow the wire becomes even thinner from where the liquid is leaving which in turn heats up the surrounding wire which melts faster which flows onto the thinner areas cooling it down as less current will flow when it's thicker with more liquid creating a thicker area with more resistance. This would also explain why the center point doesn't have thicker unduloids despite being at a lower point: if the metal continued to flow to the lowest point toward the center as water would, the wire would become too thick there to continue to have maximum current flow which would cool the metal relative to the rest of the wire heating up at thinner points. I'll think about this more...
Maybe the beads could be due to the current in the wire inducing a magnetic field in the wire, causing the beads to be formed due to the magnetic field attracting the liquid metal.
Metals tend to lose magnetism in their liquid phase
what does the tip of the tungsten needle look like under a microscope?
It is so pleasing to see and hear Martyn's voice in 2019. Just like it will be in 2029, 2039, 2049 and 2059. Long life to you professor!
This needs to be continued.
I remember playing with such things as a kid. Not quite 46 A but just enough to cause sore eyes and a metal smoke poisoning. I had some arcing taking place too.
All electronics i touch results in exploding wires
Practice makes perfect.
I wonder how Nichrome wire will behave.
My first thought was the AC frequency as well.
I'm supporting the frequency theory but with a bit of a twist... an important twist.
It is forming along the electromagnetic flux.
(electro negative) - (magnetic north) - (electro positive) - (magnetic south) - (electro negative) - (magnetic north) - (electro positive) - (magnetic south)
(for easy of explaining)
The electricity isn't going through the wire in a 100% straight line, it is creating an electromagnetic helix, similar to the 2 vertices of a photon.
Through that line the magnetic/molten molybdenum will ease itself into the shape of 1 of the vertices of electromagnetism.
The way we visualize a path of a photon is not just a straight line either, the photon is simply 2 helixes, 1 for electricity and 1 for magnetic flux.
In this wire the molten metal just aligns to the magnetic helix that's formed through the line by the passing of electricity and that is also the reason there IS spacing in between, because the missing helix isn't tangible or felt by the metal's properties.
Thank you everybody, especially Neil for doing the bulk of the work.
Nice video, but I thought that the term "exploding wires“ is used for capacitor bank stuff?
WHY DIDN'T YOU DO THE MOLYBDENUM VERTICALLY D:
Wouldn't the blobs fall down the wire disguising the effect?
@@Aengus42 the whole point is to see if the blobs fall down which would support the prof's hypothesis of a melted top layer
@@nicktohzyu But if it is a resonance thing with nodes & nulls then verticality would hide this totally.
The next experiment should be; keep everything the same except change AC to DC.
Then we'd have an in idea of how to narrow down what causes these beads.
You guys can't stop here!!! There's far too many unanswered questions!! Why not vertical w/the Molybdenum? Different AC hertz? What happened with DC? Why not try silver? Etc etc
Convection around the wire should keep the inner of the wire hotter than the surface, so something interesting is driving this surface tension effect. Molybdenum oxidises rapidly when temperatures exceed 500 C. The interesting thing is the outcome MoO3 has actually lower melting point (800 C) than the pure metal (2600 C). This means the Mo wire heats up as the current increases and builds an oxide layer which starts to melt before the inner pure Mo. The molten MoO3 starts beading due to the high surface tension as indicated. If this is true a copper wire coated with thick layer of tin (solder) should bead in a similar way. Or maybe a Mo wire heated in argon should not bead as in air.. Both are relatively easy checks. Will be interesting to see those if possible.
Best words out of modern science aren't "Eureka! I've got it!"
The best words are, "Whoa, that was weird. Let's do it again…"
You can get similar regular spot heating by using RF standing waves current. It is pretty interesting and my old Professor had a demonstration setup for the exact effect.
But unless something is seriously wrong with your transformer those beads should be kilometers apart if they were caused by the mains current frequency.
Hey, alright! Periodic Videos lives! Nice to see the professor & Neil.
well - for Tungsten, the technical description for Tunsten in a lightbuld is that the wire is in a coil, and therefore has inductance, this resists the flow of electrons, suspending this in Argon resists the properties mentioned that burns away the metal over a given time (until the lightbuld fails)
who else was yelling "inert gas" when posed the question "why doesn't tungsten burn as well in a bulb.."
Everyone: ...
Neil: What if I rig up a contraption to vaporize metal with electricity 🤔
Everyone: Oh hey, new Periodic Videos upload
Neil is kind of how I imagine Mac from the Dresden Files in my head- a man of many talents and few syllables.
I've heated up moly wire in a vacuum and it also does something interesting. It can go for quite a while emitting white light, then it fails rather unspectacularly. The failure point is still about the same diameter of the rest of the wire, and the break point is a nice clean "cut". I think what is happening is at the high temperatures the crystallites grow until they are about the same size as the diameter of the wire. Any contaminants in the wire may segregate to the grain boundaries of the crystallites. When a grain boundary grows to the cross section of the wire and the contaminants accumulate there it is a more resistive zone. This higher resistivity then heats up more than the rest and cleaves the grains. Maybe.
Thats a large Variac
5:00 - Also, in a light-bulb, the tungsten filament is much, much longer than the wire you used. If you look closely at a light-bulb filament, you'll see that the wire is coiled up very tightly to allow a very long wire to fit into the bulb.
6:17 - You said the molybdenum pulsated. Wouldn't that vibration have something to do with the nodule spacing? 🤔
10:42 - Apple is brilliant? 🤨
A couple of weeks ago my computer became sufficiently self-aware to perform this self-same scientific demonstration: I was able to watch this video only after my brother had installed a replacement power supply for me. The bright flash was blue-green, a couple of seconds after I pressed the "boot" button!
Plasma physicist here. That pattern in the molybdenum wire looks very much like a m=0 magnetohydrodynamic instability that often occurs in Z-pinches. I am not sure there is quite enough current, but you could probably calculate the growth rate of the most unstable wavenumber, which will determine the spacing of the blobs, by looking at the m=0 instability growth rate vs the stabilization due to surface tension (high wave numbers perturbations cause m=0 to grow the fastest, but are also stabilized the fasted by surface tension so there will be a peak somewhere where the two effects balance). I really doubt that it is a PT or RT instability that others have been suggesting.