Testing the LONGEST LOOP OF WIRE!!! to Turn a Lamp On

[@ElectroBOOM]

Thanks for the nice comments, people! One common question that you ask is if twisting the wire adds significant length to the wire and is a reason the light speed seems much slower in my cable. From my calculation and experiment, it seems twisting the wire contributes to 1 to 2% length difference. My light is 50% slower! So although twisting the wire does leave an illusion of slower light speed, its contribution is MUCH less than the actual slower light speed in cable dielectric.

[@cartolla]

Twisting the wire makes the light dizzy and thus slower.

[@MaulikParmar210]

Im still amused how this talk converted from electrons to photons. Complex things have alot of things taken for granted when trying to understand fundamental laws of universe! P.S. with snells law EM field inside conductor would enter always in direction of the normal of the surface regardless of angle of incident, so it doesn't matter if wire is twisted or not, EM field will follow the tunnel upside down wherever it takes it. Besides speed of propogation would depend on permitivity of the material and it depends on whole lot of parameters including mass( not the weight but actual mass created by energy) of the material and time, as it would have displaced underlying electric field because atoms would displace actual field in order to register itself as atom in universe, which provides it's charge or other properties. At the end it's the energy of atoms which bends the rules of EM propagation inside it's own region, what happens inside these fields of different energies is still field of study by scholors. Thought experiments are cool, but everybody would need to understand past 200 years of physics and discovery of atomic level interactions in order to go further. We may only see combined effect in one experiment, it's usually collective knowledge that brings solutions and conclusions. This opens up new challenges and might inspire others to explore beyond traditional education.

[@elewyth]

In school we learned that electricity travels at ~2/3 the speed of light (through copper cables). We didn't go into the details of it, but just used that as a sort of "constant". Nice to see this validated through this experiment :D.

[@erykopata2668]

I was thinking lately about you're previous video with Veritasium, and your conclusion. You both get to consensus about electrons traveling only on outer surface of wire and energy traveling in electromagnetic field around wire. So the purely copper wire and copper coated alluminum wire should behave exactly the same even when conducting DC whichin real life is surly not true. I was looking here and there on internet and can't find explanation of this phenomen. Sorry for leaving the unrelated question under your comment but I'm seeking answer so badly...

[@robertb6889]

In regards to conductance of copper wire versus copper coated wire: The charge is located on the surface of the wire, but for DC or low-frequency AC (that mostly reaches steady state) that means the charge fixed relatively quickly, creating an electric field inside the conductor, but the electrons inside the conductor actually move in the electric field created by those charges.

[@ZapAndersson]

I love how you almost by accident turn this into probably the best KZbin tutorial/explanation of the science behind Twister Pair cabling.

[@Qwarzz]

Was lovely how well this showed the benefit of a twisted cable

[@TheDoh007]

Absolutely! I knew twisted pairs were apparently a good thing for signal quality, but i had no idea it was so dramatic, not to mention how it works!

[@brad8122]

Might be a bit far-fetched but this LVDS is also the main reason why AMD B450 boards actually support PCIE4.0. All the PCIE4.0 components are inside the CPU. Only thing left on the motherboards is the LVDS pair of copper paths. Being LVDS they are really powerful. (Scmbags) They later removed it by AGESA bs updates just to make it B550 exclusive to incentivize stupid spending.

[@thedubcritic]

@@Qwarzz e U

[@brad8122]

@@thedubcritic No U

[@115maxx]

The calculation of the speed of light is actually pretty spot on. In my lectures on the topic of communication systems we estimate the speed of light to be (2/3)*c_0 with c_0 estimated as 3*10^8 m/s, meaning your value fits perfect to these estimations.

[@jimmysyar889]

Was about to comment this

[@kuriel07]

it should be speed of electron, no photon involved in the experiment

[@MaulikParmar210]

@@kuriel07 Speed of propagation of electromagnetic field inside a conductor to be exact.

[@jimmysyar889]

@@kuriel07 they’re pretty much the same thing. Speed of light has nothing to do with photons, it’s just the universal speed limit

[@ataraxia4526]

@@MaulikParmar210 Inside, or rather around, on the surface of the conductor.

[@MakinBacon0651]

As a Network Engineer I have never seen the breakdown of twisted pair like this and it actually is very eye opening. Sad thing is I learned it through some random video I clicked on 15 years down the road lol.

[@MakinBacon0651]

@@BrainScramblies Nope no degree. Been self taught for most things and just learning on the job.

[@mandarbamane4268]

​@@BrainScramblies there are some branches similar to electronics where they don't teach about transmission lines. So it's possible for some to get a degree without knowing this.

[@joshuathornton6293]

Thanks!

[@danielmewes]

Such a great experiment to make all the theory actually visible! First time I'm seeing this effect clearly visible like this.

[@NitinKumar82889]

Comment 10hr ago vid 10min ago.😅😅

[@jimmytvfclassic]

@Don't Read My Profile Photo I did read it... What do i do now?

[@Geniusinventor]

Man this video have the best intro in history it's very *Loooooooooonnnnnnnggggg

[@pirojfmifhghek566]

This whole youtube debate being fought out through all these demonstrations has been amazingly fun and informative. Everyone manages to find a new way to approach the demo with a new *twist.*

[@NewtoRah]

Also a great demonstration of impedance matching and reflections!

[@ItsEverythingElse]

Seeing the waveform difference when you connect and disconnect the circuit is amazing, how it jumps at the point predicted by the speed. Really drives home the point.

[@waldolemmer]

That makes me really want a scope

[@derrekvanee4567]

I dknt understand. Did I connect my scoop wrong? Is ice scream scoop ok for this? I soldered usb to it

[@siontheodorus1501]

@@derrekvanee4567 you probably need another kind of scoop. maybe a giant ice scream scoop?

[@Tinil0]

@@arletottens6349 Oh man, that is brilliant and so simple. You need to know the speed of light in that medium pretty dang accurately though to find distances that are relevant for searching, right?

[@olmostgudinaf8100]

@@arletottens6349 Indeed. The timing gives you the distance and the nature of the reflection (up or down) gives you the nature of the fault (broken line or short circuit).

[@YouPlague]

This is the perfect companion video to the whole discussion! The visual output when you keep opening/closing the loop is absolutely perfect, thank you!

[@ThePurza]

Yes I've followed this whole thing closely since Veritasium released his first video, it's been incredible watching the ideas reverberate through the KZbin science community. Fantastic science communication in action, thanks Mehdi and Derek

[@GhostsOfSparta]

hopefully this puts end to the debate.

[@foobars3816]

@@GhostsOfSparta

[@CT-pi2gl]

Seeing the initial transient signal remain unchanged whether the loop was open or closed was so cool. Also, showing exactly how changes to the setup could be made to drastically reduce time and effort while not affecting anything important is a tremendous skill to showcase for modern engineers and technicians.

[@tanelehala6422]

ElectroBOOM really knows how to make ends meet.

[@Nick-rs5if]

😂

[@MadScientist267]

🙄

[@Paxmax]

Top pun!

[@blucat4]

Very good! :-)

[@michaelmotorcycle1789]

🤣🤣🤣🤣

[@camroncall7774]

This concept has been used for many years to find the location of electrical faults in systems that use long wires. Time Domain Reflectometry has uses in many industries. Find open connectors or short circuits or unexpected impedance changes.

[@das250250]

we test cat5 cable this way for faults in buildings

[@orlandoarriaga7148]

Agreed 👌

[@Thriron]

I loved those problems and labs in my high speed digital class. Calculating the loads along the length of the transmission lines just by analyzing a pulse at one end was one of those electrical things that feels like magic.

[@inucune]

you can do the same thing in broken fiber optic too, as light will reflect off any break or damage back to the transmitter(testing device). quick calculation and you know where to splice.

[@blahorgaslisk7763]

@@das250250 This is even a function in some network drivers. You get a tab in the driver config that allows you to run a test on the cable that reports back if there is a break or short and approximately how far from the port it is. Never had to use it in the field just experimented with it in the shop.

[@taylankammer]

Using a CAT 5e cable for this experiment is absolutely brilliant! I'm a software developer and mess with networks a little bit on the side. I used to think networking is relatively simple, until I started to learn more about it. What I've found really fascinating is how much raw physics plays a role at the lower levels, like how twisted pairs are used to eliminate interference. (On the other hand, software development is so abstract that it has virtually no connection to the physical world. It's mostly just pure logic.) So, seeing network cables used for a physics experiment like this, making use of their unique properties, was really exciting!

[@pistonsjem]

this is only cat 5e Cat 6 100Gb/s cables are much crazier!

[@nocturn9x]

As a software developer and cloud engineer, I second this :)

[@Berkeloid0]

At least until you start looking at things like rowhammer, when your code can start interfering with the physics of memory chips!

[@jek__]

Everything becomes more physical and less abstract as you move towards smaller more fundamental components. Most modern software development is done with plenty of spare resources, to the point where resources arent even considered. Software development which is low down, jammed into extremely limited contexts, or stretched to extremes shows its physicality. Software development is the only field that theoretically runs into the upper bounds of physical time itself, if your algorithm is so bad / your problem so complex that there isn't enough time in the universe to complete it

[@piiumlkj6497]

Get into digital electronics and microcontroller fundamentals, arduino stuff and different communication protocols ( i2c, uart, spi ) then you will be able to couple software engineering with electronics and physics ;)

[@Bizzmark11]

In network cabling, we use VOP testers (Velocity of Propagation) to check for breaks in lines, or to tell us how long a CAT5/CAT6 cable is even if there's nothing on the other end. Most testers can be calibrated, but default at about 70% the speed of light, so 66% seems about right for CAT6. I find it helps to think of electricity as 'bouncy', being able to bounce back from the other end of an open loop. Perhaps imprecise, but helpful. Thank you for the more nuanced, and in my opinion, more technically accurate explanation of the subject.

[@Soda88]

It's called NVP, not VOP and it ranges from 60-80%. The actual speed of the signal is calculated by multiplying c with NVP. In fiber it is called Index of Refraction and it is around 1.47 but is calculated differently, c divided by IoR.

[@BenjaminGatti]

Think about it, this would not be possible if the energy moved through the fields and not through the wires. Try interrupting the field outside the wire, does this technique tell you when the wires go through a metal wall? If electricity travelled in the region outside the wire, it would care about moving through a metal wall, it doesn't. This is bullocks.

[@asimramay1069]

@@BenjaminGatti @Benjamin Gatti I'm confused by what you mean ? as in your saying the charge doesn't move on the outside of the cable through fields ? it actually absolutely does or can theoretically, its just that we don't know if the electron 'pressue' is the driver of the field or the field is the main driver of the 'pressure', its just that they work mainly only through the metal or conductive parts of the wire, the rest of the cable you see is shielded for the exact reason u described of passive or active interfernce, in fact coax without an antenna being able to pick-up perfectly clear signal while it's unshielded shows this , I actually once spent 2 hours of my life trying to figure out why a tv in one of the rooms was having random drop outs some days , after tracing the problem the wallplate cable of the coax plugged into the TV went into a metal box outside where the tech left the wire unterminated with 15 mm stripped on the end, suspended in the middle of the (metal) box meaning it had no direct connection to the box or an antenna and it was still working , if u took it out of the metal box it wouldn't work , if you shielded the cable it wouldn't work , similarly if you run a unshielded cable through a metal wall it is absolutely effected even without direct contact and this is measurable, in fact interference is one of the greatest problems in copper Ethernet cables , its why lower cat grades can only run certain lengths at 1gbps and u need cat6a to run 10 gpbs to 100m , because not just metal walls but all sorts of fields effect the charge of the cable even when shielded, the thing you also have to remember is that we are dealing with huge amounts of energy yet even the passive interferences have great effect let alone active ones

[@BenjaminGatti]

@@asimramay1069 yeah, I'm not buying what veratasium is selling. There is some effect outside the wire (radio and magnet) but the vast majority of the energy moves in the conductor, not in the dielectric. Rf works, but is very inefficient. Magnets are better, but DC magnetic coils don't really propagate energy. In all, it's sus. Wires conduct electricity, next?

[@odometric5946]

A quick Google shows that "NVP" stands for "Nominal Velocity of Propagation", and the Wikipedia article for "Velocity Factor" (aka. VoP) has a table of factors for different cables including CAT6. It shows CAT6 at 65% for "minimum velocity factor". Learn something new every day, I always thought it was the speed of light.

[@patchnplay]

You basically just taught a semester of Transmission Lines, a class we had in my industrial engineering studies. Didn't understand anything about it until years later when I went for my HAM certificate. Keep it up!

[@edwardpaulsen1074]

Mehdi is the ULTIMATE teacher!!! I have been mostly rejecting Derek's experiment and supposed demonstration due to a number of his weak or questionable examples and the vague way he posited the question. I have been watching various people attempting to clarify the question and/or prove/disprove the experiment. Many were pretty cool, and Mehdi's previous video about it was good but left a lingering doubt...... ... But in this video he covered the same ground and explanation as previously, but then added the extra bits to complete the whole experiment and the last connections I needed to fully understand both the problem in the original question and in the original (and some subsequent) experiments. Mehdi wins by explaining it so that anyone, even an old fart like me in electrical and electronics field, could overcome the bias of practical and empirical knowledge and experience to understand the underlying reasoning that was meant to get across in the first place. Mehdi is the an excellent communicator and deserves your subscription!!! DO IT!!! **SUBSCRIBE NOW**!!!!! - (Thank you Mehdi) -

[@reedmayhew18]

LITERALLY, I love Veritasium, but I could not understand that video for the life of me, and kind of dismissed it as well. This perfectly explained it and makes so much sense. Wow

[@BM-pu1vt]

Medhi is giving Veratasium a lot of wiggle room to make this work at all. By using twisted pair wire, he's increasing the capacitance by at least 1000 fold and still barely lighting an LED. Yes, capacitive coupling functions at the speed of light across the air, but in Derek's experiment/demonstration, it would never send enough power to ever light the bulb or even an LED until you close the end of the loop. The only way to get around that is if you increase the voltage to impractical levels AND send A/C down the lines as Medhi did. It's become clear Veratasium is a click-baiter that posts questionable content to create conflict and get views. If he just said capacitive coupling occurs across air at the speed of light, nobody would have cared because it's well-known.

[@johnberkers434]

The difference in the wave-form when opening and closing the loop, both with the full 8000' loop and the shorter loop also clearly demonstrates the effect of conductor resistance over longer distances, and goes some way to explaining the distance limitation of CAT5/5e and CAT6 cable runs. As always, love seeing things demonstrated practically!

[@Pho7on]

This is one of the most beautiful practical experiments I've ever seen. Your ability to invest the skeptics with the disclaimers and later explain the disclaimers, after you've constructed the experiment, really knocks this one out of the park.

[@BenjaminGatti]

Except the important loopholes aren't even mentioned, much less addressed. This video actually demonstrates the opposite of the claim being made: if electricity moved as a field, the resultant signal would reflect the chaotic reality of wires coiled around in a box, instead the signal reflects a reality in which the energy is tightly constrained to the physical wire.

[@NeverTalkToCops1]

Agreed!

[@MrMaselko]

5:06 Ah. A man of culture.

[@ddopson]

The hidden gem of this video is 8:12 when Mr BOOM quantifies the effectiveness of twisted-pair at reducing parasitic inductance effects, measuring 1/100th the inductance for there-and-back on a twisted pair (184 uH) vs one-way on a single wire (18 mH). Fantastic!

[@ThunderMuffinMan]

this has been my favorite episode recently. I really liked the part where you posed potential hitches in your plan and screamed "it doesn't matter!" I was thinking that because it was a coil of wire it would act like a transformer; something I learned from you.

[@Oasty]

Measuring stuff that seems untouchable like the speed of light by bringing it down to earth with big but reasonable measurements is exciting, you're pushing the limits of the universe. If the speed of light was different, that speed of the waves bouncing back and forth would be different in a way we can clearly see, spooky!

[@j100j]

I love how much the youtube team is doing to combat the bots.

[@OrbitalCookie]

@@j100j They are probably thinking how to justify remove of the reply button.

[@LordDragox412]

@@j100j What KZbin team? No human has any input in what's going on with moderation nowadays due to Google being too greedy to hire countless people to go through stuff. It's all the algorithm's job, as they claim it "learns" things and deals with them automatically. Which is clearly a lie as the bots have been a problem for years, and on every new video from even smaller channels, you'll find at least 3 instant bot comments and 2 to 3 different bots that spam comments in the replies (most common ones are the variation of "Finally it's here [link]" and "Don't read my name". There's also the thotbots, comment copying bots that farm subs and are usually bought checkmarked accounts (A, B, C.... all the way to to Z, Blexzy, Pepper etc.), there's just too many kinds to name. And the best part? Reporting them does absolutely nothing, no matter how many people report them. KZbinrs themselves need to use scripts to deal with bots (deals with the most common ones that use the same comment format, doesn't with comment stealbots) or go through their comments to delete them manually. It's pathetic, and the sub farmers that later sell accounts for big bucks have been going strong for over 3 years on the same accounts without getting banned, so my hopes for anything happening to them and the stupid algorithm "learning" are an absolute zero. It would take an actual human just 5 seconds to copy-paste a common bot comment and add it to ban list to deal with a big chunk of thotbots who almost all use the same variation of broken English comment (and haven't fixed "butter to "better" for 1.5 years). It would take at most 10 seconds to deal with other kinds of bots, one by one. Yet for the almighty algorithm? It will take forever, because that's what it's set up to do - nothing, because Google loves bots as they, just like on Twitter, make the company look better in terms of statistical user interactions to ad companies. It's really sad. I can almost imagine them introducing microtransactions like "Pay us $100 and we'll deal with bots on your channel for you!". Hell, now that I gave them the idea, they may actually do it. So get used to bots, as they're not going anywhere, ever.

[@Zebo12345678]

Oasty watches ElectroBOOM too? You've got good taste.

[@MeepChangeling]

OMG! The workings of the natural world are things we see and experience! SPOOOOOOKKKEEEEY! Those electrons are moving through totally eldrich means. ooOooOoOOOOOOooo!

[@CrappyCanadianContent]

Your analysis of the twisted wire cancelling eachother out was very interesting. Learn something new everytime I watch your videos.

[@OverUnity7734]

Seems like this information could be used to make a more efficient motor.

[@lvlinty]

@@EarthSouthside 300ft has to do with the speed of light more than interference. It's really more of a legacy from the days when we built networks with hubs and every packet was send to every node. It's a timing/deconfliction problem more than an outside interference issue.

[@crosswire7777]

@@EarthSouthside "outside forces start leaking in" lmao

[@ame7165]

that's how GFCI circuit breakers work. (like the bathroom electrical outlets with "test" and "reset" buttons). the two wires are wrapped around a transformer core, but in opposite directions, so they create opposing magnetic fields that cancel each other out. a third coil on the same transformer is used to detect a voltage when the current going out doesn't match the current coming back in. if you get electrocuted, some current goes through your body and back through ground, so the current going back won't be as much as the current going out of the outlet, so the transformer's two magnetic fields won't match, so the third sense coil will induce a voltage and that's used to trip the breaker open to save your life. it's simple, elegant, and brilliant

[@Z80Fan]

@@lvlinty Exactly, 100m is based on the time a packet can travel, so that CSMA/CD can do its magic and detect collisions. In switched networks this is no longer necessary, i personally witnessed 300m long links negotiating gigabit speeds and working for some seconds before failing!

[@keithhumanitzki4219]

This was an amazing experiment now I understand how a TDR can measure the distance to a break or short.

[@Paxmax]

AAaaaah that's effin brilliant!

[@johannoas1]

we did this in school once, calculate how far the break in the cable is so you can find the broken part without digging out the whole cable. but I totally forgot it.

[@alweerjeroen]

Hi, I work with TDR cable diagnostic tester at my work to troubleshoot connection, and this was a very clear explanation of how this tool works and calculates the distance of a wire break (open loop). It also gave me a deeper understanding of those reflected waves back and forth. (And now i know why that tool is so expensive 😜 it's basically a function generator and high sample rate scope in a handheld device) Thanks Mehdi

[@phillyphakename1255]

Holy fucking science! I didn't know those were a thing, that's pretty incredible!

[@blahorgaslisk7763]

Some network drivers have the capability to calculate the length of a cable connected to the network port or the distance to a break in a cable. They work in the same way by measuring the time for the echo to return to the NIC. And if the times differ a lot between the cables then it can tell you how far away the break is. It's not really something that requires very expensive hardware unless you need the distance reported to be very accurate, say with millimeter accuracy or the distances are better measured in KM than in meters. I've also used network measurement tools that certify that a network match the requirements for secure and reliable use. These are very good at reporting the cable lengths but back then they tended to start at about $1000 for the cheap and cheerful versions with the sky as a limit when you needed more robust testing and higher bandwidth testing. While setting up a small network is pretty simple it makes a huge difference when you have proven signal integrity and connection everywhere. First time I used something like that was when I bult the network for a huge company. Just having a map with the printouts of every network cable in the house made everything feel better. Never heard of any kind of problem with the network there either.

[@Paxmax]

This is unintentionally a BRILLIANT way to very clearly practically visually teach why we use twister pairs, transmission lines, importantce of matching driver/target impedance and show the magic "reflections". Fantastic job Mehdi!

[@nohandleleft]

TwisteD, not twister

[@Paxmax]

@@nohandleleft indeed

[@FrikyMediaLP]

This entire discussion is soooo helpfull on understanding high frequency applications and reflecting waves inside the cable! Thx Mehdi, you´re the best

[@clovemao329]

share ur wisdom sir, i hv no idea after rewatching this clip for n times. how does it help you understanding hfr application?

[@awesomedavid2012]

Love the long long man reference! I hope people have seen those commercials 😂

[@theherk]

These and the Panda cheese commercials are some of the most hilarious ever made.

[@Znatnhos]

Fantastic! What a great demonstration! I had my doubts in the beginning, but you and Derick have once again proven that when we discuss the things we disagree on, we all learn something new and exciting!

[@DieuDeMort]

It's crazy to see Mehdi's voice changing reflected on the oscilloscope. Just goes to show how even small differences, like the pressure of sound waves, can change electric fields in unprotected wires and components. Really hits different when you consider how many of these simple components are in the phone/computer you're watching this on, which surely have no problem dealing with loud neighbors, or the like.

[@nikkiofthevalley]

That's because your phone doesn't have loose wires in it...

[@wilsonrawlin8547]

This was absolutely an amazing demonstration. I've learned more from you than all of my 30yrs of electrical experience. The more I learn about this, the more I wonder about how power supplies interact in multiple circuits such as in cars. This is why grounds/drains are so important.

[@isaacbrewer5616]

Super cool experiment! To actually see the reflecting waves on the scope is amazing! Easily one of my favorite Electroboom videos! And he didn’t even have to blow anything up this time! 😂

[@DiscoFang]

Almost every time he went to twist the wires together I winced expecting a shock. He's conditioned us.

[@stillblazzinit]

This is such a great video! It may be that im finally starting to catch on to more of whats being explained. Ive been a power lineman now for a few years and i really wish they taught us all more electrical theory stuff like this, but maybe more practical to our equipment and wire. It would be great for engineering and troubleshooting

[@jandobbelsteen8953]

I've been using RG-58 coax cable for this experiment for some years. Works very nicely and you don't have to make your own drivers. This is because everything has a 50 ohms impedance: bothe generator output and coax cable. It's a length of somewhere between 70 and 75 meters on a spindle. We calculate from the scope timing what the actual length should be, and sometimes students then actually measure it. Really nice experiment where you can see the effect of an open termination, a short circuit termination, and the correct 50 Ohms termination.

[@ReservedForFutureUse]

You made a TDR

[@sc1fi250]

0:24 what an amazing reference

[@ManyHeavens42]

this guy's crazier than me, if you don't talk to yourself you'll never survive and you'll never work it out

[@brasilianguy5437]

Another great video, Mehdi. After more than 30 years when I starded to play with CB and amateur radio, I finally see the speed of light being stretched on a transmission line. Many thanks for that !

[@Daaannn]

Thanks for the effort in bringing us this test and showing us this theory in a visible way. Sometimes, practical things can explain better the theory, at least for me. Great video as always!

[@YTshashmeera]

This is one of the best experiments I've seen, simple yet proves the point beautifully And seeing the speed of light through wire approximating to 2/3 c is so cool Edit: that cultured meme of the "long long man commercial" in the intro I see that!

[@streetsurfer420]

What does he prove though? I really wish he did a summary explaining everything he did at the end. Kinda crazy he didn't tbh. There's too many higher level concepts just casually being thrown around in this video for any casual viewer to understand imo.

[@-danR]

@@streetsurfer420 This is a video for people with ~2 years of Electrical Engineering at college, or people who have been fiddling around with electricity or electronics projects.

[@hebl47]

@@becomingdoctor3766 True, it's not a completely "stand-alone" video. It would have to be an hour long otherwise. But I think most of the concepts here are covered in his 101 series so it's a good excuse to watch those. ;)

[@Bialy_1]

@@streetsurfer420 He changed everything... so he hardly proved anything. For example the distance betwen the wires is 1/1000 of what he is trying to prove. It is like trying to prove that you can transmit with your radio to a reciever 1000km awey by making an experiment where your radio is only 1km awey from the reciever(plus he changed the light bulb with a led diode...). Also the calculation that you gonna get energy to light up your bulb in only 3.3ns is complete nonsense and there are videos where some YT actualy tested that it is not the case...

[@ethandemille2585]

@@Bialy_1He literally explains all of the changes he made in the video and why they don’t matter. The point isn’t how long the gap between wires is, the point is simply that there is a gap between the wires.

[@jonnyphenomenon]

I just had four 1000 meter boxes of cat6 cable delivered to my classroom for a rewiring project in the fall. This experiment is awesome for demonstrating how the twisted pair cancels out the noise between adjacent transmission lines. I absolutely need to do this demonstration in class in the fall, with ALL FOUR BOXES!

[@CaptainDangeax]

Thank you Mehdi, your video is far more comprehensive than Derek's one. And I also learned a lot of things about transmission lines.

[@palharley]

You probably did the best explanation of line transmission and impedance matching that I've ever seen. Thank you!

[@aL3891_]

Derek can learn a thing or to you about explaining things clearly, great video also, 5:06 nice

[@ebincd2362]

that unlocked a memory of mine i havent seen dickbutt in such a long time

[@thaer_me]

You beat me to it 🤣 I laughed way too much when I saw his drawing.

[@thear1s]

I'm really impressed how you managed to explain impedance matching in very simple terms with a very nice demo. I never really understood why the impedance of the load had to match the impedance of the cable or antenna till now.

[@onradioactivewaves]

Just look up Thevanin and max power transfer. Its easy to show that max power transfer accours when. Impedance is equal/matched.

[@funky555]

I love that all these engineering youtubers have basically just started doing actual research and science

[@jeremym5331]

i mean they all hve like masters degrees or higher

[@Paxmax]

Announcer: "Weeeeeeelcoooome to SCIENCE FITE Nite! ...In the Blue corner Mehdi "Twisted Boom!" Sadaghdar...! .. and in the Red corner Derek "LiteSpeed" Mulleeeeer"

[@Alxium]

This solved the whole puzzle for me. Actually being able to see the speed of light (in the wire) visualized on the screen was facinating and really convicied me of the whole wave theory.

[@Paxmax]

It's bloody amazing when you get a visual nudge to get the noggin' joggin' ! by now I'm convinced, we could skip school and just have the tutors carefully select/curate videos with these almost magical properties to teach abstract concepts such as refections, magnetism, reactive power, how charged surfaces behave etc. Much too often schools focus on formulas, numbers and math examples... which are to quite alot of students *completely utterlessly useless* unless they understand the underlying behaviour first.

[@tonylee1667]

@@Paxmax You say that because you don't know what you don't know, so you think you've learned much more than what you've actually learned from these videos

[@Paxmax]

@@tonylee1667 Fair point, I was not educated, tried and tested "from scratch" by the method I described... I am a product though by teachers who suck at teaching to some degree... and teachers that suck at breaking down new concepts in smaller chunks to make it understandable / unable to approach from different angle.

[@Paxmax]

@@tonylee1667 Maybe I misread your comment slightly; I did not learn much new from this Mehdi video, I have worked in R&D as electronics designer for 16 years, I have designed and tested both copper and optics communication designs/devices during the years. I am definitely by no means an expert at all. It felt easy to indentify how I wished certain concepts would have been explained rather than wait until you learn by work experience or independent struggle. Early in the Mehdi/Veritas "fight" I have even suggested an analogy of my own: Imagine instead of copper wires a garden hose. You suddenly turn on the water, it is detectable at 1m distance very much sooner than you can get full power because of the accoustic effect of the ever so slightly sudden bulge of the hose. The noise travels through air and imparts some energy into the "target hose" section before the water comes rushing into target hose. It aint much powah delivered by accoustic... but its there. I have previously designed a "water world" to explain electricity/energy transfer through various components as a different way to make electricity more approachable and perhaps relateable to learning for rascal brained people like myself.

[@Maninawig]

2:17 "Aroused" will be a new gif. Like "Emotional Damage"

[@MoritzvonSchweinitz]

Twisted pair is such a great invention! Looks so simple when you have it in your hand, yet it does so many smart things and allows us these great communication speeds.

[@bilinasmini3480]

Man, I am so happy I stumbled on this channel! Your content rocks dude, keep doin what you're doin!

[@Lucie_tronvert]

This video is a thousand times better than the actual original one by Veritasium. Thanks for the effort for making things simple, accessible and fun ! 🖤

[@lvlinty]

probably because its accurate and not an inaccurate twisting of the concepts with a click bait title... Veritasium really messed up on that video.

[@springrollwang4441]

Because he's very clearly explaining transmission line theory with experiments, probably the best I've seen so far. It's amazing how he put really complex knowledge into digestible bits.

[@ExsoLam]

It's also better than EE's original video on the topic. It isn't some contest. They both talked to each other for hours, spent even more hours thinking through the problem, and it resulted in a better explanation on both sides.

[@adymode]

@@ExsoLam Veritasium will not be able to process this video easily, he explains that batteries have a force field around them which determines circuit timings in any wires connected to them. He explains a light will turn on in the time that it takes the force 'wave' or something, to travel between the battery (or switch) and the light, and that even 'thinking' about the length of the wires is wrong. His video repeats this idea and even includes graphics to illustrate it. At least that's how I remember it % }

[@talideon]

@@lvlinty Not really. The difference here is that it's a concrete demonstration, which is what the Veritasium video lacked. But it wasn't inaccurate.

[@comet.x]

LONG LONG MAAAAAAAAN! The best advertising campaign! Being referenced here! Truly the best channel

[@TheBanancer]

Was looking for someone who got it

[@KableMrDan]

Thank you @ElectroBOOM!!! This explanation of twisted pair and inductance in cat5 is so clear and helpful for anyone!

[@ColonelGerdauf]

And this is another situation where I learned a lot more from one "silly KZbin video" than I did spending a decade or so in engineering classes and using credible sources. Before this, I simply could not understand what crosstalk even was and assumed that wires randomly transmitted electrical noise.

[@MarkLeinhos]

The thing about classes is that they want to teach you how to model or test or predict something more than they want you to understand why it happens. Using the example of this video to find the length of wire with an oscilloscope, you wouldn't need to understand why it works in order to use the concept, which is what an employer would be more interested in (results). It's not wrong, but for folks like us who like to understand things it's frustrating.

[@ColonelGerdauf]

@@MarkLeinhos I suppose I am just the type of person who cannot understand for the life of me where theoretical knowledge "here is everything about this" would be useful versus practical "here are the important details put in short form" information. Formal education is nice IF you want to be a teacher, which then perpetuates the vicious cycle of artificial usefulness. When it comes to getting anything done, like in a future job, there are much, much better resources. There are so many subjects such as arts, politics, psychology and sociology, etc., that absolutely require not only practical understanding but also a bigger-picture lens. In those situations, post-secondary and "official" whatevers would be a horrible fit and despite that people are still being pushed to get a PhD in... fine cuisine. I am sorry, but whut??

[@ColonelGerdauf]

To give an example of what I mean, look at all of the tangential details that has Mehdi screaming "IT DOESN'T MATTER". He is very correct in that those details are insignificant. Sadly, they are also the level of detail that are explicitly demanded from you to evaluate to ensure with absolution that all loose ends are covered... despite the fact that none of them were worth talking about in the first place. The tests that LinkedIn provides for you to "prove your skills" is a perfect illustration of this point; over a third of the questions that it expects you to know revolve around topics that an employee will never actually encounter in his/her line of work, regardless of where exactly he chooses to work.

[@cvkline]

Good explanation of how twisted pairs eliminate cross-talk! One thing I've never been able to quite understand, though, is why the four pairs in a single Cat-5 cable all have different twisting rates. Some pairs are tightly twisted and others are looser. How does this help improve the transmission characteristics of the cable?

[@ElectroBOOM]

I had a similar question. My guess is, if they all had the same pitch, then they wouldn't really cancel the cross-talk. same wires would always face each other in two adjacent pairs. But with different pitches different conductors face each other canceling the cross talk.

[@thomass2809]

So they will not resonate, I believe.

[@TechnoHackerVid]

Not an electrical engineer so take with a grain of salt, but I'm willing to hazard a guess. If it so happened to be that two twisted pairs had the exact same twist frequency that'd probably allow twists to line up exactly (with essentially the same gap distance between them) such that there's some sorta resonance or constructive interference situation. By twisting at different rates, you could potentially make it such that these matching twist spots are less likely to happen. Again, just my guess and I'd love to be informed by someone more well versed

[@ruben307]

@@ElectroBOOM so are the twistes in some kind of prime pattern that the different wires don't have the same repeating touching wire?

[@lperkins2]

@@ElectroBOOM That is the explanation I got when I worked in a network department. It's also why most Cat-6 cable has (or had, 10 years ago) an insulating +-shaped separator inside, to help ensure manufacturing defects don't wind up with the same pair of wires lining up "in phase" too often.

[@slazinger]

Incredible video Mehdi, seeing the led turn on with an open circuit is mind blowing, I wanna be like you when I grow up (I'm 30 but you get the idea), knowledgeable yet humble and fun, best wishes for you!

[@stefanbalauca7481]

I love your experiment and explanations and the fact that Derek's original video started this whole debate on KZbin is just amazing! Keep these videos coming! :D

[@williamtakacs7466]

Hey Mehdi, I appreciated you not blowing yourself up too mutch, then focused on the theory at hand.

[@christopheralbano3570]

At work, I've been playing with a lot of the same general principles lately. Incidentally, the cross-talk permitted between adjacent pairs in a length of CAT-5e cable is a remarkably low amount of energy, and cross-talk between adjacent lengths of cable is even smaller. Manufacturers go to a lot of effort to ensure that these cables can reliably transmit an acceptable signal, and the behavior seen on the oscilloscope proves they do a good job. Very nice experiment, which demonstrates a lot of the red herrings in Veritasium's original video. I also thoroughly enjoy this style of demonstrating concepts like propagation delay and impedance matching experimentally.

[@EthanTrewhitt]

This is the best explanation of transmission lines I've ever seen. That trick at 11:52 is fantastic.

[@wgm-en2gx]

Hi Mehdi, for me this really cleared things up. It really clicked when you showed that the initial waveform didn't change regardless of shorted or not shorted. Thanks for a great video!

[@AZREDFERN]

Every radio operator’s nightmare. The speed of light through different conductors and dielectrics. Also impedance matching.

[@Ultra-Widescreen-Gaming]

12:30 - This is what my professor told me but never proved that, because “it's too hard for an experiment”… . Thanks for proving it!

[@nigeladams8321]

this is insane, we are actually measuring the travel of energy through a simple circuit

[@bilinasmini3480]

video!

[@user-tf2cq1uq6s]

This was the best explanation/demonstration yet. Very clear and understandable. The demonstration of impedance matching was eye-opening. Knew about the need, but never seen it so clearly. Awesome!

[@raditz9676]

I LOVED this clip! It was so good to SEE what is going on! I can't even imagine how excited a scientist could feel who discovers something and proves the theory! As of the speed of light, the fastest thing in existence... now it feels slow... It's not just the speed, but also the distance I guess :)

[@cdburner5911]

I find this kind of learning/science/discussions SO much more meaningful than the original video. Anybody can make a video claiming "what you thought you knew was wrong" and you just have to believe them. This video did a good job of explaining complex topics in easy to understand bites, then SHOWS that reality matches predictions, more or less. I am also amazed any time anything can be done with measuring the time it takes light to travel. I think one of the most amazing things I have ever seen was the '1 trillion fps camera' that can (with a little cheating) image light in slow motion

[@raditz9676]

​@@cdburner5911 I'm totally with you mate :) WORD ;)

[@weiweiwang4603]

I love your videos -- very educational in a joyful way! However, I do disagree with this one in some part. I think a quite important misconception in this experiment is that we all look at the distance between the battery and the bulb. But the actual important thing is the distance between the switch and the bulb. The bulb changes status (dark, lit) as a result of flipping the switch. Any change in charge/field distribution propagates starting from the switch, along the waveguide (wire), to the bulb. So it DOES matter that you placed the switch right beside the bulb (through battery). If you do the same experiment but place the bulb away from the switch, you will see a delay of L/c (where L is the wire length between bulb and switch) before any significant amount of current is observed, no matter where the battery is.

[@curtkeisler7623]

This is a fantastic video. I'm going to have to watch it numerous times to catalog all the things I didn't know I didn't know. Please keep making videos like this!

[@dazz98524]

0:26 LOONG LOOOOOOONG MAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA-AAAAAAAAAAAAAAAAAAAANNNNNNNNNNNNNN

[@chitlitlah]

8:29 The part about the inductances cancelling each other, I'm pretty sure that's exactly what happens in a transformer too. When there's no load on the secondary, the primary winding acts like a big inductor and very little current is able to pass through it. As load is increased on the secondary, it starts to produce an opposite magnetic field that partly cancels out the one produced by the primary and more current flows through the primary preserving conservation of energy (when you include that there's a little energy wasted as heat).

[@westelaudio943]

Makes sense, that's why a transformer isn't as much of a low-pass filter as you would expect it to be.

[@tobiasL1991]

He's explaining such complex topics with such ease, it's quite remarkable really!

[@IPagma-n7f]

It doesn't matter what the wire/conductor is for, It still has resistance.

[@eliasmussa2392]

I wish i had this video a few years ago, when i was studying transmission lines haha. Is soo cool to see reflextions in real time. Thanks.

[@AulisA.O.T]

0:19 Long LOOoong MA- i mean LOOOOOOoooOOoooOoooooop!

[@rowdybliss]

Congratulations on making it through a video with no injuries :) This was really interesting, and I actually understood it!

[@SquirrelTheorist]

That seems like a first for him XD He always does such a good job explaining electrical matters!

[@martinda7446]

This was the best episode ever. Super. I can't even remember what we were doing as it was over twenty years ago, but we had dozens of reels of Cat5 in our stores and made a ridiculously long run in the same manner with maybe five or six boxes. We were probably just looking at attenuation. I remember wasting a lot of time.

[@SimonBauer7]

it isnt wasted time if it is paid time lol.

[@harvey66616]

_"This was the best episode ever"_ -- agreed! And that's saying something, considering there have been some really great episodes. But this one takes all the counterintuitive electrical field theory stuff and merges it with the much easier to grasp "liquid in plumbing" analogies us mere mortals have been using all along to stumble through understanding electricity, using the oscilloscope to allow us to actually **see** what's going on. I mean, this one video covers so much ground, it clears up _all kinds_ of gaps and misunderstandings I've had about electricity for years. Just one example: I learned a long time ago that data cables needed to be "terminated" with a resistor to prevent "reflections" from disrupting the communications (came up a lot when using SCSI devices...apparently other types of devices often have internal termination). But the whole idea of electricity reflecting didn't make much sense to me. I took as granted the EEs knew what they were talking about, but _seeing_ the actual effect of the reflections here in this video really opens up the whole concept for me.

[@Manabender]

Those scope plots are *gorgeous* and show so much information. Love it. Stay awesome!

[@nicFOODS]

i love how i dont understand a single thing because i have nothing to do with electricity. But your passive-aggressive teaching style makes it worth to watch all of your videos :D

[@Wpjgdmtu]

Veritasiums question was great for the discussion of the problem, but his own videos asking and answering the question were either intentionally misleading or did not suffice to explain the answer. This video helped me to understand perfectly what's actually going on.

[@acirb86]

The real-time modifications to the circuit were a very nice touch. Definitely helped show how the circuits behave.

[@mikethor009]

Top notch as always. Though I miss the explosions.

[@darkSorceror]

This is a great explanation of why high speed network cables use twisted pairs 😁 Oh, and you also performed a fun physics experiment I guess

[@gloomyblackfur399]

Transmission lines have always been a mystery to me. This video helped me a lot. I wont claim to be an expert, but it gave me a general grasp that I didnt have before.

[@phillyphakename1255]

I've come a long way in my understanding, even now saying some things before Medhi, but this still clarified and made "click" a bunch of things in my brain.

[@craigrotay3732]

Nailed it! Crushed Derek's video. This is exactly how Derek should have presented the concept of transmission lines. A really be circle of wire would have closed the loop on the speed of light, but too impractical. This is the next best solution, and enabled you to cover the 2 important concepts at the same time. Brilliant! Derek should send you all his subs.

[@jeanf6295]

That's such a beautiful demonstration, I'm in awe.

[@CruseCtrl]

Such a great video! Thank you for taking the time to explain it properly. It was great being able to clearly see the waves, and how there's no difference before the first wave returns

[@theinterruptedlife1783]

When I learnt about transmission lines in my college it was all theory and I could not wrap my mind around it at all And now everything is crystal clear

[@TacComControl]

I love the idea that Veritasium was like "Nah, I dunno", then "Okay maybe", and now he's probably just like "The humiliation continues, I'm never, ever going to live any of this down..."

[@LordZordid]

What are you smoking?

[@theunseen010]

Wow, I learned something yet again! that makes total sense now about my twisted pairs question. Also I did not expect 5:06 and almost fell out of my chair

[@amirfaisal1835]

Yes

[@Kamel419]

I didn't get this the first time i watched and just let it fly over my head dismissing it. I'm glad you pointed it out, for some reason it now makes perfect sense the second time around.

[@JohnSmith-cb6qx]

This why ElectroBOOM is the best.

[@mtrghost]

mehdi is a man of culture, he knows what dickbutt is

[@decnacyt4690]

That works as a TDR as well! . You can now measure the length of wires taking into account the speed of light in that wire limited to 69%

[@vanerek]

nice!

[@Ahmedhkad]

fluke ethernet tool can show the length of rj45 without end connection

[@YTshashmeera]

Nice

[@stuu42]

Way more clearly explained and illustrated than any of Veritasium's videos on the subject! I guess trying to educate rather than stir controversy has an effect on the content.

[@ExsoLam]

Is there a reason for your toxic attitude? You realize the guy you're praising doesn't even share your opinion on Veritasium, right?

[@rdizzy1]

Derek (Veritasium) literally has a doctorates degree in physics education, he's a physics teacher, so I'm confident that he knows how to educate people.

[@pashootanmashhuri9555]

فوق العاده بود . چیزی به جز ذوق و سلیقه و نبوغ ندیدم❤️

[@drewbola]

I seriously understand none of this. But I still love watching it.

[@TaylorChildAkaWeapon]

Man, I am so happy I stumbled on this channel! Your content rocks dude, keep doin what you're doin!

[@Custmzir]

11:25 "Mine is long" -Mehdi 2022

[@notsonominal]

3:22 no sparks?! i must be watching the wrong channel..

[@deathsheir2035]

Finally an explanation for why Twisted Pairs work, that is easy to understand. By which I mean, entertaining enough that I was able to focus.

[@marcomoraschi3537]

You are the most clever hero on KZbin. Your way to feel what you have to "fail" for help our comprension is Majestic.

[@simonanderson3961]

I totally agree "it doesn't matter!!" But why didn't you just connect the led at one end of wire and the battery at the other end just to avoid all the people giving you grief? Lol

[@texasyojimbo]

I'm not as awesome in my knowledge as Mehdi but the 66 percent thing isn't a surprise to me as a ham radio operator. Every transmission line (coax cable, twisted pair, parallel line, etc.) has a quality called Velocity Factor. As Mehdi said the speed of light decreases due to dielectric properties. Most common lines have a VF somewhere between about 66 percent and 80 percent. Hams have to take into account VF when preparing antennas because cutting the feed line to certain wavelength fractions can have interesting effects.

[@malamut2]

Thanks a lot for giving us the correct term to google for: 'velocity factor'. Wikipedia has the numbers: en.wikipedia.org/wiki/Velocity_factor . It has Cat-5e twisted pair at 64% of vacuum speed of light. Awesome video & comments, I never knew anything about all that before! 👍🍪

[@user-ri7fo6tp5e]

One of the greatest teachers maybe of the last few generations! Your unique personality and energy just infects me and makes me want to learn! Thank you for making such quality content!

[@Paxmax]

Hehehe, I bet his energy would even rivet/pacify ADHD people or was it ACDC...? anyway that letter combo they are claiming people/students are "suffering" from. Less Medication more Mehdivision.

[@paaao]

This whole thought experiment Derek started, really shows the difference between the abstract/mathematical mindset of physicists/scientists, compared to the practical/physical mindset of engineers.

[@LordSaliss]

I'm glad you brought up something about the speed of electricity through wire in this video. It was the same thing I once said on a computer forum years ago now when people were talking about how performance shouldn't change much for AMD's new Ryzen processors before they launched when the first chiplets were introduced to market. One side of the argument said AMD would introduce too much latency issues for a CPU because CPUs are sensitive to that and moving logic apart by 1/2" would add significant latency. The other side said that electricity travels at the speed of light and so the extra 1/2" distance wouldn't add more than like 1ns of latency and it was inconsequential. I butted in and pointed out that the speed of electricity is said to be that while in a vacuum. It actually drops to around 70% in something like an 18 AWG wire, and as you showed here drops to 66% in a Cat5e cable that is most likely 24-26awg. I pointed out that CPUs wire sizes are nanometer in scale and that through such a tiny wire the speed of electricity is actually closer to 25% the speed of light, MUCH slower than most people were thinking. Of course, I got yelled at for being an idiot and everyone said AMD and Intel couldn't even design CPUs if the speed of electricity were so slow. lol