The hidden link between electricity and magnetism
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- čas přidán 21. 01. 2019
- Have you ever wondered why the electric and magnetic fields are so closely connected? The unbelievable answer lies in special relativity. What looks like a magnetic field in a stationary frame of reference transforms into an electrostatic field in a moving frame of reference. I show you how to derive the strength of the magnetic field using only the equations of special relativity and electrostatics.
At last! You see, about 40 years ago my friend Tony explained this to me (we both did electronics degrees at Bangor University, UCNW earlier) saying how amazing it was - there is only an electric field. I never forgot this, but I could not remember the details, only the gist of it. I asked him about it some ten years ago, but he insisted he had no recollection of such a thing. I searched in vain for a simple explanation. Now I have it! I wish I could tell Tony - but sadly he died three years ago, though this is one of the many memories of him that lives on in me! Thanks.
All things return to God lady everything that is done is not for man's vanity but he who created all things! The AMEN TRINITY AMEN ✨🌠📕🙏♾️
@@tenoarrive841 Sad that the Enlightenment went over some peoples heads.
Regards ✍️
Videos have made the visualization and comprehension of the principles involved in this, and many other phenomena so much easier than when I learned this in the 60’s.
By making particular subject matter like electromagnetism, relativity, and quantum physics accessible even to dull minds, it has reduced the relative value and accomplishments of my fellow colleagues at our institution.
@@commanderthorkilj.amundsen3426
At what institution?
I remember first reading about this in a HAM radio magazine. It blew my mind. I wish it was taught as part of a more basic curriculum. Thanks for disseminating it to a large audience. It's such an important insight about the universe.
I am an ignorant electrician and I tend to think visually. I very much enjoyed this video and the visual representation of electrons and proton nuclei in a copper wire. I even followed the ideas visually represented when special relativity was introduced. I found the mathematical equations beautiful and entertaining but was lost within about 30 seconds. I guess I need to do a maths course, probably several maths courses! And I need to see more of your videos. So please continue the good work. With much appreciation......
I'm a Post Ph.d EE.... and I commend your enthusiasm...there are a lot of good vids on youtube....start your technical journey..algebra is good enough to get 80% of high tech stuff...it's fun..
That would be very exciting if you could also think mathematically. I too, encourage you to pursue some mathematics courses for that.
I am sure you aren't an ignorant electrician, but an excellent electrician. I would hire you any time.
Sparky gang
Good one
Damn... I saw this first in Veritasium's channel, but seeing the proof with the equations is more satisfying
True that and solving more problems makes it more intuitive
Link?
I was keeping up intellectually until you busted out the equations. Now I need to go back to school.
Good idea, we all need to reiterate what we think we know, continuously.
well, I guess you're stumpfed
Friend, equations are nothing in Physics. Concepts are all. That's the exact reason behind the terrible proximity between physics and philosophy. For example, using lorentz transform you easily perceive that c is the mathematical limit of velocity. However c is the physical velocity limit of WHAT? Well, c is the speed limit of any material point you would say to me (photons included) which are in the same inertial frame. For instance, if you shot different very accelerated protons in opposite directions they recede (going to their opposite "sides") almost two times the speed of light. Therefore the space itself doesn't obbey the lorentz transform!!! But empty space is a physical entity? Do you catch up what I am saying, friend? This is physics. Unfortunately in Physics you also need to be a very good mathematician (despite not outstanding bright) inside the field of physics. However math is not physics because physics is a study of concepts coupled with empirical observations.
Brasil
@@KRYPTOS_K5 Your example isn't true under the perspective of special relativity.
You've mentioned that every subscriber gets you excited, but seeing this video, and seeing it published this recently (meaning there is more to come), gets me excited. This video hits a special point I had been searching for for so long that explains a concept like this simply enough to be appreciated by someone without a PhD in the area but with enough education (say, undergraduate university) to understand and appreciate the formulae. Great work
This was published in 1905
You're a lucky guy Jonathan. Please get so knowledgeable about this that you obtain the understanding necessary to effect the medical and transportation and communication benefits it has to offer. This can work from the DNA level of molecular technology all the way out to Near Speed of Light travel; including atmospheric transportation. Also remember to enjoy life. Kiss some girls. It's related to this at a level that is of cosmic proportions.
@@clavo3352 cringe.
@@igvc1876 yeah, youtube took a while to catch up! Great video in my view.
We need folk with depth, but we also need folk with breadth, in education. Neither is individually sufficient. We must value all work equally.
We need more videos of this quality on CZcams
Agreed.
yes
I still remember when i was in my 12th i asked the same question to my Physics Sir, in reply to that he shut me off saying that charge itself means electric field and moving charge itself means magnetic field, I think he meant that time that my question is useless as magnetic and electric field are very basic nature of charges, today i am feeling blessed after finding your channel accidently on CZcams, couldn't thank you more, although couldn't got along with the equation part but understood the theory of relativity involved here, A very big salute and huge respect to you for uploading this nice explanation ,Huge Love and Respect to you from India , Big fan of yours from today onwards, Subscribing and liking your channel videos is just a tiny token of appreciation which can never reflect the respect to you...
indian teachers be like:
I am an electronics engineer, and my 2nd year in college in honors physics we learned this. I was blown away! It was the single most fascinating thing I learned during my entire education.
I think you are amazing.
I didn't see a subscription link to subscribe to you. But I'll be looking for more of your videos.
You dwell within the intuitiveness of math we've accumulated as math students. Then blend it well with the changes one can't intuitively see with the shortcomings of SR.
Making it so simpler to comprehend.
Thank you.
awesome. thank you. what tool do you use to do this editing and even select portions, scale and shift them.. Could you extend this to explain back emf and as to why V = dphi/dt? It would be really really great to be seeing inductors and transformers and imagining their principles in terms of electric fields.
Wow!! I was mind blown by this!!
I'm a physics student currently in College, and I never even imagined there was a connection there between electromagnetics and special relativity. You're awesome man. Great quality video right there. I wish I could subscribe twice to make you twice as excited...
Thank you! You could create another account :p. Often this phenomenon goes untaught - I first read about it in Purcell's Electricity and Magnetism
Indeed, the original name of the paper that Einstein published when he moonlighted what is now called The Theory of Special Relativity was:
On the Electrodynamics of Moving Bodies
And it was this connection that made it famous. Not so much the implications about interstellar scheduling.
Einstein had a lot of help writing this paper; from people who didn't necessarily agree (yet) about the implications about interstellar scheduling. In particular, Ernst Mach provided some insight about the equations regarding Doppler Shifting for the paper. And from this approach, you can get a much more intuitive sense of how a moving body observes different charge values than a relatively stationary body, regardless of the constancy of the speed of light.
If you're familiar with Doppler Shifting, you know that an approaching siren sounds higher pitched, because the sound waves are relatively compressed. Now, rather than frequency of sound, as an analogy consider density of electrons. That is, the frequency at which an electron passes by an observer. Thus, a charge source moving relatively towards the observer is ""Doppler Shifted" to a frequency, that is to say charge density which is higher. And so with no knowledge at all of the spacetime topology implied by Special Relativity, it is clear that an current approaching closer to the observer has a relatively higher charge density than a current moving farther away from the observer
The mathematics works out the same, since in this hypothetical thought experiment there is a chosen universal frame of reference. (The ground.). Indeed, the only situations where time dilation needs to be considered is in cases where General Relativity comes into practice, i.e. solutions to the Twin Paradox. Because in these situations alone, there is no longer that universal frame of reference.
But that's another matter entirely.
@@andrewcrawford2977 Einstein has been proven wrong daily by the Thunderbolts project though. We know how magnets work today based on experiments you can do on home youself with a Ferrocell and a neodymium magnet.
Special Theory of Relativity is based on Logical Reasoning. Though the end results like time dilation, variation of mass etc. are as per predictions in my view there are some inaccuracies in the approach like unverified assumption of unidirectional speed of light as constant, unsatisfactory reasoning of Twins Paradox etc. I have worked-out a Physical Model years back. According to it the moving system undergoes Lorentz Contraction and the rays emanated from it at first focus of an imaginary ellipse will converge at a point at the second focus of that ellipse such that the observers eye-piece reaches there at same instant. I have worked-out Mathematical details of it.
Seetharam
svaram55@gmail.com
@@andrewcrawford2977 this made my day, thank you for the this intuitive explanation
I have a vague memory of this from my sophomore E&M physics course in college, but your explanation is clearer. Thanks for this elegant derivation!
This video was incredible. I'm a new engineering student and this is something that I have ALWAYS wondered about. I knew they were connected, but I hated how I never had an answer as to WHY. I haven't encountered this in school yet but I will certainly be recommending this video to people. Maybe you could make one on why electromagnetic fields and magnetic fields propagate off of each other? I'm sure it is related to the fact that they are both electric fields, but I can't quite figure it out. Thanks!
Absolutely fascinating. A number of things are now much clearer to me. Well done! I hope you will produce more material of this kind.
I got here from veritasium too... its just AMAZING how these two forces are so deeply connected... and I would never imagine that the magnetic force formula comes from ELETROSTATIC concepts!!!! I have no words for thanking you, that was a masterpiece demonstration
such a well done video; to actually see the Math of it all work out to the same result in both frames of reference is profound!
Thank you, this is an amazing video. Kudos on your knowledge of these formulas and excellent hand writing!
Fantastic video, really, great job!
You kind of lost me a bit when it came to explaining the frame of references but I think I got there in the end (I gave up on the formulas tho haha).
I'd recommend using more visual elements to complement what you're talking about as you explain it verbally. Sometimes I have to pause the video, rewind and re-listen to what you said to digest it properly. I think like visually highlighting the frame of reference you're talking about would've gone a long way in helping my dumb face understand how it works. But yeah, I say do more visuals, the ones you already make are awesome!
On another note, can I just say I really love your channel. Especially your enthusiasm for the things you're explaining and the way you do it I find really understandable. Also you have a soothing voice which doesn't hurt :p keep up the great work!
There was an example, I think in Scientific American, some years ago. A train is moving, on this train near the engine is the escaping criminal, and a detective or policeman is on the train somewhat to the rear of it, and adjacent to the train is another policeman. At exactly the same instant, the two policemen, one moving with the train and one stationary beside the train, shoot lasers at the criminal. Do the lasers hit the criminal at the same time? Yes, presmably they do. The velocity of the train does not make the laser beam go any faster. Now if it was a bullet, then you would add the velocity of the train, to the velocity of the bullet, and it would get there before a bullet fired from the side of the train. But as you approach the speed of light, you cannot do it that way. And AT the speed of light, the velocity of the train becomes completely irrelevant; light goes at exactly one speed (in a vacuum) regardless of any velocity of its origin.
It is this phenomenon that contributes to non-obvious behaviors in a wire.
Wonderfully explained. Thanks for solving the riddle of my mind.
That was absolutely stunning. Thank you so much for putting this together.
Wooow!!, I searched to compare Electrostatics and Magnetostatic so I could remember the magnetism formulas better because I never understood why the magnetic force has that equation. Now the puzzle is complete! Thanks a lot and good luck with the future videos
This video answers all the questions I had about electric currents and magnetic fields!! Amazing work
I have never saw that proof before. Nicely done.
GORGEUSLY DONE, makes me more excited to take EM field II course this year
I'm glad I could pique your interest!
Hello! I would like to point out a very minor aspect that, in a way, has been overlooked in your video. Recently I did a similar calculation but instead I took a long single line of electrons and spaced them out so that 1 coulomb of them would stretch to roughly 1e8 metres. This means that for 1 ampere of current the electrons need to move at 1e8 per second. This is a good fraction of the speed of light, which is what I wanted because then I could work out the length contraction and not have to worry about the decimal accuracy. From this I calculated the perceived extra number of electrons per m. When I then use this result to calculate the force between two current carry wires. I get perfectly the result 2.00e-7 N/m as it should be. But there is a twist. If I keep increasing the spacing between the electrons so that the electron speed required for 1 ampere gets even closer to light the calculated force begins to increase beyond 2.00e-7 N/m. This means that in your equation there should be another Lorentz factor for describing situations with very large drift velocities. I presume that this must be contained within the definition of current in your equation.
I initially wasn't sure about my result but then I found the following from Feynman's Lectures in Physics Vol II,
chapter 13, page 13-9, where he derives the equation for the same force given as
F = qpA(v/c)^2
---------------------------------
2PIe0r sqrt(1- (v/c)^2)
here p is the charge per unit volume. Feynman goes on to say.
" Comparing this result for F' with our result for F we see that the magnitudes of the forces are almost identical from the two points of view. ...... We can say that for low velocities, at least, we understand that magnetism and electricity are just "two ways of looking at the same thing."
I find it quite ironic that we use special relativity in one way to justify the magnetic force and then say it eventually deviates from this standard equation because of the effects of relativity.
Please let me know if I've made some silly mistakes - one of them might be that the length that I initially started with actually is not correct because of the effects or relativity. Thanks!
This is a gem that you've put here! I'll try to work this out soon to find out if it's correct.
At 15:28, in the last fraction should be squared nominator as well, not gust denominator. So right expression is:
(1+{vv_0}/C^2)((1+{vv_0}/C^2)^2-(v+v_0)^2/C^2)^{-1/2}. The video is great, many thanks!
correction is the best form of collaboration we have. Top post.
Absolutely mindblowing! Your explanation of the concept was so easy to understand that even I could understand, with only an absolute beginner level understanding of electricity. Bravo!
Absolutely awesome. I got more explained to me than I bargained for from this vid.
A simple but elegant way of explaining is most impressive to me and I hope more of these videos.
Deviprasad
Thanks for such an informative video! In the derivation, (V+Vo)/C^2 should be (V+Vo)^2/C^2 for anyone else working through the algebra.
Error correction is one of the most useful things in humanity. Never stop.
humanity, and beyond!
Best video on this topic I have seen so far . Thanks a lot brother
Just subscribed! more physics videos please. Would love to know equations for the motions of planets with sample problems. Again nice vid.
Thank you for that insightful through line.
Hey, I love your video. I just stumbled on your channel. Just a recommendation, please, take out the background music I can't hear you very well with it.
That was a totally awesome video that you produced although I must admit I didn't understand half of it I sure would like to take a course so that I can understand the complexities of all the mathematics equations in the video. Can't wait to see what you produce next thanks
Wonderful! Please, keep going with this channel!
The best explanation of the relationship between magnetism and electricity I've seen. I noticed this video is now 4 years old. I'm sure in that time your priorities have changed, but if growing your channel is still a desire, put less stress on the math, and more stress on the principles. If I understand your video correctly, whether you're experiencing a magnetic, or an electric field, actually depends on your velocity (reference frame) relative to the field in question. If that is true, then the implications are pretty astounding. Most people can grasp that psychologically. However, fewer than 1 in 10,000 people can understand the math involved. Good luck, and thanks for your knowledge and hard work!
We need a bridge between 'hard maths' and typical folk. Geometric representation of equations can help greatly, but it's not easy! My art work is appalling, I've tried doing this stuff, I typically get the words about right, but my drawings are rather childish. Still, it makes folk smile at my incompetence!
I first came across a similar derivation in "Electromagnetic Fields and Waves" by Paul Lorrain & Dale R. Corson as an Undergrad.
www.amazon.com/Electromagnetic-fields-waves-Paul-Lorrain/dp/0716703319
What is the software are you using to draw the diagrams?
Simply extraordinary and deeply moving. Thank you for sharing this Art. I watched it 3 times to follow the math.
Excellent explanation !
Great stuff brother. I want to learn more of this.👍
This video was absolutely amazing and incredibly well explained; thank you!!
Thank you for sharing this, I've been questioning if they were the same force for awhile but didn't know how to prove it; and then your video popped up 😁.
Excellent video to understand Magnetic field generated by steady current (DC).
Thank you for the clear and compact explanation.
It’s really neat how one can explain the magnetic field by looking only at the electric field and relativity. By using different frame of reference, one can also explain the electric field as a magnetic field of charged particles that move through time at the speed of light. I wonder which explanation is more fundamental in explaining the electromagnetic fields?
Beautifully explained.
Very good, thank you and I'll look forward to seeing anything you may cover on Maxwell 's Equations and possibly Quantum Mechanics? .....please! !
oh wow! The fact that we can explain electromagnetism using special relativity with everyday velocities also shows just how much stronger the electromagnetic force is compared to gravity.
Amazing video, great that you don’t shy away from the algebra!
This is beautiful. Thank you.
This is very interesting, thank you for presenting this and I liked your clear way of doing it. I love explanation as to what is actually taking place. So here's a question, why are magnetic fields in lines?
Congrats! Excellent work.
We didnt talk about special relativity in my undergrad program but i could kind of follow and this really illuminates the topic (and also validates my confusion i guess…)
Thank you for brushing on my rusted fundamentals on electromagnetism !
The best video I have seen in youtube. Wow relationship between special relativity and electromagnetism explained. Don't think all this physics happened by chance in the universe. More astonishing is the human brain. On the side, i saw a video of the James Web telescope and how it will open up in space with more than 300 activations. Then I saw a video of a baby in the womb of a mother and how it is just present alive there just to unfold when it is born. Talking about greatness
Excellent work !!
What is this software??
Awesome video STEM cell!
Thank you very much for the the video, it makes things a lot easier to understand. I would like to know if there is an explanation for the Lorentz Force felt when the test particle moves instead perpendicular to the wire (approaching or getting far from it), according to "F = v x B" it would feel a force in the same direction of the current, but these should not be related to relativity since the motion is perpendicular to the current.
Such a phenomenal video
Great video, especially adding the historical context. What about permanent magnets?
Permanent magnets in nature are not very strong. We make super strong ones by running current through certain metals in which all the atoms domains (the atoms electrons spend more time on one side of the atom) line up perfectly and you have exactly half of the metal with a north or positive charge and half with a south or negative charge. How does a magnet repel or attract another magnet. By what mechanism is going on? We don’t know. We only know the rules of the game. Like poles repel, opposites attract. Like the atom itself we do not know how the proton repels other protons but attracts electrons. We just know they do. Also we don’t know what the hell gravity is. All stuff I took for granted. We just know the rules and when you know the rules you can do a lot with it.
I had seen this topic on veritasium a long time ago but i really really appreciate your breakdown and approach. I was also surprised to learn special relativity was behind all of this
"I had seen this topic on veritasium a long time ago"
I have a feeling that Veritasium is wrong about some aspects of this. He dismisses the importance of the wire and the electrons contained in it.
@@thomasmaughan4798 maybe you should make your own video so I can know what you mean because you’re giving me no info here. I think the main idea is how length contraption is a main cause of the phenomenon.
@@earag31415 "I think the main idea is how length contraption is a main cause of the phenomenon."
So it seems. But whether it is a cause or a consequence of what is actually happening (or both together) is unclear. At time zero, everything is not moving and there is no charge.
There is also no cat to rub on amber. So you must introduce charges or holes (protons that want electrons) to one end of the wire.
WHY then will anything move? Obviously it is the presence of an electrostatic field; not yet magnetic since nothing is moving. But the electrostatic charge of the battery, for instance, on contact (or an instant before contact) repels the electrons in the wire nearest the battery. They repel the next, and the next, and so on. This creates movement, movement creates magnetism, and magnetism further moves electrons.
@@thomasmaughan4798 yesss I absolutely agree. I will not go back and check whether he mentioned that or not but I do agree and believe that there it a time of sole electrostatic which then evolves into electromotive force.
Thank you so much for your input. 😇😍❤️👍
beautifully explained. even though the mathematical proof in the last part I didn't understand due to my lack in mathametical knowledge but still its worth.
Excellent. Thank you!
Very impressive! A youtube video that actually does blow one's mind! Well done!
Wow - I thought i went to school for Electrical Eng and I knew this stuff - still remember the puzzle as to how two wires attracted when current flows in opp directions, when I first encountered mag field between moving currents - just the curiosity faded away with rigor ~~ never thought it as sp relativity.
Great video 👌
It is known that a magnetic field around a permanent magnet is caused by the alignment of 'magnetic domains' which said in a clearer, more physically precise way means the alignment of electron spins. Electron spins normally are randomly aligned and no magnetic field occurs. When electron spins are aligned (in iron or cobalt or nickel permanent magnets), a magnetic field manifests.
It is known that the speed of electrons in a current-carrying wire is NOTHING like the analogy of 'flowing water in a pipe' - the "drift current" velocity of electrons is astonishingly slow. Look at the 'drift velocity' page on wikipedia.
Given these two facts, it is reasonable to say that electron spins are aligned in the wire and that is why a magnetic field is created around the wire, when a battery or power supply is attached to the wire. The application of a power source across the wire aligns electron spins.
The 'drift velocity' of electrons in a wire is about 23 microns per second (that's a distance of 0.000002 meters per second). That's for a wire carrying 1 amp of electric current with a wire diameter of 2mm.
.
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I’m trying to visualize this, but I’m having one struggle with this idea. It is the electric field that is applying the force on the charge carriers, and electric charges need not come in dipoles like magnetic fields. The property known as spin is associated with the magnetic field, and electrons will align with magnetic fields in one orientation or the opposite (as evidenced by the Stern Gerlach experiment, to name one), but I have never heard of electrons orienting their spins in the same direction in the presence of an electric field alone. So my question is, if a magnetic field is required to align magnetic domains (assuming the material isn’t ferromagnetic, like the average current carrying wire made of copper isn’t ferromagnetic) then what would cause the alignment of domains that would produce the magnetic field about a wire. In other words, you can’t cause alignment, in say copper, without a magnetic field. So claiming aligning domains create a magnetic field doesn’t make sense with my knowledge that a magnetic field is required to align these domains. The electric field does apply a force on charged particles, but the charged particles in the wire aren’t electric dipoles, and spin is not affected by the electric field as far as I can tell. Without a doubt I’m more than interested in any information you have that would help me understand the model you are describing, I’m perfectly happy to be wrong and learn something new.
From what I can tell the relativistic effects show a direct and accurate prediction of the origin of the magnetic field about a wire. Even though drift velocity is very slow the change in apparent electric charge density in the wire due to length contraction does predict the magnetic force is simply and electric force in disguise. This was what special relativity was originally about, and why it was invented.
I am currently in my third semester of EM, and we are currently studying relativistic effects for electric and magnetic fields. While I wouldn’t claim to be any sort of expert in the field (I do really well with the classical EM, but definitely need more study in relativity), it seems like this videos explanation is the most well respected and calculable theory.
@@isaacjohnson8752 The simplest atom (hydrogen) is nothing more than a dipole. Proton nucleus (positive charge that has a magnetic moment) and electron (negative charge that also has a magnetic moment).
I understand your point. But there is no getting around the magnetic field that manifests around a wire when a charge separation (aka electric field) on the ends of the wire is applied.
The charge separation that is polarizing the constituents of the wire is supplied by a battery or a power supply.
There is also no getting around the fact that in order for a magnetic field to manifest, aligned electron spins are required.
If you want to propose a new physical mechanism that would allow a magnetic field around the wire - or anywhere, really - to become manifest, with completely randomly-aligned electron spins, I want to hear that.
An analogy: the physical existence of paint is required to paint a fence. If you have a brush, and the fence, and an empty paint can, the fence will remain unpainted.
You cannot paint the fence without paint.
You cannot manifest a magnetic field without aligned electron spins.
@@isaacjohnson8752 Another issue SR/GR did not account for is the possibility of electric and magnetic field carriers in the Vacuum.
Remember - all magnetic field-generating entities - wire with current, a permanent magnet - function in space.
The QED Vacuum is said to consist of electron-positron pairs that quickly self-annihilate.
Our working theory relies on the fact that electron-positron pair annihilation produces gamma rays - this has been demonstrated in labs across the globe for decades.
Yet there is no gamma ray background that is detectable in space (or anywhere) that should exist, if the QED Vacuum actually consisted of rapidly-annihilated electron-positron pairs.
We work on artificial gravity devices and rely on the persistence of electron-positron pairs throughout the Vacuum for our work.
In General Relativity, Einstein said "space is empty, there is no aether" and also said "space is curved".
If there is nothing in space, there is nothing to curve. This is a problem. In Einstein's defense, Dirac and the existence of electron-positron pairs came many years after GR.
When a propagating electric and magnetic field leave our Sun (a light wave for e.g.) - when electromagnetic waves have left our Sun, but have not yet reached Earth, they are in the Vacuum.
In order to manifest the electric field and the magnetic field in the Vacuum, there must be electrically and magnetically polarizable constituents in the Vacuum.
You will NOT find 'Vacuum Engineering' taught in the university - artificial gravity tech has been perfected and sequestered for many decades.
WOW, great instructor>!
So far the best of a kind i have ever seen
Thank you! Exactly what I needed
I listen to this repeatedly, to remind myself. Brilliant
Pleasure to watch!
Thank you very much for this, though i do not understand, if the charged particles are moving slow in the wire, even though it is relative to the speed of the charged particles outside the wire, i assume that the gamma/Lorentz factor would be 1. what did i miss?
Excellent... thanks.
I work as a trainer at a power plant. I was creating a training video for how the generator makes electricity and I was talking about the magnetic field created when we energize the rotor. I said to myself "Someone is going to ask why a magnetic field is created when current goes through the wire," which led me on a quest. haha
Sir, NOBODY knows why it happens. Well, except you. haha
I asked everyone out here and they were like "Uhhhhhh, I've never thought about it." And I was like "Me, neither, but I'd like to have an answer in case someone asks."
I Googled it and found nothing.
Your video popped up a few days later on CZcams and BAM, it's explained.
So, thank you, very much, for taking the time to explain this. Just a fantastic job. 👍👍
this was crazy helpful
Really good video!
Amazing! Can magnetic field from magnets and magnetic force be explained in terms of electric field and charge movement too?
One question still rises. If the charge outside the wire stays still. It'll still see more negative charges in the wire than positive charges. So it should feel a force. But we know, it won't feel any force in static condition. Can you explain please?
yes please someone explain this
As i understood even though moving electrons appear contracted to the stationary charge outside, distance between their middlepoints is still the same as distance between two positive ions that don't move. Because of that there is no difference in charge density between electrons and ions in wire, there are same number of electrons over distance as ions no matter if electrons are contracted or not.
Don't take this seriously this is just my understanding, i didn't read it anywhere. I am happy to hear someone who really know this stuff and can explain it correctly and with proof.
Given more time I could have understood this! Good job!
🙂
Many thanks
Can you show (demonstrate) it in a vectorial form ? Can we show that this emerging electric field is indeed E=UxB ?
I think it makes nautral for the Lorentz factor of v_nut to show up in the current I, where I = I_nut/gamma(v_nut), to take into account the time dilation, observed by a stationary observer, instead of using it as the extra multiplication factor under Lorentz contraction in the moving frame. (We know current by definition is dq/dt = 1/(gamma(v_nut) * dq/dt_nut)
It moved too quickly for me, but I can rewatch, pause and think. Don't you go slowing down :) I still got the gist of it, and was educated further on my journey of understanding whether electrons moving in the wire deliver the power or whether its the sum/compliment of the EM field and the wire. Some assert that the wire is not the vessel of the power, but the director (my words) that the EMF around it follows to deliver power at the circuit load. I am enjoying the research and enjoyed your video thanks. Tim
great video, thanks.
Thank you. 👍
an excellent watch
Almost a 1000 subscribers now :0, I think a huge part came from the 3b1b explanation video you did and also the shoutout he did later
If that was intentional then he is a genius
I didn't think it would get me so many new subscribers, I was really just trying to get involved in the math youtube community!
I guess most of the crowd from Veritasium
What are the pre-requisites of understanding the derivations?
Overall dude it's a great video . It's just prompted me to know more about this . Thank you really!
Your brain is a super computer, your brain can figure out anything. No one is born knowing anything. Be very interested and try to understand it, what you don’t understand go and try and understand that and keep repeating. Read the same concept from multiple sources and try to conceptualise it in your mind… you can learn anything, the hard part is to keep going when you don’t understand something, just keep taking in the info thinking it over, at some stage it will just click - I’ve done this many times, I just treated myself like a robot and didn’t spend time with all the unhelpful thoughts like “this is so hard”, “why don’t I understand this?”, “I dont get it, I’ll never get it!”, “some people are just naturally smart and I’m not”
Kids don’t tell themselves these things and they are able to acquire language and other things better than adults - I think this is a consequence of what mental baggage they carry versus actual physiological differences. Try it!
All those negative thoughts take away from the actual goal, be a robot 🤖 or be like a child again, drop the baggage
Undergraduate electrostatics and magneto-statics will explain the E and B fields of lines of charge and linear currents, respectively. (it's late 19th C physics).
The length contraction / Lorentz transformation is 1st semester undergrad special relativity. (It's early 20th C physics, 1905 to be exact).
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Loved this video! Keep it up(:
4:49 Shouldn't the magnetic field around the fire be to the opposed direction by the right hand rule?
In special relativity we very often hear about the "stationary" system, well this system is contrary to the relativity: the "stationary" system (a resting system) is equal to a moving system.
Amazing stuff man you are a genius
Thank you soooo much. Your video is amazing. Thanks!
This is the best way to guide students to understanding special relativity: I started asking if the "v" in Lorentz force didn't look fishy .... "v" with respect to what? And so on.
This is well explained (of course) by Richard Feynman in his wonderful Lessons.
This is a precise and somewhat concise explanation of the relativistic effects of electric current flow in a wire. One small criticism I have is this. Don't you think it would be better if you chose V1 and V0 in the multiplicative term, thereby avoiding the appearance of W in the term? It threw me for a brief second until I paid attention and saw what the term represented and not another variable.
Wow, this is great, I couldnt resist your request for subscription...from tanzania;;congrats...
briliante intuição! ...
Great video 👍🏻!
I am still failing to conceptually understand how this can all happen at such low speeds though…
Thanks !
Well special relativity doesn't 'switch off' at a particular speed. Yes, the effects get v.small at low speeds, but you don't need much imbalance to impact a charge - think about how little effort is needed charge amber or a balloon.