8.02x - Lect 16 - Electromagnetic Induction, Faraday's Law, Lenz Law, SUPER DEMO

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  • Published on Feb 14, 2015
  • Electromagnetic Induction, Faraday's Law, Lenz Law, Complete Breakdown of Intuition, Non-Conservative Fields. Our economy runs on Faraday's Law!
    Lecture Notes, Non-conservative Fields - Do Not Trust Your Intuition: freepdfhosting.com/d5fc27ec92.pdf
    THIS LECTURE IS A MUST - Read the Lecture Notes of this Lecture.
    Assignments Lecture 13, 14, 15 and 16: freepdfhosting.com/68fc720c7c.pdf
    Solutions Lecture 13, 14, 15 and 16: freepdfhosting.com/5d4c550dc5.pdf
  • Science & TechnologyScience & Technology

Comments • 2 606

  • Abhishek Prakash
    Abhishek Prakash 11 hours ago

    why my mistake

  • Troy Lange
    Troy Lange Day ago

    When did Neil Young start teaching?

    • Troy Lange
      Troy Lange Day ago

      Also could you explain the mysterys of things that don't get lost or coins that won't get tossed.
      But seriously, thank you. Your my new hero. Just hope your coming home soon.

  • Hariom Rai
    Hariom Rai 2 days ago

    If u are alive
    Please make video with subtitle. Please

    • Hariom Rai
      Hariom Rai 2 days ago

      I m sorry for that coz video was upload in 2015 and it is long time.....
      Thq a lot sir
      But i am not understanding what are u actually teaching..... ...sir i need your help......

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  2 days ago +1

      My 8.01 & 8.02 lectures and all my Bi-weekly Physics Problems and Solutions have subtitles. Only 8.03 does not have cc. If you will write the cc files for 8.03, I will upload them. It will take you more than 50 hours to do that.

  • Muhammad Shafiq
    Muhammad Shafiq 2 days ago

    good

  • Shiv Dayal Sharma
    Shiv Dayal Sharma 5 days ago

    Physics .....Respect Sir

  • Ahnaaf Naaeer
    Ahnaaf Naaeer 6 days ago

    I'm in tenth grade. I wish that one day I get to be his student

  • Pieter den Boer
    Pieter den Boer 7 days ago

    So what if you move the solenoid together with the bar magnet? No current since there is no relative motion between the solenoid and magnet? Wrong. There is current since the magnetic field is not in relation to its source, it has some absolute frame of reference. This also proves the induction equation wrong since you don't need to move the solenoid in relation to the magnet, you just need to move them. Faraday's homopolar motor proves it.

    • Pieter den Boer
      Pieter den Boer 6 days ago

      @Lectures by Walter Lewin. They will make you ♥ Physics. Well, that's why they call it The Faraday paradox

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  6 days ago

      place a magnet at rest near a solenoid (solenoid in closed loop with resistor R) in a car which does not move and which is shielded from the Earth' magnetic field, no induced emf in the coil, no induced current through R. When the car moves no induced EMF, no current through R.

  • Наталия Логвина

    What happens if we move a solenoid connected to the battery inside an even bigger solenoid?
    As far as I understand this would create an electric current inside the outer solenoid, which would, in turn, create magnetic field inside both solenoids and change the dB\dt, which will change current and this will again change B and dB\dt... This infinite loop makes me stuck

  • I'M HAMMAD
    I'M HAMMAD 8 days ago

    Watching from pakistan great work sir..thanks

  • Universaldenker
    Universaldenker 8 days ago

    Hey guys, can you check out my first video about Maxwell's equations:
    thexvid.com/video/hJD8ywGrXks/video.html

  • Reeti Chauhan
    Reeti Chauhan 9 days ago

    “WHY” does time varying magnetic field ( or change in flux) induce EMF?

  • Ethan Krauss
    Ethan Krauss 11 days ago

    If you would like to see an ion thruster lift its power supply, please click on the channel icon to the left. It is a scientifically important development in terms of physics. I hope you agree.

  • Dheeraj Mishra
    Dheeraj Mishra 12 days ago

    When I became a Faculty for electromagnetic field theory for training Indian students for Gate exams, I love to follow your lectures and the way you deliver them in real classroom I mimic the same Prof Walter, I received the compliments and blessing from my students from the day one class, I never found such an amazing lectures and enthusiasm, and distinguishing demonstration of each topics of physics ,The way you bestow the fundamental along with academically proven physics ideas ,You help us measure anything which belongs to physics ,I love the prof Walter lewin ,The very first lecture I saw in the year of 2011 ,when I was in pre final year of an engineering degree in India, Those days I was unable to realise and understand due to English pronunciation as Indian accent are different as we from village background were unable to pick up exactly with less digitally driven hand held devices .But now when I took teaching as a profession ,I began understanding each instinct and intuitive ideas which you showed to us .Whole world witness the fact that all tyro in realm of physics becomes in allure of physics due to your fascinating demonstration. I would love to meet you in near future and get a signed copy of your books .Many Thanks professor Walter.
    regards
    Dheeraj Mishra
    From India
    City: Rewa (Madhyapradesh)

  • Prasad Pawar
    Prasad Pawar 14 days ago +1

    My question is that if E and dl are in same direction shouldn't E•dl in the integral be zero?

  • KUSHAL SARKAR
    KUSHAL SARKAR 15 days ago +1

    We Study this concepts for iit jee and also solve more tough problems than their college exam..... lot of pressure 😶

  • Donald Amaele
    Donald Amaele 15 days ago

    And it runs our health.

  • Donald Amaele
    Donald Amaele 15 days ago

    TOP LECTURER.

  • Donald Amaele
    Donald Amaele 15 days ago

    A man who teaches his students the problem, deep Cerebration and after all these celebration.

  • Donald Amaele
    Donald Amaele 15 days ago

    A man of pure integrity.

  • Wilfrido Gonzalez
    Wilfrido Gonzalez 17 days ago

    Teacher i´m playing with Neodimium i really appreciate any comment thexvid.com/video/x0WAs2TRvUk/video.html thanks :)

  • Steve Decker
    Steve Decker 19 days ago

    So at 51:06, that would explain why a 100ft wire wrapped around a coil that is directly connected to a 120v outlet doesn't short out and cause a fire because only for a few milliseconds current flows but then stops. Very interesting!

  • Steve Decker
    Steve Decker 19 days ago

    It's Faraday's Law! NOT Fireday's Law! LoL!

  • Deep deep
    Deep deep 23 days ago +1

    Sir make video for important and relevant questions to jee advanced

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  23 days ago +1

      Watch all my 94 MIT course lectures. Start with 8.01, then 8.02, then 8.03. Do all the homework and take all my exams. Homework and exams are posted below the video thumbnails. *I guarantee you that you will then not fail the Physics portion of any exam*

  • pavitra jain
    pavitra jain 26 days ago

    At 2:14that girl was so pretty

  • Engr Alam
    Engr Alam 27 days ago

    such a Good terminology of education lecture.......

  • First Name Last Name
    First Name Last Name 28 days ago +1

    Sir,
    What is the actual reason that a steady magnetic field cannot induce current

  • rh001YT
    rh001YT 28 days ago

    To those questioning the result shown at the end:
    1) It is not necessary to use twisted test leads or magnetically sheilded leads because the effect being measured is way greater in magnitude than any errors caused by the average test leads.
    2) the direction of rotation of current induced in the loop is due to the little known fact that the electro-magnetic field from a solenoid has something like a spiral or helix shape. (same is true for permanent magnets). As the field is increasing, the growth of the spiral is akin to a rotation. The pseudo rotation sweeps the electrons along the loop. The same emf inducing force is swept across the 100 ohm resistor and the 900 ohm resistor in the same direction, thus as measured in this experiment the emf induced across the 100 ohm resistor will be opposite that measured across the 900 ohm resistor. The voltmeters have to be positioned as shown so as to be measuring the one side of the loop or the other.
    3) if the leads of the meter across the 100 ohm resistor are reversed then both meters will measure the same directional flow of the current and the result will be +0.1 and +0.9, thus equally 1 which is what everyone expects.

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  28 days ago

      *I demonstrated at the end of my lecture #16 of my 8.02 E&M course at MIT that two identical voltmeters attached to the same 2 points in a circuit can show very different values.* thexvid.com/video/nGQbA2jwkWI/video.html *The reason is that in the case of an induced EMF (Faraday's Law) potential differences are no longer determined; they depend on the path. This also applies to the secondary windings of transformers as the EMF in the closed loop of secondary windings is induced.* thexvid.com/video/b7i2uMx7gHo/video.html
      *Of course, in cases where Kirchhoff's loop rule (KVL) applies, 2 voltmeters attached to the same 2 points in a circuit will always show the same value.*
      *My demo was first suggested and published by Romer in December 1982 in the American Journal of Physics.* *This demo has now become a classic; it's done all over the world at many colleges and universities.*
      *Kirchhoff's original text can be found in the following link, pages 497-514:* books.google.de/books?id=Ig8t8yIz20UC. *Clearly he was fully aware of the prerequisite for his "loop rule". KVL is a special case of Faraday's Law. That's why Faraday's Law is one of Maxwell's equations and KVL is not.*
      *By teaching students that KVL always works without telling them when it does not work, makes many believe that the closed loop integral of E dot dL is always zero. ElectroBOOM and Dirk Van Meirvenne therefore believe that 2 voltmeters attached to the same 2 points in a circuit must always show the same value which is not true as demonstrated in my lectures.* *They each posted a video on their channel in which they claim to have proof for their wrong ideas which violate Maxwell's equations.* *Apparently they do not know, or do not understand, that in the case of an induced EMF potential differences are no longer determined; they depend on the path.* *MIT students who took my 8.02 course (Electricity and Magnetism) would not make this mistake!* *I therefore believe that to introduce a "modern version" of KVL and then teach students that KVL always holds is not advisable as you may set them up for making the same embarrassing mistake that both Dirk Van Meirvenne and ElectroBOOM made.*
      *Also read Professor John Belcher's thoughts on Faraday's Law and on KVL. Professor Belcher is my former colleague at MIT.* freepdfhosting.com/0813df09f5.pdf

  • Ashish Singh
    Ashish Singh 28 days ago

    Can someone provide me timestamp Of Thumbnail....??

  • Kishor Daryani Kishor Daryani

    There should be not a dislike option for such a great professor it is abusive him he taught us how to love physics even instead of watching movie I m here to attend his lecture even at 1:37 a.m. u r so dedicated sir in love with ur teaching after watching this I want to go MIT but I can't afford that so .....😔 but I will try my best to get in MIT

  • Bhavesh Buzz
    Bhavesh Buzz Month ago +3

    Sir @Walter Lewin , do you think migratory patterns have anything to do with Electromagnetic Induction

  • Vladimir Zadiran
    Vladimir Zadiran Month ago

    There is no violation of the laws of Kirghoff, there are manipulations with equivalent electrical circuits, would you try this in the physics audience at MEPhI, the answer would be instant, would you like the current to flow without an emf source? This does not happen. Return either the current source or the battery, this is the piece of wire that is in real life, but not in the circuit. You have to play poker.

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  Month ago

      Apparently you do not fully understand Faraday's Law. But, as I already wrote, you are not alone. This is my last attempt to teach you Physics. thexvid.com/video/wz_GqO-Urk4/video.html If this does not work then I cannot help you anymore. You can lead a horse to water, but you can't make it drink'. If you do not want to drink, that's ok with me. You are entitled to make that choice. *This is my last msg.*

    • Vladimir Zadiran
      Vladimir Zadiran Month ago

      @Lectures by Walter Lewin. They will make you ♥ Physics. Dear professor, I know this physics. You do a voltage measurement at the resistances and these are different points in the circuit. You removed two current sources from the equivalent circuit. These are two wires of an electric circuit in the circuit. You replaced them with nodes A and D. Everything is easily explained by the physics of electrical transients. Node D is divided into D and D "node A is divided into A and A" between them place two current sources of 1 mA each. Here is the correct equivalent electrical circuit at time t 0.
      You perfectly understand what I'm talking about.

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  Month ago

      *I appreciate the fact that this Physics may not be familiar to you. Don't feel embarrassed about it; you are not alone. However, it's never too late to get educated. The choice is yours. Maybe this will help you.*
      *I demonstrated at the end of my lecture #16 of my 8.02 E&M course at MIT that two identical voltmeters attached to the same 2 points in a circuit can show very different values.* thexvid.com/video/nGQbA2jwkWI/video.html *The reason is that in the case of an induced EMF (Faraday's Law) potential differences are no longer determined; they depend on the path. This also applies to the secondary windings of transformers as the EMF in the closed loop of secondary windings is induced.* thexvid.com/video/b7i2uMx7gHo/video.html
      *Of course, in cases where Kirchhoff's loop rule (KVL) applies, 2 voltmeters attached to the same 2 points in a circuit will always show the same value.*
      *My demo was first suggested and published by Romer in December 1982 in the American Journal of Physics.* *This demo has now become a classic; it's done all over the world at many colleges and universities.*
      *Kirchhoff's original text can be found in the following link, pages 497-514:* books.google.de/books?id=Ig8t8yIz20UC. *Clearly he was fully aware of the prerequisite for his "loop rule". KVL is a special case of Faraday's Law. That's why Faraday's Law is one of Maxwell's equations and KVL is not.*
      *By teaching students that KVL always works without telling them when it does not work, makes many believe that the closed loop integral of E dot dL is always zero. ElectroBOOM and Dirk Van Meirvenne therefore believe that 2 voltmeters attached to the same 2 points in a circuit must always show the same value which is not true as demonstrated in my lectures.* *They each posted a video on their channel in which they claim to have proof for their wrong ideas which violate Maxwell's equations.* *Apparently they do not know, or do not understand, that in the case of an induced EMF potential differences are no longer determined; they depend on the path.* *MIT students who took my 8.02 course (Electricity and Magnetism) would not make this mistake!* *I therefore believe that to introduce a "modern version" of KVL and then teach students that KVL always holds is not advisable as you may set them up for making the same embarrassing mistake that both Dirk Van Meirvenne and ElectroBOOM made.*
      *Also read Professor John Belcher's thoughts on Faraday's Law and on KVL. Professor Belcher is my former colleague at MIT.* freepdfhosting.com/0813df09f5.pdf

  • Alexander Hemp
    Alexander Hemp Month ago

    This is wrong, the measurements are not clean, self-induction of the test leads was ignored, as well as no twisting of the test leads was performed, which in principle leads to measurement errors. No special cables with magnetic insulation were used, the results of the experimental setup are worthless and the statement that Kirchhoff's law does not apply is simply fundamentally wrong. Who makes such mistakes and builds on a thesis that Kirchhoff was wrong, should retire and spread no falsehood as a teacher.

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  Month ago

      You are wrong, apparently you do not understand Faraday's Law. But, as I already wrote, you are not alone. This is my last attempt to teach you Physics. thexvid.com/video/wz_GqO-Urk4/video.html If this does not work then I cannot help you anymore. You can lead a horse to water, but you can't make it drink'. *If you do not want to drink, that's ok with me. You are entitled to make that choice. This is my last msg.*

    • Alexander Hemp
      Alexander Hemp Month ago

      use an electrotechnically error-free test setup and repeat the experiment. Then you will notice that the difference you have measured corresponds exactly to the induced fault current on the test leads. I repeated this experiment with a flawless experimental set-up and could not find the "phenomenon" described by you, so the experimental setup has confirmed Kirchhoff's law. The magnetic field induces as well on the measuring lines as on the wire (and the resistors, which additionally represent a coil), you do not consider the whole system but only the core, so your view of the experiment is incomplete and therefore your argumentation is nonsense.

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  Month ago

      *I appreciate the fact that this Physics may not be familiar to you. Don't feel embarrassed about it; you are not alone. However, it's never too late to get educated. The choice is yours. Maybe this will help you.*
      *I demonstrated at the end of my lecture #16 of my 8.02 E&M course at MIT that two identical voltmeters attached to the same 2 points in a circuit can show very different values.* thexvid.com/video/nGQbA2jwkWI/video.html *The reason is that in the case of an induced EMF (Faraday's Law) potential differences are no longer determined; they depend on the path. This also applies to the secondary windings of transformers as the EMF in the closed loop of secondary windings is induced.* thexvid.com/video/b7i2uMx7gHo/video.html
      *Of course, in cases where Kirchhoff's loop rule (KVL) applies, 2 voltmeters attached to the same 2 points in a circuit will always show the same value.*
      *My demo was first suggested and published by Romer in December 1982 in the American Journal of Physics.* *This demo has now become a classic; it's done all over the world at many colleges and universities.*
      *Kirchhoff's original text can be found in the following link, pages 497-514:* books.google.de/books?id=Ig8t8yIz20UC. *Clearly he was fully aware of the prerequisite for his "loop rule". KVL is a special case of Faraday's Law. That's why Faraday's Law is one of Maxwell's equations and KVL is not.*
      *By teaching students that KVL always works without telling them when it does not work, makes many believe that the closed loop integral of E dot dL is always zero. ElectroBOOM and Dirk Van Meirvenne therefore believe that 2 voltmeters attached to the same 2 points in a circuit must always show the same value which is not true as demonstrated in my lectures.* *They each posted a video on their channel in which they claim to have proof for their wrong ideas which violate Maxwell's equations.* *Apparently they do not know, or do not understand, that in the case of an induced EMF potential differences are no longer determined; they depend on the path.* *MIT students who took my 8.02 course (Electricity and Magnetism) would not make this mistake!* *I therefore believe that to introduce a "modern version" of KVL and then teach students that KVL always holds is not advisable as you may set them up for making the same embarrassing mistake that both Dirk Van Meirvenne and ElectroBOOM made.*
      *Also read Professor John Belcher's thoughts on Faraday's Law and on KVL. Professor Belcher is my former colleague at MIT.* freepdfhosting.com/0813df09f5.pdf

  • Roy Rosales
    Roy Rosales Month ago

    I just discovered these lectures. So happy they have been posted. Better than Netflix.Thank you for sharing and please keep them coming. Walter Lewin is a very good instructor.

  • WatchitAll
    WatchitAll Month ago

    I had just wanted to watch some minutes but I couldn't stop until the end...

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  Month ago

      This is the most difficult but most important lecture of my E&M course at MIT. It shows that 2 identical voltmeters attached to the same 2 points in a circuit will read very different values in case of induced EMF (that's the "power" of Faraday's Law). *And because of that, and ONLY because of that it runs our entire economy as it makes it possible to convert any form of energy into electricity.* It is understandable that many of my viewers have difficulties with Faraday's Law because their high school knowledge of Physics is insufficient to properly deal with induced EMF.

  • Surinder Kumar
    Surinder Kumar Month ago

    Source of EMF=?
    Flux changes equivelent=?

  • Falcon Lin
    Falcon Lin Month ago +1

    @ Dr Lewin I am a bit confuse with the KVL demonstration and I definitely am a beginner to Physics. I am wondering if Va-Vb = 0.9V, Vb - Va = 0.1V, after you add up two equations, you get Va-Va = 1V. So what does it even MEAN that "the potential difference of the same point(aka Va)" is 1. Does it means Va-Va=0=1V? How should I even interpret the potential difference of one point? Is there any intuitive meaning? Thank you for your answers and please attach any reference readings if necessary!!! I love your lectures !! Thanks

    • Falcon Lin
      Falcon Lin Month ago

      @Lectures by Walter Lewin. They will make you ♥ Physics. thx for quick response

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  Month ago

      *I appreciate the fact that this Physics may not be familiar to you. Don't feel embarrassed about it; you are not alone. However, it's never too late to get educated. The choice is yours. Maybe this will help you.*
      *I demonstrated at the end of my lecture #16 of my 8.02 E&M course at MIT that two identical voltmeters attached to the same 2 points in a circuit can show very different values.* thexvid.com/video/nGQbA2jwkWI/video.html *The reason is that in the case of an induced EMF (Faraday's Law) potential differences are no longer determined; they depend on the path. This also applies to the secondary windings of transformers as the EMF in the closed loop of secondary windings is induced.* thexvid.com/video/b7i2uMx7gHo/video.html
      *Of course, in cases where Kirchhoff's loop rule (KVL) applies, 2 voltmeters attached to the same 2 points in a circuit will always show the same value.*
      *My demo was first suggested and published by Romer in December 1982 in the American Journal of Physics.* *This demo has now become a classic; it's done all over the world at many colleges and universities.*
      *Kirchhoff's original text can be found in the following link, pages 497-514:* books.google.de/books?id=Ig8t8yIz20UC. *Clearly he was fully aware of the prerequisite for his "loop rule". KVL is a special case of Faraday's Law. That's why Faraday's Law is one of Maxwell's equations and KVL is not.*
      *By teaching students that KVL always works without telling them when it does not work, makes many believe that the closed loop integral of E dot dL is always zero. ElectroBOOM and Dirk Van Meirvenne therefore believe that 2 voltmeters attached to the same 2 points in a circuit must always show the same value which is not true as demonstrated in my lectures.* *They each posted a video on their channel in which they claim to have proof for their wrong ideas which violate Maxwell's equations.* *Apparently they do not know, or do not understand, that in the case of an induced EMF potential differences are no longer determined; they depend on the path.* *MIT students who took my 8.02 course (Electricity and Magnetism) would not make this mistake!* *I therefore believe that to introduce a "modern version" of KVL and then teach students that KVL always holds is not advisable as you may set them up for making the same embarrassing mistake that both Dirk Van Meirvenne and ElectroBOOM made.*
      *Read Also Professor John Belcher's thoughts on Faraday's Law and on KVL. Professor Belcher is my former colleague at MIT.* *"Most Physics College Books have it WRONG!"* freepdfhosting.com/0813df09f5.pdf

  • nawaz uddin
    nawaz uddin Month ago +1

    Love is to watch physics lectures by you sir

    • Lord X
      Lord X Month ago

      @Lectures by Walter Lewin. They will make you ♥ Physics.
      sir i want to ask u that arent religions the biggest scam of human civilisation? I mean i hv found many thesis in ancinet cultures which r now used in quantum science(unified field theory, neuro termjnology,conciousness,mund sciences) from hindu culture or the vedas but when it comes to religions they r belief and should have dealt that way but ppl seem to take it as an absolute moreover i like the thing about which i geard from sadhguru in science is that it does accept that theyre exist more ignorance than knowledge and our idea should be to try to explore other dimesions of intelligence rather than just intellect

    • Lectures by Walter Lewin. They will make you ♥ Physics.
  • Aaqib Khan
    Aaqib Khan Month ago +1

    Sir u r a brilliant teacher

  • Pradyun Devarakonda

    Thanks a lot for publishing the lectures of the "legendary professor, Walter Lewin".

  • Ashish Negi
    Ashish Negi Month ago

    Watch my video - thexvid.com/video/ySZd99Cy2N0/video.html

  • Arnaud Berard
    Arnaud Berard Month ago

    What’s the students grade ?

  • turban lovers
    turban lovers Month ago

    It was really very helpful...thank you so much☺

  • Technical සිංහයා

    please help me also.

  • Souradipsoudipa Bhattacharjee

    by the thumbnail i thought it to be a big condom

  • Rynne Max
    Rynne Max Month ago

    What is MIT

  • Michael La Moreaux
    Michael La Moreaux 2 months ago

    Professor Lewin does not know Ohm's Law! It is emf plus potential difference equals current times resistance. Either emf or potential difference can be zero, and in this case I suspect that the potential difference is zero. The emf is 0.9 volts through the 900 ohm resister and 0.1 volt through the 100 ohm resister for a total of one volt. The voltmeter should only be able to measure potential difference, not emf.
    Michael S. La Moreaux

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  2 months ago

      *I appreciate the fact that this Physics may not be familiar to you. Don't feel embarrassed about it; you are not alone. However, it's never too late to get educated. The choice is yours. Maybe this will help you.*
      *I demonstrated at the end of my lecture #16 of my 8.02 E&M course at MIT that two identical voltmeters attached to the same 2 points in a circuit can show very different values.* thexvid.com/video/nGQbA2jwkWI/video.html *The reason is that in the case of an induced EMF (Faraday's Law) potential differences are no longer determined; they depend on the path. This also applies to the secondary windings of transformers as the EMF in the closed loop of secondary windings is induced.* thexvid.com/video/b7i2uMx7gHo/video.html
      *Of course, in cases where Kirchhoff's loop rule (KVL) applies, 2 voltmeters attached to the same 2 points in a circuit will always show the same value.*
      *My demo was first suggested and published by Romer in December 1982 in the American Journal of Physics.* *This demo has now become a classic; it's done all over the world at many colleges and universities.*
      *Kirchhoff's original text can be found in the following link, pages 497-514:* books.google.de/books?id=Ig8t8yIz20UC. *Clearly he was fully aware of the prerequisite for his "loop rule". KVL is a special case of Faraday's Law. That's why Faraday's Law is one of Maxwell's equations and KVL is not.*
      *By teaching students that KVL always works without telling them when it does not work, makes many believe that the closed loop integral of E dot dL is always zero. ElectroBOOM and Dirk Van Meirvenne therefore believe that 2 voltmeters attached to the same 2 points in a circuit must always show the same value which is not true as demonstrated in my lectures.* *They each posted a video on their channel in which they claim to have proof for their wrong ideas which violate Maxwell's equations.* *Apparently they do not know, or do not understand, that in the case of an induced EMF potential differences are no longer determined; they depend on the path.* *MIT students who took my 8.02 course (Electricity and Magnetism) would not make this mistake!* *I therefore believe that to introduce a "modern version" of KVL and then teach students that KVL always holds is not advisable as you may set them up for making the same embarrassing mistake that both Dirk Van Meirvenne and ElectroBOOM made.*

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  2 months ago

      yes, ofcoz, voltmeters measure a current but since the internal resistance of the voltmeter is a given (e.g., 100 million Ohms), it is calibrated to show the potential difference over the voltmeter. Watch this video and that will make it clear.
      thexvid.com/video/wz_GqO-Urk4/video.html

  • David Rees
    David Rees 2 months ago

    Walter Lewin; such a beautiful mind, great teacher, and he tells it as it is (as currently known). Love him!

  • craquelure20
    craquelure20 2 months ago

    Every part of a conductor induces emf when the magnetic field changes. The difference between the voltages across R1 and R2 in Prof Lewin's demo is simply the result of ignoring the induced emfs of wires connecting two resistors under transient state.

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  2 months ago

      *I appreciate the fact that this Physics may not be familiar to you. Don't feel embarrassed about it; you are not alone. However, it's never too late to get educated. The choice is yours. Maybe this will help you.*
      *I demonstrated at the end of my lecture #16 of my 8.02 E&M course at MIT that two identical voltmeters attached to the same 2 points in a circuit can show very different values.* thexvid.com/video/nGQbA2jwkWI/video.html *The reason is that in the case of an induced EMF (Faraday's Law) potential differences are no longer determined; they depend on the path. This also applies to the secondary windings of transformers as the EMF in the closed loop of secondary windings is induced.* thexvid.com/video/b7i2uMx7gHo/video.html
      *Of course, in cases where Kirchhoff's loop rule (KVL) applies, 2 voltmeters attached to the same 2 points in a circuit will always show the same value.*
      *My demo was first suggested and published by Romer in December 1982 in the American Journal of Physics.* *This demo has now become a classic; it's done all over the world at many colleges and universities.*
      *Kirchhoff's original text can be found in the following link, pages 497-514:* books.google.de/books?id=Ig8t8yIz20UC. *Clearly he was fully aware of the prerequisite for his "loop rule". KVL is a special case of Faraday's Law. That's why Faraday's Law is one of Maxwell's equations and KVL is not.*
      *By teaching students that KVL always works without telling them when it does not work, makes many believe that the closed loop integral of E dot dL is always zero. ElectroBOOM and Dirk Van Meirvenne therefore believe that 2 voltmeters attached to the same 2 points in a circuit must always show the same value which is not true as demonstrated in my lectures.* *They each posted a video on their channel in which they claim to have proof for their wrong ideas which violate Maxwell's equations.* *Apparently they do not know, or do not understand, that in the case of an induced EMF potential differences are no longer determined; they depend on the path.* *MIT students who took my 8.02 course (Electricity and Magnetism) would not make this mistake!* *I therefore believe that to introduce a "modern version" of KVL and then teach students that KVL always holds is not advisable as you may set them up for making the same embarrassing mistake that both Dirk Van Meirvenne and ElectroBOOM made.*

  • Amrit Singh Chauhan
    Amrit Singh Chauhan 2 months ago

    Sir have you made lectures on newton's law and friction

  • our life
    our life 2 months ago +1

    Love from India ❤️

  • frank broodrooster
    frank broodrooster 2 months ago

    I came randomly across this video. Now I'm here watching this to refresh my memory in the middle of my holidays instead of wasting my time. I'm a first year EE student. I want to thank you very much. You're a great teacher with very clear instructions. Is there a way we can support you?

  • Mike Cimerian
    Mike Cimerian 2 months ago

    I had the privilege of having a teacher who would answer students questioning their C, - you have passed, this is the average. Produce something above average and you might obtain a A. I am no peddler, you will earn your marks. -

  • Sahil_RanJan
    Sahil_RanJan 2 months ago

    Hello professor, I wanna ask if you have videos on potentiometer and meterbridge. Further, are there any channels that you would like to refer for chemistry and mathematics for high school final year?

  • Adolf0is0winner
    Adolf0is0winner 2 months ago

    The bloody magnetic field needs to travel faster then ten seconds though

  • Adolf0is0winner
    Adolf0is0winner 2 months ago

    Dr Lewin , do you agree that magnetic fluxes are virtual photons ?
    Can you elaborate the geometry of magnetic fields.
    Does a magnet only have magnetic fields.

  • subhankar paira
    subhankar paira 2 months ago

    Sir if we move a rod (not in the form of closed loop) , then does it appropriate to use Faraday's law to determine the emf induced in the rod using the concept that change in flux d phi =B.area swipes out by the rod in dt

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  2 months ago

      if we move a conducting rod in a magnetic field charge polarization occurs (q*VXB force) and an Electric field will be present in the rod so that the net force on free charges is zero. web.mit.edu/8.02t/www/802TEAL3D/visualizations/coursenotes/modules/guide10.pdf

  • Benjamin Otto
    Benjamin Otto 2 months ago

    Thanks for preparing a free online version of your lectures. I'll have to let you know once I've watched this course how it compares, in my opinion, to Dr. Muller's Physic's for Future Presidents.

  • Nicolas Schmid
    Nicolas Schmid 2 months ago

    I love the "Kirchoff is for the birds, and Faraday is not !" part :)
    It's actually logic that Vd - Va depends on the path, when you keep in mind the E Field isn't conservative.
    And also the Problems in the description were very instructiv, thank you.

    • Lectures by Walter Lewin. They will make you ♥ Physics.
      Lectures by Walter Lewin. They will make you ♥ Physics.  2 months ago

      *You got it!* You have no idea how many of my viewers cannot accept that 2 voltmeters attached to the same 2 points can read very different values. They do not know, or do not understand, that in the case of an induced EMF (thus non-conservative E-fields) potential differences are not determined, they depend on the path. They do not understand the consequences of Faraday's Law which, by the way, runs our entire economy.

  • Roberto Fong
    Roberto Fong 2 months ago

    Great lecture to support what I just learned today at my Electromagnetism Theory class today in my University

  • Lectures by Walter Lewin. They will make you ♥ Physics.

    *I demonstrated at the end of my lecture #16 of my 8.02 E&M course at MIT that two identical voltmeters attached to the same 2 points in a circuit can show very different values.* thexvid.com/video/nGQbA2jwkWI/video.html *The reason is that in the case of an induced EMF (Faraday's Law) potential differences are no longer determined; they depend on the path. This also applies to the secondary windings of transformers as the EMF in the closed loop of secondary windings is induced.* thexvid.com/video/b7i2uMx7gHo/video.html
    *Of course, in cases where Kirchhoff's loop rule (KVL) does apply, 2 voltmeters attached to the same 2 points in a circuit will always show the same value.*
    *My demo was first suggested and published by Romer in December 1982 in the American Journal of Physics.* *This demo has now become a classic; it's done all over the world at many colleges and universities.*
    *Kirchhoff's original text can be found in the following link, pages 497-514:* books.google.de/books?id=Ig8t8yIz20UC. *Clearly he was fully aware of the prerequisite for his "loop rule". KVL is a special case of Faraday's Law. That's why Faraday's Law is one of Maxwell's equations and KVL is not.*
    *By teaching students that KVL always works without telling them when it does not work, makes many believe that the closed loop integral of E dot dL is always zero. ElectroBOOM and Dirk Van Meirvenne therefore believe that 2 voltmeters attached to the same 2 points in a circuit must always show the same value which is not true as demonstrated in my lectures.* *They each posted a video on their channel to prove what cannot be proven as their ideas violate Maxwell's equations.* *Apparently they do not know, or do not understand, that in the case of an induced EMF potential differences are no longer determined; they depend on the path.* *MIT students who took my 8.02 course (Electricity and Magnetism) would not make this mistake!* *I therefore believe that to introduce a "modern version" of KVL and then teach students that KVL always holds is the wrong thing to do as you set them up for making the same embarrassing mistake that both Dirk Van Meirvenne and ElectroBOOM made.*