Maxwell's Equations - Basic derivation

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  • Опубликовано: 6 сен 2012
  • A basic derivation of the four Maxwell equations which underpin electricity and magnetism.
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Комментарии • 582

  • @ProfessorMastermind
    @ProfessorMastermind 5 лет назад +72

    One of the best teachers . I wish I had a teacher like him in college . So clear and precise .

    • @gahangwasteve8789
      @gahangwasteve8789 4 года назад +1

      Now you do

    • @jacobvandijk6525
      @jacobvandijk6525 3 года назад

      Or didn't you pay enough attention at the time? It's always the other guy, huh?

    • @alwaysdisputin9930
      @alwaysdisputin9930 3 года назад +4

      @@jacobvandijk6525 Yes. It usually is. For example it's not impossible to derive e = mc² quickly & mathematically in YT videos. However, 95% of teachers are not able to do it. They simply do not have the skill that DrPhysicsA has. The ones that try don't get many views because their videos are confusing & unsuccessful.
      Great teachers are like gems
      I found some other things that have gem-like properties:
      1) A book: Engineering Mathematics by Stroud - very gentle & clear with many questions & problems to work through
      2) Supermemo software uses flashcards to make it almost impossible to forget the stuff we learn
      3) Meditation on compassion & loving-heartedness.

    • @verysimplephysicsinthamil1436
      @verysimplephysicsinthamil1436 3 года назад

      Good Expectation

    • @lawliet2263
      @lawliet2263 2 года назад

      @@alwaysdisputin9930 hey man i too love goddesses but in bed since they hav huggge bobos

  • @imagination7710
    @imagination7710 8 лет назад +488

    Net flux and chill

  • @lesking6541
    @lesking6541 3 месяца назад +2

    At school, we were given a copy of George Gamows Biography of Physics to read.
    I was bowled over by the story of James Maxwell showing mathematically that radio waves are emitted by an oscillating charge and that he had calculated the velocity of these waves and it was the same as the velocity of light.
    I think it was this that enthused me to do a degree in Physics, along with Special Relativity.
    Unfortunately, my maths wasn't up to the task, so I changed to a Mechanical Engineering degree, but I have always regarded Maxwells equations with awe.
    I now understand them, at seventy-seven years of age.
    Got there eventually.

  • @meroxyersox
    @meroxyersox 9 лет назад +175

    You have saved my degree, that's not a joke or an exaggeration, I honestly do not believe I could have passed my electromagnetism module without the help of this video.
    Thank you DrPhysics!

    • @DrPhysicsA
      @DrPhysicsA  8 лет назад +36

      +HighFiveTRex Thanks.

    • @robertoflavioarguellesarre5836
      @robertoflavioarguellesarre5836 7 лет назад +9

      HighFiveTRex This comment made me suscribe without even watching the video yet.

    • @ssemakulapheastus2651
      @ssemakulapheastus2651 7 лет назад

      HighFiveTRex
      thank n keep up

    • @qwerty90615
      @qwerty90615 6 лет назад +1

      I sure wish I had this video when I was taking electromagnetics. It is the same basic materials presented by countless others, but the clarity, the delivery, and pace are excellent. The handwriting and screen movements are natural, quick and legible. I get the idea DrPhysics has been delivering such material for some time.

    • @jeroenfeher8107
      @jeroenfeher8107 6 лет назад +3

      Understanding how to explain a subject is an incredibly undervalued communication skill isn't it.

  • @osoyconam
    @osoyconam 9 лет назад +26

    I'm spanish, and I have to say this is the best video I have found about the Maxwell's Equations. GOOD JOB!

  • @DrPhysicsA
    @DrPhysicsA  12 лет назад +7

    I'm not sure either. It's not my doing. I welcome all comments, although I can't respond to them all. I would delete comments only if they were rude or abusive. And I'm pleased to say that so far, that has not been the case for any of my videos. A tribute to physics enthusiasts.

  • @MarcelRGuimond
    @MarcelRGuimond 9 лет назад +4

    Wow ! Who needs a classroom when you have this quality of presentation and delivery?!

  • @DrPhysicsA
    @DrPhysicsA  12 лет назад +15

    Classes are really important. I just cover the basics or provide revision material. Classes go deeper and allow you to do worked examples. Good luck.

  • @seannyman5844
    @seannyman5844 10 лет назад +5

    you are freaking awesome. I've been through a few physics/engineering classes and none of them know how to "dumb" down the idea and equations as well as you have. You're a great teacher.

  • @warrenchu6319
    @warrenchu6319 3 года назад +16

    7:54 Maxwell's 1st Equation; 17:29 Maxwell's 2nd Equation; 37:44 Maxwell's 3rd Equation; 50:40 Maxwell's 4th Equation.

  • @brianb2627
    @brianb2627 8 лет назад +1

    Simply put... This is a prime example of an excellent educational video. Thank you very much for not only sharing your knowledge, but delivering it spot on!

  • @fergaltierney8672
    @fergaltierney8672 Год назад +1

    Brilliant. It's almost 30 years since I studied these in university but I never remember them being explained in such an intelligent way.

  • @abrahamgetahun39
    @abrahamgetahun39 6 лет назад +9

    This man is literally awesome! Thanks for the crystal clear explanations sir!

  • @StephenRayner
    @StephenRayner 10 лет назад +28

    30 minutes in, this is bloody good!

  • @DrPhysicsA
    @DrPhysicsA  11 лет назад +8

    Thanks. And greetings from the UK.

  • @cartermonroe4377
    @cartermonroe4377 9 лет назад +1

    This is the best presentation of Maxwell's original theory that I have ever seen. You really captured the spirit in which he went about solving the problem. He was not afraid to let geometry be his guide, which of course yielded astounding results. I never pass up a chance to look at any of his original derivations, since they are so beautifully done. Thanks again.

  • @diogomussum
    @diogomussum 7 лет назад +8

    A very simple explanation , you summed up one book in little time.

  •  2 года назад

    Ahh - to the point. No background music, animations etc. Always enjoyable to listen to a teacher that knows his stuff and sets the right level.

  • @steveschein2619
    @steveschein2619 5 лет назад +1

    Wow, brought back my entire EM fields one course, okay maybe not all of it. This is one of the best derivations of Maxwell's Equations I've seen.

  • @zacht4368
    @zacht4368 9 лет назад

    Thank you so much for these videos. I can not tell you how much they have helped me learn new material and refresh through older material in electromagnetism!

  • @bluefishactcl1464
    @bluefishactcl1464 2 года назад

    Excellent !!!!!
    Basic, complete, accessible !!
    Entertaining!!!
    Brings Maxwells equations down to its most basic truths .
    Thank you

  • @m3g4nf0x1zH0T
    @m3g4nf0x1zH0T 7 лет назад +1

    This is the perfect summary of my undergraduate physics course. Excellently explained! thank you very much for your efforts :)

  • @itseasyitspractical
    @itseasyitspractical 4 года назад

    One of the best physics videos I have ever watched! Congratulations! Great explanation!!!

  • @hugoperozo4895
    @hugoperozo4895 3 года назад

    This is the BEST explanation I have seen on a complex subject. Thank you for taking the time to make these videos. All your videos explain the concept in simple terms and the math behind it with simple derivations. I know there is more to it but derivations clearly outline the concepts behind the equations. Thank you.

  • @cochisewolf
    @cochisewolf 11 лет назад +1

    Thanks. I very much appreciate the time, energy and effort put in to making these available.

  • @Overunity357
    @Overunity357 5 лет назад +1

    You sir, have just created a future physicist. This is the coolest stuff i have ever seen.

  • @pbraju123456
    @pbraju123456 6 лет назад +4

    I wish I had such a tutor in my engineering days. You have dissected down every equation to tiniest bit and explained I can really call you Master of Electromangetic Engineering. Awesome

  • @TheR971
    @TheR971 7 лет назад

    Thank you very much for this summarization! Concise and does not require too much knowledge. Very nicely done!

  • @clakoclakson
    @clakoclakson 6 лет назад

    It's amazing how easy you make it look. Your pace of speaking, the pronounciation (I'm not english), and the presentation is excelent. Thank you very very much!!! Greetings from Spain

  • @michaeljburt
    @michaeljburt 11 лет назад

    Wow this video is incredible! Just took a physics course last semester on electricity and magnetism, and this is an excellent refresher. Going in to my second year of electrical engineering in the fall and this is the perfect video to review.
    Your explanation of fields is very clear and simple- if anyone asks me about them I will definitely point them here.
    Thanks!!

  • @sablezubshruz9811
    @sablezubshruz9811 7 лет назад

    Very, very clear and clean explanation. Probably best i see so far on youtube.

  • @adrianboni2132
    @adrianboni2132 6 лет назад

    i remember my Physics 73 instructor Mr Lozano with your lecture. Very informative. Feels like i was a in college again.

  • @natrajsarma9938
    @natrajsarma9938 4 года назад

    One of the best physics teachers . Makes even the hard topics easy and clear .

  • @fcslash
    @fcslash 8 лет назад

    OMG I love you. If it wasn't for your wasn't for your videos I would be struggling so hard studying for my General Physics exam!!! All of this is SO well explained

  • @philoso377
    @philoso377 3 года назад

    Of all the RUclips on this topic, this is the only one I understand completely. Thank you.

  • @linanouman9545
    @linanouman9545 3 года назад

    Everything added up really well. Thank you for the explanation!

  • @markkinnard796
    @markkinnard796 11 лет назад

    Excellent discussion. The best I have ever seen. I wish I had you as a professor when I was in college. Keep up the good work and thank you very much.

  • @dudeskidaddy
    @dudeskidaddy 7 лет назад +1

    Wish I had this guy teaching my electrical engineering classes. Great jon

  • @dae1366
    @dae1366 5 лет назад

    As with your lecture on the General theory of relativity. Extreme clarity achieved by explaining what all the terms mean and not assuming that we know them. Extremely useful for the none physicist.. many thanks

  • @thetimijs
    @thetimijs 11 лет назад

    Thank You for covering this material! As You've already said, this if perfect stuff for revising the material for the upcoming exam! I am verry pleased, that I found this channel at the right time so thanks again and greetings from Latvia! :)

  • @theprocessionist6442
    @theprocessionist6442 7 лет назад

    I'm probably going to watch this dozens of times. :D Thank you. It's going to help me work out some seriously cool stuff.:)

  • @marcolopes1180
    @marcolopes1180 9 лет назад

    I'm going through some reviews for my electric machines class. Your video was really helpful thanks alot.

  • @mfelix3511
    @mfelix3511 Год назад

    Thank you so much, I cannot even express how much better you are at teaching this than my lecturers are. You are saving my degree.

  • @ayushipandey3857
    @ayushipandey3857 8 лет назад

    From Electrostatics to the starting chapters of Wave optics, this video covers everything! (I even remember the equations now XD )
    Thank you so much DrPhysics!

    • @lawliet2263
      @lawliet2263 2 года назад

      Hey baby, where do you live?

  • @arjunvadlamani3248
    @arjunvadlamani3248 7 лет назад

    This is what I'm doing my IB Math Internal Assessment on. Absolutely spectacular.

  • @StephenRayner
    @StephenRayner 10 лет назад +17

    19:00 I agree with Pablo P, the magnetic field lines travel through the bar magnet. So although they don't spread out like they would at the edge of the south pole, there is just as many magnetic field lines passing through the midpoint of the magnet as there are field lines exiting the norht point.
    Not suggesting Dr Physics is wrong, just that there are different ways to look at this and I hope it helps others to consider this from different angles.

  • @jaideepdadi8119
    @jaideepdadi8119 3 года назад +1

    Your video saved my QA session in college. Thanks a lot

  • @supershaye
    @supershaye 8 лет назад

    You explained it so intuitively. Thank you very much.

  • @georgegrech5347
    @georgegrech5347 Год назад

    18.50.I think that the second law holds because the flux going from south to north inside the bar magnet balances out the flux emerging from the N pole and then going out of the closed surface. The closed surface is just a mental construction and may be considered closed even when a bar magnet goes through it. A great teacher.

  • @soumya508
    @soumya508 Год назад

    The equations that made me fall in love with Electromagnetism and finally i spent 4 years of my life learning Electronics and communication engineering! Ah Good old days :)

  • @Christe4N
    @Christe4N 10 лет назад +5

    re: magnet partly inside the sphere (18:23): Even then the equations still hold. The magnetic flux outside of the magnet goes from the north pole to the south pole. Inside the magnet the flux always goes (back) from the south pole to the north pole. If the magnet is placed such that only the north pole is inside the sphere the amount of flux exiting and entering the sphere is still equal: the same amount of flux going from the north pole, out of the sphere to the south pole is going inside the magnet from the south pole, entering the sphere to the north pole.

  • @alibabatwist
    @alibabatwist 8 лет назад

    your method of presentation, your fantastic accent, and the clarity of your teaching made me impressed and I sincerely say : thank you very much.

  • @EmyllSomar
    @EmyllSomar 12 лет назад

    I needed this. I spent about an hour trying to explain it to a friend a few days ago. This video would saved me that time. ;)

  • @hanzishiguro8866
    @hanzishiguro8866 8 лет назад +1

    We need more teachers you like you sir.

  • @DrPhysicsA
    @DrPhysicsA  11 лет назад +2

    Thanks for drawing this to my attention. You are quite right. I had intended to say that the dot product was the product of two vectors. But as I suspect you are aware, the dot product is actually called the SCALAR product. The “vector product” can also be called the cross product. I have made a small annotation on the video to make this clear. Thanks again.

  • @fuahuahuatime5196
    @fuahuahuatime5196 10 лет назад +10

    19:00 I think even if you could do that, there would be just as many magnetic field lines leaving the area as magnetic fields going into the area, so it would still be 0 either way.

  • @mrdobbles3481
    @mrdobbles3481 10 лет назад

    Thank you thank you thank you!! This was extremely helpful!

  • @Furiouslyfunnyfizzix
    @Furiouslyfunnyfizzix 11 лет назад

    Really liked this video. Very clearly and succinctly explained - well done. Thanks!

  • @amritmalhi4216
    @amritmalhi4216 6 лет назад

    really easy to understand and very helpful thankyou soo much sir and keep posting such kind of helpful videos for us

  • @DickHoskins
    @DickHoskins 2 года назад

    Excellent presentations. Just shows how a pen and paper or chalk and blackboard is all a great teacher needs. Of course this iPad I am watching it is very handy.

  • @akarshsingh1540
    @akarshsingh1540 8 лет назад

    Thank u Dr. physics for providing such in depth knowledge of basics of em

  • @danieldanieldadada
    @danieldanieldadada 7 лет назад +1

    As someone who saw this 2 years ago in college and needs none of it in my faculty (civil engineering) I can say this was pretty neat. I thought I'd never unverstand Maxwell's equations. At this moment I understand 100% of the 1st equation.

    • @hacsince1991
      @hacsince1991 7 лет назад

      dan iel I was just thinking the same thing. I couldn't even remember more than one definition out of every two hour Chem class.. and that in the
      tenth grade. Hahaha i and I'm 25 and can't believe how beautiful it is now. New favorite subscription!

  • @philippelaperle4679
    @philippelaperle4679 6 лет назад

    Thank you for an exciting lecture replete with details.

  • @babulkumarsamaddar98
    @babulkumarsamaddar98 5 лет назад

    Sir, your presentation is very nice and easily communicable.

  • @rajmohann.t252
    @rajmohann.t252 12 лет назад

    thank you very much for responding to my request and making this great video. Its absolutely superb.

  • @wolfisr
    @wolfisr 5 лет назад

    Wow, you're doing a very good job here! Thanks!

  • @NehadHirmiz
    @NehadHirmiz 9 лет назад +1

    Excellent Tutorial. thank you for your time :)

  • @Cannongabang
    @Cannongabang 8 лет назад

    wow i understand everything right now... congrats and thanks so much!

  • @robertsalazar2770
    @robertsalazar2770 Месяц назад

    Best treatment of this topic I've seen.

  • @ottoomen5076
    @ottoomen5076 7 лет назад

    I appreciate your insight. Thanks for you time.

  • @joemartin2916
    @joemartin2916 9 лет назад +1

    very simple and methodical class ...thumbs up!!

  • @johnmcguire3763
    @johnmcguire3763 4 года назад

    You are so concise! Thank you!

  • @sakuraudyani3576
    @sakuraudyani3576 9 лет назад +3

    I'm having a great time with your videos. They are really interesting and very helpful. Thank you so much Sir

    • @DrPhysicsA
      @DrPhysicsA  9 лет назад +6

      Thanks. Very kind of you to say so.

  • @jdrv9353
    @jdrv9353 5 лет назад

    This is a truly enlightening video.

  • @rayyan21d
    @rayyan21d 3 года назад +4

    I'm a high schooler and thanks for helping me 🥺

  • @MyWorldvisit
    @MyWorldvisit 11 лет назад

    Very nice explanation, unable move to another video, great voice and great presentation of the subject....Thank you for sharing your knowledge......great full to you sir......

  • @crazymonkeyVII
    @crazymonkeyVII 9 лет назад

    awesome stuff, really clarifies a lot!

  • @DrPhysicsA
    @DrPhysicsA  11 лет назад

    I am currently producing a series of videos on electromagnetic radiation. The first, “what is the light?” Is already up. I am using Maxwell's equations to derive the nature of electromagnetic radiation and the wave equation.

  • @outrospection4all
    @outrospection4all 5 лет назад

    Excellent lecture, many thanks. One simplification, to derive the displacement current, you only need to multiply and divide by epsilon, q/epsilon is the flux... no need for the dA

  • @enochbrown8178
    @enochbrown8178 5 лет назад

    Truly brilliant! Thank you very much!

  • @s.platini9390
    @s.platini9390 7 лет назад

    Very clearly explained! Thank you sir.

  • @DrPhysicsA
    @DrPhysicsA  11 лет назад

    You are right. I have made that clear in other videos on electromagnetism. This was intended to be a basic derivation and I missed out the explanation that the EMF is always such as to oppose the change that causes it.

  • @guitarttimman
    @guitarttimman 5 лет назад

    This is an awesome video. Thank you.

  • @musthafamb1757
    @musthafamb1757 2 года назад

    A very interesting presentation... Thank you so much ❤️

  • @MrKraftyy
    @MrKraftyy 11 лет назад

    Really loving what you are doing, keep it up.

  • @ahmedgaafar5369
    @ahmedgaafar5369 10 лет назад

    super well done...i wish you were my teacher years ago.

  • @fantasticmrbond
    @fantasticmrbond 11 лет назад

    Fantastic video. It is exactly as you described: if you already have a grasp on these topics, than this video will help you prepare for a test as well as fill in any possible gaps in your understanding. The definition of flux at 22:22 is missing the integral symbol; or you could just suppose the flux is phi = B*A (not B*dA) and you still get the correct form of the Emf. Again, thank you so much for posting this. Your videos are fantastic.

  • @jimdogma9890
    @jimdogma9890 12 лет назад

    Another awesome video Doc. Can't wait for the video relating the permeability constants to the speed of light which I heard constrians the oscillations of magnetic and electric fields to propogate only at c? I guess I'll find out soon! Also, I like how you're producing longer videos now. More of a good thing. Keep it up!

  • @jameshamilton356
    @jameshamilton356 2 года назад

    You have made difficult subjects in simple terms.Thank you Sir.....

  • @enriquecruse310
    @enriquecruse310 7 лет назад

    This video helped me a lot....Because I am not good in electrostatic and this helped to make my base strong for PGRE entrance.

  • @AlexSchuu
    @AlexSchuu 11 лет назад

    This is fantastic! Thank you!

  • @JoseFerreira-de7oe
    @JoseFerreira-de7oe 2 года назад

    Loved the video it made me understand the laws like if it was basuc arithmetics. I think it would be cool if you made a video going into detail about the divergence and curl of the fields... You know... the standard form of the equations

  • @Willster451
    @Willster451 7 лет назад

    Great explanation! Thank you 😊

  • @DrPhysicsA
    @DrPhysicsA  11 лет назад

    Thanks. As the title explains, this is only supposed to be a very basic derivation. My approach with a number of these videos is to give enough basic information to enable the viewer to derive a broad sense of what is going on. If they want the detail and the rigour of the derivation they can then go to more advanced sources.

  • @sinangemicioglu2353
    @sinangemicioglu2353 4 года назад

    Perfect lecture. Most useful in all

  • @AsifMahmoodAbbas
    @AsifMahmoodAbbas 11 лет назад +2

    Thank you sir, it really helped a lot.

  • @sergiofranczak7595
    @sergiofranczak7595 4 года назад

    Parabéns pela aula, você é um excelente professor 👍

    • @Arthur-so2cd
      @Arthur-so2cd 2 года назад

      "derivada simples" o vídeo dura 1 hora kkkkkkk

  • @eerp13
    @eerp13 9 лет назад

    Your video have helped me a lot in physics

  • @Francesco_Armillotta
    @Francesco_Armillotta 10 лет назад

    Amazing video. Just thanks you so much.

  • @DrPhysicsA
    @DrPhysicsA  11 лет назад

    The key is that the plate has to be infinite for the situation you describe. So at any point in space the E field is the vectorial sum of the fields from all the charges on an infinite plate.