i guess im randomly asking but does any of you know a way to log back into an instagram account..? I stupidly lost my password. I would love any assistance you can give me
This website contains all my 94 course lectures (8.01, 8.02 and 8.03) with improved resolution. They also include all my homework problem sets, my exams and the solutions. Also included are lecture notes and 143 short videos in which I discuss basic problems. ENJOY!
As an engineering graduate I have seen my fair share of commutators in text books and labs, but Dr. Walter you are the only commutator likely to stay in my memory after this lecture haha :D. The buildup of the concepts leading to two very important real world applications (the current meter and the motor) was seamless and excited an intuitive approach to these. This lecture was such a good treat with my coffee ! Thank you so much for the upload, love from India !
now 8 years ago..., even though it was filmed back in 2002, he referenced it at 21:24, he never could have imagined so many people would be watching it 2 decades later, not on such screens as he described, but on flat panel screens which make almost no noise, sip little power and aren't affected by magnets, with color accuracy unimaginable by most standards... now, oled, lcd or led so widespread... how much will change in 20 more years? But, these lectures will still be watched, so would any good lecture given in the last 60 years, physics is constant, even though this info is new to me, it was new to people 60 years ago and people discovered it 100 or 150 years ago by this point... yet, it was exactly the same for millions and billions of years
The distortion that came from the magnet is outstanding...The best teaching ever coming from the best Professor ever that teach the subject of reality...Transparently changing our perception of the world at full potential...I wish a great health and an extreme care to you throughout this crisis time.
I did my B.Sc in physics way back in 1977, but I really understood electromagnetism only after watching your videos! Amazingly what a fascinating phenomenon is this EM ! Thank you professor sir 🙏
It is fascinating that you've gone through Electricity and Magnetism and through Maxwell's equations and more, Professor, which is one the pillars of Physics, with such clear cut explanation. Thank You. Very good with all those experiments for each and very concept and equation. Truly helps concepts sink in.
exactly, the professor at my high school tries his best to show us experiments, but he can't get 200A of current just randomly or such large magnets, he also has to set it up every time... it's all really old stuff, Russian or Yugoslavian equipment from the 60s, this guy's lectures really help me conceive the topics I learn at school
Admire your teacher Most don't even try Plus demonstrations are not so easy. if you don't believe me check out Shankar's Yale lectures he tells you how difficult they are @@aquss33
i can't help but envy MIT students for their courses and contests A MOTOR CONTEST! seriously... they've got all the parts etc i started these lectures a week ago and i can't get enough, the assignments are fun, the lectures are even more fun, i make sure to watch them at least twice to make sure i don't miss a thing.. I am so grateful for professor Walter Lewin for making his lectures available online Greetings from Morocco... where the education system is free but sucks!
Hello Mr Walter Lewin, first I apologize for my bad english. it's because I'm french. And you know french people speaks often bad english. But with your famous science lectures I understand you so well !! You're the best teacher I never had, really I'm fond of your lectures. So tahnk you very very very much for your sharing of your knowledge : it seems so easy to understand with you.
Honestly Professor, I am watching this lecture for fun and as I view more and more of your lectures it becomes obvious how much rehearsal time you put in. You don't hesitate at all during the lecture and speak with conviction.
What are my lecture secrets? A typical preparation time for 1 lecture is 60-80 hr. I do not write a script. But I dry run all my lectures 3 times before I give the lecture. 2 weeks before, 1 week before and at 6 AM of the day of the lecture. Every 5 min I have a LARGE time mark in my lecture notes (starting with 50 min, going down to zero). I have a large digital clock on the lecture desk which is set at 50 min when I start the lecture and it is counting down. Thus at ANY moment during my lecture I know within about 1 minute how much time I have left and how much time is needed to finish. Thus I NEVER overrun, I never have to do an interesting demo in haste with a sloppy explanation. I typically finish my lectures within 1 minute of 50 min. Of course during the first dry run, it ALWAYS takes near 60-70 min. I then have to do careful surgery as changes are needed. By the time it is 6 AM in the morning of the day I give the lecture I am always well synchronized between my time marks and the digital clock. My lectures have therefore become performances (like an actor on the stage). my secrets are: *imagination, go outside the box with examples and with demos. I do often demos that will make them sit on the edge of their seats. I make the students laugh at times, make them cry, make them stop breathing, even make them wet their pants at times. I confront them as much as possible with experiences in their own lives. Where possible I include a student in a demo. I also do demos in which I take risks. I never become boring. I make them look through the equations to make the eqs come alive. I always keep their attention with my clarity, sense of humor and my LOVE for Physics. I radiate my enthusiasm - it's contagious. I can make ANYONE love physics and one of my "famous" quotes is: "if you hate physics it's only because you had a bad teacher".*
Thanks for the reply Professor! I hope I didn’t keep you up late at night writing that. I was watching the feynman lecture series you have pinned on your account and there is another one who could teach! Feynman was teaching you physics and making you understand the concepts as if you were a physicist without you knowing it. He used excellent examples and real life experiences connecting the physics to the real world much like yourself. You may not think so but you are on the same level of Feynman to *me* and I think its wonderful you continue to do this throughout your senior years. Thanks so much for the dedication and preparation time put in. It truly reflects so and you are to be admired for such amazing work 👍😃
You’re very welcome 😊 by the way the demonstration of distorting the television image with the magnetic is awesome and I definitely have to check out some of pikes work
Sir Walter Lewin, your lectures are one of the best aid to me in studies of CBSE 12th, India. I try to grasp maximum from the contents from you. I'm grateful to such the best human. I wish I could do something for others in future. For now, I sends you your good health wishes. May you live long and, one day I could be in your vicinity. Oh! That day will come, I wish with optimism.
these are performances, not lectures! never seen a lecture as entertaining as this. binge watching these with popcorn! thank you professor. with every lecture you change the world!
*yes all my 94 MIT lectures are performances* - What are my lecture secrets? A typical preparation time for one 50 min lecture is 60-80 hr. I do not write a script. But I dry run all my lectures 3 times before I give the lecture. 2 weeks before, 1 week before and at 6 AM of the day of the lecture. Every 5 min I have a LARGE time mark in my lecture notes (starting with 50 min, going down to zero). I have a large digital clock on the lecture desk which is set at 50 min when I start the lecture and it is counting down. Thus at ANY moment during my lecture I know within about 1 minute how much time I have left and how much time is needed to finish. Thus I NEVER overrun, I never have to do an interesting demo in haste with a sloppy explanation. I typically finish my lectures within 1 minute of 50 min. Of course during the first dry run, it ALWAYS takes near 60-70 min. I then have to do careful surgery as changes are needed. By the time it is 6 AM in the morning of the day I give the lecture I am always well synchronized between my time marks and the digital clock. My lectures have therefore become performances (like an actor on the stage). my secrets are: *imagination, go outside the box with examples and with demos. I do often demos that will make them sit on the edge of their seats. I make the students laugh at times, make them cry, make them stop breathing, even make them wet their pants at times. I confront them as much as possible with experiences in their own lives. Where possible I include a student in a demo. I also do demos in which I take risks. I never become boring. I make them look through the equations to make the eqs come alive. I always keep their attention with my clarity, sense of humor and my LOVE for Physics. I radiate my enthusiasm - it's contagious. I can make ANYONE love physics and one of my "famous" quotes is: "if you hate physics it's only because you had a bad teacher".* --------
@@lecturesbywalterlewin.they9259 for this I am certain you will go down in history as one of the greatest physics teachers of all time, similar to Feynman :) even 20 years later your lectures still inspire hundreds of thousands of students. Back in India students would pass down your lectures on thumb drives because we never had teachers like you, very rarely any demonstrations and courses focused on mathematical difficulty and rigor over understanding and inspiration. Your contributions to pedagogy are, I suspect, dwarfed by your (direct and) indirect contributions to physics , mainly by inspiring all these students and teachers to have a better understanding and instilling an awe for physics and raising the standard for stem education worldwide. Thank you professor for all that you have done for generations of students and physics in general.
To add some context , I am a physics educator myself and am on constant lookout for newer and better educational materials. I have yet to see physics lectures or demos of your caliber , as comprehensive and extensive across TH-cam . In fact often I have to simply play video clips of your demonstrations due to some of the demos being infeasible to replicate.
From Prof.Herb Gross to Prof.Lewin,MIT have always been one of pioneers in helping students all around the World. Thank you MIT and Prof Lewin -from Himalayas
Dear Professor, i hope this message reaches you. 1.) Can you explain me 11:10 is this actually for positive charge?So for electron moving from us to the table would be from left to righ actually (magnetic)? Because i am trying to visualize whole concept, and that helps me also for other topics. So if positive charge flows from us to table then magnetic field goes from left to right, like screw. And if electron goes from us toward table than it goes from right to left? I thought electron flowing from us to table cause right screw rule, but... en.wikipedia.org/wiki/Lorentz_force#/media/File:Lorentz_force.svg 2.) And why some show current of the battery flows from plus to minus, when it actually flows from minus to plus, so whole schematics of electronics are wrong, even diode, it flows in other direction from minus to plus. 3.) I also wanted to ask if flowing current through conductor causes magnetic field in some direction, is that the same reason why "flowing" conductor in magnetic field causes current? Thanks!
Oh wonderful challenge! I am the lab TA for the Electric Machinery course for EEs at my university and have been pushing to have the course include a project aspect that involves either building a motor or a transformer and thoroughly analyze their build as a way for students to apply their understanding of the course's material. I wish this had been done for me in either my physics or my ee courses!
I'm a software engineer taking a career break to start a new master in photonics (16 years after graduating! :)) and I was looking for some online materials to help me refresh my knowledge on electromagnetism. Your lectures have been an enourmous help. Thanks! Bedankt!
sir, you are great.I became a big fan of you. I never seen, even I never thought a professor like you. There is lack of quality education in India. Thank you! For these lectures.
At timestamp 20:30 where WL says..."but no one would ever say that...". Maybe, they would! Rearrange "Ns/Cm" and you have: (N/C)/(m/s), that is " Newtons/Coulomb PER meters/second, and it makes a 100% intuitive difference WRT E fields, and speed through those fields!! Unit combinations usually make all the sense in the world if you look at them differently!!
Sir I have a question Is there any footage of the MIT motor competition ? It would be really interesting to see what all the students came up with . I would also like to thank you for these amazing lectures that are 2nd to none They make these concepts so simple so that we can think beyond the lines rather then being regimented in our thinking like in many schools
many proff: know Physics but they dont love to share with students Your Lectures are great, so enthusiastic and fun to watch. Thank you from PAKISTAN..
Great Sir, I salute you for your knowledge and teaching method. you are a teacher for all teachers of physics on the earth. Whoever teaches physics to students in school/college/university, He must watch your lecturer before going to teach to students.
fantastic lecture professor! im on the 2nd semester and has to deal with fundamental physics for another 2 months or so. you have officially brought back my love for physics!
These lectures are really helpful for indian high school students for jee advanced. Very easy to understand and gives very intriguing conceptual understanding
easier and more in detail compared to my highschool class (it's a special one focused on engineering). U carry me trough homeschooling. Greetings from Austria.
sir, first of all thank u so much to help us for making our concepts so strong. i used to think that i love physics but physics does not love me but as i started to see your videos it really helped me to retain the concepts.your way of teaching is mind blowing!
watch all my 94 MIT course lectures. Do all the homework and take all my exams. They are all posted (pdf files) below the video thumb nails. to take the 3 courses will take you about 5 months as a full time commitment. start with 8.01.
here current is conventional current flow correct? (opposite dir of the flow of negative electrons) in terms of the magnetic field direction right-hand rule? edit: spoke too soon. answer was at 29:00
Sir, your style of teaching is very different nd innovative which makes physics very simple. Sir, your lectures makes environment for students, I i like your lectures
28:10 literally me during the previous lecture. and i realized the same conclusion. 35:48 the difference between the two currents is mainly an issue when using the right hand rule. for conventional current, it's actually the left hand rule. easy enough.
Hello dear Professor. First I want to thank you for these classes and the passion that you put for over 40 years. I'm a student and his classes are the best in the world, my teacher is boring and makes the physical look totally frightening. Thanks to you I fell in love with physics. I wanted to ask you Professor, because I want to create a kind of book with these classes, that is, write your notes and your words and compile them in a kind of book. The idea is to study better, and practice through your readings. I wanted to know if you do not have a problem with this. I await your answer Walter. I congratulate you, your readings are really exciting. Nahuel Nitz
go ahead! Make sure you always give me credit and always mention the source of all you print. If you sell the books, you should pay me 50% of your revenue.
Ja klar Herr Lehrer!!! Obviously I'm going to do that! You and this great work deserve it. Once again I want to thank you teacher, I am very happy for your approval. keep in touch! Dankeschönnnn
27:0429:26 Is that a drift velocity? 🤔 Should be v{d}= aτ ~a∆t~∆v , then. But you give it as: v{d}=dℓ/dt...😵 So, is v{d} a velocity or _change_ in velocity? Also, is it over the same time scale "τ" ?
Dear professor at 10:18 you drew the magnetic field direction in clockwise but you said that it is outward after that but before in lecture you said if you rotate cork screw in clockwise direction than the magnetic field will point inwards ( into the blackboard) , so how here at 10:18 you showed it outwards? :)
47:43 sir the magnetic fields should be from north to south isnt it? By the way I am grade 10th student from India maybe my knowledge is low in this concept. But I think the coil should go down.
I have a question that at 11:07 of your lecture you say that F=I×B where all of these are unit vectors,how current will be vector quantity?how can we do cross product of current?As we know current is a scalar quantity.Is there any special case where we consider current as a vector quantity?Please reply sir.I also enjoy your lectures very much when you say "Have a fun".
In general current is not a vector but in the case of the Lorentz force it is a vector as it is the direction of the moving charges in the wire that counts. F=qvXB. In the case that I discuss here it too is a vector foer the same reason. Thus the unit vector F is the cross product of the unit vector of v (this I) and the unit vector of B.
Dear Professor Lewin, at 10:52 you show that wire experience a force that is perpendicular to current and magnetic field. But why does it experience this force? What is happening with the wire that it wants to move? Best regards, Tomasz Studziński
What is your problem? I mention the unit of Tesla. Just like I use Farad (for Faraday) and Amp for Ampere, Newton for Newton, Curie for Curie. Volt for Volta, Henry for Henry, Coulomb for Coulomb, Gauss for Gauss, . . .,
In 8.01 you used to say something about scientists, when you mentioned the unit named after them. That was a good habit. I just want to point out that you didn't do the same with all scientists. That's it. Sorry for any misunderstanding.
>>>In 8.01 you used to say something about scientists>>> PLEASE remind me what did I say about Joules (unit of energy), what did I say about Pascal (unit of pressure).,what did I say about Newton (unit of force), Celsius (unit of temperature). Kelvin (unit of temperature), Fahrenheit (unit of temperature), Mach (unit of relative speed), Torr (unit of pressure), Planck units, Just to name a few I mentioned in 8.01.
Sir, At 13:21 you said that above the wire carrying current i1 the direction of magnetic field is out of the black board but you said that direction of magnetic field below the wire carrying current i1 is into the blackboard. I am a bit confused about how are you finding the direction of magnetic field. Can you please clear my confusion.
36:40 How is the net force 0 prof? The wire coming out of the blackboard is larger than the wire behind the blackboard because of the GAP in the backside wire. Doesnt that make the force on the outside wire larger? Or is the gap soooo small that net Force is approximately 0?? Thanks.
Professor Lewin, how come you don't use the cross product for the example @ 33:37? You have the equation Fb = ILB. Shouldn't you take the cross product of L and B? Is this just the magnitude of the magnetic force along this wire?
+q charge on one side of a conducting plate . The +q charge will be attracted to the conductor due to induction. +q charge on both sides the 2 will not repel each other. en.wikipedia.org/wiki/Method_of_image_charges
the magnitude of the Lorentz force is ILB (I indicates the motion of charges with velocity v, v and B are vectors. thus the force is perpendicular to I and to B.
Professor at 14:40 , for below wire ,how we get to know that magnetic field is going inside the black board? Actually I could not feel it how it is going inside.
Just use right hand rule. Point your thumb in the direction of current and check out in which direction your fingers curl around the wire, (below the wire and above the wire). Hope you got it.😊
Professor at 39:26 - *Wasn't that gap between D and A have any effect on the Value Force between two opposite sides?* and Because "F = iLB" - force depends on length. and that gap shorter the length and So, Value of Force would be different on two opposite sides.
Professor I'm not talking about Torque correctly or Incorrectly or whatever. I'm talking about Force on the Backward Side of Loop at 39:26 in video. *Wasn't that gap between D and A create any effect on the Value Force? Because "F = iLB" - force depends on length.* and due to that gap length would be lesser.
okay! professor So, If we talk very very Exactly then Net Force is not Zero. 🙂 but I can understand that that's not the Case. *Well, My name is not "Anonymous for some days" you can call me with any other short name - I don't Mind at all.*
23:45 How can Lorentz Force doesn't change the kinetic energy if it changes the direction? If the direction changes,the Lorentz Force must gain a new velocity vector which perpendicular to the main velocity vector of the charge.So net vector will be the sum of them and this is bigger than the old one.And if velocity goes up, kinetic energy goes up. is it wrong?
>>>If the direction changes,the Lorentz Force must gain a new velocity vector which perpendicular to the main velocity vector of the charge.So net vector will be the sum of them and this is bigger than the old one.>>> *this is incorrect* watch my lectures in which I cover this in detail.
How about tourge? Thinking about if we do not fix the movement of the front againts the mortor or the perpendicular direction. Do you know that some of the fan engine will design to have the tourge direction going into the machine and some in the opposite direction? Electric Fan and Air plane fan will oppose tourge into the front direction while the turbulant in some jet engine will do in the opposite direction. There is unique of the electric field and manetic field that is why it has effect againts aluminum. If we choose the right frequency maybe it can effect the different metal also. Thinking about the frequency fork and its identical frequency.
Sir I’m a high school student in Turkey. In our country, teacher’s teaching skills are so low they don’t even talk about what magnetism is. They’ll just give you some equations and then they’ll jump into the solving problems. (And I’m not even mentioning schools are too broke, teachers are too careless for showing experiments.) Because all they care about is university exam. Not just teachers also the students are behaving that way too. No one really wants to learn. They just want to memorize how to solve problems until the exam. But why did I wrote this? *I wrote this to show how much appreciate your teaching skills* When started to learn magnetisms I had bunch of unanswered questions waiting in my head. I still have those bunch of questions but at least some of them answered because of your videos. Thanks a lot
At 25:25 you say : "magnetic field can never do work on a moving charge" I agree with your further explanation : F created by the magnetic field acting on the moving charge is perpendicular to the motion. But the charge will get kinetic energy in the direction of F, perpendicular to the motion because F=ma. So the charge will not get extra kinetic energy in the direction of its initial motion, but the charge will acquire kinetic energy in the direction of the force caused by the magnetic field acting on the moving charge, did I get it? One more time thanks a lot for your lecture, it's very enlightening
>>>But the charge will get kinetic energy> *that is incorrect* the force on a charged particle is in the direction of VXB which is perpendiclar to V. KE of the charge does not change.
@@lecturesbywalterlewin.they9259 I agree with you, the KE will not change in "the direction " of V, but since the magnetic force on a charged particle is in the direction of VXB, the particle will be accelerated in the direction of VXB, so a new kinetic energy will appears in "the direction " of VXB, and it will affect the initial motion, the direction of the velocity will then change. I think it can be seen if we put a wall perpendicular to the direction of the velocity : the energy dissipated by the impact will be larger than without the magnetic field. If I'm wrong, could you tell me please where I misunderstand the concept?
@@guilhemescudero9114 *incorrect* the force VXB is always perpendicualr to V thus the KE will not change. The KE energy of Earth in orbit also doesnot change are the force on Earth is perp to its motion. This is my last msg
@@lecturesbywalterlewin.they9259 THANKS, this quote "The KE energy of Earth in orbit also doesnot change are the force on Earth is perp to its motion" enable me to understand where I was wrong : the component of the velocity along the direction of the motion if there was no magnetic field is a probably a cosine-like function over time when we add a magnetic field because the force due to the magnetic field curve the motion and in the same time the component of the velocity perpendicular to the direction of the motion if there was no magnetic field is a sine-like function over time when we add a magnetic field because of the force due to the magnetic field. So I can think about the magnetic field acting on the moving charge as a modification of space, when the moving charge wander in this space under a magnetic field, the charge change the configuration of space, thus the cinematic of the charge changes according to the modification of space. I really appreciated the time you took to help me, thanks a lot Lectures by Walter Lewin. They will make you ♥ Physics. !
I used google and found that the motor is designed so that the current changes the direction when the plane of the loop is parallel to the B-field and that was my questuon .
Sir, at 35:50 is the magnetic field B produced by the curent in the wire or is it just a magnetic field from some magnet that we've put next to our current loop
Hello Sir, thank you very much for providing this great lectures. I think I am ready to start building my motor and earn some imaginary credit. In order to start in the right direction, can you give us more details about the size of the magnets and the dimaters of the copper wire?. In the PDF provided it just says two magnets and 2meters of copper wire. Thank you again Mr. Lewin.
The content: Informative physics lectures and demonstrations
The thumbnail: *C H E E R I O S*
i guess im randomly asking but does any of you know a way to log back into an instagram account..?
I stupidly lost my password. I would love any assistance you can give me
@@braylenwyatt5528 reset the password
This website contains all my 94 course lectures (8.01, 8.02 and 8.03) with improved resolution. They also include all my homework problem sets, my exams and the solutions. Also included are lecture notes and 143 short videos in which I discuss basic problems.
ENJOY!
Can you tell me where are these short module lectures, please ? because I can't find them
I too would like to find these.
What website are we referring to, here?
Thank you so much.
Love from Pakistan!
How can I download MIT physics book
As an engineering graduate I have seen my fair share of commutators in text books and labs, but Dr. Walter you are the only commutator likely to stay in my memory after this lecture haha :D. The buildup of the concepts leading to two very important real world applications (the current meter and the motor) was seamless and excited an intuitive approach to these. This lecture was such a good treat with my coffee ! Thank you so much for the upload, love from India !
This video was posted 5 years ago and it's still helping me passing the Electromagnetism course. Thanks professor 😝 you inspire me a lot
now 8 years ago..., even though it was filmed back in 2002, he referenced it at 21:24, he never could have imagined so many people would be watching it 2 decades later, not on such screens as he described, but on flat panel screens which make almost no noise, sip little power and aren't affected by magnets, with color accuracy unimaginable by most standards... now, oled, lcd or led so widespread... how much will change in 20 more years? But, these lectures will still be watched, so would any good lecture given in the last 60 years, physics is constant, even though this info is new to me, it was new to people 60 years ago and people discovered it 100 or 150 years ago by this point... yet, it was exactly the same for millions and billions of years
Had to watch this lecture as soon as possible to figure out what the cheerios thumbnail was all about :). I wasn't let down
Did you see it
Thank you for sharing, sir. As a student, I admire your passion for Physics. It inspires me a lot to study about this subject!
Great
The distortion that came from the magnet is outstanding...The best teaching ever coming from the best Professor ever that teach the subject of reality...Transparently changing our perception of the world at full potential...I wish a great health and an extreme care to you throughout this crisis time.
Never get enough of your lectures. I view and review,Watch and re-watch and never get tired. You nailed it prof
Ohhh!🤯 I get it:thumbNAIL!😂
Thank you Sir ... I am improving my grade with the help of uh lectures and assignments ... Simple and beautiful .. Greetings from India _ /\_
That's GREAT!
@sahithmucherla3131Yes I agree with you, thank you, Sir!🙏👏😊👍
This is the best lecture I’ve ever seen! Very, very, very conceptual. Brilliant Professor Walter Lewin.
thank you
Your Lectures are great, so enthusiastic and fun to watch.
Thank you from New Zealand!!
:))
@@lecturesbywalterlewin.they9259
Your lectures matches exactly with NCERT Physics book.
@@sandman3402 that's very true
@@lecturesbywalterlewin.they9259 Thanku from India sir
@@sandman3402NCERT? HUUUUUUH ? WHAT'S THAT? WOOPS!SORRY FOR THE CAPITALISATION!😬😬
I did my B.Sc in physics way back in 1977, but I really understood electromagnetism only after watching your videos! Amazingly what a fascinating phenomenon is this EM !
Thank you professor sir 🙏
It is fascinating that you've gone through Electricity and Magnetism and through Maxwell's equations and more, Professor, which is one the pillars of Physics, with such clear cut explanation. Thank You. Very good with all those experiments for each and very concept and equation. Truly helps concepts sink in.
exactly, the professor at my high school tries his best to show us experiments, but he can't get 200A of current just randomly or such large magnets, he also has to set it up every time... it's all really old stuff, Russian or Yugoslavian equipment from the 60s, this guy's lectures really help me conceive the topics I learn at school
Admire your teacher
Most don't even try
Plus demonstrations are not so easy. if you don't believe me check out Shankar's Yale lectures he tells you how difficult they are @@aquss33
i can't help but envy MIT students for their courses and contests
A MOTOR CONTEST! seriously... they've got all the parts etc
i started these lectures a week ago and i can't get enough, the assignments are fun, the lectures are even more fun, i make sure to watch them at least twice to make sure i don't miss a thing..
I am so grateful for professor Walter Lewin for making his lectures available online
Greetings from Morocco... where the education system is free but sucks!
Hello Mr Walter Lewin, first I apologize for my bad english. it's because I'm french. And you know french people speaks often bad english.
But with your famous science lectures I understand you so well !! You're the best teacher I never had, really I'm fond of your lectures. So tahnk you very very very much for your sharing of your knowledge : it seems so easy to understand with you.
Honestly Professor, I am watching this lecture for fun and as I view more and more of your lectures it becomes obvious how much rehearsal time you put in. You don't hesitate at all during the lecture and speak with conviction.
What are my lecture secrets?
A typical preparation time for 1 lecture is 60-80 hr. I do not write a script. But I dry run all my lectures 3 times before I give the lecture. 2 weeks before, 1 week before and at 6 AM of the day of the lecture. Every 5 min I have a LARGE time mark in my lecture notes (starting with 50 min, going down to zero). I have a large digital clock on the lecture desk which is set at 50 min when I start the lecture and it is counting down. Thus at ANY moment during my lecture I know within about 1 minute how much time I have left and how much time is needed to finish. Thus I NEVER overrun, I never have to do an interesting demo in haste with a sloppy explanation. I typically finish my lectures within 1 minute of 50 min. Of course during the first dry run, it ALWAYS takes near 60-70 min. I then have to do careful surgery as changes are needed. By the time it is 6 AM in the morning of the day I give the lecture I am always well synchronized between my time marks and the digital clock. My lectures have therefore become performances (like an actor on the stage).
my secrets are: *imagination, go outside the box with examples and with demos. I do often demos that will make them sit on the edge of their seats. I make the students laugh at times, make them cry, make them stop breathing, even make them wet their pants at times. I confront them as much as possible with experiences in their own lives. Where possible I include a student in a demo. I also do demos in which I take risks. I never become boring. I make them look through the equations to make the eqs come alive. I always keep their attention with my clarity, sense of humor and my LOVE for Physics. I radiate my enthusiasm - it's contagious. I can make ANYONE love physics and one of my "famous" quotes is: "if you hate physics it's only because you had a bad teacher".*
Thanks for the reply Professor! I hope I didn’t keep you up late at night writing that. I was watching the feynman lecture series you have pinned on your account and there is another one who could teach! Feynman was teaching you physics and making you understand the concepts as if you were a physicist without you knowing it. He used excellent examples and real life experiences connecting the physics to the real world much like yourself. You may not think so but you are on the same level of Feynman to *me* and I think its wonderful you continue to do this throughout your senior years. Thanks so much for the dedication and preparation time put in. It truly reflects so and you are to be admired for such amazing work 👍😃
thank you for your kind words
You’re very welcome 😊 by the way the demonstration of distorting the television image with the magnetic is awesome and I definitely have to check out some of pikes work
Sir Walter Lewin, your lectures are one of the best aid to me in studies of CBSE 12th, India. I try to grasp maximum from the contents from you. I'm grateful to such the best human. I wish I could do something for others in future.
For now, I sends you your good health wishes. May you live long and, one day I could be in your vicinity.
Oh! That day will come, I wish with optimism.
This is now in 10th grade, of course not the all of it, only flux, magnetic intensity, flemings right and left, electric motors, etc.
these are performances, not lectures! never seen a lecture as entertaining as this. binge watching these with popcorn! thank you professor. with every lecture you change the world!
*yes all my 94 MIT lectures are performances* -
What are my lecture secrets?
A typical preparation time for one 50 min lecture is 60-80 hr. I do not write a script. But I dry run all my lectures 3 times before I give the lecture. 2 weeks before, 1 week before and at 6 AM of the day of the lecture. Every 5 min I have a LARGE time mark in my lecture notes (starting with 50 min, going down to zero). I have a large digital clock on the lecture desk which is set at 50 min when I start the lecture and it is counting down. Thus at ANY moment during my lecture I know within about 1 minute how much time I have left and how much time is needed to finish. Thus I NEVER overrun, I never have to do an interesting demo in haste with a sloppy explanation. I typically finish my lectures within 1 minute of 50 min. Of course during the first dry run, it ALWAYS takes near 60-70 min. I then have to do careful surgery as changes are needed. By the time it is 6 AM in the morning of the day I give the lecture I am always well synchronized between my time marks and the digital clock. My lectures have therefore become performances (like an actor on the stage).
my secrets are: *imagination, go outside the box with examples and with demos. I do often demos that will make them sit on the edge of their seats. I make the students laugh at times, make them cry, make them stop breathing, even make them wet their pants at times. I confront them as much as possible with experiences in their own lives. Where possible I include a student in a demo. I also do demos in which I take risks. I never become boring. I make them look through the equations to make the eqs come alive. I always keep their attention with my clarity, sense of humor and my LOVE for Physics. I radiate my enthusiasm - it's contagious. I can make ANYONE love physics and one of my "famous" quotes is: "if you hate physics it's only because you had a bad teacher".*
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@@lecturesbywalterlewin.they9259 for this I am certain you will go down in history as one of the greatest physics teachers of all time, similar to Feynman :) even 20 years later your lectures still inspire hundreds of thousands of students. Back in India students would pass down your lectures on thumb drives because we never had teachers like you, very rarely any demonstrations and courses focused on mathematical difficulty and rigor over understanding and inspiration. Your contributions to pedagogy are, I suspect, dwarfed by your (direct and) indirect contributions to physics , mainly by inspiring all these students and teachers to have a better understanding and instilling an awe for physics and raising the standard for stem education worldwide.
Thank you professor for all that you have done for generations of students and physics in general.
To add some context , I am a physics educator myself and am on constant lookout for newer and better educational materials. I have yet to see physics lectures or demos of your caliber , as comprehensive and extensive across TH-cam . In fact often I have to simply play video clips of your demonstrations due to some of the demos being infeasible to replicate.
These courses are helping me a lot in my JEE prep... Thank you professor! :)
"If you come with a magnetic monopole tomorrow, I can do this."
Hahahahahaha thank you sir you just made my day
From Prof.Herb Gross to Prof.Lewin,MIT have always been one of pioneers in helping students all around the World.
Thank you MIT and Prof Lewin -from Himalayas
:)
Thank God for this human. Thats what resonates throughout the galaxy.
Hello from Serbia.
Dear Professor, i hope this message reaches you.
1.)
Can you explain me 11:10 is this actually for positive charge?So for electron moving from us to the table would be from left to righ actually (magnetic)? Because i am trying to visualize whole concept, and that helps me also for other topics. So if positive charge flows from us to table then magnetic field goes from left to right, like screw. And if electron goes from us toward table than it goes from right to left?
I thought electron flowing from us to table cause right screw rule, but... en.wikipedia.org/wiki/Lorentz_force#/media/File:Lorentz_force.svg
2.)
And why some show current of the battery flows from plus to minus, when it actually flows from minus to plus, so whole schematics of electronics are wrong, even diode, it flows in other direction from minus to plus.
3.)
I also wanted to ask if flowing current through conductor causes magnetic field in some direction, is that the same reason why "flowing" conductor in magnetic field causes current?
Thanks!
Oh wonderful challenge! I am the lab TA for the Electric Machinery course for EEs at my university and have been pushing to have the course include a project aspect that involves either building a motor or a transformer and thoroughly analyze their build as a way for students to apply their understanding of the course's material. I wish this had been done for me in either my physics or my ee courses!
your videos are so engrossing..i never thought i will be watching physics on internet..you are a great professor.
:)
I'm a software engineer taking a career break to start a new master in photonics (16 years after graduating! :)) and I was looking for some online materials to help me refresh my knowledge on electromagnetism. Your lectures have been an enourmous help. Thanks! Bedankt!
welcome
What a magic you did it sir !!
I'm just in love with physics nowadays. Greetings from India ❤️
No word's to describe your way of explanation ,your the great teacher thank you for the uploading the video
It's my pleasure
sir, you are great.I became a big fan of you.
I never seen, even I never thought a professor like you.
There is lack of quality education in India.
Thank you! For these lectures.
thanks for your kind words
The best Indian physics teacher moved to the US (Shankar).
At timestamp 20:30 where WL says..."but no one would ever say that...". Maybe, they would! Rearrange "Ns/Cm" and you have: (N/C)/(m/s), that is " Newtons/Coulomb PER meters/second, and it makes a 100% intuitive difference WRT E fields, and speed through those fields!! Unit combinations usually make all the sense in the world if you look at them differently!!
That is the best lecture I seen in my entire life about Magnets.
4:38 vier :) one's native tongue never does disappear does it? Great lecture as always!
what language
Sir I have a question
Is there any footage of the MIT motor competition ? It would be really interesting to see what all the students came up with .
I would also like to thank you for these amazing lectures that are 2nd to none
They make these concepts so simple so that we can think beyond the lines rather then being regimented in our thinking like in many schools
4:36 he said the Dutch word "vier" meaning four instead of English "four".
We love you professor :)
many proff: know Physics but they dont love to share with students Your Lectures are great, so enthusiastic and fun to watch.
Thank you from PAKISTAN..
Great Sir, I salute you for your knowledge and teaching method. you are a teacher for all teachers of physics on the earth. Whoever teaches physics to students in school/college/university, He must watch your lecturer before going to teach to students.
:)
fantastic lecture professor! im on the 2nd semester and has to deal with fundamental physics for another 2 months or so. you have officially brought back my love for physics!
:)
Your lectures are not only very interesting they are also very intertaining.
:)
Really make you fall in love with physics! Thank you so much! You are a living legend!
Wow, thanks!
These lectures are really helpful for indian high school students for jee advanced. Very easy to understand and gives very intriguing conceptual understanding
Thank you for everything professor, you inspire me and are my role model
You are very welcome
Sir, I am curious about technology .... I love physics . explanation is awesome. Thank you .
easier and more in detail compared to my highschool class (it's a special one focused on engineering). U carry me trough homeschooling. Greetings from Austria.
These lectures are awesome! Detailed, yet simplistic.
thank you
sir, first of all thank u so much to help us for making our concepts so strong. i used to think that i love physics but physics does not love me but as i started to see your videos it really helped me to retain the concepts.your way of teaching is mind blowing!
:)
sir i m preparing for medical exam and my physics is so weak .how can i solve my problem
watch all my 94 MIT course lectures. Do all the homework and take all my exams. They are all posted (pdf files) below the video thumb nails. to take the 3 courses will take you about 5 months as a full time commitment. start with 8.01.
thank u so much sir
:)
what an awesome explanation . Great professor.
here current is conventional current flow correct? (opposite dir of the flow of negative electrons) in terms of the magnetic field direction right-hand rule?
edit: spoke too soon. answer was at 29:00
I am really addicted to your lectures i am constantly watching them like a netflix series.you are brilliant sir
Keep watching
Sir, your style of teaching is very different nd innovative which makes physics very simple. Sir, your lectures makes environment for students, I i like your lectures
:)
I love the wealth of experiments you do.
28:10 literally me during the previous lecture. and i realized the same conclusion.
35:48 the difference between the two currents is mainly an issue when using the right hand rule. for conventional current, it's actually the left hand rule. easy enough.
Your videos give me a huge help in understanding high school physics stuff! Thanks sir
24:32 for those who are here just figure out that "Cheerios" in the thumbnail
17:05 why the hell the students are looking so sleepy with this great teacher... ?
those are the students who chose the wrong course.
😂those aren't called student
50+ hours a week gets old after some time.
Answer: They’re students. Tired does not mean they aren’t enjoying it. They might just be- you won’t believe this- tired.
@@floydbenedikter9345 Indian 11th and 12th class is more stressful than these
Hello dear Professor. First I want to thank you for these classes and the passion that you put for over 40 years. I'm a student and his classes are the best in the world, my teacher is boring and makes the physical look totally frightening. Thanks to you I fell in love with physics. I wanted to ask you Professor, because I want to create a kind of book with these classes, that is, write your notes and your words and compile them in a kind of book.
The idea is to study better, and practice through your readings. I wanted to know if you do not have a problem with this. I await your answer Walter.
I congratulate you, your readings are really exciting. Nahuel Nitz
go ahead! Make sure you always give me credit and always mention the source of all you print. If you sell the books, you should pay me 50% of your revenue.
Ja klar Herr Lehrer!!! Obviously I'm going to do that! You and this great work deserve it. Once again I want to thank you teacher, I am very happy for your approval. keep in touch! Dankeschönnnn
wonderful piece of teaching!!!!!!
well done and long live Mr walter lewin.
Magnetic fields and electric motors are fascinating! Thank you professor!
You are welcome!
Thank you sir, it was a great lecture. I was able to understand the concepts clearly.
I am a big fan of you prof ❤
Greetings from Indonesia..
27:04 29:26 Is that a drift velocity? 🤔
Should be v{d}= aτ ~a∆t~∆v , then.
But you give it as: v{d}=dℓ/dt...😵
So, is v{d} a velocity or _change_ in velocity?
Also, is it over the same time scale "τ" ?
Dear professor at 10:18 you drew the magnetic field direction in clockwise but you said that it is outward after that but before in lecture you said if you rotate cork screw in clockwise direction than the magnetic field will point inwards ( into the blackboard) , so how here at 10:18 you showed it outwards? :)
It is according to Fleming's Left Hand Rule
47:43 sir the magnetic fields should be from north to south isnt it?
By the way I am grade 10th student from India maybe my knowledge is low in this concept.
But I think the coil should go down.
sir, can I remove the effect of experiment done at 24:10 minute( I just did it on my old TV):D
sure
Feel free
at 14:55, is the current going at the same direction as the magnetic field or is is perpendicualr?
my first lecture but have to say have fallen in love at first sight .
I have a question that at 11:07 of your lecture you say that F=I×B where all of these are unit vectors,how current will be vector quantity?how can we do cross product of current?As we know current is a scalar quantity.Is there any special case where we consider current as a vector quantity?Please reply sir.I also enjoy your lectures very much when you say "Have a fun".
In general current is not a vector but in the case of the Lorentz force it is a vector as it is the direction of the moving charges in the wire that counts. F=qvXB. In the case that I discuss here it too is a vector foer the same reason. Thus the unit vector F is the cross product of the unit vector of v (this I) and the unit vector of B.
Thanks a lot to you sir from india🙏🙏🙏
13:44 *the krrk sound was perfect* 😂
Dear Professor Lewin,
at 10:52 you show that wire experience a force that is perpendicular to current and magnetic field. But why does it experience this force? What is happening with the wire that it wants to move?
Best regards,
Tomasz Studziński
I gave the explanation as given in college books F=qVxB but that is not the correct explanation as the vXB force can do no work.
I never noticed until now, at about 4:35, did you slip and say vier? :)
20:44 In the name of Nikola Tesla, one of the greatest minds in physics. So much we owe him. You had to mention him, professor.
What is your problem? I mention the unit of Tesla. Just like I use Farad (for Faraday) and Amp for Ampere, Newton for Newton, Curie for Curie. Volt for Volta, Henry for Henry, Coulomb for Coulomb, Gauss for Gauss, . . .,
In 8.01 you used to say something about scientists, when you mentioned the unit named after them. That was a good habit. I just want to point out that you didn't do the same with all scientists. That's it. Sorry for any misunderstanding.
>>>In 8.01 you used to say something about scientists>>>
PLEASE remind me what did I say about Joules (unit of energy), what did I say about Pascal (unit of pressure).,what did I say about Newton (unit of force), Celsius (unit of temperature). Kelvin (unit of temperature), Fahrenheit (unit of temperature), Mach (unit of relative speed), Torr (unit of pressure), Planck units, Just to name a few I mentioned in 8.01.
Sir, At 13:21 you said that above the wire carrying current i1 the direction of magnetic field is out of the black board but you said that direction of magnetic field below the wire carrying current i1 is into the blackboard. I am a bit confused about how are you finding the direction of magnetic field. Can you please clear my confusion.
use Ampere's Law
36:40 How is the net force 0 prof?
The wire coming out of the blackboard is larger than the wire behind the blackboard because of the GAP in the backside wire.
Doesnt that make the force on the outside wire larger?
Or is the gap soooo small that net Force is approximately 0??
Thanks.
it's zero bcoz sin of angle between v and B is zero
Lorentz force is a cross product
I mean, when the loop turns. That time the cross pro is not 0.
And the forces on the front and back wires do not quite cancel due to the gap.
Is they are using half wave rectifier to make the motor which doesnt produce current at sometimes
Sir your's demonstration helps alot to know physics ❤️🙏🏻 in depth
Professor Lewin, how come you don't use the cross product for the example @ 33:37? You have the equation Fb = ILB. Shouldn't you take the cross product of L and B? Is this just the magnitude of the magnetic force along this wire?
Of course I used the cross product. I wrote down the magnitude of it.
Ah that's what I thought. Thank you sir.
moving charge is the cause for magnetism as I relatively move fast along with the charge I would be feeling any force of magnetisation ?
43:48 but even when we didn't have a commutator, the current changed direction ( due to rotation) , what's the difference ?
the torque reverses
I started to love the Netherlands as a country just as I started watching prof. Lewin. Coincidence?
What will happen to force in two wires which has net charges and you put the conductor in between them. As you show at 17:00
+q charge on one side of a conducting plate . The +q charge will be attracted to the conductor due to induction. +q charge on both sides the 2 will not repel each other. en.wikipedia.org/wiki/Method_of_image_charges
12:21 is the force of charged particles being forced down in the wire really strong enough to move the wire itself downwards?
u saw it yourself. so yes?
thank you so much for this impressive lecture professor :)
35:50 Sir, doesn't the Lorentz Force only change the direction of the motion?How come it gives a torque to the metal frame and gives it energy?
the magnitude of the Lorentz force is ILB (I indicates the motion of charges with velocity v, v and B are vectors. thus the force is perpendicular to I and to B.
@@lecturesbywalterlewin.they9259 so is it gives a torque and therefore an energy to the metal frame?
Professor at 14:40 , for below wire ,how we get to know that magnetic field is going inside the black board? Actually I could not feel it how it is going inside.
Just use right hand rule. Point your thumb in the direction of current and check out in which direction your fingers curl around the wire, (below the wire and above the wire). Hope you got it.😊
Professor at 39:26 - *Wasn't that gap between D and A have any effect on the Value Force between two opposite sides?* and Because "F = iLB" - force depends on length. and that gap shorter the length and So, Value of Force would be different on two opposite sides.
I calculated the torque correctly
Professor I'm not talking about Torque correctly or Incorrectly or whatever.
I'm talking about Force on the Backward Side of Loop at 39:26 in video. *Wasn't that gap between D and A create any effect on the Value Force? Because "F = iLB" - force depends on length.* and due to that gap length would be lesser.
Anonymous for some days yes there will be forces on the wires near D & A. They were irrelevant for me as I explained the rotation of a DC motor.
okay! professor So, If we talk very very Exactly then Net Force is not Zero. 🙂 but I can understand that that's not the Case.
*Well, My name is not "Anonymous for some days" you can call me with any other short name - I don't Mind at all.*
23:45 How can Lorentz Force doesn't change the kinetic energy if it changes the direction? If the direction changes,the Lorentz Force must gain a new velocity vector which perpendicular to the main velocity vector of the charge.So net vector will be the sum of them and this is bigger than the old one.And if velocity goes up, kinetic energy goes up. is it wrong?
>>>If the direction changes,the Lorentz Force must gain a new velocity vector which perpendicular to the main velocity vector of the charge.So net vector will be the sum of them and this is bigger than the old one.>>> *this is incorrect* watch my lectures in which I cover this in detail.
@@lecturesbywalterlewin.they9259 which lecture did you cover it?
😂😂 23:36 that remote though 🤣
I am from Pakistan. Thank you so much Sir. 🎉🎉🎉
How about tourge? Thinking about if we do not fix the movement of the front againts the mortor or the perpendicular direction. Do you know that some of the fan engine will design to have the tourge direction going into the machine and some in the opposite direction? Electric Fan and Air plane fan will oppose tourge into the front direction while the turbulant in some jet engine will do in the opposite direction.
There is unique of the electric field and manetic field that is why it has effect againts aluminum. If we choose the right frequency maybe it can effect the different metal also. Thinking about the frequency fork and its identical frequency.
At 39:35 the net force will be zero only if we take the distance between A and D negligible right ?
no
Sir I’m a high school student in Turkey. In our country, teacher’s teaching skills are so low they don’t even talk about what magnetism is. They’ll just give you some equations and then they’ll jump into the solving problems. (And I’m not even mentioning schools are too broke, teachers are too careless for showing experiments.) Because all they care about is university exam. Not just teachers also the students are behaving that way too. No one really wants to learn. They just want to memorize how to solve problems until the exam.
But why did I wrote this? *I wrote this to show how much appreciate your teaching skills* When started to learn magnetisms I had bunch of unanswered questions waiting in my head. I still have those bunch of questions but at least some of them answered because of your videos.
Thanks a lot
thanks for your kind note. Stay healthy in Turkey! The number of people there with confirmed infection is growing every day!
3rd year electrical engineering student (not in MIT) visiting for a good refresher.
At 25:25 you say : "magnetic field can never do work on a moving charge" I agree with your further explanation : F created by the magnetic field acting on the moving charge is perpendicular to the motion.
But the charge will get kinetic energy in the direction of F, perpendicular to the motion because F=ma. So the charge will not get extra kinetic energy in the direction of its initial motion, but the charge will acquire kinetic energy in the direction of the force caused by the magnetic field acting on the moving charge, did I get it?
One more time thanks a lot for your lecture, it's very enlightening
>>>But the charge will get kinetic energy> *that is incorrect* the force on a charged particle is in the direction of VXB which is perpendiclar to V. KE of the charge does not change.
@@lecturesbywalterlewin.they9259 I agree with you, the KE will not change in "the direction " of V, but since the magnetic force on a charged particle is in the direction of VXB, the particle will be accelerated in the direction of VXB, so a new kinetic energy will appears in "the direction " of VXB, and it will affect the initial motion, the direction of the velocity will then change. I think it can be seen if we put a wall perpendicular to the direction of the velocity : the energy dissipated by the impact will be larger than without the magnetic field. If I'm wrong, could you tell me please where I misunderstand the concept?
@@guilhemescudero9114 *incorrect* the force VXB is always perpendicualr to V thus the KE will not change. The KE energy of Earth in orbit also doesnot change are the force on Earth is perp to its motion. This is my last msg
@@lecturesbywalterlewin.they9259 THANKS, this quote "The KE energy of Earth in orbit also doesnot change are the force on Earth is perp to its motion" enable me to understand where I was wrong : the component of the velocity along the direction of the motion if there was no magnetic field is a probably a cosine-like function over time when we add a magnetic field because the force due to the magnetic field curve the motion and in the same time the component of the velocity perpendicular to the direction of the motion if there was no magnetic field is a sine-like function over time when we add a magnetic field because of the force due to the magnetic field.
So I can think about the magnetic field acting on the moving charge as a modification of space, when the moving charge wander in this space under a magnetic field, the charge change the configuration of space, thus the cinematic of the charge changes according to the modification of space.
I really appreciated the time you took to help me, thanks a lot Lectures by Walter Lewin. They will make you ♥ Physics. !
@@guilhemescudero9114 use google; this is too elementary
Why we can think as magnetic field produce by constituent particles Magnetrons like the electron-proton and neutron?
At 36:00, why is the magnetic field in the same direction even though current is in the opposite direction?
The magnetic field is an EXTERNAL field. The current in the wires is due to a battery in the circuit.
Sir , at 48:56 would not it be better if we change the direction of the current when the plane of the loop is perpendicular to the magnetic field ?
I suggest you ask Maxwell
I used google and found that the motor is designed so that the current changes the direction when the plane of the loop is parallel to the B-field and that was my questuon .
I covered that in my lectures. You should have watched them. *I discussed commutators!*
Thank you, I now understand Monsoon
Sir, at 35:50 is the magnetic field B produced by the curent in the wire or is it just a magnetic field from some magnet that we've put next to our current loop
I give the answer in my lecture. watch it again
Lectures by Walter Lewin. They will make you ♥ Physics. I've got it, thank you
Hello Sir, thank you very much for providing this great lectures. I think I am ready to start building my motor and earn some imaginary credit. In order to start in the right direction, can you give us more details about the size of the magnets and the dimaters of the copper wire?. In the PDF provided it just says two magnets and 2meters of copper wire. Thank you again Mr. Lewin.
I gave this lecture 18 yr ago
4:36 native language never goes away 😀
Thank you, I wish I could have been one of your students. I am now by watching the video.