8.02x - Lect 19 - Magnetic Levitation, Human ❤, Superconductivity, Aurora Borealis

[@lecturesbywalterlewin.they9259]

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!

[@homer5263]

+Lectures by Walter Lewin. They will make you ♥ Physics. Thank you.

[@overcastandhaze]

Many thanks!

[@SethGlover]

+Lectures by Walter Lewin. They will make you ♥ Physics. Thank you!!! This is spectacular.

[@udakangwa6091]

I can't believe you retired sir

[@lecturesbywalterlewin.they9259]

I am 80 years old now

[@hahahahaha651]

I am a computer engineer now, switched from electrical engineering (in my first year uni) just because i did not have a lecturer like this Prof. No concept were explained in electrical engineering in my class, just given, find,.. solution.. my brain becomes a calculator... and it makes electric/physic boring... and worst it makes me understand nothing. I watch this video, so i can learn physics and electric as they are truly my passion. Thank you prof. U re great!

[@lecturesbywalterlewin.they9259]

Lectures by Walter Lewin. They will make you ♥ Physics. kzbin.info/door/iEHVhv0SBMpP75JbzJShqw 300+ videos. Many of them with high resolution. This channel has all my lectures and talks.

[@slevinshafel9395]

+Lectures by Walter Lewin. They will make you ♥ Physics. wath is the "802 site"?

[@HATTERYT]

are u the real walter lewins..

[@HATTERYT]

because i love all your video and one time i saw that it say : walter lewins last lecture, i really sad

[@HATTERYT]

i wanted to say that you are a great great teacher

[@lecturesbywalterlewin.they9259]

my.clevelandclinic.org/services/heart/heart-blood-vessels/coronary-arteries

[@jimhealey4961]

You are the guy I needed in the 70's. I had a plan to make every house self electrified. No more outages from storms, 100% self electrified, I showed my design to a nuclear physicist i happened to work with, he had no reason it would not work,. I'm a 16 year old forklift driver, I never had the funds to make it happen, I also designed robots to help the old folks that could climb stairs back in 1985 and never went further than a white board in my home. I'm now 64 and have done nothing with my knowledge, You have inspired me, Now with 17 grand kids, 3 great grand kids and a hope that we can be carbon neutral and develop all the power we need with out the power company and A MONTHLY EXPENSE. I know I'm not 17 anymore but I still have that Dream!

[@lecturesbywalterlewin.they9259]

Publish your results and new ideas before you tell me about them. And by all means get patents!!! My friend Luc van Ocken would be very interested in your new ideas as he himself has many. Maybe you can publish together. You can contact him at [e-mail]

[@Asylums.]

I wish this was my professor, I've binge watched nearly all his lectures and I love every single one.

[@lecturesbywalterlewin.they9259]

Thanks, Nate, for your kind words

[@computerscientist5953]

I'm not a physics student, I am a computer scientist, but I watch his lectures anyway because they are enjoyable

[@lecturesbywalterlewin.they9259]

:)

[@tanhazjustdance2024fan4ever]

Me too, I am computer engineer :)

[@js1579]

same to me too I am a computer engineer but with a heart door open for science as well.. I just gave it a go to see how is the talking about this but then couldn't stop it till the end!

[@randomdudr]

I am a Pharmacist and I really enjoy his lectures

[@shadowcasterstudios4042]

i am a 3D animator and cant get enough of these lectures

[@ElementalMaker]

What an amazing professor! Such fantastic explanations and insight towards practical applications. Professors with this level of passion are very rare!

[@lecturesbywalterlewin.they9259]

ElementCollector1001 Thanks for your kind words \\/\////////@lter

[@odysseus3835]

Lectures by Walter Lewin. They will make you ♥ Physics. If this is truly Walter Lewin, I want to thank you deeply for your methods of teaching. You have inspired me and many of my peers to love physics.. It takes an incredible teacher to inspire such passion in areas such as physics. Sir, you truly are a blessing. I cannot thank you enough for opening my eyes through your lectures. I truly enjoy every minute and wish I could be there sitting in your classes. Thanks again, Cheers.

[@lecturesbywalterlewin.they9259]

Odysseus yes this is truly \\/\//////@lter Lewin

[@LaTortuePGM]

goohz has a channel : i think it's just for the aesthetics.

[@bobsaxen183]

Great professor indeed! I grew up in Europe and these kind of professors we had at our high schools in the 70's. And not only one but the majority of them were this good. Fast forward to today where you asked to pay exuberant tuition to get this kind if quality in univerities.😑

[@cliffcraig5594]

I am a retired civil engineer using your very entertaining lectures to brush up on electricity to examine the electric universe hypothesis. I love your passion for physics.

[@lecturesbywalterlewin.they9259]

:)

[@supercellonova]

It's been a while since I've attended college, and even for someone like me who finds it hard to understand certain things, your methods and word choices have got to be the most clear I have ever heard. As I am following along, every single step makes perfect sense!

[@Rookerfro]

This is one of the best instructors I've ever seen. A very knowledgable man.

[@johnedwards4394]

He's a legend. May he live another 100 years. Personality, brains, humor and humanity. Terrific guy.

[@tkdev2023]

This is what we really call a class, teaching and education. In India we lack this type of intellectual stimulation and what we have here is bookish knowledge. Thankyou Professor, this is my favourite subject and I wish if I was born as your student❤️

[@VladimirMozhenkov]

Hello, I would like to say that i'm in education and that you are one of the people who inspire me quite a lot. Thanks a bunch for what you are doing.

[@lecturesbywalterlewin.they9259]

Thank you Volodya for your kind words.

[@pakshaljain8437]

49:04 THIS IS WHAT YOU CAME FOR

[@profyle766]

You Joker!!!🤣🤣 I was at the Aurora Borealis bit when i clicked on your comment.

[@peeper2070]

Came for 49:04 Stayed for 00:00

[@damercadoo]

Back in 2010 their lectures made me want to go to MIT I could not become the dream come true but my passion for physics grew thanks to that, i hope professio lewin is well

[@dirksaenen436]

Walter Lewin, het archetype van de prof die we allemaal graag als leermeester gehad hadden. We zouden géén enkele les spijbelen. Fantastisch dat ook wij zijn lessen kunnen beleven via het web. Eigenlijk had Walter een deel van zijn lessen ook moeten geven aan onderwijzend personeel : "hoe maak ik wetenschap fun" Het zijn uiteindelijk de leraars en proffen die de jongeren warm maken voor wetenschap - en de stijl en flegma van Walter zijn meeslepend. Er zouden véél meer jongeren kiezen voor een wetenschappelijke opleiding. Walter, hartelijk dank voor het delen van uw inspirerende lectures.

[@dirksaenen436]

oke - kzbin.info/www/bejne/g2LXYZidib-MapY ;-)

[@valveman12]

Wish I had a Prof like you when I was in College taking Engineering. You can tell how engaged your students are because you make learning fun.

[@lecturesbywalterlewin.they9259]

:)

[@ishansheikh3058]

Physics is perhaps the best thing that ever happened in my life and it all started with this teacher. Bless u Mr. Lewin.

[@1.4142]

The mad scientist teacher we all want.

[@XxYucayequexX]

Damn right.

[@1.4142]

Just came to this video one day and realized I had already commented. Hello past me!

[@lecturesbywalterlewin.they9259]

@@annettebertora4434 given your ignorance about physics, I wonder who the idiot is. Yep.... Very sad.

[@ubergeraldine]

Along with Brian Josephson. They even look alike!

[@mid7699]

@@lecturesbywalterlewin.they9259 ??

[@SRJ...4]

Sir i am 15 years old and i have interest in physics subject After watching ur videos i get more and more motivated to study physics Thanks alot sir i wish i was in the class while were showing the experiments Genuinely never liked a subject so much in my school years as i like physics now and that is all because of u sir Thanks alot Hats off to u sir Great respect from India

[@lecturesbywalterlewin.they9259]

keep it up!!!

[@gingin7828]

When I was a student my teachers told my parents I have concentrations problem need a psychologist😅 but now I’m listening! This teacher has magic and power of attraction🤟🏼

[@lecturesbywalterlewin.they9259]

great!

[@anibaldk]

I understand 1% of what was presented and yet, watch this lecture in full attention for 49 minutes. Now THAT is one hell of a teacher!!!

[@lecturesbywalterlewin.they9259]

Thank you!

[@er.rcreddyphysics9191]

The way he is explaining the physics with practical is excellent

[@lecturesbywalterlewin.they9259]

:)

[@gregortheclone8913]

Absolutely magnific! I can't stop looking at these lectures of Mr Lewin and I am convinced is the best channel I've come accross. Too bad there are not so many teachers so dedicated. This may also called art!

[@lecturesbywalterlewin.they9259]

Wow, thank you!

[@danielbaronarommy8124]

Hi professor, I am a medical doctor, and a physics aficionado. The classes are great! thank u for that. Acording to e EKG of the student, is perfectly normal , the p wave is there, you might think is the U wave. Also , its not a typical qRs, but rather a rS complex ( small r , big S wave) that is normal in DI, DII, and maybe AVL and AVF derivative. Had lot of fun watching the whole class. very helpfull for me and my interest. Best regards

[@lecturesbywalterlewin.they9259]

Thank u

[@mr.technicalverma7506]

43:42 I actually felt that when I was putting a pot on induction cooker, the pot becomes lighter little bit, I thought about that and also got your explanation. Thank you very much.

[@tehyonglip9203]

besides making me love physics, i have more appreciation to Biology because of you, Thank You for teaching how the heart works(most physics teacher wont cover)

[@satinderjit4]

Professor Walter is a fantastic lecturer. I love to listening to him. I wish more professors taught classes with as much passion and enthusiasm as him!

[@buketpehlivan9971]

Every teacher could give his profession the right in this way, everything would be very different

[@lecturesbywalterlewin.they9259]

:)

[@shreyasharma951]

I have always dreamed of becoming physicist but somehow lost interest in physics in my undergrad. But now, after watching all these lectures, i am not sure if i can think of anything other than physics. The way he make us understand the concepts in fun way is mind blowing.

[@Shubham-wu5jv]

I love his lecture because he proof everything right in class practically no teachers do that in india 😵😵

[@saggio8720]

I used to hate physics and math in general until this year, because I got a new teacher who made me love them that addressed me to your lectures! Thank you too!

[@lecturesbywalterlewin.they9259]

:)

[@1qtom]

I imagine how pleased a physics student is watching these videos as I'm delighted to watch without having any connection with physics.

[@ZeedijkMike]

Can only admire the enthusiasm you show when giving lectures.

[@realcygnus]

"world class" instruction......thE best of the best

[@lecturesbywalterlewin.they9259]

Thank you!

[@mickeymoroco]

What do you think on the approach for the “girl levitation experiment “ ... didn’t saw it as world class example to my eyes. Little sad for that. Point beside. Yes he’s good .

[@rutujapilgar3421]

In times where people enjoy binge watching web series, we like to binge your lectures!...that speaks volumes

[@CatbertDeVil]

Thanks a lot for the lectures! You made me realize that it's not because I didn't like Physics, but my high school teachers had ruined it for me. I ended up in EE just because electronics had little coverage in the Physics curriculum I had. I wish I had watched your lecture videos 15 years earlier :) By the way, at 11:35 you said there are typically 12 electrodes (ECG). I think you meant there are typically 9 (10 if they do right leg drive to improve common mode rejection). The last 3 leads are mathematically derived, called augmented limb leads. The term 12-lead ecg is very confusing because in EE, leads are physical wire contact points like electrodes as well, not some sort of abstract notion. The medical community must have abused the notation so they can pretend there's a ground lead from the heart when there wasn't physically any.

[@lecturesbywalterlewin.they9259]

+CatbertDeVil Thanks for your interesting information. My doctor told me 12 and I believed it.

[@mickeyk8023]

Cannot stop watching his lecture,his lecture is the best ever and i wish if i could take his lacture for real!!!!! Thank you for uploading this video and again,i really L O V E!!!!!!it!!!!!!

[@lecturesbywalterlewin.they9259]

I am delighted you cannot stop watching my lectures. That's a very nice addiction and they may make you fall in L O V E with Physics!

[@ybthr]

i still remember taking the call from from the MIT auditor's office double checking that yes indeed we did buy a blow up love doll from jack's joke shop for a physics class! 😂🤣😂🤣

[@theprofessor1484]

Legend 😂😂😂😂😂

[@yvesstocky9936]

@ybthr did you work there?

[@JEENEETMotivation2024]

sir you are a great teacher not like others who just teach physics only for salary or motivate us to only remember the theorems and definitions coming in exam

[@lecturesbywalterlewin.they9259]

:)

[@suhasshanbhogue5617]

One of the greatest physics teacher. Anytime I don't understand a concept in PHYSICS I google for Walter Lewin video on it. Thanks a lot sir for your dedication to education and physics in particular. :)

[@pradeepsharma8718]

I ENJOY MORE WHEN PRACTICAL ARE INCLUDED WITH LECTURES , THE PROF. IS ULTIMATE, EXCELLENT.

[@arjuns2219]

wow couldnt express my joy in words.fantastic lectures.its a shame that we dont get such good quality education here in India.

[@s.s.l2858]

Best lectures, I have watched on Entire internet. It is so ease to get the concepts through his lectures which consists of theory and practicals also...& Everyone would like to study with a teacher like him.

[@rohitkantipudi6605]

"Danny, you are a great Danny"

[@squatchusmc9133]

no relation to what it was i was looking at except for the work magnet. Looking at newtons of magnets for something mechanical im welding. BUT that being said, i had to stay and watch. This guys is amazing, and at 40 im far from being in school or having interest in such lectures however ill be watching more of this guy! Well done grabbing the attention, im sure your producing good young people and that is definitly something we need. Salute!

[@abhaybedi7680]

Professor I have a question... We say when electric current flows through a spring it compresses because of attraction due to magnetic force ... But why do we ignore the fact that there has to be some electrostatic repulsion between the electrons flowing in the spring... As since we know electrostatic repulsion is far greater than magnetic attraction in this case... The string should rather elongate... ( This question was asked in jee and I had a doubt in the answer... The answer was that spring would compress when current flows through it)

[@telecorpse1957]

There aren't more electrons in the spring when the current is flowing than when it isn't, so the electrostatic forces stay the same.

[@shillstompers3793]

A physics teacher with a sense of humour? That's a new one to me! This man is a very good teacher.

[@BenA-bu1cz]

First time on this page and I really enjoyed the professor lecture. I would love to see his garage at home. Thank you Professor and Thank You EdX.

[@habibusaidu9393]

That is very good, i was being courageous to learn physics because physics has become part of my life

[@fallenmango8420]

I used to look for interesting things to listen to while I did other things. I think I've finally found it.

[@Thuglifepb35]

Love from India I wanted my physics teacher like you our study system focuses more on bookish language rather than tge practical language like you do in your lectures i watch your all lectures and i am medical student 😇😇😇😇

[@sahil3735]

When someone asks me what's your goal in life. I just show them present day photo of Dr. Lewin and tell them to do something so that I have this smile and this satisfaction of my face when I will be his age.

[@lecturesbywalterlewin.they9259]

:)

[@ron2788]

This is one of my favorite lectures. You cover unique topics all very interesting and have great concepts and perform an awesome demonstration without too much theoretical proof on the blackboard making it simple. Thanks Professor!

[@lecturesbywalterlewin.they9259]

:)

[@ImprEcr]

This side effect its low pulse behind the U. You want to know. It's a carrier I have it on my theory field. I like you to make more videos, I watch. Thank you Lewin! Best regards. CA

[@Salah.alkhalifa]

rotating disk example at 2:00 is similar to Nyquist or Shanon rate used in communication theory (sampling rate shall be at least 2 times the bandwidth). In the lecture, you see still text at a specific position determined by the light flash instant. so light is ON only at the time where text reach same exact position... if disk is rotating 10 times per second, the light should flash 20 times per second. this is a fundamental concept in analog to discrete time signal conversion.

[@lecturesbywalterlewin.they9259]

I agree with you. You can be sure we have measured the rotation frequencies of the motors made by students correctly.

[@soldtobediers]

48:46 This cleverity, underscores You're will to deliver truthful facts.. Bravo! 21818

[@womanoftheshire5591]

These lectures are immensely helpful! Recently, I’ve interested in physics, but I had trouble finding teachers who really got across to me. This all changed when I happened upon your YT channel. If you were able to put some work/exercises regarding the lecture, or some sources you think are helpful in the description it would be very helpful. Either way, thank you so much! ❤️

[@the_mastermage]

Thanks to you i've got a pretty good idea for a Pressentation in School about Electromagnetic Levitation ;D

[@lecturesbywalterlewin.they9259]

:)

[@kiwi4731]

I can only describe your lectures in one word : Divine!

[@AlmightyMatthew]

At 19:30 the prof. should have said he's going to run a defibrillator's cycle (as a joke). It would be funny seeing the student's heart beat go faster if he got worried a little

[@lecturesbywalterlewin.they9259]

ha ha ha

[@garychandler4296]

Want to see him dance...???

[@ravichandra4332]

Before this video class i read electrostatic many times.But i didn't get complete clarity.Now i got complete clarity.Thank you Dr.walter lewin sir.

[@lecturesbywalterlewin.they9259]

***** you are welcome! \\/\////////

[@Aqwlegendjason]

I like the way he says RPM. He's totally a dutch guy.

[@yuanyi827]

Your lecture is very impressive for me.I am now watching 2 episodes per day.And I can dream your lecture when I was sleeping 😴.hahaha.

[@jimijakjones99]

I love this guys lectures. He knows his stuff. But I can't help but to wonder if anyone else thinks he sounds like the aardvark from the ant and aardvark cartoons?

[@NondescriptMammal]

The aardvark's voice is an impersonation of the comedian Jackie Mason

[@butler-diazfamily1335]

he is dutch

[@arnavroy6882]

walter lewin you are really awesome your lectures are really simple

[@lecturesbywalterlewin.they9259]

:)

[@drbendover7467]

for a moment I thought I was going to hear, zip ah levitation:)

[@cayezara8110]

Very …very conceptual and fascinating lecture and demonstrations by Professors Walter Lewin.

[@hackandtech24]

HOW DOES HE DO THE DOTS SO FAST???? WOW

[@lecturesbywalterlewin.they9259]

kzbin.info/www/bejne/qJLYo59qqJWjoLc kzbin.info/www/bejne/e36almyYbbGNeJo kzbin.info/www/bejne/fZnEqKqOmLami9U

[@hackandtech24]

thank you

[@m.maggionim]

You are really great. Best professor ever

[@jordanthomas3346]

In med school so this really solidifies the physics behind EKG for me. THANKS.

[@lecturesbywalterlewin.they9259]

:)

[@damianoledda5497]

36:31.... Degrees Kelvin? Seriously? Just Kelvin.

[@lecturesbywalterlewin.they9259]

I always say 80 degrees Fahrenheit and 21 degrees Celsius, and 300 degrees Kelvin. I have done that ever since my high school days and I see no need to change that. I will respect anyone who wants to do it the correct way (ha ha ha).

[@damianoledda5497]

Lectures by Walter Lewin. They will make you ♥ Physics. Wow fast answer! Nice lesson by the way.

[@rsg1682]

Amazing lecturing, if only i had you in my classes 20 years ago :) I was good at school and was never doing anything, i was so bored in class and they were always telling me i was so laisy. I was not laisy, I was just bored of no explanation, it was just feeding of information, that's all. Today I am very good with my hands and understand most of the principles (I am an own made man) but such a lack of theory to go further in life sometimes. Thanks to you :) I love the woman at the end...

[@lecturesbywalterlewin.they9259]

+Jack Eventreur Thanks for your kind words. The "woman at the end" is already married!

[@rsg1682]

Oh ok, thanks for the woman, i prefer to spend time with physics right now ;) and by the way, dank u wel :)

[@lecturesbywalterlewin.they9259]

+Jack Eventreur niets te danken

[@MrThaiko]

That moment when u gets confirmation of Things u thought before, by an experienced teacher. Cant complain lol

[@gamingboys1953]

Way you teach sir is insane and practical application is good thanks inspiring me

[@lecturesbywalterlewin.they9259]

Glad to hear that

[@colliehouse3133]

Thanks for the upload. Excellent.

[@mr.technicalverma7506]

You are very genuine and passionate.

[@abrahamgamez6043]

i study a lot of math calculus ,geometry and others but i dont now use in real living

[@HDitzzDH]

As far as geometry, it is 100% necessary when building structures etc, a big part of engineering, calculus on the other hand can be used to calculate any projectile (spacecrafts, missiles etc), basically to measure the rate of chance in engineering, economy, physics and other topics.

[@adityasalunkhe8156]

wut you taking about man look at world around you its all made of math... sequences of events and series of those sequences its all every phenomenon that happens around you is written in the language of math...you just have to change your abstraction(view) of looking at things.

[@saahtommy2968]

More respect from me to you, my Prof🎖🏆🏅

[@crex-pd1vv]

I knew he was dutch because of his accent

[@TheMainsheet]

c88.rex I thought he came from Austria

[@shivanisethi8864]

Now we know why MIT is one of the best engineering collages.. They are inculcating high levels of practical knowledge.

[@Necropiet]

He wouldn't be as interesting with another haircut

[@distudio7499]

I have never seen such a good physics lecturer like him❤️🔥. Enjoying the physics

[@peterbonnema8913]

I'm seeing no aurora's from space. Im seeing a deathstar

[@studywithjosh5109]

I thought that eddy currents were only produced when a changing magnetic flux passes through the surface of a conductor. Does the rotation of the magnet above the superconductor provide enough change in magnetic flux by itself? 37:30

[@lecturesbywalterlewin.they9259]

Meissner effect

[@raja777m]

I came here to learn levitation ;)

[@lecturesbywalterlewin.they9259]

+Raja Ram Mummadavarapu Google Magentic levitation of trains. Japan just finished their 2nd generation. These trains are not in contact with a rail; they float and the one that was recently finished can go 600 km/hr. That would take 35 min from Boston to NY City. It takes 4 hours with the fastest express US train

[@masada2828]

Raja Ram M - so did I!

[@xcriss2898]

Well done, Prof. Lewin! Thanks!

[@lecturesbywalterlewin.they9259]

:)

[@WongH]

when you know anatomy and look at his heart xD

[@lecturesbywalterlewin.they9259]

❤️

[@VickysTuition]

@6:26 flux doesn't determine the electric field.. For example, take a dipole of +q & -q charge separated by distance d & consider a gaussian surface around it... the enclosed charge will be 0 and the flux will be 0, but the electric field is NOT 0 everywhere. Electric field, E becomes zero only at infinity where the dipole distance d becomes negligible. So, the reason why Flux = 0, but E ≠ 0 is... one side of the gaussian surface has positive flux and on the other side negative flux. Therefore total flux is 0.. but electric field E ≠ 0 everywhere. For example, even at @7:39, the gaussian surface enclosing the HALF depolarised cell will have 0 total enclosed charge... therefore flux = 0 and E field should be 0 by the logic of @6:26 So the reason why (i think) the E field is 0 in one case and not the other is because of the SHAPE of the charge configuration. When it's completely spherical, i think it behaves like a CAPACITOR having E field only in between the concentric plates & 0 everywhere. A capacitor is a SPECIAL dipole which has E field only on the inside. Even in Lec7 @20:23, the professor demonstrates by tearing open a live capacitor and showing the charged plates inside are rolled into concentric circles... So i think this is a circular capacitor like in Lec7.. And when it's halfway depolarised, the perfect circle shape of the capacitor breaks, and we get dipole like field lines near the fringes that's detected outside the heart. (I may be wrong)

[@jeffbrown5318]

Were was you during my physic courses. My teacher just showed up and maybe once a month did some experiments, but rest of the time was told read the books and only come to him if he had questions.. could been alot funner if we had a engaged teacher such as you. Good job and explaining things alot easier

[@lecturesbywalterlewin.they9259]

I am here for you now

[@jeffbrown5318]

thanks.. i see you retired but your one of the best. I gain a better knowledge on your swing. Time that just right.

[@bedobos]

The QRS curve was simply up side down, but it was perfect. (scope input can be negated as well)

[@Daniel-OConnell]

I am a little confused as to source of the energy to spin the magnet at 37:10. I know that the forces are due to Lenz currents , but surely it cannot be a "perpetual motion" machine.

[@lecturesbywalterlewin.they9259]

nothing is perpetual not even the rotation of the Earth about the sun. I believe that I touched the magnet to start the rotation.

[@Daniel-OConnell]

@@lecturesbywalterlewin.they9259 Thank you for the reply. Yes I absolutely understand that there can never be perpetual motion. That is why I was a little confused at what was making the magnet oscillate . Now I can see that it is due to the initial little push, when you put it in position. I really appreciate that you took the time to respond To my query.

[@obayev]

Magnetic levitation is so spectacular... especially with superconductors 😯🤩 Thank you! 🙏

[@lecturesbywalterlewin.they9259]

It really is!

[@physicguy92093]

I have a question , the structure of a generator is stator and rotor when in rotor has its own coils and stator has its own coils, in rotor coils, its used to rotate and it will born and emf and in coil will pass current , but what are coils in stator used for ?

[@lecturesbywalterlewin.they9259]

if the magnets are static then the coil must rotate. rotatng coil will generate an induced EMF (Faraday). The current will go the circuit and through the coil. If the coil can stands still the magnet shoud rotate. An Emf will then be induced in the circuit and the current will again go through the coil. Ask google whether both configurations exist. If ONLY 1 exists most of the time, ask why.

[@physicguy92093]

@@lecturesbywalterlewin.they9259 but i still dont get it why there should be coils in stator when the magnetic fiel can be created very well by poles, and from combination of poles and coils around the pole its called excitation circuit just to hard

[@siddhantjagtap2392]

Sir i am student from India i love your way of fun learning with live demonstration ❤️

[@DigilusionStudios]

Ah HA! The Sodium/Potassium pump. You do a much better explanation of this than any book Ive seen and I work as a Hear Monitor Tech in a Hospital

[@mattevans5812]

I never enjoyed high school until I took physics. Now I found all science fascinating. The problem is when science becomes only about memorizing human given terms it takes the life out of biology the same way walking on a human hamster wheel under artificial light in a cage called a gym takes the life out of going for a walk on a forest trail. We need more Walter Lewin's who demonstrate how amazing things are.

[@damercadoo]

Professor like that is what makes MIT the best university on earth

[@stevenbryant4718]

Oh. Look a little deeper!

[@shivankarsingh7913]

Professor♥ *Thank you very much* for Sending me back to my work , Now I am paying more attention to my SAT and more Enthusiastic for my Physics Learning ( Ast. & Cosm. ) with more Concentration , (( I didn't ask any question of physics in this message but I fell it was necessary to thank you ♥♥ )).

[@lecturesbywalterlewin.they9259]

If the many course in edX, OCW, Coursera and Udacity do not answer your questions that means that *you are not yet able to understand those lectures.* Do not feel bad about that. In the next 5 years you will take courses in cosmology, astrophysics and astronomy and *you will then find your answers all over the web.* That's by far the best way to learn. Your knowledge is yet too low for you to properly interpret and digest my answers. Besides I would have to refer to many existing lectures which is too time-consuming for me. I have a 5 minute upper limit to answering questing.

[@kurtbogle2973]

The Man from the Elegant Universe!

[@omsingharjit]

15:19 what that device called build in PM ????? is it same thing that called Artificial Hearts ????

[@lecturesbywalterlewin.they9259]

ask google - these devices are very common.