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!
The sound of the magnetic domains clicking in the material is amazing. I had read about the domains and interpreted it as a hypotethical explaination(may be because I was not able to understand it completely) but now I know these domains are for real! This demonstration made me shiver and not believing it, I heard it thrice. Hats off to you, Sir.
I don't know why are people watching series and movies having these incredible lessons and demonstrations. You are excellent professor Lewin, I'm really glad every time I see one of your lectures. Thank you for this channel and your life job.
@@vitalino1981 I disagree. I think that the series are more closely related for whatever they're studying/preparing (exam oriented education system, yey!) and hence studying them makes more sense. To-the-point material.
Mr Lewin, this lecture had me stand up, take the battery from TV remote and assemble my own motor. Your courses are such a precious gift to students all over the world. Amazing! What is the formula of such great teaching? Thank you!
@@viratrobbie3259 that's not advertising it's truth How can he tell it in a comment Books are not just written to earn Do you think he would be having problem in earning remember he was a teacher at MIT
Lectures by Walter Lewin. They will make you ♥ Physics. professor,Thanks to your videos,I got a 49 out of 50 in my class test,nobody bettered me,and I will expect to do so in my board exams as well..THANK YOU Professor
This guy makes me feel good about not knowing this stuff, because he makes it seem so simple, even while the equations and descriptions he uses are very complex. Thank you Walter Lewin for helping me remember what it meant to learn about interesting topics, and for being so open to sharing such information. I have lots of respect for you, sir!!!
I was very much excited of this lectures contains 4 demonstrations and a powerpacked Theory class by lewin.....Im so jealous of those people listening lively lewin's class, if im there in lewin class i more luckier but while seeing this lecture via utube....it's ok to be a great fan of him and watching through online.....🙂
Dr. Lewin, I wish I could have studied under you. Such a brilliant man. A friendly science genius who shares his knowledge so artfully and entertainingly. That poor dog in Australia! “You can’t teach an old dog new tricks.”
Hats off for prof Walter. You truly made me love for physics. Believe it or not before I started to watch your videos I hate physics and did study it just for passing the exam. Yet now I have changed myself and started to carry on my entire life linked with physics ❤️❤️
Sr 71 blackbird comes to mind. At Fourth Avenue Jr High Yuma Arizona, I a seventh grade student was lucky to have had amazing teachers. The motor that won in this video I as all of the class built. The winner was whom could biild it faster. I truly enjoyed this video not just for free knowledge, but of how easily he explained it all as commonsense. Muchas gracias from a high school dropout.
Lecturers reduced physics to formulas, and forgot it's about real life, thank you for giving a beautiful visual representation of the concepts you explain, you make all of us love physics
With cracking sound, we infer that atoms changing positions - domain alignment with the field. Will a polycrystalline ferromagnetic material become a single crystalline material so that making single crystals easier? I am wondering this for a quite long time.
Very good. There is an explanation for the domains. In a ferromagnetic material, all the electrons spins at the same direction, both in translation and rotation movements. A pleasure listen to you.
🥰 You are a wonderful teacher❣️ Your students are very blessed to have you for a professor. 💝 Thanks for the great lessons in magneto-electric fields. 🙏💝 I have quite a passion for magnetic fields, piezoelectricity & longitudinal (super~luminal) waves. ✨ 😜 Woo-hoo! 👍😁
Sir ur way of teaching physics inspire many youngminds who come to teaching fields. It's unbelievable to me I cont express my feelings when I hear the sounds of domains. Tq sir
What an absolute mind blowing lecture! Never thought magnetism chapter could be so interesting. Just amazed. Thnx a lot professor for making my brain work ! 🙏🙏🙏🙏🙏🙏🙏
Dear professor, do you have any plans in doing some content in theoritical physics? I would love to see an overview of physics like a guideline for those that gone through your lectures and wants to dive into physics more but does not know where to start. Let me tell you that your lectures are truly amazing and i really miss them when i can't find one in a topic i am currently working on.
Thank you for this amazing lecture and the so many others :) I am actually a master student (in Tunisia) and i would like to know if you have any suggestions on books or lectures about ferromagnetism paramagnetism and diamagnetism on microscopic scale ?
tq u so much sir now I understood diamagnetism.u are the great teacher u make us fall in love with physics. seriously in our college teachers won't explain like u sir .A great HADSOFT TO YOU SIR
While it maybe pedagogically warranted and simpler to explain as Prof Lewin has presented it but domains do not really change their direction of polarization in response to an external bias field, instead the boundaries between neighbors move in such a way as to increase (or decrease) the overall magnetization along with the bias field. The Barkhausen noise is not because the domains change their polarization but because the boundaries are moving and thereby changing the relative size of the several domains. The hysteresis can be conceived as resulting from the boundaries moving but with friction.
Walter Lewin for physics and Andrew Szydlo for chemistry and Matt Parker for math. Just as every teacher should be - they totally grasp you and even if you already know what they are talking about, you can not stop listening and watching.
Amazing experiments! U are teaching us from miles away and coming from past taking us to future. I was a impertient, ignorant teenager while this video was being recorded :)
Im agravated to have never had the oppurtunity to be tought by Lewin. im late to the facination of physics. the Lectures i study on youtube are like treasure.
Sir u are great. Ur problem solving and concept classes really help to solve the extraordinary problems of jee advance. Can u plz come with many more conceptual lectures on u tube. I really thankfull to u to blow my interest in physics Also.
Professor, what metal do you suggest to use in a solenoid for being able to reverse its field by changing the current. Soft iron is incredibly expensive and difficult to find. I would appreciate it if you could reply to me with an easy-to-access substitution of soft iron I could use in my project :)
Sir, why are the ferromagnetic materials used as magnetic shields? Ferromagnetic materials have large magnetic permeability, thus the magnetic field inside a ferromagnetic material increases to a larger value as compared to that in vaccum or air. Then, how does a ferromagnetic material stop or shield the external magnetic field ??
Dear Walter, from the lecture i understand that your idea of B field energy source of permanent magnet (PM) is kinetic energy of (charged) electron circle movement, if this idea reflect real nature then what happens when this energy used (as example when PM lifting metal and keeping it on the fly - oppose gravity force)? Regarding conservation law we have only 3 options to see this energy used from - a) charge loose? b) speed loose (and so radius decrease) c) mass decrease? Do you think some of this happens really in nature?
Lectures by Walter Lewin. They will make you ♥ Physics. as i understand it is directly related to KE (as I generated by circle movement of charged electron - change speed of rotation and we will see I change)...if i wrongly understand you explain please in short from where energy coming then of B field of permanent magnet?
Imagine you have 2 permanent magnets. They attract each other. You pull them apart. YOU have to do work to do that. Now you release them and the work that YOU did is now released. In other words, YOU did the work.
The Bohr-van Leeuwen theorem, discovered in the 1910s, showed that classical physics theories are unable to account for any form of magnetism, including ferromagnetism. Magnetism is now regarded as a purely quantum mechanical effect. Ferromagnetism arises due to two effects from quantum mechanics: spin and the Pauli exclusion principle.
en.wikipedia.org/wiki/Ferromagnetism The Bohr-van Leeuwen theorem, discovered in the 1910s, showed that classical physics theories are unable to account for any form of magnetism, including ferromagnetism. Magnetism is now regarded as a purely quantum mechanical effect. Ferromagnetism arises due to two effects from quantum mechanics: spinand the Pauli exclusion principle.
In the demonstration with the speaker and ferromagnetic material in the coil.After the magnetic domains align and you pull away the magnet will the disalignment of the domains in the ferromagnetic material cause a magnetic flux change.
+daniel; njuguna Make them LOVE physics and let them feel that you LOVE them too. Your enthusiasm and energy and love should be contagious. Make them laugh, make them cry, make them sit on the edge of their seats, make them stop breathing and even make them sometimes wet their pants. YES, I CAN DO ALL THAT whenever I want to.
I have tried n it is working. Thank you prof. I need more resources because some of the experiments you do are too lively n motivate students because they can associate themselves with it
Respected sir, at time 9:03 you said that 'all materials when you exposed them to an external magnetic field will to some degree oppose the external magnetic field. However, in the case of paramagnetic materials, the induced magnetic dipoles are such as to increase the external magnetic field. Here, I am confused about the phrase 'all materials'.
Hello proffesor, B=KB does that mean that even if the material is paramagnetic, a really strong magnetic field would be able to counter it´s weight and thus making it possible for it to hang on the magnet?
sir if I want to learn more about quantum mechanics do I have to learn langrarian or hamiltonian mechanics? I want to understand magnetic dipole moment more clearly.
Hello, in the laboratory I saw the following phenomenon: A metal ball is held by an electromagnet but if the switch is opened or the source is disconnected, it remains there for a long time, it does not fall. Sometimes it happens, sometimes it doesn't, for no apparent reason. The strangest thing is that if the voltage of the source is increased and then disconnected, the sphere is less magnetized than when the voltage was lower. The voltages are small values of 1.5 v of 3v What could be the reason for this?
Prof at the end of the lecture liquid oxygen the magnetic force is horizontal , because domains align parallel to magnetic but where does the vertical force comes into play, I could not get could you please clarify ❤️❤️
Hello Professor, Merry Christmas! You said that there is a reason why the induced magnetic moments on an atomic scale try to oppose the external *stationary* magnetic field can you please name this phenomenon so that I may read up on this? As always thank you for your support :)
+Lectures by Walter Lewin. They will make you ♥ Physics. Thank you Professor, and thank you for showing us both fire and ice in the same video.. (Robert Frost reference anybody?)
Professor Lewin, in this lecture you stress repeatedly that the poles of the magnet need to have a nonuniform field for the ferromagnetic material to have an effect and have a stronger field than the vacuum field. Could you elaborate on this please?
Hi Prof. Do you also have a course or lectures that deal with magnetism in terms of quantum mechanics? Topics that were left untouched in 8.02 simply because the scope was limited?
How current depends on loudness created by change in domains direction? Is it because of heat generated through out or any other reason? Please anyone having answer ,Respond.
sir electron moves around the the nucleas. when the magnetic dipole moment due to this motion of the electron the magnetic moment of the atom = current *area of the orbit in which electron is moving. sir electron also spin is there will be magnetic dipolemoment associated with this motion of the electron.
Sir, I am not having Gaincoli's physics for scientists and engineers instead I have physics for scientists and engineer by Serway and Jewett. Is it okay to solve problems from it. It has topicwise problem set at the end of each chapter. So, should I solve those topicwise problem after watching the lecture of a certain topic?
When a material having permanent electric dipoles is placed in an external electric field, we say that the electric field inside the material is reduced. But when a material having permanent magnetic dipoles is placed in an external magnetic field, we say that the magnetic field inside the the material is increased. Why is that sir? The below dipole configurations with E and B +Q/ -+ -+ -+ -+ /-Q N/ sn sn sn sn /S The magnetic situation should be similar to electric situation. Correct?
@@lecturesbywalterlewin.they9259 thank you much sir for a fast reply. Another question sir. With cracking sound, we understand that atoms changing positions. Will a polycrtstalline ferromagnetic material become a single crystalline material? I am wondering this for a quite long time.
Professor, I had a very general doubt. I am not able to understand this: When a material with many electric dipoles (say polar molecules) is placed in an electric field, its dipole align to create surface charge densities which OPPOSE applied field. But, when a material with magnetic dipoles (say paramagnetic or ferromagnetic) is placed in magnetic field, its dipoles align to ENHANCE the applied field to a certain extent. Can you tell why does dipole alignment in magnetism enhances the field. Or why not the alignment of electric dipole enhance the field ?If I am wrong in facts, please correct me.
Place a compass in the Earth magnetic field. It will rotate till it has reached the minimal energy state. That is when the B field of the magnet of the compass aligns with the B field of the Earth magnetic field and that enhances the B-field. Take two permanent magnets bring them close to each other. They will also align (minimum energy state) which will also enhance the magn field.
take a permanent magnet #1. Draw field lines at its North Pole. Take a 2nd magnet #2 and draw field lines near its S pole. Now place the N pole of magn 1 against S pole of magnet 2. The B-field at the N pole of #1 has doubled.
Professor, since paramagnetic materials have an increase in relative permeability with decrease in temperature, and ferromagnetic materials lose their ferromagnetic properties with increase in temperature beyond the Curie point, does that mean that ferromagnetic substances will have an increase in their ferromagnetic property with decrease in temperature, like paramagnetic substances?
Castor Gemini Castor that is a very good question. Clearly if you move away (by cooling) from the Curie temperature, T_C, the strength of the ferromagnetic properties increase. However, if you go far enough below T_C the increase is very very small and asymptotically approaches the maximum. I suggest you look at the schematic figure 3.8 in the following article. www.cmp.liv.ac.uk/frink/thesis/thesis/node40.html
@8:30 Why it is the area A that is the vector rather than the current I in the formula for magnetic moment?! I see current having the direction, rather then a surface.
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!
Thnx sir!!☺
Sir what is the cause of diamagnetism ...Why the atoms oppose the external field ??..Plz.help me sir!
@Anupam he told that it has something to do with quantum mechanics
@@anupambiswas8746 if you have studied 12th grade physics , you will know
which website?
Really, the domains generating a sound is unbelievable. I don't know, who would ever imagine such a possibility of demonstrating domains! Hat's off!
guitar pickup.
The sound of the magnetic domains clicking in the material is amazing. I had read about the domains and interpreted it as a hypotethical explaination(may be because I was not able to understand it completely) but now I know these domains are for real! This demonstration made me shiver and not believing it, I heard it thrice. Hats off to you, Sir.
+Anery Patel yes Anery, it is amazing!
The more I listen to Dr. Lewin, the more I love him. One of kind. Thank you for sharing your wisdom.
I don't know why are people watching series and movies having these incredible lessons and demonstrations. You are excellent professor Lewin, I'm really glad every time I see one of your lectures. Thank you for this channel and your life job.
:)
Mauricio Barda
People like to watch series because it's not require brain, in opposite to learning process.
@@vitalino1981 I disagree. I think that the series are more closely related for whatever they're studying/preparing (exam oriented education system, yey!) and hence studying them makes more sense. To-the-point material.
😄 I agree. 🧐 I could watch this guy all day. 😍 He's wonderful! 👍
Mr Lewin,
this lecture had me stand up, take the battery from TV remote and assemble my own motor. Your courses are such a precious gift to students all over the world. Amazing!
What is the formula of such great teaching?
Thank you!
+Vadim Tikanov Thanks for your kind words. You can find the formula of "such great teaching" in my book "For the Love of Physics".
@@lecturesbywalterlewin.they9259 that is some amazing advertising professor! XD Big fan from india,and of the book!!
@@viratrobbie3259 that's not advertising it's truth How can he tell it in a comment
Books are not just written to earn
Do you think he would be having problem in earning remember he was a teacher at MIT
Lectures by Walter Lewin. They will make you ♥ Physics. professor,Thanks to your videos,I got a 49 out of 50 in my class test,nobody bettered me,and I will expect to do so in my board exams as well..THANK YOU Professor
SUPER
This guy makes me feel good about not knowing this stuff, because he makes it seem so simple, even while the equations and descriptions he uses are very complex. Thank you Walter Lewin for helping me remember what it meant to learn about interesting topics, and for being so open to sharing such information. I have lots of respect for you, sir!!!
I was very much excited of this lectures contains 4 demonstrations and a powerpacked Theory class by lewin.....Im so jealous of those people listening lively lewin's class, if im there in lewin class i more luckier but while seeing this lecture via utube....it's ok to be a great fan of him and watching through online.....🙂
Whenever I watch this teacher I'm amazed the way he explain the teachings and also the experiments. My highest tespects.
Sir, you have explained to me the concepts of dia-, para- ferro- magnetism better than anybody else.... thanks for making me a fan of Physics again...
Dr. Lewin, I wish I could have studied under you. Such a brilliant man. A friendly science genius who shares his knowledge so artfully and entertainingly. That poor dog in Australia! “You can’t teach an old dog new tricks.”
Hats off for prof Walter. You truly made me love for physics. Believe it or not before I started to watch your videos I hate physics and did study it just for passing the exam. Yet now I have changed myself and started to carry on my entire life linked with physics ❤️❤️
Sr 71 blackbird comes to mind. At Fourth Avenue Jr High Yuma Arizona, I a seventh grade student was lucky to have had amazing teachers. The motor that won in this video I as all of the class built. The winner was whom could biild it faster. I truly enjoyed this video not just for free knowledge, but of how easily he explained it all as commonsense. Muchas gracias from a high school dropout.
Lecturers reduced physics to formulas, and forgot it's about real life, thank you for giving a beautiful visual representation of the concepts you explain, you make all of us love physics
This man has a talent for explaining physics + the budget obviously
What a legend. Grateful to be alive in the same era as him.
I don't think who is this first time I saw you in RUclips but u r every best teacher of physics 🙏🙏🙏🙏🙏
With cracking sound, we infer that atoms changing positions - domain alignment with the field. Will a polycrystalline ferromagnetic material become a single crystalline material so that making single crystals easier? I am wondering this for a quite long time.
I am indian and i watched professor s 21 lectures straight ❤ may be many of them I watched twice❤❤❤
Very good.
There is an explanation for the domains. In a ferromagnetic material, all the electrons spins at the same direction, both in translation and rotation movements.
A pleasure listen to you.
This lecture had greatly helped me for my seminar... Thank you Lewin sir...
🥰 You are a wonderful teacher❣️ Your students are very blessed to have you for a professor. 💝 Thanks for the great lessons in magneto-electric fields. 🙏💝 I have quite a passion for magnetic fields, piezoelectricity & longitudinal (super~luminal) waves. ✨ 😜 Woo-hoo! 👍😁
Sir ur way of teaching physics inspire many youngminds who come to teaching fields.
It's unbelievable to me
I cont express my feelings when I hear the sounds of domains.
Tq sir
It's my pleasure
Dear professor your guidance is inspiration for young generation.salute to your great efforts.❤from India.
jee 2024 aspirant ?
Wowwwww
What an absolute mind blowing lecture! Never thought magnetism chapter could be so interesting. Just amazed. Thnx a lot professor for making my brain work ! 🙏🙏🙏🙏🙏🙏🙏
Most welcome!
the Dipoples-domain experiment at 28:35 certainly put a smile on my face, truly amazing
Dear professor, do you have any plans in doing some content in theoritical physics? I would love to see an overview of physics like a guideline for those that gone through your lectures and wants to dive into physics more but does not know where to start.
Let me tell you that your lectures are truly amazing and i really miss them when i can't find one in a topic i am currently working on.
I retired in 2009. Use MIT OCW and edX for lectures on theoretical Physics,
Best ever lecture. 👌🏾👌🏽👌🏿👌🏾👌🏽👌🏿👌🏾👌🏽👌🏽👌🏾👌🏿👌🏽👌🏿👌🏽👌🏿🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏💎💎💎💎💎💎💎💎💎💎😘😘😘😘😘😘😘😘😘😘💪💪💪💪💪💪💪💪💪💪👼👼👼👼👼👼👼👼👼👼Keep it up 👍
This man's ability to communicate is amazing.
Can u tell ur magnitude and direction
Thank you for this amazing lecture and the so many others :) I am actually a master student (in Tunisia) and i would like to know if you have any suggestions on books or lectures about ferromagnetism paramagnetism and diamagnetism on microscopic scale ?
search the web
ok i will :)
tq u so much sir now I understood diamagnetism.u are the great teacher u make us fall in love with physics. seriously in our college teachers won't explain like u sir .A great HADSOFT TO YOU SIR
It's my pleasure
29:30 That was impressive!!! Thanks a lot Prof
demonstrations are very good and amazing. thank you Sir!!
great sir
this is the actual teaching of science through experiments
i am also trying to teach chemistry to my students
thanku sir
with LOVE
While it maybe pedagogically warranted and simpler to explain as Prof Lewin has presented it but domains do not really change their direction of polarization in response to an external bias field, instead the boundaries between neighbors move in such a way as to increase (or decrease) the overall magnetization along with the bias field. The Barkhausen noise is not because the domains change their polarization but because the boundaries are moving and thereby changing the relative size of the several domains. The hysteresis can be conceived as resulting from the boundaries moving but with friction.
:)
Utube must add a love button....atleast for such awesome lectures:)
Many thanks for such a breathtaking demonstrations!
You're very welcome!
Walter Lewin for physics and Andrew Szydlo for chemistry and Matt Parker for math. Just as every teacher should be - they totally grasp you and even if you already know what they are talking about, you can not stop listening and watching.
Absolutely legendary lecture, I miss having lectures like this.
When the bolt cooled down, would it be more magnetic than before? I’m guessing it would since the atoms are in a magnetic field as they stop moving.
Amazing experiments! U are teaching us from miles away and coming from past taking us to future. I was a impertient, ignorant teenager while this video was being recorded :)
Dear sir, i am your great fan, i am a PGT physics teacher from India, Bihar 🙏.
Great 👍
The demonstrations are undoubtedly very insightful. Would appreciate a reciprocation from Prof. Lewin so that I can share ideas.
First rate demos, and very clear explanations.
Thank you kindly!
Passion is obvious & makes this fun and understandable
Im agravated to have never had the oppurtunity to be tought by Lewin. im late to the facination of physics. the Lectures i study on youtube are like treasure.
Thanks for making your lectures available.
Sir u are great. Ur problem solving and concept classes really help to solve the extraordinary problems of jee advance. Can u plz come with many more conceptual lectures on u tube. I really thankfull to u to blow my interest in physics Also.
Great Lecture from a great Prof.
He is the gift that keeps giving.. if you dont love him, see your cardiologist!.. you don't have a heart!!!
:)
Professor Lewin, thanks for sharing all this information. Greetings from Santiago-Chile.
Thank you for your contribution to worldwide science.
29:41 that's the most fascinating demonstration of yours
Professor, what metal do you suggest to use in a solenoid for being able to reverse its field by changing the current. Soft iron is incredibly expensive and difficult to find. I would appreciate it if you could reply to me with an easy-to-access substitution of soft iron I could use in my project :)
any ferromagnetic material will do
Sir, why are the ferromagnetic materials used as magnetic shields?
Ferromagnetic materials have large magnetic permeability, thus the magnetic field inside a ferromagnetic material increases to a larger value as compared to that in vaccum or air.
Then, how does a ferromagnetic material stop or shield the external magnetic field ??
good question -use google
Dear Walter,
from the lecture i understand that your idea of B field energy source of permanent magnet (PM) is kinetic energy of (charged) electron circle movement,
if this idea reflect real nature then what happens when this energy used (as example when PM lifting metal and keeping it on the fly - oppose gravity force)? Regarding conservation law we have only 3 options to see this energy used from - a) charge loose? b) speed loose (and so radius decrease) c) mass decrease? Do you think some of this happens really in nature?
It's NOT KE
Lectures by Walter Lewin. They will make you ♥ Physics. as i understand it is directly related to KE (as I generated by circle movement of charged electron - change speed of rotation and we will see I change)...if i wrongly understand you explain please in short from where energy coming then of B field of permanent magnet?
Imagine you have 2 permanent magnets. They attract each other. You pull them apart. YOU have to do work to do that. Now you release them and the work that YOU did is now released. In other words, YOU did the work.
The Bohr-van Leeuwen theorem, discovered in the 1910s, showed that classical physics theories are unable to account for any form of magnetism, including ferromagnetism. Magnetism is now regarded as a purely quantum mechanical effect. Ferromagnetism arises due to two effects from quantum mechanics: spin and the Pauli exclusion principle.
en.wikipedia.org/wiki/Ferromagnetism
The Bohr-van Leeuwen theorem, discovered in the 1910s, showed that classical physics theories are unable to account for any form of magnetism, including ferromagnetism. Magnetism is now regarded as a purely quantum mechanical effect. Ferromagnetism arises due to two effects from quantum mechanics: spinand the Pauli exclusion principle.
In the demonstration with the speaker and ferromagnetic material in the coil.After the magnetic domains align and you pull away the magnet will the disalignment of the domains in the ferromagnetic material cause a magnetic flux change.
yes
Sound of domainsclicking is astonishing. :)
The device is basicly a nanophone if regular mic is a microphone.
:D
University Phyiscs and Oxford EEE Dictionary mention Faraday's Law to be the cause behind diamagnetism, in their latest editions.
What was that around 6:06 - 6:07 where the pink chalk is kept. Notice carefully with minimum playback speed.
Ya I noticed it
The lecture was really intuitive. I am here to brush up a bit haha. thanks, sir. Awesome! Very good your lectured.
I love physics myself. if only i can change the attitude of my students towards physics I will be the happiest person on earth
+daniel; njuguna Make them LOVE physics and let them feel that you LOVE them too. Your enthusiasm and energy and love should be contagious. Make them laugh, make them cry, make them sit on the edge of their seats, make them stop breathing and even make them sometimes wet their pants. YES, I CAN DO ALL THAT whenever I want to.
I have tried n it is working. Thank you prof. I need more resources because some of the experiments you do are too lively n motivate students because they can associate themselves with it
yours is more lively because it is interactive and deals with real objects
Inspiring teaching as always!
Respected sir, at time 9:03 you said that 'all materials when you exposed them to an external magnetic field will to some degree oppose the external magnetic field. However, in the case of paramagnetic materials, the induced magnetic dipoles are such as to increase the external magnetic field. Here, I am confused about the phrase 'all materials'.
listen again to what I said 9:03
Hello proffesor, B=KB does that mean that even if the material is paramagnetic, a really strong magnetic field would be able to counter it´s weight and thus making it possible for it to hang on the magnet?
en.wikipedia.org/wiki/Paramagnetism
sir if I want to learn more about quantum mechanics do I have to learn langrarian or hamiltonian mechanics? I want to understand magnetic dipole moment more clearly.
>>sir if I want to learn more about quantum mechanics do I have to learn langrarian or hamiltonian mechanics?>>
YES
Hello, in the laboratory I saw the following phenomenon:
A metal ball is held by an electromagnet but if the switch is opened or the source is disconnected, it remains there for a long time, it does not fall. Sometimes it happens, sometimes it doesn't, for no apparent reason.
The strangest thing is that if the voltage of the source is increased and then disconnected, the sphere is less magnetized than when the voltage was lower. The voltages are small values of 1.5 v of 3v
What could be the reason for this?
Wow
I have only one Thumbs Up.
Love You Sir.
Long Live
Prof at the end of the lecture liquid oxygen the magnetic force is horizontal , because domains align parallel to magnetic but where does the vertical force comes into play, I could not get could you please clarify ❤️❤️
Hello Professor, Merry Christmas!
You said that there is a reason why the induced magnetic moments on an atomic scale try to oppose the external *stationary* magnetic field can you please name this phenomenon so that I may read up on this?
As always thank you for your support :)
+Ayan Gangopadhyay It's dia- or para-magnetism.
+Lectures by Walter Lewin. They will make you ♥ Physics. Thank you Professor, and thank you for showing us both fire and ice in the same video.. (Robert Frost reference anybody?)
Why the rotor made by Jung Eun doesn’t oscillate like in the case of rectangular circuit shown in The Torque lecture?
Your lectures are very colourful .
Professor Lewin, in this lecture you stress repeatedly that the poles of the magnet need to have a nonuniform field for the ferromagnetic material to have an effect and have a stronger field than the vacuum field. Could you elaborate on this please?
use google
May be you can try an oscillating pendulum with a french Franc and a candle. It was a pure nickel coin for a few years and hence a common display
Love you Dr. Sanders! 💓🔭
Hi Prof.
Do you also have a course or lectures that deal with magnetism in terms of quantum mechanics? Topics that were left untouched in 8.02 simply because the scope was limited?
MIT's QM courses 8.04 and 8.05 are on my channel
How current depends on loudness created by change in domains direction? Is it because of heat generated through out or any other reason? Please anyone having answer ,Respond.
sir electron moves around the the nucleas. when the magnetic dipole moment due to this motion of the electron the magnetic moment of the atom = current *area of the orbit in which electron is moving. sir electron also spin is there will be magnetic dipolemoment associated with this motion of the electron.
use google
Sir, I am not having Gaincoli's physics for scientists and engineers instead I have physics for scientists and engineer by Serway and Jewett. Is it okay to solve problems from it. It has topicwise problem set at the end of each chapter. So, should I solve those topicwise problem after watching the lecture of a certain topic?
Sir, what is the definition of a vacuum field? Thanks for your terrific lectures.
use google
He was the heart of MIT
Congratulation for excellent presentation!
I wonder if she still has the thermometer?
I have a thermometer just like that.
When a material having permanent electric dipoles is placed in an external electric field, we say that the electric field inside the material is reduced. But when a material having permanent magnetic dipoles is placed in an external magnetic field, we say that the magnetic field inside the the material is increased. Why is that sir? The below dipole configurations with E and B
+Q/ -+ -+ -+ -+ /-Q
N/ sn sn sn sn /S
The magnetic situation should be similar to electric situation. Correct?
system goes to Low PE in both cases.
@@lecturesbywalterlewin.they9259 thank you much sir for a fast reply.
Another question sir.
With cracking sound, we understand that atoms changing positions. Will a polycrtstalline ferromagnetic material become a single crystalline material? I am wondering this for a quite long time.
Really outstanding
Inspiring preparations and demos Professor! Well Done & awesome!!
Thank you Professor
Congratulations for the 500000 followers
He. Is great, love these lectures
hello, Walter. Paper has a magnetic effect? I would rather think, it is a statical electrical charge doing that with paper.
paper - magn effect ??????
at about 19:00 You told "paper....." clips-- I gues its misundestanding at my side
Respect to Sir Walter Lewin from Pakistan 🙇
Epic lecture sir
:)
Professor, I had a very general doubt.
I am not able to understand this:
When a material with many electric dipoles (say polar molecules) is placed in an electric field, its dipole align to create surface charge densities which OPPOSE applied field.
But, when a material with magnetic dipoles (say paramagnetic or ferromagnetic) is placed in magnetic field, its dipoles align to ENHANCE the applied field to a certain extent. Can you tell why does dipole alignment in magnetism enhances the field.
Or why not the alignment of electric dipole enhance the field ?If I am wrong in facts, please correct me.
Place a compass in the Earth magnetic field. It will rotate till it has reached the minimal energy state. That is when the B field of the magnet of the compass aligns with the B field of the Earth magnetic field and that enhances the B-field. Take two permanent magnets bring them close to each other. They will also align (minimum energy state) which will also enhance the magn field.
I am sorry Professor but the thing is I can't understand is WHY IS MAGNETIC FIELD ENHANCED when magnetic dipoles align with external field.
take a permanent magnet #1. Draw field lines at its North Pole. Take a 2nd magnet #2 and draw field lines near its S pole. Now place the N pole of magn 1 against S pole of magnet 2. The B-field at the N pole of #1 has doubled.
Professor, since paramagnetic materials have an increase in relative permeability with decrease in temperature, and ferromagnetic materials lose their ferromagnetic properties with increase in temperature beyond the Curie point, does that mean that ferromagnetic substances will have an increase in their ferromagnetic property with decrease in temperature, like paramagnetic substances?
Castor Gemini Castor that is a very good question. Clearly if you move away (by cooling) from the Curie temperature, T_C, the strength of the ferromagnetic properties increase. However, if you go far enough below T_C the increase is very very small and asymptotically approaches the maximum. I suggest you look at the schematic figure 3.8 in the following article. www.cmp.liv.ac.uk/frink/thesis/thesis/node40.html
Thanks Professor!
Sir how when the magnetic dipole moment of atom is aligned with the external magnetic field than atom has minimum potential energy
yes, but classical physics is insufficient to handle this properly. QM is required.
Wow 🤩🤩 awesome thanks sir for making physics interesting 😊
@8:30 Why it is the area A that is the vector rather than the current I in the formula for magnetic moment?! I see current having the direction, rather then a surface.
You make teaching a science.
Best demonstration
thank you