This is the most beautiful presentation ever. For the first time I realize that a standing wave is nothing more than a cosine modulating the amplitude of a sine wave. Amazing. I love you!
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!
I will never forget you Professor Walter Lewin. You are the only physicist that taught Physics with great care and thoroughness in terms concept. Your demonstration proves extremely valuable that registers in my mind. I thank God for your life, and contribution to teaching physics in a way that makes me appreciate and love Physics. You enlightened me of all the topics that I didn’t really understand the concept well, or sometimes not at all because of lack of faculty by others. You are such a gift in the world of Physics. Thank you Professor 🙏.
Sir you explained standing waves to me! My physics teacher had confused me. Thank you so much!! You are the best physics teacher I will ever see. I KNOW IT
I honestly have reconsider many times going on in my University in Italy since I had no problem in mathematics but Physics was making me bored, at a point that I was going to Economics and Politics because it were more real to me. Thanks is not enough professor, if you'll come back to Europe one day and make a trip in Venice, I'll be the one unveloping the red carpet all over Venice. My next-to-be AeroSpace Engineering Degree is largely becaming a dream come true thanks to you Professor, you made me interested again in Physics and the applications it has.
The simple mention of the fact that, in the standing wave equation, the spatial and temporal information is not interlinked makes for a great tool for understanding how standing waves aren't being shifted left or right (speaking purely in terms of vertical vs. horizontal displacement). Excellent explanation of the standing wave professor. Thank you!
Dr. Lewin, I've watched several of your lectures since the start of my first year in my physics major and I just wanted to take the time today to thank you for all your dedication you put into these lectures. Thank you for your amazing teaching and making me love physics.
This is the first Walter Lewin lecture I have ever seen and this is the best lecture I came across in my entire life. Now I know why you are famous :D Cheers from India! ❤❤❤
You are an incredible teacher and a wonderful human being. You involved your students in the lecture and gave them a chance to demonstrate their talents to everyone. Very rarely is this the case - most teachers are content showing off their own talents (if even that). I will remember this lesson - to give others the chance to impress me - because you never know what amazing talents people have hidden.
sir,i'm a student of class 11. I regularly follow your lecture and your teaching come alive to me. I love u sir as well as Physics. Huge respect and love from BANGLADESH.
After i watched this lecture i downloaded a software oscilloscope(for microphone) and a frequency generator and i am testing various frequency's and harmonics to find nodes and i am sliding with my chair slowly away from the speakers to find nodes ..its really fun when i find a node i feel a drop in pressure..its been 2 hours i have been doing this LOL and not bored at all! thankyou prof. lewin
could you please share the source to download the software? I would really appreciate it. I too am interested in trying it on my piano and having some fun
✨learning, performing, playing & even listening to music over1/2 my life & I now know I never really understood music ! Actually I may/ will need watch this again & possibly again😬🤫😁 Thank you Sir! ✨
Many Thank You for the Great job you have done! Probably the only clear explanation (at least for me) of the standing waves that I have come across. Bless you!
really amazing lecture. I didn't understood these when my physics teacher thought us this . He just wrote bunch of equations that and no one listen to him . Now i am foing all these again and hopeful to find your lecture ( I am preparing for jee so i am reading all thses)
35:03 third harmonic actually because the interval with the next one is a fourth. And 35:18 is the second harmonic because the interval with the harmonic above it is a fifth.
So far I was wondering how the standing wave phenomenon possible. My mind was a mess. Now it's cristal clear how this bizarre thing happens. Thank you so much professor. I love you so much ♥️♥️♥️
Sir, great fan 🫡. I would like to know about the rope you've used and what kind is ideal for this demo. e.g., Plastic/Nylon ones are too rigid to show the reflection and standing waves. Any suggestion will be highly appreciated
In reed based woodwinds instruments, e.g. clarinet or saxophone, if one blowconstantly on a note, theb open the register hole which eliminate the fubdamental freq so you get a note in hugher octave but then you close the hole and magically you do not get the low fundamental as long as you continue blowing air in. Only when one stops and dtart again the low fundamental freq appears again. I wonder why?
First of all. These lectures are simply beeaautiful. Thank you for making them aviable for everyone. In the aparatus shown, the fact that the waves are aparently static is due to a recognition of the machine of the frequency of the particular wave?
Hello, Professor Lewin. My textbook used cosine to represent standing wave instead of sine. So, y1 + y2 = 2ysin(kx)sin(wt). I felt confused. Are they the same? Can you explain it to me?
+JunYu Lei If the string is closed at both sides, then at x=0 and at x=L the displacement must always be zero. As long as your solution meets those conditions it does not matter whether you have sin or cos. If the string is closed at one end but open at x=L, then your solution should give a displacement of 0 at x=0 at all times and dy/dx must be zero at all times. As long as your solution meets those conditions it does not matter whether you have sin or cos.
I love you, sir. You've been my whole world since 11th grade. You really made me love physics. Please don't die before I come to America ;) . I really wanna meet you.
You pick a 4 unique music instruments based by its special point. I interest in the swinging string and the instrument that produce low-tone sound as it is work like ancient music instrument, we use string pundulum and metal another one sound like some kind of shell (hard to find for a perfect voice).
In case of fundamental frequency, we always get high amplitude as compared to other harmonics so is it safe to say that if we want to have destructive resonance then fundamental frequency is the most suitable option for it?
This will often be true. However, it's in principle possible for objects to break much easier in the second harmonic than in the fundamental. Suppose you took a glass rod of length L which is thinner (thus weaker) near L/4 and 3L/4.. It may then be easier to break it when you excite it in first harmonic above the fundamental than in the fundamental. There may be many objects (including bridges and glass wear) that are more vulnerable at res freq above the fundamental than at the fundamental.
I have a question about the traveling wave equation y=2sin3(x-6t). When I search on the internet I always find that the equatin is y=2sin(wt-kx). When we write equation for AC voltage it's also u(t)=U*sin(wt + "theta" ). So I'm not sure which one is correct. Please forgive me if I am missing something obvious, thank you in advance.
+Nikola Vulinovic TRAVELING WAVES y=2sin3(x-6t) = 2sin(3x-18t). Thus k = 3 (lambda = 2.1m) and omega is 18 rad/sec. y=2sin(wt-kx) => y=-2sin(18t-3x). Again lambda = 2.1 m and omega = 18 rad/sec. The - sign is a phase change of 180 degrees. NO PROBLEM! These are TRAVELING WAVES!
+Lectures by Walter Lewin. They will make you ♥ Physics. Thank you so much for clearing that up for me and answering so quickly. I see now that I need to study a bit more before asking a question. I would just like to take the opportunity to say that I love your lectures they're so interesting and helpful, Thank you again very much.
Sir, I have a question about standing wave, if wave (when it reflects from the wall) changes its phase for 180 degrees shouldnt then the reflected and the coming wave be out of phase and cancel each other
sir, in sin(kx-ωt) , if i substitute x=vt , where is the linear velocity of the wave and you said v=ω/k. Then k gets cancelled and i get the remaining ωt. So then ωt - ωt becomes zero. I know this is not correct but pls tell me where am i making mistake. waiting sir..............
kx measures the number of radians travelled by a point on the wave to get to a particular x value. wt measures the number of radians travelled by a point on the wave to get to a particular t value. x and t are independent dimensions. By linking them you're tracking a single point not an infinite sine wave. So kx - wt becomes "take the number of radians it took to get to this place in space minus the number of radians it took to get to this place in time" which are obviously always the same.
Prof Lewin, Flute is closed at one end and through the other end, air is blown. How do we hear music? Isn't the wave trapped inside the flute? How does the music escape? Just one line from you from would suffice. Hope my dumb questions doesn't cause irritation/annoyance. I am just trying to make an analogy with antenna as I've an engineering degree.
umm in the beginning,, so 18 is the omega.. but isn't omega suppose to have pi or at least a degree symbol in it..?? I don't get why the omega can be just an integer without any degree symbol..
This is the most beautiful presentation ever. For the first time I realize that a standing wave is nothing more than a cosine modulating the amplitude of a sine wave. Amazing. I love you!
:)
@Za Yn you should mention india not kashmir we need to represent our country not unionterritory
@@sudhamshreddy2756 I guess he has deleted his comment
@@sudhamshreddy2756 bro why are you Indians so wierd. Always saying love from India. It’s not that deep
@@lukaide6359 love you from india🇮🇳🇮🇳🇮🇳
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!
Lectures by Walter Lewin. They will make you ♥ Physics. Thanks
❤❤❤❤
26:27
Then it gets to the brains, if there are any.
🤣🤣🤣🤣
Lectures by Walter Lewin. They will make you ♥ Physics. Thanks
You actually made me fall in love with Physics. You are the Legend, Sir!
I will never forget you Professor Walter Lewin. You are the only physicist that taught Physics with great care and thoroughness in terms concept. Your demonstration proves extremely valuable that registers in my mind. I thank God for your life, and contribution to teaching physics in a way that makes me appreciate and love Physics. You enlightened me of all the topics that I didn’t really understand the concept well, or sometimes not at all because of lack of faculty by others. You are such a gift in the world of Physics. Thank you Professor 🙏.
Sir you explained standing waves to me! My physics teacher had confused me. Thank you so much!! You are the best physics teacher I will ever see. I KNOW IT
😊
I honestly have reconsider many times going on in my University in Italy since I had no problem in mathematics but Physics was making me bored, at a point that I was going to Economics and Politics because it were more real to me.
Thanks is not enough professor, if you'll come back to Europe one day and make a trip in Venice, I'll be the one unveloping the red carpet all over Venice.
My next-to-be AeroSpace Engineering Degree is largely becaming a dream come true thanks to you Professor, you made me interested again in Physics and the applications it has.
The simple mention of the fact that, in the standing wave equation, the spatial and temporal information is not interlinked makes for a great tool for understanding how standing waves aren't being shifted left or right (speaking purely in terms of vertical vs. horizontal displacement).
Excellent explanation of the standing wave professor. Thank you!
I usually find animation more helpful to understand. But animation are nothing compared to these practical examples. You are a legend :).
Dr. Lewin, I've watched several of your lectures since the start of my first year in my physics major and I just wanted to take the time today to thank you for all your dedication you put into these lectures. Thank you for your amazing teaching and making me love physics.
+Enrique Morell Thanks Enrique for your kind words.
This is the first Walter Lewin lecture I have ever seen and this is the best lecture I came across in my entire life. Now I know why you are famous :D
Cheers from India! ❤❤❤
:)
"Sound" sounds very very interesting because of YOU, Sir.......
:)
You are an incredible teacher and a wonderful human being. You involved your students in the lecture and gave them a chance to demonstrate their talents to everyone. Very rarely is this the case - most teachers are content showing off their own talents (if even that). I will remember this lesson - to give others the chance to impress me - because you never know what amazing talents people have hidden.
Great teaching!. This is the way in which Physics/Math should be taught.
sir,i'm a student of class 11. I regularly follow your lecture and your teaching come alive to me. I love u sir as well as Physics. Huge respect and love from BANGLADESH.
Blessed to witness these lectures, sir! It gives me eternal happiness
well the last 2 min were really appreciable,he can do anything for physics awesome professor👍👍👍👍
After i watched this lecture i downloaded a software oscilloscope(for microphone) and a frequency generator and i am testing various frequency's and harmonics to find nodes and i am sliding with my chair slowly away from the speakers to find nodes ..its really fun when i find a node i feel a drop in pressure..its been 2 hours i have been doing this LOL and not bored at all! thankyou prof. lewin
could you please share the source to download the software? I would really appreciate it. I too am interested in trying it on my piano and having some fun
Thnx a lot :)
✨learning, performing, playing & even listening to music over1/2 my life & I now know I never really understood music ! Actually I may/ will need watch this again & possibly again😬🤫😁
Thank you Sir! ✨
Many Thank You for the Great job you have done! Probably the only clear explanation (at least for me) of the standing waves that I have come across. Bless you!
You're very welcome!
For the first time I have understood x-vt concept. Thanks a ton great sir... love you.
I love you sir. May you never stop teaching.
The best demonstration sir. So glad, that me could travel back in time to see your lectures sitting in my home from India
❤
It’s been years since ny last Physics class. This vid reminded me how much I love this stuff! Thanks!
You're very welcome!
This was like rediscovering musical instruments. Thank you so much.
This teacher can inspire anyone to learn physics. I myself am inspired by him. This is my channel about Science.
really amazing lecture.
I didn't understood these when my physics teacher thought us this . He just wrote bunch of equations that and no one listen to him .
Now i am foing all these again and hopeful to find your lecture ( I am preparing for jee so i am reading all thses)
Excellent
Thanks Professor Lewin you make your lectures very interesting. Thus makes us love physics.
35:03 third harmonic actually because the interval with the next one is a fourth. And 35:18 is the second harmonic because the interval with the harmonic above it is a fifth.
Beautiful, simple and very instructive Demonstration of standing wave with that rope.
You are true inspiration..what a extremely well thought lecture...genius,,omg
Wow, thank you
So far I was wondering how the standing wave phenomenon possible. My mind was a mess. Now it's cristal clear how this bizarre thing happens. Thank you so much professor. I love you so much ♥️♥️♥️
Anyone else notice that he played Epona's song from The Legend of Zelda Ocarina of Time at 33:50?
you think he did that on purpose? XD
Probably accidental. I could be wrong though!
Wow! With this teacher everyone would want to be a physicist!
Watch this Lecture and listen to Kind of Blue. Preferably at the same time.
Thank you, professor!
You are welcome!
I like the way you tie the mathematics to physical demonstrations. It is all to easy to to get lost in mathematics and lose sight of the physics.
I am so enlightened to watch this lecture video of the Doctor, Walter Lewin.
I love you man. you are the teacher who have understood the depth of conceptions. i really learn from your videos and i appreciate you😍😍😍
thanks for your kind words
6:00 sir how is wave exactly as 2sin3(x-6t) getting produced even if the source is also moving horizontally?
A lecture AND a concert? Now that's some real value for your money! 😂
Violinist at 43:35 played Ysaye's 3rd sonata.
beautifully orchestrated by the great Professor Lewin!
Thanks for listening
Thank You Professor... These lectures are amazing
his lectures always recover my passion for physics again after weeks of unintuitive lessons from my physics class
Sir, you are more than amazing.your presentation made me love physics.❤️❤️❤️❤️❤️❤️❤️
Glad to hear that
@@lecturesbywalterlewin.they9259 feeling so amazing that a great person chatted with me .🥳🥳
Thank you professor.
33:48 why does the flute have a whistle type opening at beginning and not just a hole?
Superb dedication Professor. Love from India ❤
may I ask what piece of music was tom playing on his violin? at 43:31 it sounds beautiful.
Ysaye violin sonata, I'm almost sure that it is n°3
nice, thank you very much! :)
Enjoyed a lot this lecture while learning!❤️
At 42:38, Sir, how did you convert the sound wave to an electric signal such that it could be observed on a cro.
feed the output of a microphone to an oscilloscope.
Wow I had a doubt about harmonics and standing waves I came here and it got resolved thanks!!
super!!!
@@lecturesbywalterlewin.they9259 oh my god you replied so quick!! I love you Walter lewin sir!! Only if I could meet you and talk to you!!!
35:27 how did u estimate the numerical values of frequency in Hz sir? Absolutely mindblowing
Wow! Very wonderful playing of ysaye’s third sonata by the student.
After filling lakhs of fees, real knowledge is found on RUclips for free.❤️
I feel like studying physics .
The most beautiful video❤️
31:37 that’s some useful information even outside of music and physics ;)
Thank you for these amazing classes ❣️😊❣️
You're so welcome!
This lecture is absolutely beautiful.
Thank you sir.
Sir, great fan 🫡. I would like to know about the rope you've used and what kind is ideal for this demo. e.g., Plastic/Nylon ones are too rigid to show the reflection and standing waves.
Any suggestion will be highly appreciated
1. which rope? 2. I do not remember I gave this lecture in 2002
Very good lecture Sir. Thanks and Regards 🙏🙏🙏🙏🙏
Most welcome
In reed based woodwinds instruments, e.g. clarinet or saxophone, if one blowconstantly on a note, theb open the register hole which eliminate the fubdamental freq so you get a note in hugher octave but then you close the hole and magically you do not get the low fundamental as long as you continue blowing air in. Only when one stops and dtart again the low fundamental freq appears again. I wonder why?
This is so beautiful. God damnit. Why are you so marvellous! Unbelievable. My hero forever !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1
:)
27:30 Sir do submarines detect underwater mines through this phenomena??
First of all. These lectures are simply beeaautiful. Thank you for making them aviable for everyone. In the aparatus shown, the fact that the waves are aparently static is due to a recognition of the machine of the frequency of the particular wave?
Hello, Professor Lewin. My textbook used cosine to represent standing wave instead of sine. So, y1 + y2 = 2ysin(kx)sin(wt). I felt confused. Are they the same? Can you explain it to me?
+JunYu Lei If the string is closed at both sides, then at x=0 and at x=L the displacement must always be zero. As long as your solution meets those conditions it does not matter whether you have sin or cos.
If the string is closed at one end but open at x=L, then your solution should give a displacement of 0 at x=0 at all times and dy/dx must be zero at all times. As long as your solution meets those conditions it does not matter whether you have sin or cos.
Best sir. this kind of visitation not seen and"herd,😀" before I would really really really really like to learn from you
Nothing can be better than this
Beautiful sin function you drew. Those aren't easy to draw.
Sound was very boring for me but because of you it is interesting
Really your lectures make love physics
Is this a university course? My school taught us at 11grade
Sir I didn’t understand 5:30. How would a wave be formed
i am a bangladeshi student and i nevet learn it like this thank you so much sir btw i am a physics lover too
:)
Woww.
Professor Walter Lewin changed his voice more sweeter than my Girlfriend..❣️
I love you, sir. You've been my whole world since 11th grade. You really made me love physics. Please don't die before I come to America ;) . I really wanna meet you.
Thanks for the practical explanation! My teacher didn't explain me exactly what it's physical meaning is...
Respect for Sir Walter Lewin from Pakistan 🎉
Sir here why you take moving graph firstly and how you thought that for positive x direction we should take minus t and vice-versa?....
You pick a 4 unique music instruments based by its special point. I interest in the swinging string and the instrument that produce low-tone sound as it is work like ancient music instrument, we use string pundulum and metal another one sound like some kind of shell (hard to find for a perfect voice).
In case of fundamental frequency, we always get high amplitude as compared to other harmonics so is it safe to say that if we want to have destructive resonance then fundamental frequency is the most suitable option for it?
This will often be true. However, it's in principle possible for objects to break much easier in the second harmonic than in the fundamental. Suppose you took a glass rod of length L which is thinner (thus weaker) near L/4 and 3L/4.. It may then be easier to break it when you excite it in first harmonic above the fundamental than in the fundamental. There may be many objects (including bridges and glass wear) that are more vulnerable at res freq above the fundamental than at the fundamental.
Came here to learn actual meaning phase. Thanks sir walter
I have a question about the traveling wave equation y=2sin3(x-6t). When I search on the internet I always find that the equatin is y=2sin(wt-kx). When we write equation for AC voltage it's also u(t)=U*sin(wt + "theta" ). So I'm not sure which one is correct. Please forgive me if I am missing something obvious, thank you in advance.
+Nikola Vulinovic TRAVELING WAVES
y=2sin3(x-6t) = 2sin(3x-18t). Thus k = 3 (lambda = 2.1m) and omega is 18 rad/sec. y=2sin(wt-kx) => y=-2sin(18t-3x). Again lambda = 2.1 m and omega = 18 rad/sec. The - sign is a phase change of 180 degrees. NO PROBLEM! These are TRAVELING WAVES!
+Lectures by Walter Lewin. They will make you ♥ Physics.
u(t)=U*sin(wt + "theta" This is not a traveling wave.
+Lectures by Walter Lewin. They will make you ♥ Physics. Thank you so much for clearing that up for me and answering so quickly. I see now that I need to study a bit more before asking a question. I would just like to take the opportunity to say that I love your lectures they're so interesting and helpful, Thank you again very much.
What aree the string in the larynx that vibrate analogously?
Sir, I have a question about standing wave, if wave (when it reflects from the wall) changes its phase for 180 degrees shouldnt then the reflected and the coming wave be out of phase and cancel each other
watch my 8.01 and 8.03 lectures on standing waves.
cancellation ONLY accurs at the nodes of the standing waves.
i did not understand how the wave was created by a rotating wheel. Won't the string just twine to the wheel?
3:35 Wave no is reciprocal of wavelength!
16:38. I didn't understand that. Why is the wavelength 2L? And 17:07. Why is it L?
In the lowest normal mode frequency half a wavelength is L, thus a full wavelength is 2L
@@lecturesbywalterlewin.they9259 Thank you!
inhaling helium for the sake of physics teaching . That is the way of W. Lewin
You see he doesn't have to try too hard because physics is the most beautiful subject in itself
Amazing teaching style
sir, in sin(kx-ωt) , if i substitute x=vt , where is the linear velocity of the wave and you said v=ω/k. Then k gets cancelled and i get the remaining ωt. So then ωt - ωt becomes zero. I know this is not correct but pls tell me where am i making mistake. waiting sir..............
kx measures the number of radians travelled by a point on the wave to get to a particular x value.
wt measures the number of radians travelled by a point on the wave to get to a particular t value.
x and t are independent dimensions.
By linking them you're tracking a single point not an infinite sine wave.
So kx - wt becomes "take the number of radians it took to get to this place in space minus the number of radians it took to get to this place in time" which are obviously always the same.
Prof Lewin, Flute is closed at one end and through the other end, air is blown. How do we hear music? Isn't the wave trapped inside the flute? How does the music escape?
Just one line from you from would suffice. Hope my dumb questions doesn't cause irritation/annoyance. I am just trying to make an analogy with antenna as I've an engineering degree.
>
we have brains! use google
Lectures by Walter Lewin. They will make you ♥ Physics. Thanks prof, I think I have got the answer.
in 16:55 in a standing wave what is the velocity "v" refereed to??
watch my 8.01 lecture on standing waves
You are definitely a GENIUS
:)
26:27 Thug life professor WALTER LEWIN 😎😎
Love you sir This made my day 😍😍
umm in the beginning,, so 18 is the omega.. but isn't omega suppose to have pi or at least a degree symbol in it..?? I don't get why the omega can be just an integer without any degree symbol..
+GThinks the unit of omega is radians per sec. thus 1/sec.
44:10 and I am clapping sitting in front of my screen.
I'm there clapping at 13:00 . Finally understand what a standing wave is
51:18
Haha
So that's how they produce such sounds in Television Cartoons...
which song did he play on saxophone ?1
if anyone knows please comment
if I am assuming young double slit experiment and I change the medium of one and the other one is air will ithe intensity of light still be affected?
refraction and reflection!!!
8.03 seems as exciting
:)