8.02x - Lect 26 Traveling Waves, Standing Waves, Musical Instruments

[@PauloConstantino167]

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!

[@lecturesbywalterlewin.they9259]

:)

[@sudhamshreddy2756]

@Za Yn you should mention india not kashmir we need to represent our country not unionterritory

[@Electrophile-d4w]

@@sudhamshreddy2756 I guess he has deleted his comment

[@lukaide6359]

@@sudhamshreddy2756 bro why are you Indians so wierd. Always saying love from India. It’s not that deep

[@drkenz0tenma]

@@lukaide6359 love you from india🇮🇳🇮🇳🇮🇳

[@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!

[@franketemesi3193]

Lectures by Walter Lewin. They will make you ♥ Physics. Thanks

[@abhijithrambo]

❤❤❤❤

[@dr.deekhounds5339]

26:27 Then it gets to the brains, if there are any. 🤣🤣🤣🤣

[@mohammedsulaimanusman525]

Lectures by Walter Lewin. They will make you ♥ Physics. Thanks

[@swanhtet1]

You actually made me fall in love with Physics. You are the Legend, Sir!

[@cayezara8110]

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 🙏.

[@matteop700]

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.

[@toothless8965]

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

[@lecturesbywalterlewin.they9259]

😊

[@cesareborgia9259]

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!

[@AsadAli-oy9dx]

I usually find animation more helpful to understand. But animation are nothing compared to these practical examples. You are a legend :).

[@emorell96]

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.

[@lecturesbywalterlewin.they9259]

+Enrique Morell Thanks Enrique for your kind words.

[@abhijithrambo]

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! ❤❤❤

[@lecturesbywalterlewin.they9259]

:)

[@Wagon_Lord]

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.

[@pulakroy4821]

"Sound" sounds very very interesting because of YOU, Sir.......

[@lecturesbywalterlewin.they9259]

:)

[@suniljoshi5315]

Blessed to witness these lectures, sir! It gives me eternal happiness

[@milenjohnthomas_original]

Great teaching!. This is the way in which Physics/Math should be taught.

[@amitkhare2013]

well the last 2 min were really appreciable,he can do anything for physics awesome professor👍👍👍👍

[@aliulazimmiraz6428]

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.

[@gypsijo]

✨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! ✨

[@alexanderkl2146]

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!

[@lecturesbywalterlewin.they9259]

You're very welcome!

[@AKBARCLASSES]

For the first time I have understood x-vt concept. Thanks a ton great sir... love you.

[@carcinogenicthalidomide3057]

I love you sir. May you never stop teaching.

[@obayev]

This was like rediscovering musical instruments. Thank you so much.

[@teddypup2424]

It’s been years since ny last Physics class. This vid reminded me how much I love this stuff! Thanks!

[@lecturesbywalterlewin.they9259]

You're very welcome!

[@adityasalunkhe8156]

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

[@ayushnema6189]

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

[@ayushnema6189]

Thnx a lot :)

[@DCBfanboy]

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.

[@sangeetanayak9589]

The best demonstration sir. So glad, that me could travel back in time to see your lectures sitting in my home from India ❤

[@freyd6768]

Anyone else notice that he played Epona's song from The Legend of Zelda Ocarina of Time at 33:50?

[@osmelsoto4907]

you think he did that on purpose? XD

[@MrJason005]

Probably accidental. I could be wrong though!

[@anomaattanayake346]

Thanks Professor Lewin you make your lectures very interesting. Thus makes us love physics.

[@erichschmidt1328]

Beautiful, simple and very instructive Demonstration of standing wave with that rope.

[@RyanDougherty]

Violinist at 43:35 played Ysaye's 3rd sonata.

[@scienceandphilo]

This teacher can inspire anyone to learn physics. I myself am inspired by him. This is my channel about Science.

[@prashanthkumar0]

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)

[@lecturesbywalterlewin.they9259]

Excellent

[@mortezakhoshbin]

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😍😍😍

[@lecturesbywalterlewin.they9259]

thanks for your kind words

[@jonayacosta3185]

Wow! With this teacher everyone would want to be a physicist!

[@not_mrfrost]

A lecture AND a concert? Now that's some real value for your money! 😂

[@anirbanghosh1451]

You are true inspiration..what a extremely well thought lecture...genius,,omg

[@lecturesbywalterlewin.they9259]

Wow, thank you

[@ransirasubasingha3713]

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 ♥️♥️♥️

[@outrospection4all]

beautifully orchestrated by the great Professor Lewin!

[@lecturesbywalterlewin.they9259]

Thanks for listening

[@nikhilsaharan7470]

6:00 sir how is wave exactly as 2sin3(x-6t) getting produced even if the source is also moving horizontally?

[@saravananrajendran4400]

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

[@lecturesbywalterlewin.they9259]

1. which rope? 2. I do not remember I gave this lecture in 2002

[@KeithandBridget]

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.

[@cayezara8110]

I am so enlightened to watch this lecture video of the Doctor, Walter Lewin.

[@tecktonikboy13]

may I ask what piece of music was tom playing on his violin? at 43:31 it sounds beautiful.

[@jcheattai]

Ysaye violin sonata, I'm almost sure that it is n°3

[@tecktonikboy13]

nice, thank you very much! :)

[@AlexandrBorschchev]

his lectures always recover my passion for physics again after weeks of unintuitive lessons from my physics class

[@martinsanchez-hw4fi]

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?

[@akshat_singh]

35:27 how did u estimate the numerical values of frequency in Hz sir? Absolutely mindblowing

[@ankitshil]

Thank You Professor... These lectures are amazing

[@ianmichael5768]

Watch this Lecture and listen to Kind of Blue. Preferably at the same time. Thank you, professor!

[@lecturesbywalterlewin.they9259]

You are welcome!

[@riteshbhartiya6155]

33:48 why does the flute have a whistle type opening at beginning and not just a hole?

[@mohammadayasha9499]

Sir, you are more than amazing.your presentation made me love physics.❤️❤️❤️❤️❤️❤️❤️

[@lecturesbywalterlewin.they9259]

Glad to hear that

[@mohammadayasha9499]

@@lecturesbywalterlewin.they9259 feeling so amazing that a great person chatted with me .🥳🥳 Thank you professor.

[@EranUserName]

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?

[@junyulei4790]

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?

[@lecturesbywalterlewin.they9259]

+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.

[@nirmalpadwal3564]

At 42:38, Sir, how did you convert the sound wave to an electric signal such that it could be observed on a cro.

[@lecturesbywalterlewin.they9259]

feed the output of a microphone to an oscilloscope.

[@ajaypratapsingh5049]

Superb dedication Professor. Love from India ❤

[@wswddl5058]

Is this a university course? My school taught us at 11grade

[@akashhera]

Enjoyed a lot this lecture while learning!❤️

[@electronicsgyan2390]

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?....

[@yash29210]

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?

[@lecturesbywalterlewin.they9259]

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.

[@amitbhartiya3003]

Nothing can be better than this

[@dv7783]

27:30 Sir do submarines detect underwater mines through this phenomena??

[@GThinks]

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..

[@lecturesbywalterlewin.they9259]

+GThinks the unit of omega is radians per sec. thus 1/sec.

[@subramaniannk3650]

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.

[@lecturesbywalterlewin.they9259]

> we have brains! use google

[@subramaniannk3650]

Lectures by Walter Lewin. They will make you ♥ Physics. Thanks prof, I think I have got the answer.

[@Jirayu.Kaewprateep]

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).

[@nikolavulinovic8678]

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.

[@lecturesbywalterlewin.they9259]

+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!

[@lecturesbywalterlewin.they9259]

+Lectures by Walter Lewin. They will make you ♥ Physics. u(t)=U*sin(wt + "theta" This is not a traveling wave.

[@nikolavulinovic8678]

+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.

[@pat6595]

16:38. I didn't understand that. Why is the wavelength 2L? And 17:07. Why is it L?

[@lecturesbywalterlewin.they9259]

In the lowest normal mode frequency half a wavelength is L, thus a full wavelength is 2L

[@pat6595]

@@lecturesbywalterlewin.they9259 Thank you!

[@JasonSulliman]

I am a professional trombonist. I really enjoyed your presentation. I have a question regarding what I believe to be standing waves. I blow air through my lips, which causes my lips to open and close rapidly. The frequency can change but it gravitates towards the harmonic series related to the length of the trombone at any particular time. If air is being displaced into the instrument, the air would also be displaced back into my body when the lips recoil back to their original position (which means my lips actually move forwards and backwards as opposed to just 'up and down'- the 'open and closed' is a byproduct of 'back and forth'). If there is also air being displaced into my body, then that would mean my body resonates like a drum. If my body resonates like a drum, then the amount of tension my body has will change the amount of resonance it can produce. Does this mean that body tension will change my overall sound (I assume amplitude)? Do you know of any information regarding body tension? I haven't really found any research addressing this type of measurement. Thanks for any help you can provide!

[@lecturesbywalterlewin.they9259]

+Jason Sulliman If you produce a 440 Hz tone with your trombone, it's the air inside the trombone that oscillates at 440 Hz and with higher harmonics. The air in your body will not vibrate at 440 Hz.

[@JasonSulliman]

+Lectures by Walter Lewin. They will make you ♥ Physics. But how than that be? I understand that the air inside the trombone will oscillate at 440Hz, but given the way the lips are moving air, *some* oscillation of air must happen in the other direction- I assume 440 in this example but at a different amplitude. I am interested in learning more about this phenomenon but no one seems to have done any research on it. I just don't understand how it could *not be a factor. The more relaxed I am, the louder and fuller my sound is. I would go so far as to say larger players have an easier time producing larger sounds (I think) because the mass of their bodies contributes in some way to sound ia standing waves. Am I really way off base? Thanks for getting back to me.

[@lecturesbywalterlewin.they9259]

+Jason Sulliman your lips do not produce the 440 Hz. Of course the 440 Hz tome, sound waves produced by your trombone, propagate in all directions. Also in the directions of your ears, lips and arms but the energy in the sound waves that reach your lips, arms and ears is insufficient to act as a driving force to make your lips, arms and ears noticeably vibrate at 440 Hz.

[@abdullahalsakka]

Sir I didn’t understand 5:30. How would a wave be formed

[@harianshsehgal9426]

I feel like studying physics . The most beautiful video❤️

[@five5059]

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

[@lecturesbywalterlewin.they9259]

watch my 8.01 and 8.03 lectures on standing waves. cancellation ONLY accurs at the nodes of the standing waves.

[@Peter-vz9ki]

Wow! Very wonderful playing of ysaye’s third sonata by the student.

[@abdulkarimhalai6708]

Wow I had a doubt about harmonics and standing waves I came here and it got resolved thanks!!

[@lecturesbywalterlewin.they9259]

super!!!

[@abdulkarimhalai6708]

@@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!!!

[@oldsachem]

What aree the string in the larynx that vibrate analogously?

[@battlewing221]

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..............

[@Tikorous]

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.

[@adityaedara3499]

i did not understand how the wave was created by a rotating wheel. Won't the string just twine to the wheel?

[@themanavthakur]

After filling lakhs of fees, real knowledge is found on KZbin for free.❤️

[@PauloConstantino167]

This is so beautiful. God damnit. Why are you so marvellous! Unbelievable. My hero forever !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

[@lecturesbywalterlewin.they9259]

:)

[@davidfelso1932]

31:37 that’s some useful information even outside of music and physics ;)

[@yash29210]

In case of wine glass, there is only one resonance frequency which if a speaker matches with then we get resonance....... Other objects also like Tacoma bridge also have only one resonance frequency but why strings and woodwind instruments have more than one resonance frequency?

[@lecturesbywalterlewin.they9259]

We drive the wine glass with its fundamental just like the HUGE string/spring in c;lass which I drive with its resonance frequencies. Anything that you drive with one of its res freq will obviously oscill only at that freq. I do not know of any musical instruments that produces only its fundamental for rather obvious reasons as NONE are driven with ONLY one of their res freq. The Tacoma bridge is more tricky. The mode that was excited is probably its lowest energy mode. Use the web to learn more about this.

[@yash29210]

So you mean that every object has fundamental frequency and harmonic? If yes then what will happen if we drive the speaker at frequency equal to 2nd harmonic of the wine glass?

[@lecturesbywalterlewin.they9259]

1. watch my lectures, it's all there INCLUDING demonstrations using various instruments 2. the glass may not break if we drive it with it with sound at a resonance freq other than the fundamental as we may not be able to generate enough sound power.

[@yash29210]

So is it safe to say that every object in the world can have more than one resonance frequency ie fundamental and several other harmonics even if we can't match it(as you said in case of wine glass)?

[@lecturesbywalterlewin.they9259]

ALLLLLL objects have many resonance frequencies. If you drive them with one of their res freq they will "react" accordingly, but that does not mean that you can destroy them. Look at my great demo of the many resonance freq of a disc (Chladni plates). I search for the res freq and you see the results !!! Lect kzbin.info/www/bejne/fXe1aYiAgJiAsMU It's even more impressive to do this with a square plate kzbin.info/www/bejne/h5eTpWenfruKfJY

[@mrdark250]

Thanks for the practical explanation! My teacher didn't explain me exactly what it's physical meaning is...

[@singh_sahab6272]

Thank you for these amazing classes ❣️😊❣️

[@lecturesbywalterlewin.they9259]

You're so welcome!

[@oldsachem]

How does the mass or density of the bow fibers affect the frequency vibration of the violin string?

[@lecturesbywalterlewin.they9259]

ask Quora

[@oldsachem]

@@lecturesbywalterlewin.they9259 Your Dutch sabot is astonished the eminent professor, or his bot, actually reads the comments.

[@animekid3947]

which song did he play on saxophone ?1 if anyone knows please comment

[@lollolzi2996]

16:34 if you only have walf a wavelength shouldnt lambda be 0,5L?

[@lecturesbywalterlewin.they9259]

>>>shouldnt lambda be 0,5L?>>> NO

[@lollolzi2996]

please explain since that part is the only thing confusing me

[@lecturesbywalterlewin.they9259]

I watched at 16:43 my lecture is x-tal clear. I cannot improve on that. The wavelength of the fundamental is 2L. I suggest you watch it again.

[@lecturesbywalterlewin.they9259]

This is a full wave ^v. ^ is half a wave. Thus the fundamental wavelength is 2L.

[@riteshbhartiya6155]

3:35 Wave no is reciprocal of wavelength!

[@fredthechamp3475]

Beautiful sin function you drew. Those aren't easy to draw.

[@schattopadhyay1901]

Sir, I guess I may be asking something a bit off topic. But I think you are the best person to answer it. My question is, when we consider a subatomic particle as a wave, then which parameter of the wave is related to the mass of the particle?

[@lecturesbywalterlewin.they9259]

Look at Schroedinger's equation

[@schattopadhyay1901]

I didn't quite understand it. I know that the wave function of a particle is expressed as (psi)=e^i(kx-(omega)t).......where can I find the mass of the particle in this equation?

[@lecturesbywalterlewin.they9259]

It is not in this classical equation. It's in Schroedinger's eq.

[@skills.abidurrahman1450]

i am a bangladeshi student and i nevet learn it like this thank you so much sir btw i am a physics lover too

[@lecturesbywalterlewin.they9259]

:)

[@synthoscitizen]

This lecture is absolutely beautiful. Thank you sir.

[@ahmadeldesokey9844]

Sir , will the amplitude of the standing wave change for different resonance frequencies ?

[@mohamedabohegy3938]

in 16:55 in a standing wave what is the velocity "v" refereed to??

[@lecturesbywalterlewin.they9259]

watch my 8.01 lecture on standing waves

[@salvatore5627]

What's the piece's name played by the saxophone ?

[@farooq8897]

Hello professor.. How are you?I have a doubt. If the magnetic force depends on the velocity of charge and accelerating charges create radiation. Then, in which frame of reference the velocity and acceleration are measured. If I accelerate carrying a charge in hand, it's stationary for me but accelerating for others.. Does it radiate?

[@ajinkyameh3890]

Best sir. this kind of visitation not seen and"herd,😀" before I would really really really really like to learn from you

[@djgoswami360]

Woww. Professor Walter Lewin changed his voice more sweeter than my Girlfriend..❣️

[@arnav-er6xl]

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?

[@lecturesbywalterlewin.they9259]

refraction and reflection!!!

[@surendrakverma555]

Very good lecture Sir. Thanks and Regards 🙏🙏🙏🙏🙏

[@lecturesbywalterlewin.they9259]

Most welcome

[@rafiabdullahzidan680]

Teacher,When I am allowed to use Y=Asin(wt-kx) instead of sin(kx-wt).. If I use two equation of travelling wave Y1=Asin(wt-kx)..going in the +x direction Y2=Asin(wt+kx)...going in the -x direction. Using superposition principle I immediately find the resultant of this two waves as Y=Y1+Y2.=2A coskx sinwt.. Here final x dependent amplitude is =2A coskx....If I solve for antinode point I find X=0,π\2,π...... #Very wired!!! I find x=0 as antinode point? Is it correc???

[@lecturesbywalterlewin.they9259]

looks ok, I cover standing waves in my 8.01 lectures

[@riajulchowdhury2039]

Why is a standing wave forming in the one open - one closed musical instrument?

[@lecturesbywalterlewin.they9259]

watch my 8.01 and 8.03 lectures on standing waves

[@alainhamel7163]

hello Mr Lewin , I'm a french cityzen and i'd like to know what means 8.02 and 8.03 ? of cours I understand that's a matter of level ,could you telle me more ? for instance in france we'v got Math sup and Math spe (1st year and 2nd year of math physisc and chemistry high level) and also in university 3 years licnse 4 /years master,5y+ doctorat (Phd in US) thanks and i'm fan of your lessons ,you suceded in melting pragmatical experiences linked cleverly with théory ! by the way I have another question about electromagnetism and elctrom. waves : how is it possible that E and Bto be immediatly linked in space propagation , why is there no" delay" between variation of one regarding the other ,why is it "instantly" ? thanks again

[@lecturesbywalterlewin.they9259]

all physics courses at MIT start with an 8. 8.01 (newtonianmechanics), 8.02 (electricity and magnetis), 8.03 Physics of waves an vibrations, 8.04 QM1, 8.05 QM2. You find the answer to your question in my 8.02 course

[@parthkatke6706]

What happens if you hold a node with your fingers, will there be any effect on oscillation?

[@parthkatke6706]

If yes, then what? If no, then why?

[@lecturesbywalterlewin.they9259]

a node does not move. Butb that is only 1 point. Your finger is not just 1 point.

[@parthkatke6706]

@@lecturesbywalterlewin.they9259 thank you professor 😊, I completed 8.01x lectures and assignments, it was really fun. I want to do the same for 8.02x but I don't know which edition you used in your lectures

[@returnroot3067]

Professor can you please explain to me why does frequency of a wave remain constant over various mediums while its wavelength does not ?

[@lecturesbywalterlewin.they9259]

lambda = v/f in change of media v changes f does not (thus lambda changes) - use google

[@returnroot3067]

Thank you Professor I'll keep it in mind