De Broglie wavelength | Physics | Khan Academy

In this video, David explains how Louis De Broglie got his Nobel Prize for the idea of matter having a wavelength.
Watch the next lesson: www.khanacadem...
Missed the previous lesson? Watch here: www.khanacadem...
Physics on Khan Academy: Physics is the study of the basic principles that govern the physical world around us. We'll start by looking at motion itself. Then, we'll learn about forces, momentum, energy, and other concepts in lots of different physical situations. To get the most out of physics, you'll need a solid understanding of algebra and a basic understanding of trigonometry.
About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.
For free. For everyone. Forever. #YouCanLearnAnything
Subscribe to KhanAcademy: www.youtube.co...

[@colinsilver1041]

Just an awesome video. I read the textbooks, I understand the books, but I just didn't get the big deal until this explanation. Thank you!

[@pehu3798]

❣️

[@secretgaming8743]

Right

[@tanmaygarg_9025]

after searching thousands​ of websites and seeing hundreds of videos this video was one the cleared every little thought in my mind. HATS OFF to you. you are terrific!!!!!❤❤

[@Akashdeep-kd5mf]

Lol

[@pachaiappanpachaiyappan869]

I love u

[@pachaiappanpachaiyappan869]

I hate u

[@pachaiappanpachaiyappan869]

Gvj

[@sjlegends]

Cleared? lol 😂

[@ankitaaarya]

"Luey deBroy" Gotchya!

[@abdullahumuthamzaogullar3315]

they're bots, dont fall for those.i

[@aishwaryajangir2909]

That's the explanation I wanted to know! Thanks a ton for not only spreading knowledge but spreading it in explicit manner. PS - This is the top channel for us(students) to learn :))

[@astro.5oh]

This is absolutely amazing. Physics has always interested me but is not my best subject. I came here because my Modern Physics professor suggested this video. I see why he did so--this video does not only make this concept extremely easy to understand, it made it interesting. I wish all my professors could make difficult topics such as Modern Physics and Quantum Mechanics so enjoyable. Thank you!

[@VG__]

You won't even realise how many more major concepts of physics he has explained just in 10min of video that would actually take you 10years to comprehend =D Simply aesthetic 🌺🌺

[@papangkonninarundech2562]

It's been three years and i'm still pronoucing the guy's name Broglie.

[@WeAreShowboat]

Me too, and I made this video :)

[@hadmeinthefirsthalfngl2717]

@@WeAreShowboat Really?

[@WeAreShowboat]

@@hadmeinthefirsthalfngl2717 💯

[@pranjalkohli183]

Ya

[@Scarabola]

but it always is pronounced Broglie. depending on how you pronounce the name "Broglie".

[@sanchisingh5117]

this is one the best videos that explains this concept so beautifully WOW

[@nymphaea888]

This was the most well explained resource of the De Broglie wavelength that I’ve come across. Thank you!

[@mahdibakkar7446]

De Beoglie's new discovery had a big importance . It is the pillar of the Heisenberg Uncertainty principle

[@utahimeiori8739]

The heinz what 🤠

[@nmarbletoe8210]

@@utahimeiori8739 uncertainty in mustard x uncertainty in ketchup = relish

[@PhilMoskowitz]

By way of Schrodinger's equation. Also, if it were only Schrodinger's equation, I don't Heisenberg would have developed the Uncertainty Principle. He would have just called Schrodinger's equation- bad math. It was only through seeing this same uncertainty in Heisenberg's Matrix Mechanics (a rival and equivalent theory to Schrodinger's) that led Heisenberg to develop The Uncertainty Principle.

[@jessereiner5401]

Excellent job framing an important idea that's hard to get a foothold on! How about making another one on the Davisson-Germer experiment itself?

[@vineetasharma3722]

When is your birthday David? We are celebrating teacher's day 2.0 on the day your birthday falls. Period.

[@PhilMoskowitz]

No one initially performed an experiment to test De Broglie's hypothesis. Instead there was an experiment that had unexpected results. De Broglie's paper was used as the explanation for those unexpected results.

[@RichardDLewis41]

This video highlights the important point about the quantum nature of light and wave particle duality. There is a somewhat different way of explaining the physical nature of light and the photoelectric effect by following the Spacetime Wave theory. In the Spacetime Wave theory, light is described as a real physical wave disturbance of spacetime moving through space. This is like a gravitational wave but at a higher frequency. In the Spacetime Wave theory light exists in discrete quanta of energy because of the way that light is emitted by a change in energy level of an atomic electron. Light waves are not inherently quantised but are quantised due to the way they are emitted. So we abandon the concept of wave / particle duality and instead consider the photon to always be a wave quantum. In the experiment to demonstrate the photoelectric effect the wave quantum is the perfect description because the wave part describes the energy (E=hf) in each quantum. The Spacetime Wave theory goes further by describing electrons, protons and neutrons as looped wave disturbances of spacetime in spacetime travelling at speed c in the loop. This provides a similar model to the de Broglie model where there must be an integer number of wavelengths in the loop and this provides the correct results for the emission of a wave quantum (photon) when an electron changes energy level. The advantage of the Spacetime Wave theory is that it provides a deeper understanding of the real physical processes taking place when looped waves in spacetime change state. For more detail see: www.academia.edu/5927513/The_Spacetime_Wave_Theory www.academia.edu/5038836/The_Unification_of_Physics Richard

[@hamidthephysicist6376]

Thank you very much . The weird thing is I was so happy watching the video ! I lived the video second by second .. I think I should specialize in Quantum Physics .

[@sakinahdil6060]

okay so this is basically the first video which made me understand the De Broglie Wavelength. I didn't even know that it was about electrons working as waves

[@albijos2684]

just great ! this piece is a real gem.

[@gautomdeka581]

That's great what debroglie found , he didn't get the formula for matter using mathematics, he just predicted that might be true as it is valid for light

[@thenaughty5441]

man! i'm in love with you ! thankyou so much

[@priyank5161]

2:43 heres come my boy... None other than... LUI DE BROY

[@hasansaleem4983]

2:15. Because of you now I have to cramm some questions and answers!!

[@CACBCCCU]

My apologies in advance if you enjoy spookiness. Dipoles interfere, massless or not. A dipole does not interfere with itself. Dipoles tend to be overlooked when they pair up 180 degrees out of phase with each other, with consequent signal drop out. Photons are extended polarized electromagnetic dipoles. Polarizers are re-polarizers. Opposing helicities of polarization can be induced by a linear polarizer. Electrons are magnetic dipoles due to their spin. Their spin is both quantized and tied to their speed. As matter dipoles they like to pair up 180 degrees out of phase. Ions are electric dipoles and spinning ions are magnetic dipoles, their spinning involves contact with surroundings and can be synchronized.

[@AfsanaKhan-hm8zr]

Really found your channel with the best explanation…hope you upload more related videos

[@Llllllllllllxjxn]

This channel is a huge disservice to physics and the next generation

[@suipheng1322]

Wow, you explained it so well, I think its the best explanation video regarding this topic on KZbin.

[@shivensaini3643]

Nice explanation, BTW We can also derive this expression from equating energy from 1. E=hf(Wave nature) 2. E=mc^2(Particle Nature)

[@darkzonegaming9169]

but how

[@shivensaini3643]

@@darkzonegaming9169 write C as Velocity, f -> c/Lambda

[@darkzonegaming9169]

@@shivensaini3643 thanks mate

[@hasansaleem4983]

Thankyou I finally understood it

[@manjulapriyadarshani8291]

Thanks . I was able to learn clearly with this video .

[@kokomokid4006]

I had no idea wtf he was talking about...but i shur enjoyed it!!!

[@kalarani6682]

Khan academy is the best. Do you agree?

[@srinivasankv2964]

Tomorrow is my final exams and now i am confident , thanks to your channel.

[@Chris-wh3yz]

Yuri Ivannov’s revolutionary discovery concerning standing waves and a new concept that fully explains gravity, probably in its truest most complete theorem, and not the past goody explanations and work around in science that has never truly captured what mechanisms by which gravity works. It’s really more basic than they thought.

[@GlynWilliams1950]

Wow. Amazing and great explanation.

[@zhraisjoy]

Really great U make the idea very easy to understand I can't know how much I can thank you

[@paulg444]

David, this is a fantastic presentation.

[@randallmcgrath9345]

Khan Academy is also nice for math practice as many know.

[@abdurrafay6150]

This guy is hands down the best physics teacher

[@aminsa9392]

Amazing video you made. I was not understanding this case but your video made it more easy for me to understand. Thank you

[@avezl]

Thank you so much, finally i could understand it

[@AM-es7of]

Beautiful lesson. Thank you!!!!!!

[@michaelgonzalez9058]

In back of the center light focus is the unknown

[@adityapendyala1413]

Best class ever.....doesn’t even sound like a class!!!!!

[@dabanfarad8756]

Great video thanks

[@talhaansari3140]

Anyone know this software which is in this video for writing please i wanna know please

[@MsQuikly]

it's been 10 months, but it's called smoothdraw

[@_Thoughtful_Aquarius_]

@@MsQuikly , thank you very much. ☺️

[@antoniovianaaa]

That dislike is so unfair. I think this lecture is very interesting for a beginner on quantum mechanics.

[@haroldbog9137]

Damn. He teaches soo well, not even tryin to sound like a cringe comment, but each of his lectures is so good.

[@afzalhakim4681]

Understood every part of it !!

[@ayushsharma0324]

truly, thank you.

[@lilitek8001]

This explanation was amazing. Thanks

[@jaahid08088]

Thanks for this explanation.

[@beyourself8085]

Thanks sir!!

[@imafan555]

david's voice is so smooth.

[@meghnameghna1498]

Thank you so much for such a elaborated and good explanation

[@keshanisakunthala8600]

Thank you so much

[@keysangyonthan]

so does that means that everything in this universe can act as a wave as well as a particle depending on the experiment we are subjecting the object to?

[@samihaislam9147]

I guess. My physics teacher told me even the particles in our bodies spread a very miniscule amount when we go through doorways... Donno if its true though, it's really weird and hard to believe

[@DapaChrons]

yes, everything has a wavelength

[@swapanmanjhi]

Great Explaination sir, Thanku 💐

[@aritrabhattacharyya2374]

Awesome class sir

[@NimrodTargaryen]

Wonderful commentary, thank you🎉❤

[@qurrotatechnology2073]

The explanation is just amazing

[@michaelgonzalez9058]

By the outcome of source h is available

[@fstopPhotography]

That was fascinating. Thank you.

[@keywordmcat2256]

best physics teacher ever...down with this expensive and inefficient u.s. university system..

[@AfsanaKhan-hm8zr]

Are you not posting any more videos…

[@nurulshamchannel9307]

Thank you sir

[@tiagotassinari1435]

Awesome video !!! Thank you!

[@ZwiffleOwnsU]

Incredible explanation

[@michaelgonzalez9058]

The double split experiment has the dark matter in the back of the center in the shadow center is dark matter

[@Said-kv7mp]

brillant👍

[@nazneenali3628]

Double slits cause interference of light waves whereas diffraction pattern results from a single slit.

[@ronasmatyar5642]

The light diffracts at both slits thats what causes the interference.

[@jayjain1033]

yow this guy can explain stuff!!

[@ambreshbakshi8648]

But this equation is derived for massless particle How can we use mass of electron

[@bananabird7584]

I think it's because the mass of an electron is ~0 kg, but there is still a mass.

[@tomnoyb8301]

Quantization always arises from boundary conditions. It's not a "particle nature" of light quantizing the photoelectric effect, rather the boundary conditions upon the electron that prevent it from accepting low energy waves. Light is always a wave and may always be calculated as a wave. Particle models are always simplifications of the more accurate wave calculation. "Wave" is always correct, "particle" might sometimes be correct.

[@aaroncurtis8545]

But... We hypothesized the photoelectric because treating light as a wave doesn't work; it leads to the ultraviolet catastrophe, even without electrons getting involved.

[@internationalremixes6440]

fabulous video...it's like crystal clear

[@TheLivirus]

So the particle nature of light was shown by light knocking away electrons in metals, but then electrons were shown to also be waves. It seems to follow naturally that one would then try to explain the photoelectric effect by considering both light and electrons as a wave. I'm sure someone tried this, but does anyone know what was the conclusion? Does the photoelectric effect not work considering both light and electrons as waves? Why?

[@vijgenboom2843]

Excellent! Thank you. ❤️❤️

[@varunl2933]

I dont think a single person in india say 'De BroY'

[@vintonrebello4347]

You do!

[@camerandme]

Right

[@rishavkru3274]

It's mentioned in Ncert physics class 12 part 2

[@aayaanhasnain4034]

I do coz i have learned French in my elementary school😁😁

[@wasimmedico4138]

in ncert class XII in dual nature chapter it actually mentioned in brackets the pronunciation,but no one pronounces it that way

[@bhavanikasiviswanathan3707]

It is very useful. Thank you!

[@physics-theworkingofeveryt6086]

I am 11 years old but still I understood every word you said Thank you sir

[@hedayatnoori6456]

Finally I could understand this.... Thanks 💯

[@qrthack]

What tablet are you using?

[@jessz-4453]

better than college chem lecture ngl...

[@TonyStarkCLC]

Dude. The Broglie effect is just... The mirror effect... That's it. Only were harnessing a mirror image of the object in the form of energy. That's why the Broglie effect occurs mostly on metallic surfaces,

[@விகாஷ்வர்தன்]

I would like to see his paper. But will i understand it or even if i don't where do i get it?

[@ashishfargade1393]

9 dislikes,,,, i mean why would people give it,, this video cleared every doubt in my mind,,, what more do these people want,,, why would they dislike it without any reason, they are cruel af!

[@FeetHuggs]

people keep saying this is a good video but it didn’t explain anything to do with the Khan Academy test on de Broglie Wavelength at all

[@martinwood744]

Quite good

[@naturegirl1999]

What if what we’ve always called particles are always just waves with super small wavelengths?

[@hasnainiqbal4870]

Is the equation only true when the particle is travelling very closer to 'c'? Or, at any velocity?

[@antoniovianaaa]

Hasnain Iqbal, i'm probably too late, but i'll try to answer. This equation is valid for "any" value of speed. You can see in books some exercises of calculation of a baseball wavelength, for example.

[@thenuyogi5751]

THANK YOU!

[@kartikeykakaria9a180]

Sir but I have a question like we are always taught e=mc² if we square that we get e²=m²c⁴ but here you showed that e²=m²c⁴+p²c² how can that be true? This just unbalances an equation?

[@lepidoptera9337]

The correct formula is the one that includes the momentum term. The simplified formula should not be taught as fundamental. It's a specialization of the full formula for p=0 (i.e. it is only valid in the rest system of the body).

[@dodoahmed3121]

Awesome video thank you sooo much

[@c260sadiaafrin2]

This video is great!!!

[@haseeb6053]

Thank you! Really, Thank you!!

[@jackiec.acosta9929]

Hahaha thought it was "lu-wis de brog-lee"

[@jmac6653]

I feel both 100x smarter and 100x more dumb from this video. Thank you.

[@JediLegend]

fax

[@iz1139]

Thank you.

[@amyralove6109]

As a french speaker I think we spell it " De Brogg_ly "

[@carl6167]

C'est une exception. Les Ducs de Broglie sont d'origine italienne et c'est en françisant leur nom quand ils ont émigré vers la France que c'est devenue Broglie. La prononciation d'origine a cependant été gardée.

[@rahulrraveeturu753]

Wait....I have a question how we can relate to quantum mechanics it was so confusing thing Because the statement proposed by de broglie is before Eisenstein right!!

[@lepidoptera9337]

de Broglie made his statement in 1924, 19 years after Einstein published the photoelectric effect paper. At the time of Einstein's paper de Broglie would have been approx. 13 years old. :-)

[@kirithish8389]

I just have a doubt...in double slit exp. the pattern that forms is interference pattern right...but you are saying that it forms diffraction pattern(which is formed for single slit exp)...??anyone do clear me out...!pls

[@lepidoptera9337]

The reason the double slit experiment works the same for light, electrons and baseballs is because what we are detecting aren't "particles". We are always detecting quanta of energy. Energy is always the same, no matter what kind of system has it.