Understanding Black Body Radiation, Rayleigh-Jeans Law, & Ultraviolet Catastrophe - Quantum Physics
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- Опубликовано: 1 окт 2024
- By the end of the 19th century, physics was sorted. We had Newton's laws to explain the motion of objects around us, Kepler's laws to explain the motion of planets around the Sun, we could explain the waves on strings, the ripples in the pond, and we had even derived the relationship between electricity and magnetism. All this, because of a carefully devised set of laws known as classical physics.
But, classical physics could not explain a new problem nature thre at us - black body radation spectrum.
According to Kirchhoff's laws, every object, at every temperature, emits electromagnetic radiation and also emit the radiation that falls on them. There are some good absorbers and then there are some bad absorbers of radiation. A blackbody is a perfect absorber and a perfect emitter of radiation.
Perfect blackbodies do not exist in nature - we only have approximations. The Sun is a blackbody, stars are blackbodies, and even a light bulb can be considered to be a blackbody. The blackbody spectrum is a curve between the energy density of the radiation and its frequency or wavelength. Classical physics could not explain the shape of the blackbody spectrum.
There are two experimental laws associated with a blackbody. The first is the Wein's displacement law. It states that the temperature at which the peak energy density of blackbody radiation is inversely proportional to the wavelength. The second law is the Stefan's law. It states that the total energy output of a blackbody, or the total luminosity is proportional to the fourth power of temperature of the blackbody. Stefan's law has many applications in astronomy.
The first attempt to explain the spectrum was made by Wilhelm Wein. He gave the Wein's distrubution law, an empirical formula that could only explain the curve at high frequencies.
The second attempt was made by Rayleigh and Jeans. They considered blackbody radiation to be made of standing waves inside a cubical box. Using classical statistical mechanics, they calculated the number of modes of vibrations or the number of standing waves inside a frequency interval. They associated average energy to each of the standing waves - kT where k is the Boltzmann's constant and T is the temperature.
By multiplying this average energy with the number of modes, we get the energy density - the Rayleigh-Jeans law. However, the Rayleigh - Jeans law can only explain the black body spectrum at low frequencies. It blows up at high frequencies. This is known as the Ultraviolet Catastrophe.
The black body spectrum was finally explained by Max Planck using quantum physics.
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this video was having a perfect , clear explanation and i didnt even get bored at any point of this video. your way of explaining the concept was so good with full of clarity.
@9:31 Every next graph you draw at higher temperature, completely envelopes the curve at lower temperature.
Love your work very deeply , i even managed to score broze merit in international astronomy and astrophysics competition IAAC by just studying your basics of astrophysics series .
Thanks
I am gratefull.
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Wow! This is so great👏
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Nice video sir...
Crystal clear concept
This channel deserves a huge respect.🙏
Thank you for your support :)
Great.....Rishabh, you are doing a awesome job... I watched your all VIDEOS and feeling great
Thank you for your support ❤
Damn, this is the first time physics has ever left me in suspense! Hats off for the explanation Rishab sir! 🙏🙏🙏
Glad you are enjoying it :) The next video will show how this problem was solved:)
@@TheSecretsoftheUniverse Eagerly waiting...😁😁🤩
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Much love ❤
@@devilnoob1958 toh kuch nhi.
@@TheSecretsoftheUniverse thanks bro..... 😍
Ever get curious about a scientific or mathematical concept? There's always an Indian man on RUclips who knows the answer.
Very well explained along with all the details which tutors usually miss while teaching such topics in physics.
We all were waiting for such type of lectures. 😁👍
Nicely explained Black Body radiation and Rayleigh -Jean Law, Rishabh sir 👍.
Thank you 😊❤
Welcome sir
I really love your channel❤️
And we love you
So Rayleigh-Jeans Law was based upon an assumption. It's no wonder it was catastrophic!!!
Why CAN ENERGY NOT take higher quanta of hf at higher frequencies? I mean put the math aside, what is intuitive reason behind intensity going down?
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I am in class 9th . And i am so fascinated and intrinsically interested in these topics of like quantum mechanics ,thermodynamics, string theory, light behavior, time travel,space and in this giantly huge and bizzare observable universe..🔥✨🚀
Im too in 9th, how far have you reached
@@KKRoy-sp6mx now in high school completing my calculus 3 course and doing many other useful things for instance :- coding (python) , studying physics and maths >> and trying to do something useful for others ..
At the age of 14.✌🚀..
@@UROOZFATIMA190 where are u from?
Well , from india u?
@@UROOZFATIMA190 yes
again his son is watching it and since i’m 8 years old it’s confusing. can you please explain a little better
Thank you for this, Rishbah. I've been explained blackbody radiation before, and I almost got. I understood everything except for the part about Wien's Displacement Law. That part slipped past me, but you explained it perfectly.
How can something absorbe, and emitt at the same time? Thats like having a magnet thats both positive and negative on the same side. Even electrons are positive, or negative, they cant be both st once. I guess like you say they dont exist in nature. I guess its really all theoretical then. Not sure what brought me to look into this subject, i think i was looking into scalar wave radiation, and i was trying to understand the different ways scalar wave radiation works.
Sir thank you so much for this lecture.I find it hard to understand this topic but you've cleared my doubt, thank you sir.
@15:10 I think you meant to say it does not explain the curve at high frequencies. (low wavelengths)
as things heat up , they expand. when they can't expand anymore the energy density increases.
Light redshifts with density.
it's very simple
I think the temperatures are actually listed in Fahrenheit in your example, not Celsius.
What an explanation sir, really mind blowing
Well doing sir 👏👏👍👍
Kirchoff's Law was about radiation emitted from a cavity. Are you thinking of Stewart's Law?
Its really amazing bro detailed and clear information 😍😍 about a topic
Thanks 😊
You should warn us in the thumbnail that, this is just textbook mathematics without actual concept involved
My god such a good explanation with a pleasant voice ❤️...thank you so much
I cannot understand y rayleigh jean's failed to discribe black body intensity...
The content is really good but the light in the video is flikering which is harmful for eyesight
I really love to learn from this channel..
Keep Watching 😍
Good one and nice way to raise interest.
Next video about Max Planck gonna be interesting, I hope.
Keep going team.
He did not explain in what terms he is explaining whether in term of matter or wave
great explanation
loved it physics never seemed that easy
Please make video on explanation of ultraviolet catastrophe.
Max Planck tried using a silver cavity. He got no blackbody radiation until he added a small carbon particle. He thought it acted as a catalyst. Dr Robitaille has shown that it was the graphite lattice that was actually required to produce blackbody radiation. This has led to his theory that the sun also has a lattice in the form of planar liquid metallic hydrogen (type 1) on its surface. Interesting ...right?
thank you sir i am also a science lover
All the best
@@TheSecretsoftheUniverse thanks
what if it is a freezing 🥶 toaster
I never got bored, by your Lecture. Really like a very attractive story with such anxiety what would be next.
Very awesome experience of blackbody radiation. 🙏🙏🙏🙏Sir you're great 🙏🙏🙏
Sir.... The board is not visible perfectly 😶.... Please sir.. use black markers and good source.... Of light...
Otherwise.. I love ur ... Videos 😋
Thank you very much indeed for this interesting and clear lesson !!!
Glad you liked it!
Sir , is a black hole a perfect blackbody/an absorber
My mother warned me about blackhole technology, but but, thanks for posting.
I intend to math
Another fantastic Video.........💓💓
Love you bro💓💓💓thanks for making physics so interesting
My pleasure 😊 Thank you so much :)
🍞🔥🤣 Beautifully done !
Amazing explanation...l was facing a lot of problems regarding this chapter...but now it's crystal clear...thank you so much...🥰
Where was this video my entire life!!!!!!!
Sir,. The video is blurr lit bit😶 I want to note down... And take screenshots
👍👍
Would like to see an appendix to this where the Rayleigh-Jeans formula is actually derived. Considering that the integration is instructive for calculus beginners and I'd also like to refresh my memory. :) Good work!
Thank you sir...
Was a bit late to watch this episode because of my personal busyness.... Going to complete every episode today till now...😊
adbhutam!!!
Oh sirr !! What even my cosmologist Prof cant't explain,U did it seamlessly.. I was confused for long.thanks for saving . You guys run the world !! :)
Happy to help
I can't thank you enough for this video. I request you to continue the lecture on Quantum Mechanics. Really your way of teaching is exceptional.
wonderful presentation.just love it ♥♥♥♥♥
In Rayleigh jeans law did you mean that N always an integer?
Thanks a lot for this video
Sir you are great.I think you will be our future professor at IIT.
very well explained :<
This was very fun!!
Sir can you define ultraviolent catastrophe please
thank you for your exceptionally clear lectures that seem to anticipate the questions we might ask
A question :
Why was it called ' Ultraviolet Catastrophe ' ?
At high frequencies, at UV and beyond, the integral blows up. That's why it is known as the ultraviolet catastrophe. This term collectively signifies that Rayleigh Jeans law gives absurd results at high frequencies such as at the UV frequency.
@@TheSecretsoftheUniverse thank you😍
Sir ,is that same scientist Rayleigh that by his theory we can say that sky is blue?
Yes
vry well explained
Excellent , Fantastic and Lucid ! Way to go !
2nd
Very Underrated Lecture
Very good explanation of black body radiation
Your vedios make me to love astronomy much more.
Man, I love this channel. Nice work, Rishabh.
Sir , do wormholes appears in the quantum level
Thank you sir for Mali physics that easy
Great lecture I ever see on utube simply great
Very nice video
Loved this video
Thank you so much sir 😊 it's really helpful
All the dislikes of the video are from Albert Einstein..
LOL!
@@TheSecretsoftheUniverse OMG!! SOU liked my comment!! Thanks Sir I am your Biggest fan !! I have a request, can you please make video on The Casimir Effect. I would be pleased if you explained that 🙏🙏
So awesome.. my great thanks
Excellent 😍
I loved the video .
Thank you :)
Really supr explanation sir.
Excellent work 👍👍
perfect, really perfect. huge respect sir.
Please explain in urdu
why
Bring in examples please
amazing explanation thank youuuu.
You’re welcome 😇
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Here again you explained it so nicely 👍
Glad you think so! Keep watching :)
This was soo amazing. Really I love ur works so much!!
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Thank you! Cheers!
Goods freinds.
Nicely done. Thank you
U r great and thank you so much for all this 👍👍
Most welcome 😊
thank you
Brilliant
Best explanation 👍
Thank you 🙂
I love this channel. 😍
Happy to hear that!
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Thanks ✌️
Why didn't I find you sooner 😭😭 i have been to so many different channels, watched so many videos and understood nothing, you make physics so easy 🥹❤️