Thermal Radiation and Stefan-Boltzmann Equation

[@seanparker4746]

I'm only 5 minutes in and I got it (what's been explained so far) - what a great presentation, love the style, repetition, clarity. Great job!

[@AKLECTURES]

+Sean Parker Thanks Sean!

[@threesAcr0wd]

At first I was like "man, he talks so slow" and then everything started to instantly click and I was amazed by the effective approach to present this information - absorbed it like a sponge!

[@KeenestObserver]

You, sir, have helped me understand so many different topics throughout my first 3 years as a physics student. I am really grateful for your continued effort and I hope that life is treating you well.

[@amxya1337]

Dude! You have earned yourself a million points for this amazing video. I got what i required for my test in 5 days in just 10 minutes! A special thanks

[@hans_____]

As a brain-fried engineering student, I couldn't grasp any of this. Now, two years later, I watch this video on 2x speed and have no problem whatsoever. You teach well. Thank you.

[@KoustubhBhattacharjee]

Use 1.25x speed. Thank me later.

[@connorcow7894]

2 times

[@dennercassio]

English is not my first language 🤣🤣🤣🤣🤣 And he's accent is very different them the standard American English hahaha. I got it though cuz he speaks very slow

[@mavihs26]

I use speeds higher than 2 (chrome extension) lmao he's a great teacher nevertheless

[@kirubeltekle9553]

Thanks

[@mcr8309]

thanks

[@chaitanyachalapathitarra2176]

Iam from India.English is not my mother tongue.But duration of COVID ,i was only fallow your classes and passed my bachelor degree.Good explanation. I can easily understand your Retyhym. Thank you sooo much. 🙂

[@AI-oy8zm]

Absolutely Brilliant. Eloquently delivered. Well done.

[@AKLECTURES]

Thank you!

[@floorless]

you are so good at explaining things, keep it up. and i love your accent

[@tswell2]

Flows really well so easy to listen to thanks.

[@AKLECTURES]

Thank you!

[@gabrielatem1121]

You so kind person, may God bless you❤

[@PasseScience]

Hi, which microscopic process creates those kind of electromagnetic radiation, is it collision of particles that can result in a photon creation + a slow down of the colliding particles? (I know there are some other kind of emission, like energy states jump within a given quantum objects, let's say an atom, but those kind of radiation seem to be quantized and highly restricted so specific values which makes me wondering from which other process the continuous spectra of thermal radiation comes from, thus explaining my initial question)

[@Eric-sq4hd]

He's gotten a lot better since 2013

[@lukemaheeb4553]

your style is scintillating! thank you so much

[@LucyRockprincess]

Very clear and articulate - thank you.

[@vedantprajapati3545]

wonderful teaching method, sir thanks a lot

[@mmolokiandrea533]

Thanks for your lesson

[@JosephPMcFaddenSr]

Concise presentation!! Great job

[@aaminadurrani5131]

Thank you sir... I learnt a lot from your videos. please upload more lectures on such topics

[@nkosivumiletzhou3336]

simply explained, surely u do understand it.

[@ceyhunserfeliyev1935]

Great Explanation, but why in the last example your final answer has a positive sign? I think person losing much more energy than absorbed it, so the final answer should have NEGATIVE sign. If I am not right, please clarify it)))

[@kjartanasger]

What if the walls in the room in the example where white and had a epsylon value lower than the persons skin? it would hardly radiate at him, right? wouldn't that be taken into consideration or why is it only the temperature difference we care about?

[@amitmodak21]

simply brilliant

[@WadcaWymiaru]

With error in result?

[@goddess_ofchaos]

Thanks! This is very helpful

[@frankvalenti8350]

i have been watching his videos for a while. Now that i am in grad school, i am still watching them .. ha ha

[@Amiablegirl-m7e]

Nice lacture sir😊

[@railwayschoolandeducationc6312]

Good teacher

[@fractalnomics]

9:22 Snow is white, but has an emissivity of near 1. ?? This means it is a perfect absorber and emitter - this is not intuitive and is a real arm waver. On the other hand, shiny gold has an emissivity of near 0. So, very hot (near melting) shiny gold does not radiate - if it does it is at near 0. Something is wrong. Again, I have the answer: is modern physics willing to listen?

[@m.d.chetankumarmanjula4113]

great job sir I liked it a lot!!!!

[@rainwaterforthefuture8407]

What if there is no information about the surrounding temperature, but we know that the object still radiates energy since the surrounding temperature and the object temperature is not the same.. The reason for me asking this question is because other reference didn't really consider the surrounding temperature, they did their calculation only based on the object temperature. So what do you think is the proper argument or justification for this case?

[@erszebet]

very well put!

[@razoon93]

very helpful and simple ... thank u

[@michellechal4669]

how do i calculate the net radiation? would it be the same as the net rate radiation?

[@debojitacharjee]

What is heat radiation and is it like electromagnetic radiation? Heat can transfer in vacuum also but how? When anything is heated then its molecules vibrate rapidly but why anything that comes near that object also heats up? Is it something like electromagnetic radiation?

[@michelleodumodu135]

I like this topic

[@GKProducts]

nice and clear, thanks

[@ahmadfrahmand]

sir, what is short wave and long wave bands in satellite images like Landsat satellite images?

[@suzantayem802]

Thanks

[@americajutz4682]

Im a little confuse, question: should a person provide radiation waves? because here in any room it is surround of molecules, thanks ;)

[@nanu6440]

thanks a lot it really helped me

[@Itsjusttim365]

As detailed as you were I would think you would still have all the units in your final equation and show how they drop off.

[@fariqyasin4596]

superb

[@ayeyeikmon3228]

thank so much share knowledge for great learn

[@AKLECTURES]

You're welcome! Great to hear that :-)

[@soul5626]

thanku

[@OmarioKing_15]

Smart Guy

[@jakovmilas7753]

Very helpful, thank you :)

[@ayeyeikmon3228]

I like his teach physic

[@mariawulandari8623]

Thanks, very clear indeed! :)

[@cat1995jesus]

Brilliant. Thanks.

[@AKLECTURES]

Welcome! Glad you liked it!

[@fractalnomics]

It is amazing that air is a poor thermal conductor (0.024 no units) and is equally a poor IR radiator - only the 1% of it ( the GHGS) radiate. That is 400ppmv CO2 and 1300part per billion(!). Yet we are told the radiated GHG air particles collide with the 99% non-GHG oxygen and nitrogen to transfer heat by convection when they can't conduct. So what gives?

[@WadcaWymiaru]

If you talk about the gas...you need to use *Ideal Gas Law* - the combination of 6 Gas Laws: PV=nRT So T= 101.3 / (8.314 x 1.225/28.97) = 288.14 K ~15°C Earth black body temperature is -18.8 °C degree or 254.3 K All of that 33 degree rise without greenhouse gas effect. How this is happen? Because S-B law IGNORE the gravity with non-zero energy that is NOT going out as radiation! This is WHY we measure 255K in and 255K OUT! No difference in energy but atmosphere is 33 °C warmer! The "greenhouse gas effect" theory is already *DEAD*

[@fractalnomics]

thank you

[@anantatikar]

Plz make a video on heat radiation model

[@fractalnomics]

I have a thought experiment/ situation that doesn't make sense : can anyone help with it. Air (by which I assume 100% N2 and O2) is heated by a 'hair dryer' or the like by radiation: how can this be if 'air' has next to 0 conductivity properties and both N2 and O2 by greenhouse theory cannot absorb or emit any radiation. There is no convection involved. The air is quickly heated, so hot one cannot hold their hand in front of the fan. How can this be? I think radiation theory is incomplete and air ( N2 and O2) do emit and absorb radiation.

[@flipballaz93]

wow you have so much passion, have made an equation to measure passion?

[@AKLECTURES]

Thanks! I really appreciate that :)

[@fractalnomics]

2:22 "Every object radiates IR", yes, but not greenhouse oxygen and nitrogen (99% of the dry atmosphere). By greenhouse theory thermodynamics and quantum mechanics is contradicted. If N2 and O2 do radiate, as they must - for the reasons you said - greenhouse theory is contradicted. What gives? The greenhouse does. I am researching and writing on this right now: greenhouse theory and emissivity has to go; and radiation theory (and greenhouse theory) is bias to 20th Century experiments and needs updating.

[@waqarahmad-zq1mq]

Sir please do a video on Boltzmann transport equation and it's Drift component and Collision component........

[@fractalnomics]

The emissivity of all shiny metals are near 0. This says there power output of shiny metals is near 0 (even if measured 'hot' by other means). But the emissivity of shiny snow or even water is near 1, this mean snow if a perfect absorber. Something is wrong and it is not me. I have discovered where the problem lays: anyone interested?As it stands Nitrogen and Oxygen do not radiate any IR heat energy - at any temperature. If this is true there is a contradiction to thermal dynamics and quantum mechanics: if it is wrong greenhouse theory collapses. I have found the solution to the problem - they do (of course) radiate. Anyone interested?

[@obeahsf]

Because water and snow are transparent, not "shiny."

[@fractalnomics]

In any other discussion in geography etc, snow and water has a high albedo - reflectivity. This is common sense, but by emissivity this albedo of water is totally contradicted. I hypothesis it has to do with the measurement of emissivity via the thermopile. Water, by the thermoelectrics, generates electricity very effectively.

[@ZoyaKhan-we8zi]

great

[@mdtanviralam3595]

hey..plz upload numerical this topic...

[@alinaqi5716]

thumbs up! a very nice explanation of the topic.. but i need to ask something, I didn't get the sentence that what it actually means, "the object that radiates energy well also absorbs energy well"... i don't understand that how is it possible for a single object to be good in radiating energy and absorbing energy at the same time???

[@Whalturk]

***** I'm not really qualified to answer the question, but I guess logically, if an object is good at radiating, is must also be good at absorbing energy in order to keep the energy-level balanced. For example if the Earth was only absorbing energy, it would get hot very quickly, so it has to radiate energy to maintain the balance. Also, if the Sun was only radiating energy, it would "dry out", so it also has to be good at absorbing energy. I don't know if it makes sense; as i said, I'm not qualified to answer the question :)

[@bartonpaullevenson3427]

You are mistaken in thinking an object must be hotter to transfer energy to an object. A cooler object also radiates energy and the photons don't care what direction they're going in.

[@danieltrigo2928]

Can you explain me in more detail?

[@bartonpaullevenson3427]

@@danieltrigo2928 Bodies give off radiation according to the Stefan-Boltzmann law -- the flux density is F = ε σ T^4 where ε is the emissivity, σ is the Stefan-Boltzmann constant, and T is the absolute temperature. So the sky, for instance, can radiate to the Earth even though the Earth is warmer, and the "back-radiation" from the sky helps warm the ground (the greenhouse effect). Net heat transfer must be from the warmer object to the cooler one, but there can be some transfer from the cooler to the warmer.

[@WadcaWymiaru]

@@bartonpaullevenson3427 The "greenhouse gas effect" is proven wrong. I can show you if you wish to learn.

[@bartonpaullevenson3427]

@@WadcaWymiaru No, it hasn't been proven wrong, and I don't think you can show me anything.

[@WadcaWymiaru]

@@bartonpaullevenson3427 Then sit, learn...and CRY: en.wikipedia.org/wiki/Ideal_gas_law *Ideal Gas Law* : PV =nRT T = 101.3 / (8.314 x 1.225/28.97) = 288.14 K ~15°C Earth black body temperature is -18.8 °C degree or 254.3 K All of that 33 degree rise without greenhouse gas effect. Venus: T=9200/8.314 x 65/43.35 = 737.99 K or ~464°C Titan: T=146.7/8.314 x 5.25/28 = 94.1K or -179°C Let's see evidence on other worlds: kzbin.info/www/bejne/eKa3nnt5h6-irMU kzbin.info/www/bejne/Z4rCn2VuaMuMmMU because NO ONE defeated me in this subject!

[@lalegulbuz3496]

what if the walls were white?

[@synchrotron3000]

I LOVE U

[@MosomoCharity]

Can you fix the handwriting or make it more visible

[@deadmxss]

Omg you sound like Ray Gillette from Archer

[@samirmaliqi1253]

Let me know...Russian? (Exziemple 😂😂😂😛)

[@mamtagopani4945]

.

[@Vwcaddy-jo9ij]

thank you