The Photoelectric Effect shows the Dual nature of light | What is a Photon?

[@FortheLoveofPhysics]

If light energy was quantised in Photoelectric Effect, now it is colliding with electrons in the Compton Effect :) kzbin.info/www/bejne/pYWxmn2MmaqsecU

[@alexandrekassiantchouk1632]

About Millikan's unnoticed until recently mistake read "We Have Lost a Half of Solar Energy, the Half that We Never Had".

[@lifetheories2452]

No one can understand quantum physics according to Feynman but we are lucky to have you. you have explained it in the best and easiest way possible. I haven't seen better way from this. Thankyou Sir... 💕💕❤️

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You are an outstanding teacher. I enjoy it more than Netflix

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You are my god

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31.10 The moment that you feel the satisfaction of being able to understand and explain even a small part of the universe.

[@saleemsurthy]

Very well explained. Better than Einstein himself. Congratulations

[@love2fly558]

Love that sigh towards the end, not a sigh of tiredness or disappointment, but rather of a job well done and maybe of some admiration towards Planck and Einstein. Your transition from classical to the quantum world in the last couple of lectures is brilliant. I enjoy Physics in layman’s term (a little Calculus and Diff Eqs is OK). I didn’t know about this sequence of events between Black Body Radiation, UV Catastrophe, Planck’s resolution and Einstein’s PEE. No more googling, you’re now my Master and I’m your Grasshopper.

[@sanjayyashwantsohani4820]

I totally agree with you.I also noted the sigh towards the end of lecture.Max Plank to Bhor to Enstein connection is amazing.

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[@chyldstudios]

The best video on the photoelectric effect. Well done!

[@snigdhamohanty9228]

Beautifully explained. A good book even wouldn't be able to explain a concept as good as he can.

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[@jakomuya6444]

Sir I lack the best words to express not only your teaching methodology but also how you make Physics look simple and interesting. You explain the concept of Photoelectric Effect in a hilarious way, making it get perfectly absorbed in my brain. Thanks so much. I am subscribing to your channel. It can be wonderful to attend your live classes online incase you have an online teaching and discussion platform.

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Each lecture is a masterpiece in itself

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I have no words sir.. best explanation on the KZbin till now

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Thankyou so much sir. You are really energetic. : )

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Sir, tusi great ho, you've made quantum mechanics easier to study for me.

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the passion you put into teaching made me listen and understand better

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Good teaching and breakdown of such a challenging concept

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A dedicated and passionate teacher... Great lecture😊...

[@Goldslate73]

100th comment on the video. You are absolutely unreal. The passion radiates from the way you speak and move. Bloody Brilliant! Thank You.

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Oh! Marvelous teaching skill!

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Hats off to your passion for teaching. The lecture was exciting the whole time.

[@fromaphysicistviewpoint2786]

How do you theoretically calculate the classical time delay (hours, days, etc. as you mentioned)? How do you theoretically calculate the quantum mechanical time delay (10^-9 sec as you mentioned)?

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Excellent teaching

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Great video as usual. Thanks.

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Awesome Explanation sir

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[@pakisium]

So pleasant learning from u Love from Pakistan to u

[@sukrishnascience8705]

Sir, can we have Foucault pendulum lecture? Coz your derivations and explanations are way easier to understand.. Currently in BSC Physics 1st year.

[@Ndiedddd]

Hello there! Could you make videos for Astronomy too? It is a topic that I don't see covered in much detail online

[@pauldirac6243]

Great presentation

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Congrats on a very astute, clear and comprehensive presentation. Cheers.

[@rishukumar7158-h1w]

18:00 failure of classical

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The interest. And the concept's 🔥

[@nikhilgarg1992]

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Thank you very much!

[@MrRoladeeb]

Thanks a lot sir, I have one question please, The cross section per atom depends upon approximately Z* for high atomic number materials and on Z4.8 for low Z materials. Since each atom contains Z electrons, the coefficient per electron depends upon Z³ and Z3.8 for high and low Z materials respectively. Since the number of elec- trons per gram is more or less independent of Z, we would expect the mass coefficients to vary as Z3 and Z3.8 for the two classes of materials. These statements are at best rough guides. That the variation of the mass coefficient depends roughly on Z³ can be seen from Figure 5-5. Above the K edge in lead, the coefficient is one thousand times as large as it is in water (slightly over 3 cycles on the vertical scale), while their atomic numbers of 82 and 7.5 are in the ratio of about 10:1. If you can explain it ,

[@schmetterling4477]

This isn't an atomic process. The electrons that are absorbing the energy of the photon are in the conduction band of the metal, i.e. their binding energy is much lower than the ionization energy of the individual atoms will suggest. In practice we also have to consider the thermal excitation of the conduction band, so unless the metal is cooled, there will be a considerable amount of thermal "smearing" of the work function.

[@xbrlinfinity9399]

I understand before the light is shone on the anode there is no current across the vacuum tube. Whilst the excited electrons might fly against the force of the electric field to the cathode, the momentum of their flight is not going to push them any further than the cathode; its not going to push them through the wire to the negative terminal of the battery (something else might though). I expect the arrival of the electrons at the cathode reduces the electric potential at the cathode (raises its negativity) compared to that at the negative terminal but then the electric potential will equalise between the cathode and the terminal (through the ammeter), which reduces the potential at the positive terminal (through the battery), and then the potential will equalise between the positive terminal of the battery and the anode of the vacuum tube, in the process replacing the electrons that were bumped off it, that were shot through to the cathode. Is this how the reverse current is created (effectively recharging the battery to some extent)?

[@madforlyf3811]

Sir shouldn't the electrons go from cathode to anode???

[@mdzaid523]

We have read in earlier classes that in photoelectric effect incident photon acts on metal surface due to which electrons are emitted from metal surface . But here you are using electric current instead of photons . Can you please explain why?

[@astikkumarmandal5766]

Great video

[@Jayapriyatnpcclasses]

Excellent

[@bobtannous5464]

if f' is the threshold frequency , we have the emkssion of photoelectrons for f> or =f'

[@bobtannous5464]

emission

[@abdullahshah3847]

Very thanks sir

[@ashishyaduvanshiofficiall]

Sir iit jaam ke liye book ko study krne ki need hai please reply 🙏🏼

[@sandeeppatidar1106]

Thankyou sir

[@Gaurav-um4oh]

You are a great teacher , sir ❤ If you don't mind , would you please tell about the courses you studied, sources where you get all the knowledge from?

[@ajithg796]

He is the Prof of Physics IIT Delhi

[@sakhiali4751]

I love you alot sir from Pakistan

[@ajithg796]

Sir, is this is the correct position of Ammeter to measure photo electric current?

[@schmetterling4477]

Yes. One could, of course, insert it in the anode branch of the circuit as well. Since this is a series circuit, the current will be exactly the same. Please note that in technological applications (photomultiplier tubes), the metal surface that is illuminated is usually called the "photo cathode" and that the polarity of the external voltage source is opposite. Why? Because in a photomultiplier tube we are trying to capture every single electron, so rather than trying to suppress the photo current, we are trying to maximize it.

[@madhu.c9845]

Sir flow of electrons cathodes to anode right 😢 I'm getting confusion about experimental setup 😢

[@FortheLoveofPhysics]

Yes it will flow *against* the potential difference

[@divyakumar8147]

thanks sir

[@arnabbanerjee417]

Awesome

[@ms4van53]

Sir recently Government announced a Rs 6000 cr funding initiative for Quantum technology development in India? According to you a Fresher or a job going person in mechanical engineering who has interest in Quantum technology hence to get a research job what in Quantum technology branches what should be his/her first foremost basic step to start with? Can you please guide us with this???.

[@alokbhushan9026]

@FortheLoveofPhysics If the observer is moving at relativistic speed. He will observe a red shift or blue shift depending upon whether he is moving towards or away from the source. So if a target is accelerated to relativistic speeds, photon with frequency lower than the threshold frequency should be able to produce electron emission. Has this been ever confirmed experimentally? On the other hand, we know that speed of light is constant for all inertial observers. Irrespective of whether they are moving with uniform velocity or are at rest. So the speed of light cannot be anything other than c in all the inertial reference frame. So a moving target is no different than a resting target for the light. Hence we should see no photo-electric effect when shining a light of frequency lower than the threshold frequency. Which of these two contradictory observations true? Or is there a way to resolve this contradiction?

[@gok_dogan]

Professor I wonder is it possible for an individual electron in free space absorb photon ? Not in an electron atomic shell .

[@schmetterling4477]

No, but there can be a scattering process in which the electron and the photon change their energy and momentum. If the photons have high enough energy, they can also create additional electron-positron, muon or even quark pairs.

[@gok_dogan]

@@schmetterling4477 thank you

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[@cnusrinivas226]

Sir, one question I had gone through is ..what is the maximum distance a photon can travel inside a metal in photoelectric effect?

[@schmetterling4477]

All these processes are very close to the surface. For metals like gold the optimal thickness of a photocathode material is on the order of 10nm (a few dozen atomic distances), for semiconductor photocathodes it seems to be about an order of magnitude larger (100-150nm for the few papers that I could find in a hurry that report the optimal thickness).

[@cnusrinivas226]

Ok sir... Thank you

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​@@cnusrinivas226untill , the energy of photon < h×f

[@Sarcasmka14]

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[@FortheLoveofPhysics]

It will start first week of June

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Sir next video please

[@samridhbajpai4295]

Sir it,s 10 days I am waiting for another video .sorry sir if I disturb you

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We want COMPTON SCATTERING, we want COMPTON SCATTERING... Bet you haven't heard that chant before. Haha

[@FortheLoveofPhysics]

Coming up :)

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First viewer❤

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[@rajatverma3112]

The light is incident on cathode and not on anode

[@FortheLoveofPhysics]

Light is incident on the positive terminal (anode) and photoelectrons go into the negative terminal (cathode). This setup is necessary to introduce a potential barrier that the electrons need to overcome with their KE.

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[@djessitemfack2157]

I have a question, what frequency represent ?(for photon?)

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Thank you sir!

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