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

The Photoelectric Effect sowed one of the earliest seeds for the ideas of Quantum Mechanics, which ultimately got Albert Einstein his Nobel Prize in Physics.
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The photoelectric effect is the emission of electrons from a material when light falls on its surface. This phenomenon was first observed by Heinrich Hertz in 1887 and explained by Albert Einstein in 1905. Einstein's explanation showed that light could act as both waves and particles, leading to the development of quantum mechanics. The photoelectric effect has become a crucial aspect of modern physics, with applications in solar cells and photoelectric sensors. The effect occurs when photons of light transfer energy to electrons in the material, causing them to be emitted from the surface. The energy of the photons must be greater than the material's threshold frequency for the effect to occur.
00:00 Introduction
01:51 Photoelectric Experiment
07:32 Experimental Observations
18:33 Einstein's Quantum Theory of Light
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[@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... 💕💕❤️

[@charleszerbib7768]

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

[@sayangayen7627]

You are my god

[@chyldstudios]

The best video on the photoelectric effect. Well done!

[@eternalthoughts-wu5lo]

excellant lecture...this professor is a brilliant teacher Bengali people are naturally brilliant and genius...most of them....some atel guys also exist

[@kadirayn2051]

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

[@astrobear8790]

you're absolutely amazing at what you do. definitely one of the best lecturers out there

[@snigdhamohanty9228]

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

[@saleemsurthy]

Very well explained. Better than Einstein himself. Congratulations

[@_chocolatecat_]

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

[@nadeeshanimunasinghe]

You are a wonderful lecturer…. Thank you sir!!!

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U are the type of teacher ..which makes student feel physics ..nd feel why are we studying physics ..u make it interesting..in every way possible..which very few teachers do..nd when u teach ..u give details bout every small thing in ur knowledge..which is truly appreciable..best teacher❤️

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Good teaching and breakdown of such a challenging concept

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Great video as usual. Thanks.

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

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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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Oh! Marvelous teaching skill!

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[@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.

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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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Great presentation

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Awesome Explanation sir

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The interest. And the concept's 🔥

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He is best man no word to experse

[@Ndiedddd]

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

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Excellent

[@Subham.Prusty]

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[@djessitemfack2157]

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

[@sukrishnascience8705]

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

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Awesome

[@sandeeppatidar1106]

Thankyou sir

[@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?

[@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?

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He is the Prof of Physics IIT Delhi

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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???.

[@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.

[@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)?

[@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

[@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

[@bobtannous5464]

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

[@bobtannous5464]

emission

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

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[@graceideas3387]

Sir next video please

[@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

[@Akash-by8jf]

First viewer❤

[@Sarcasmka14]

Sir csir NET ki bench kab start hogi???

[@FortheLoveofPhysics]

It will start first week of June

[@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)?

[@akashnamdev7711]

sir UPSC physics optional related course bhi start karege kya...... ya abhi koi vichar nhi ?????????

[@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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Join the Emversity community and connect with like-minded learners.

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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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The thumbnails r getting ridiculous 🤣

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hindu is studying from HRC

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