Wave-Particle Duality and the Photoelectric Effect

Look, up in the sky, it's a particle! It's a wave! Actually it's both. It's light! How do we know about this stuff? Well, because of Einstein for one. He did more than E = mc^2, you know. But don't stare at the sun to see for yourself, we've got science now.

Check out "Is This Wi-Fi Organic?", my book on disarming pseudoscience!

[ProfessorDaveExplains]

Guys! When I said that the smallest fundamental unit of energy is the Planck energy, that's totally wrong. That is a completely different parameter that is actually a macroscopic amount of energy. I confused it with the Planck time and Planck distance, so that label is being used incorrectly. Sorry!

[mariamhashemi]

This saved my life! thank you. Especially, your saying "confused? you should OF

[malpacukierek]

You make Khan Academy seem like a wast of the attention span; not bagging on them but you are literally the most efficient and effective teacher I've seen on the internet; especially when we consider this is chemistry. Don't stop dude! Explain everything forever yo.

[maaslander]

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[Kamoj]

Thank you for this channel. it's very refreshing to have these chemistry topics explained easier than just reading a very wordy textbook that doesn't exactly explain the topic in terms to someone still learning the subject.

[poorvalele]

heyy I am from India and I was browsing through so many videos and it was so much of textbook language and the concept wasn't really explained properly.I just discovered your channel and your videos are really amazing.They help to understand the concept quickly.Keep making more amazing videos. -Love from India

[zapperz]

Hi Prof. Dave. Thanks for your videos. I've linked a couple of them in my astronomy class that I taught last Spring.

With regards to the PE effect, the notion that no electrons will be emitted for photons with energy lower than the work function, no matter how intense the light is, is only true for single-photon photoemission phenomenon. Since we now have intense laser sources, we can detect multiphoton photoemission. This is where photons with energy lower than the work function can cause an electron in a band (conduction band usually) to be raised to an intermediate state. But before it can decay back to a lower state, another photon comes by and excite it to another higher state. If this final state is a vacuum state, then it has the chance to escape.

Multiphoton photoemission technique has been used in the study of materials, and also is a common phenomenon in particle accelerator photoinjectors. None of these means that Einstein's original model is wrong. It is just that we now know that the standard photoelectric effect is specific to the single-photon photoemission.

Cheers!

[majidamaqbool]

And then it happened as I am now loving science.
It was a journey from boredom to awesomeness and lastly to curiosity about everything

[sehmio]

Hi Professor Dave, I've probably said this a million times but thank you for these videos. They make me feel super nerdy because I get excited to learn about science!c

[prixynealojado]

THANK YOU for this aaackk I'm a visual learner and I've been having a headache just watching other lengthy lecture videos explaining everything by word and description when all I needed is a clear visual illustration of how this works and this short video did it for me

[NeymarJR-durb]

He does a lot about the science stuffs
Professor Dave explains!

[conormcgregor]

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[nipunisaumyaepage]

I am watching your videos for these two days for my quantum chemistry assignment..it is very easy to understand basic theory ..thank you very much..keep it up

[mshdbbdrbbdbd]

Time saving, 3 min, only one mid roll ad at the end of the vid, teachs actually better than my teacher
OUTSTANDING

[missmoxie]

best channel ever. I'm acing chemistry because of you! You know so much!

[-mwolf]

hands down most concise, clearest explanations out there

[sharmaravikant]

Sir, u seriously explaining physic in very simpler way, i deeply feel satisfy after clearing concepts explain by u.

[miethadar]

i only understand what is quantized when i see Professor Dave, Thank you Dave

[johntucker]

Nice video man, you explain things really clearly, keep them coming :)

[nani-msm]

"confused? you should be!" ... "Thanks to Einstein and others ..." XD
Thanks for this, very helpful