Began learning algebra 3 weeks ago; immediately put it to use studying light/ electromagnetic radiation; 11 hr master class on Sp. Relativity and now the Photelectric Effect. Its really hard work but immensely satisfying, and with videos like this my progress is unstoppable. Thank you!
Michel van Biezen I love how you always seem to have videos for everything I am wondering about in physics. This is exactly what I am studying for right now, so I tried searching "compton scattering van biezen", and sure enough, you had a ton of videos about the whole photoelectric effect. xD Thanks a lot.
Michel Van Biezen do you have anything specific towards properties of matter?? Such a molecular degrees of freedom of a hydrogen molecule and such aswell, thanks for all the help with the maths and stuff, your a lifesaver haha
You're GREAT! Definitely saving my butt this semester. I watch your lecture on the subject before I read the book to help keep me focused on the main idea. Thank you so much!
Laura, Increasing the intensity of the beam would increase the number of photons emitted. Each photon can free one electron. Thus increasing the intensity of the beam would increase the number of electrons freed from the metal.
padard The energy contained within each photon depends on the frequency of the photon, but increasing the intensity of a beam of light can only be done by increasing the number of photons.
Thank you for another excellent lecture. Professor I am wondering if you have a video where you discuss Feynman's sum-over-path method. If I hear you discuss it, I know I will understand it.
Hello Michael. We know that the work function of a metal depends on the type of metal. So let the value of the work function of the metal be W1 when it is uncharged. Now let's charge that metal with positive electricity. In this case, is the work function still W1? I think the metal will have a greater work function when it is positively charged. Because when the metal has a positive electrical charge, I think it requires more energy to remove the electrons we want to remove. Can I get your opinion? Thanks.
Not likely. The work function depends on the forces between the valence electrons and the atom to which they belong. That force is a constant and does not depend on the charge of the metal.
I'm curious if there is a central place to download the entire ilectureonline library? I can do it one video at a time on TH-cam, but if there's a central deposit with everything archived I'd love to have access to that for posterity!
So I suppose the photon transfers no energy to the electron then? All of the energy of the photon is conserved and it deflects off the metal. What happens if the energy of the photon = work function? Does the photon get absorbed into the metal? Or does it again deflect? Thanks for your excellent videos as always!
Yes, if the photon does not have enough energy to liberate the electron it will deflect and keep its energy. If the energy of the photon is exactly equal to the work function (an unlikely scenario) the theoretical answer is the the electron will be liberated but will not have any kinetic energy after it is liberated.
@@MichelvanBiezen yeah you are right but now I have watched the full video and realised that it would not work because wavelength and frequency are inversely proportional to each other. I think I said it quite quickly and without much critical thinking.
That is correct. The energy contained within one photon only depends on the frequency of the photon. The energy or intensity of the beam depends on the sum of all the photons and the intensity of each photon.
Assuming photon has mass spread over its wavelength in the direction of motion, photon will impart greater momentum & will have more penetrating power if mass is concentrated in a smaller wavelength.
michel is this atomic physics? because i cannot tell if it is atomic physics when it says modern physics is photoelectric effect in atomic physics and modern physics?
"Einstein's first Nobel Prize." I thought he one more than one too! Turns out he only won one. John Bardeen is the only person to win the Nobel Prize for physics twice! Crazy, for the transistor and then for working on the theory of conventional superconductivity (a mouthful).
+CrushOfSiel yeah, those bastards at the Nobel prize committee didn't want to give him a prize for general relativity because they thought it was "a Jewish Theory." They actually weren't initially not going to award Einstein anything and just nullify the 1921 Nobel prize for physics until they had their arm twisted by other people. So brutal!
Hello sir : If a photon of energy (hf =E2 - E1 ) is incident on the atom which in the metastable state . One possibility is that the photon energy is sufficient for the photon to ionize the atom. Another possibility is that the interaction between the incoming photon and the atom causes the atom to return to the ground state and thereby emit a second photon with energy ( hf = E2 - E1) My question is what conditions make the first possibility and what conditions make the second one ? Thanks sir
What takes place inside an atom at any given time when it is struck by a photon is non-deterministic because of the size and Heisenberg uncertainty principle. We can only observe what happens after and make deductions.
There are many good books out there and many videos you can watch. The entire physics content is available in order on this channel covered by almost 2000 videos.
+leejy2 The kinetic energy of the electrons can be affected by creating a potential difference and hence an electric field which may stop the electrons or slow them down or speed them up (depending on the direction of the electric field).
+Michel van Biezen Is there a formula to calculate how much it affects the kinetic energy if the +1.0V is applied to the metal in your example? Thank you so much
+leejy2 First convert all energies from Joules to eV. 1 eV = 1.6 x 10^-19 J Then subtract the 1.0 eV (1 volt * 1 electron charge) from the difference of the work function (the energy required to free an electron from the metal) and the energy of the incoming photon.
Began learning algebra 3 weeks ago; immediately put it to use studying light/ electromagnetic radiation; 11 hr master class on Sp. Relativity and now the Photelectric Effect.
Its really hard work but immensely satisfying, and with videos like this my progress is unstoppable. Thank you!
Keep it going.
Wow, you are spending a lot of time studying! Keep it up.
(Thanks for the feedback)
Michel van Biezen I love how you always seem to have videos for everything I am wondering about in physics.
This is exactly what I am studying for right now, so I tried searching "compton scattering van biezen", and sure enough, you had a ton of videos about the whole photoelectric effect. xD
Thanks a lot.
Michel Van Biezen do you have anything specific towards properties of matter?? Such a molecular degrees of freedom of a hydrogen molecule and such aswell, thanks for all the help with the maths and stuff, your a lifesaver haha
Just wanted to say thank you so much. No one explains physics better than you.
Glad to hear it and glad the videos are helping
You're GREAT! Definitely saving my butt this semester. I watch your lecture on the subject before I read the book to help keep me focused on the main idea. Thank you so much!
Laura,
Increasing the intensity of the beam would increase the number of photons emitted. Each photon can free one electron. Thus increasing the intensity of the beam would increase the number of electrons freed from the metal.
padard
The energy contained within each photon depends on the frequency of the photon, but increasing the intensity of a beam of light can only be done by increasing the number of photons.
This is like the PERFECT video I literally can't belive I got those videos
Your video should be the first one that comes up when you search photoelectric effect on youtube
Thank you for another excellent lecture. Professor I am wondering if you have a video where you discuss Feynman's sum-over-path method. If I hear you discuss it, I know I will understand it.
We do have videos on the principle of least action, but not what you mention.
I now understand how to get the kinetic energy. thank u sir!
Hello Michael. We know that the work function of a metal depends on the type of metal. So let the value of the work function of the metal be W1 when it is uncharged. Now let's charge that metal with positive electricity. In this case, is the work function still W1? I think the metal will have a greater work function when it is positively charged. Because when the metal has a positive electrical charge, I think it requires more energy to remove the electrons we want to remove. Can I get your opinion? Thanks.
Not likely. The work function depends on the forces between the valence electrons and the atom to which they belong. That force is a constant and does not depend on the charge of the metal.
@@MichelvanBiezen Tank you very much .
i am amazed that till now why i did nt found ur video series . u r doing great job sir ,,,
sir thanks for teaching this topics so nicely without any confusion!!
Awesome! Very helpful for my test next week
An excellent explanation! I shall link this for my students.
Captain (professor) calculus, a character of one of our favorite comic books Tin Tin (Kuifje). And thank you for the link.
1 thing I would say: Einstein didn't discover the photoelectric effect, he was the first to explain it.
He set up an experiment that "proved" that light was quantized for which he was recognized.
I'm curious if there is a central place to download the entire ilectureonline library? I can do it one video at a time on TH-cam, but if there's a central deposit with everything archived I'd love to have access to that for posterity!
You are the great teacher.
ilhjkef I always find myself going "ah, so THAT is how it works...!" when I watch professor Biezen's videos. =)
So I suppose the photon transfers no energy to the electron then? All of the energy of the photon is conserved and it deflects off the metal. What happens if the energy of the photon = work function? Does the photon get absorbed into the metal? Or does it again deflect? Thanks for your excellent videos as always!
Yes, if the photon does not have enough energy to liberate the electron it will deflect and keep its energy. If the energy of the photon is exactly equal to the work function (an unlikely scenario) the theoretical answer is the the electron will be liberated but will not have any kinetic energy after it is liberated.
Excellent explanation, helped me understand the theory. Might be better to just use Planck's "h" value of 4.14e-15 which is already in eV, though!
Though it is trivial but I would like to point out Einstein got Nobel prize in 1921. U r magician
Yes it would work because the wavelength of photon is 5×10^-7m which is slightly higher than 4.6×10^-7m of the sodium metal.
A longer wavelength means a smaller frequency and therefore less energy.
@@MichelvanBiezen yeah you are right but now I have watched the full video and realised that it would not work because wavelength and frequency are inversely proportional to each other. I think I said it quite quickly and without much critical thinking.
That is easy to do with physics. My first instincts are often wrong until I start looking at the definitions and equations carefully. :)
@@MichelvanBiezen thanks for the advice.
Thanks, everything is sooo clear
Sir, the intensity of the beam doesnt affect the energy of a photon does it ?
The intensity of the beam depends on the number of photons per unit time, and the energy of each photon.
Michel van Biezen so, though the intensity is either high or low. it doesn't affect the energy of a single electron given by a photon?
in other words,the energy of a photon doesn't change as the intensity of the beam changes?
That is correct. The energy contained within one photon only depends on the frequency of the photon. The energy or intensity of the beam depends on the sum of all the photons and the intensity of each photon.
Assuming photon has mass spread over its wavelength in the direction of motion, photon will impart greater momentum & will have more penetrating power if mass is concentrated in a smaller wavelength.
Photons do not have any mass.
michel is this atomic physics? because i cannot tell if it is atomic physics when it says modern physics is photoelectric effect in atomic physics and modern physics?
modern physics encompasses nuclear physics, atomic physics, special relativity, quantum mechanics, and particle physics.
thank you
"Einstein's first Nobel Prize." I thought he one more than one too! Turns out he only won one. John Bardeen is the only person to win the Nobel Prize for physics twice! Crazy, for the transistor and then for working on the theory of conventional superconductivity (a mouthful).
had*, had more than one.
+CrushOfSiel yeah, those bastards at the Nobel prize committee didn't want to give him a prize for general relativity because they thought it was "a Jewish Theory." They actually weren't initially not going to award Einstein anything and just nullify the 1921 Nobel prize for physics until they had their arm twisted by other people. So brutal!
Sir, thank you so much
Glad this was helpful.
is that valid for the nonmetal elements?
This is typical for metals. But work functions can be measured for non-metals as well.
Thank you so much for putting that effort to help!!! God bless you!
Thanks so much for this video!
Hello sir :
If a photon of energy (hf =E2 - E1 ) is incident on the atom which in the metastable state . One possibility is that the photon energy is sufficient for the photon to ionize the atom. Another possibility is that the interaction between the incoming photon and the atom causes the atom to return to the ground state and thereby emit a second photon with energy
( hf = E2 - E1)
My question is what conditions make the first possibility and what conditions make the second one ?
Thanks sir
What takes place inside an atom at any given time when it is struck by a photon is non-deterministic because of the size and Heisenberg uncertainty principle. We can only observe what happens after and make deductions.
@@MichelvanBiezen thanks sir
@@MichelvanBiezen does the probability of ionization equals to the probability of stimulated emission?
so helpful sir
thank you
Thanks for the videos.
Could someone tell me what effect the intensity of the beam has on the photoelectric effect?
more intensity means more photons hitting the metal, which means more electrons will be emitted
7 years later lmao
Uh would you please tell me a reference I can study from? I'm a freshman and this sucks not knowing what's the best reference to study from
There are many good books out there and many videos you can watch. The entire physics content is available in order on this channel covered by almost 2000 videos.
You could use Fundamental of Physics by Halliday. It is one of the best physics book for freshman out there.
Brilliant, thank you!!
Thank you so much. You're an awesome teacher :)
How would the Kinetic energy be affected if the metal has +1.0V applied with respect to ground?
+leejy2
The kinetic energy of the electrons can be affected by creating a potential difference and hence an electric field which may stop the electrons or slow them down or speed them up (depending on the direction of the electric field).
+Michel van Biezen Is there a formula to calculate how much it affects the kinetic energy if the +1.0V is applied to the metal in your example? Thank you so much
+leejy2
First convert all energies from Joules to eV. 1 eV = 1.6 x 10^-19 J Then subtract the 1.0 eV (1 volt * 1 electron charge) from the difference of the work function (the energy required to free an electron from the metal) and the energy of the incoming photon.
+Michel van Biezen So just to confirm what you mean is the
KE(final)= Eph - w(in joules) - 1eV(in Joules)
A Einstein was awarded nobel prize in 1921 not in 1905
Yes, he was awarded the Nobel price in 1921 for what he discovered in 1905.
oh my u are amazing
very very goood
Just tried it on brass with a 450 nm 50,000mW Laser. No effect.
your the best
Thanks Abdul