This guy is outstanding. Speaking as an electrical & computer eng prof for 30 years. So clear, easy to understand. Minor errors don't really affect the key learnings.
You're welcome. I am pouring through all your lectures, sometime 4-5 per day and enjoying it immensely. They are all of very high quality. A great service to the public who are interested in these topics.
I wish these videos had existed when I was doing my physics degree. Having all the concepts put together in such a short time and being able to rewatch it is so useful.
As I think I set out, this is a very simplistic way of showing how the Schrödinger equation can be illustrated to be derived from classical physics equations.
e is the charge on an electron (and also the proton but opposite sign). So if a nucleus has Z protons it will have a total charge of Ze. This approach works for single electron atoms (eg Hydrogen or ionised Helium or even Uranium if you could drive off 91 of the electrons! The force between the nucleus and the electron will then be given by Coulomb's law F - Ze e/ 4 pi epsilon r squared.
I'm not quite sure which part of the video you were referring to, but the potential energy between two charges involves the product of the two charges.
I'm not sure where you think I am refering to three charges. Is it because I use the term Ze^2? If so that is because the nucleus has a charge Ze and the single electron has a charge of e.
Shouldn't -h^2/2m be multiplied to all of the second order differentiate of wavefunction for x, y, and z coordinates (Laplacian)? I'm complete noob in quantum physics so sorry if I'm wrong.
8:34 "p is quantized" - this equation says that rp is integral. it does not say that p is integral. (r is not a constant - r can change when an electron switches orbits).
¡Excellent!!!! May be you noted that you have proved that the electron moving IS NOT probabilistic as most scientists want to make us believe. The movement of the electron is a satationary wave that comes from the Scrödinger Equation. Thus the position SEEMS probabilistic due to its wave properties. ¡Congratulations! You did it.
At 4:12, shouldn't the Coulomb force be negative because the elemental charges of a proton and electron are of opposite signs, i.e. (-ze^2)/(4pi*epsilon*r^2)?
Thanks, still a little foggy on why the potential force wouldn't be squared, but I guess that's because you didn't cover it. These videos are great, please do more of the quantum mechanics videos. Also, I didn't get what the Z in the Ze squared term came from. What is it? I'm guessing that the e squared is just the proton charge multiplied by the electron charge? But I'm not sure.
Actually, the Schrodinger Equation stated here is wrong. The stated equation is simply the formula for the Euclidean Hamiltonian. The left-hand side should be replaced with i\hbar partial/partial t. The equation the video states is obvious.
If you're talking about potential (V), then yes. But if you're talking potential energy (U), then you have to multiply it by your "test charge" (q), which in this case is the electron charge `-e`. This amounts for the `e²` in the formula after multiplying by the charge of the nucleus, `Z·e` (and accounting for the sign flip, because the Coulomb force has a negative sign before the entire expression, being an attractive force).
A broken clock also tells the correct time twice a day. Which doesn't mean that we should use broken clocks to tell time. That's the problem with the Bohr model too: it tells you the correct answers "by coincidence", but those correct answers come out from an incorrect model which has nothing to do with the truth.
It's not really anything related to the Coulomb force per se. It's just the *atomic number* , that is, the number of protons in the nucleus. It's just a natural number that tells you how many units of charge, `e`, you have to take into account in your Coulomb's force calculation.
8:24 "r is the radius and that is a constant" - lol :) what??? if r is a constant then p cannot change. because m certainly cannot change. then if v changes, then we are no longer balancing coulom's law. lol :)
@@DrPhysicsA It has nothing to do with _standing_ waves. A moving wave would have the same constraint. The constraint really comes from PERIODICITY: the wave function cannot have two different values at the same place. But it happens that the beginning and the end of the wave meet each other at the same place, and they must have the same value there, leading to a requirement that the wave function must have the same value at the beginning and at the end of the circumference (which you unfortunately called `L` - poor physics students who used to `L` being angular momentum :q ). That is, `Ψ(θ) = Ψ(θ + 2π)`. So if the wave function is some sort of a sine wave, in order for it to be periodic, its wavelength must be an integer multiple of `2π`.
oh okay then DrPhysicsA i haven't watched this video yet,i don't mean derivation of commutator but commutator in general (properties,application,relating with theory) ,sorry for my bad english!
nobody ever solves the schrodinger equation for the uranium atom .... probably because it can't be done and it devolves into gibberish ..... but everybody can solve for one proton and one electron
Because it's not really calculating the Schrödinger's equation - it's just plain old incorrect Bohr model disguised as modern quantum physics for clickbaiting.
This guy is outstanding. Speaking as an electrical & computer eng prof for 30 years. So clear, easy to understand. Minor errors don't really affect the key learnings.
Many thanks.
You're welcome. I am pouring through all your lectures, sometime 4-5 per day and enjoying it immensely. They are all of very high quality. A great service to the public who are interested in these topics.
I wish these videos had existed when I was doing my physics degree. Having all the concepts put together in such a short time and being able to rewatch it is so useful.
As I think I set out, this is a very simplistic way of showing how the Schrödinger equation can be illustrated to be derived from classical physics equations.
isnt this Bohr's model ?
e is the charge on an electron (and also the proton but opposite sign). So if a nucleus has Z protons it will have a total charge of Ze. This approach works for single electron atoms (eg Hydrogen or ionised Helium or even Uranium if you could drive off 91 of the electrons! The force between the nucleus and the electron will then be given by Coulomb's law F - Ze e/ 4 pi epsilon r squared.
The force between two charged particles has an r squared term. The potential energy between the two charges has an r term.
I'm not quite sure which part of the video you were referring to, but the potential energy between two charges involves the product of the two charges.
You are a very good lecturer. Thank u sir.
absolutely the cleanest and most insightful presentation of Bohr's model.
Just got why the potential isn't squared from your Maxwell's equations video, thanks, its all coming together, keep it going!
I derive the Bohr radius in part 2 of this video. I'm not sure what you mean by derivation of commutator.
I'm not sure where you think I am refering to three charges. Is it because I use the term Ze^2? If so that is because the nucleus has a charge Ze and the single electron has a charge of e.
Shouldn't -h^2/2m be multiplied to all of the second order differentiate of wavefunction for x, y, and z coordinates (Laplacian)? I'm complete noob in quantum physics so sorry if I'm wrong.
yes. the parenthesis were forgotten.
you did in 23 minutes what my prof. couldn't properly over 4-5 lectures in university
I remember this approach being used in my physics textbook to show how the energy level of the Bohr hydrogen atom were determined.
8:34 "p is quantized" - this equation says that rp is integral. it does not say that p is integral. (r is not a constant - r can change when an electron switches orbits).
Excellent lecture, but why does the electron wave around the proton have to be a standing wave?
¡Excellent!!!!
May be you noted that you have proved that the electron moving IS NOT probabilistic as most scientists want to make us believe.
The movement of the electron is a satationary wave that comes from the Scrödinger Equation.
Thus the position SEEMS probabilistic due to its wave properties.
¡Congratulations!
You did it.
At 4:12, shouldn't the Coulomb force be negative because the elemental charges of a proton and electron are of opposite signs, i.e. (-ze^2)/(4pi*epsilon*r^2)?
Thanks, still a little foggy on why the potential force wouldn't be squared, but I guess that's because you didn't cover it. These videos are great, please do more of the quantum mechanics videos. Also, I didn't get what the Z in the Ze squared term came from. What is it? I'm guessing that the e squared is just the proton charge multiplied by the electron charge? But I'm not sure.
Do you have variational methods anywhere on you channels? Tried looking for them, but not sure if they even exist...
Excellent teaching Sir.
I had a doubt how at 6:28 e^ikx =e^ik(x+L) =e^ikx e^ikL.
Kindly solve my problem.Thanks in advance.
a^(b+c) = a^b · a^c (basic rule of exponents)
Great lectures, but why is the coulomb force 1/r and not 1/r^2?
Oops at eqn 2 it changed to the equation I was expecting
Great videos, Dr. I'm not sure, though, how your coulomb potential relates to the one I learned with q1 and q2, and why just r instead of r squared?
What you're thinking of is probably Coulomb's law that defines the electrostatic force between 2 charges
What does it mean of that when electron turn around it goes x+L?
This videos helped me in my inorganic chemistry 🙏
This video is very useful. Thank you! I was wondering if you could make a video solving the Einstein Field Equations for the sun or any other object?
shouldn't the terms have partial derivatives when writing in three dimensions 1:30
If you really "cheated", and it still works, why do we use the schrodinger equation at all when we try to calculate for the hydrogen atom?
this only works for hydrogen atom not all atoms
Umm at time 3.52 it said electron goes round in a circle - is that true? Do electrons even travel?
Actually, the Schrodinger Equation stated here is wrong. The stated equation is simply the formula for the Euclidean Hamiltonian. The left-hand side should be replaced with i\hbar partial/partial t. The equation the video states is obvious.
why there is Z in electrical potential energy ??
Do you make those awsome "Artist Interpretation" videos on physics?
I think z is number of protons, so total charge of proton is -ze, the q1q2 is -ze^2
I'm a little rusty, but shouldn't it be V = -Ze/4.pi.epsilon.r ?
ie: ze and not ze squared?
If you're talking about potential (V), then yes. But if you're talking potential energy (U), then you have to multiply it by your "test charge" (q), which in this case is the electron charge `-e`. This amounts for the `e²` in the formula after multiplying by the charge of the nucleus, `Z·e` (and accounting for the sign flip, because the Coulomb force has a negative sign before the entire expression, being an attractive force).
To all who complain that this is the Bohr model, I'm not sure but I think it works for atoms with only one electron.
A broken clock also tells the correct time twice a day. Which doesn't mean that we should use broken clocks to tell time.
That's the problem with the Bohr model too: it tells you the correct answers "by coincidence", but those correct answers come out from an incorrect model which has nothing to do with the truth.
Isn't this just the Bohr atom? (Which is incorrect)
What is Z in coulomb force?
I think it is the atomic number.
It's not really anything related to the Coulomb force per se. It's just the *atomic number* , that is, the number of protons in the nucleus. It's just a natural number that tells you how many units of charge, `e`, you have to take into account in your Coulomb's force calculation.
4:47 explained me whole stuff
dear DrPhysicsA please do derivation of hydrogen atom radius and commutator!
8:24 "r is the radius and that is a constant" - lol :) what??? if r is a constant then p cannot change. because m certainly cannot change. then if v changes, then we are no longer balancing coulom's law. lol :)
yeah very good lecture but pictures are wrong electron is no on orbit but orbital
Why must n be an interger ?
+Minh Dat Ha Basically because if it isn't then the wave won't be a standing wave and each succeeding wave will cancel out the previous waves.
ah i see. thanks about the lecture btw. It was very easy to understand :) Keep up the good work
@@DrPhysicsA It has nothing to do with _standing_ waves. A moving wave would have the same constraint.
The constraint really comes from PERIODICITY: the wave function cannot have two different values at the same place. But it happens that the beginning and the end of the wave meet each other at the same place, and they must have the same value there, leading to a requirement that the wave function must have the same value at the beginning and at the end of the circumference (which you unfortunately called `L` - poor physics students who used to `L` being angular momentum :q ). That is, `Ψ(θ) = Ψ(θ + 2π)`. So if the wave function is some sort of a sine wave, in order for it to be periodic, its wavelength must be an integer multiple of `2π`.
thank you Dr PhysicsA
7:31 "KL=n2π"
oh okay then DrPhysicsA i haven't watched this video yet,i don't mean derivation of commutator but commutator in general (properties,application,relating with theory) ,sorry for my bad english!
nobody ever solves the schrodinger equation for the uranium atom .... probably because it can't be done and it devolves into gibberish ..... but everybody can solve for one proton and one electron
why is this a cheat?
Its not really cheating but it is deriving a quantum mechanics equation from classical mechanics instead of from first principles.
Because it's not really calculating the Schrödinger's equation - it's just plain old incorrect Bohr model disguised as modern quantum physics for clickbaiting.
this is just bohr's model , which is wrong
***** No, not incomplete but wrong. The bohr model has no concept of a probability wavefunction.
thank you sir.
Wtf
Indeed.