By far it is the best description of the Maths I have found yet and been at it or a couple days. To see that this comment is 8 years old is nothing short of Amazing as it seems not much have come along better since you created this. A tad be worrying as well considering I literally just subbed before coming down to read this comment and now I am simply praying you still created videos of this sort as it would be a crying shame if you have moved on like so many others have.
Sir, You are a very good teacher, amazing at making things easy and actually not boring. These Videos might replace my teachers in school as the videos are so informative in little time. Schools would pay for these videos. Thanks
Yes, the probability density allows the electron to be at varying distances from the nucleus. But the point about the electron spiraling into the nucleus is the consequence of thinking of an electron as a charged particle radiating energy as its accelerates (in orbit) and thus losing energy and spiraling in. Treating an electron as a wave means that it occupies only certain energy levels and cannot therefore fall in.
I know this video is really old so it is unlikely you will see this question but I will still give it a shot - may I know why did broglie decide that the electrons in orbit are standing waves and not moving waves? likewise, then why are photons or other particles described as a moving wave in Schrodinger's equation? Your videos have been unbelievably helpful so thank you nonetheless!
Perhaps it might be a little easier to think of an electron as having wave like and particle like properties. The real issue is that our classical understanding of the world just doesn't apply in the quantum world. So classical analogies are very limiting.
Sadly dont really have facilities to do videos of experiments. But for spring constant take the spring and hang differing weights on it. Make sure you dont go beyond the limit of proportionality or the spring will become distorted. Measure the extension of the spring associated with each weight. Plot a graph of weight against extension. The gradient is k (the spring constant) since F = kx.
Semantics question: Is the first harmonic really equal to the fundamental? From what I understood in my lectures here in Germany, the fundamental wave is the first mode (i.e. L equals one half wavelength) and the first harmonic represents the second mode (where L equals lambda). I like your videos, the one on Maxwell's equations used a completely different notation and slightly different interpretation than what I learned, so that made everything fall into place in my head.
You've spoken several times of the significance of the standing wave concept being that it explains why the electron doesn't spiral into the nucleus. However, if we look at the "electron cloud" model of the atom, we see that the electron orbits at widely varying radii from the nucleus and at many times is very close to the nucleus. How does this fact square with the idea of a standing wave preventing the electron from orbiting too close to the nucleus?
Thanks for the video! speed of the wave is often given as: v = root(Tension)/root(mass per unit length); I have seen the derivations of it, and the derivations equate v^2/r to Tension/(Mass Per unit length)*r; r is the radius of curvature. I seem to think that they have ignored gravity in the derivation.
Very nice video. I still have one question though. If the electric and magnetic field only oscillate perpendicular to the direction of propagation and there is no medium, how does the electromagnetic wave then propagate?
Thanks for your time in making this video, it really helped. When you spoke about a wave pulse going down a string which is fixed at one end why does it invert when it hits the end? In my book it also says that they don't invert when the end is free (e.g. a ring) but it doesn't say why this is so?
Dear Sir, firstly I'd like to thank you for this video. Secondly, I would like to know that why the incident and reflected wave in stationary case are 180 degree out of phase but not any other values. Where does this come from? Regards.
Is it possible to create strong standing wave around spherical object? I am very interested in answer. Lets say that I would like to stop evaporation gases coming out of holes made in spherical object and keep them around it. (or to slow them down as much as possible) I would really appreciate answer on this question.
At 11:55 Sir, you say that there are only two nodes as the ones at the ends are very obvious to stay stationary and thus aren't counted as nodes. But my textbooks say that they too are counted as nodes and there are actually n+1 nodes, if there are 2l/n waves in a string of length l.
Thank you once again sir for making this video on my request.. I made my whole class watch your video.. They are the happiest person to have you as online teacher..
Hi. Your explanations are excellent. However, as a chemist I'm having difficulty conceptualising the standing waves through models based on fixed orbitals in the manner of pilot waves, which I believe comes from de broglie, when we know that these are not the correct models of electron energy levels. I've watched the particle in the box potential energy video, which shows the 1 dimensional solution of schrodinger equation for s electrons. Do you have any videos on three d solutions for p and d electrons rather than standing waves on a fixed orbital. In the absence of the underlying maths I've always been stumped trying to understand let alone explain why we have the 4 leaf clover probabilities for d electrons let alone the dumbbell and doughnut shaped dz2.
Ps. There've need a couple of occasions in videos which refer to centripetal forces on electrons and decay of orbits which I'm having difficulty contextualising with chemical quantum models that deny their existence
I woud rader consider an atom as a sfere, not as cirkle. If so, what hapens with electron in other meridians plains? Is it so, when you have 1 electro, he is always in same meridian plain, if 2 of them, they are in diferent plains, or elektrons also tilting in diferent plains, or they are all over the sfere simultaniusly?
This equation: 4pi Rv2=sd (v.+)∞(m.c) dt Re2∞ represents the unbroken symmetry of finite matter existing within the backdrop of an infinite universe. Inward spherical wave's of future probability cascading down from a distance Radius velocity equals Space Density forming electrical potential oscillating volume of mass between antimatter and matter an infinite future and a limitless past compressing+4-0-4+decompressing eXpansion of Time Log+Re2∞ infinity the ref-frames that make up our Universe
Dr.physicsa can you please send me the link for the problem on the standing wave formula. You said that you were going to make a video on how you got 2A sin kx cos wt
Every expression of Nature negated by its opposite expression 4pi R2= (+m.c2) Re2∞ Two masses are involved: One is +/-mass the other equivalent mass +Mu, of universe acting upon accelerating mass +/-m, from a distance radius. The inward absorption+/-outward emission EMR forming antimatter+/-matter annihilation electric change and electromagnetic fields. Each Entangled Wave-Front's Becoming Wave-Center's Compressing+/-decompressing eXpanding sphere's dissipating gravity or dividing time symmetry.
Stationary waves don't travel. They vibrate between fixed points. But you are right that the wave is set up by the combination of the outgoing wave (from fixed point A to B) and the return (reflected) wave (B to A).
Hey, i totally love your vids. I have one big wish for christmas: Could you be so kind and do video about bloch theorem and band structures? You are my last hope to understand that one day ... ;)
Hey doc, isn't the equation of the reflected wave -Asin(kx-wt) instead of the positive one. The reflected wave's amplitude is upside down so therefore won't the amplitude have a negative sign?
Its the other way round. In classical physics an accelerating charged particle gives off radiation. So if an orbiting electron (subject to centripetal acceleration) radiates energy it would (classically) spiral in.
DrPhysicsA it can also be accelerating without spiraling in. does it spiral it just because, or is there any proper explanation for it? thanks for the reply btw.
I beleive Atoms and Particle's are a spatially extended spherical rings series compressing+4-0-4+decompressing eXpanding sphere's dissipating gravity. Spherical cascading down from a distance radius wave's must propagate non-linearly at the central region producing two coupling resonances compressing+/-decompressing, its expression in the two opposing Fibonacci vortex wave motions is negative. Interchange between these two unbalanced opposites is the basis of all motion in this rythmic Universe.
If you referring to the fundamental Freq diagram shown in the video, then to complete once cycle of the wave you need another equal size of the rope Thus completing one cycle = 2 times the rope size or 2L And completing one cycle of will give you one wavelength, length So Lambda = 2L
May be, because they possess kinetic energy and cancelling waves would mean cancelling their K.E. which I think is not possible and hence the standing waves. However, I too, would like +DrPhysicsA to respond to this question.
Spherical Wave's from all three-dimensional wave-center's of the Universe combine their intensities forming the wave-medium density (space) opposing vorticies at each point of space. The total amplitude of inward spherical wave's at every point colliding at wave crest's and through's always seek a minimum as trillion's of wave's cancel equally balanced by opposite expansion at interchaning point's the sum of opposite vector's is always zero, this is reason for the symmetry or conservation laws.
This really isn’t what A-Level Physics’ syllabus is about. At least be precise with the content, please. Your channel is really helpful but sometimes it gets harder to understand the actual syllabus.
Wave's from all wave-center's of the universe combining their intensities forming the wave-medium density (space) opposing vorticies at each point of space. Inward spherical wave's at every point colliding at maximum compression point's forming wave-amplitude at wave crest's amd through's always seek a minimum as trillion's of wave's cancel equally balanced by opposite eXpansion at interchanging point's the sum of opposite vector's is always zero is reason for the symmetry or conservation laws.
I do not know how i can appreciate you.
Excellent work
Thanks for your kind comments. I have about 100 physics videos on my DrPhysicsA channel. And I am continuing to make more from time to time.
By far it is the best description of the Maths I have found yet and been at it or a couple days. To see that this comment is 8 years old is nothing short of Amazing as it seems not much have come along better since you created this. A tad be worrying as well considering I literally just subbed before coming down to read this comment and now I am simply praying you still created videos of this sort as it would be a crying shame if you have moved on like so many others have.
I have rarely seen someone ,who can explain so well .Thank you dear Sir .
I would give anything to have him as my tutor. Great work, sir.
Very clear descriptions here that have really helped the students I teach. Thanks.
Sir yr videos are also great. Very helpful.
Sir, You are a very good teacher, amazing at making things easy and actually not boring. These Videos might replace my teachers in school as the videos are so informative in little time. Schools would pay for these videos. Thanks
Thank you. I am most grateful and flattered. I hope the class found it helpful.
Yes, the probability density allows the electron to be at varying distances from the nucleus. But the point about the electron spiraling into the nucleus is the consequence of thinking of an electron as a charged particle radiating energy as its accelerates (in orbit) and thus losing energy and spiraling in. Treating an electron as a wave means that it occupies only certain energy levels and cannot therefore fall in.
If you plot it you will find that a wave sin kx-wt moves to the right and a wave kx+wt moves to the left.
Hey doc. Especially here to let you know I scored an A grade on my physics exam and a chunk of credit goes to you. Thank you. God bless you!
Only A???
Waaaaaa ahahhahhahah
Anonymous 😁😁
I know this video is really old so it is unlikely you will see this question but I will still give it a shot - may I know why did broglie decide that the electrons in orbit are standing waves and not moving waves? likewise, then why are photons or other particles described as a moving wave in Schrodinger's equation? Your videos have been unbelievably helpful so thank you nonetheless!
Perhaps it might be a little easier to think of an electron as having wave like and particle like properties. The real issue is that our classical understanding of the world just doesn't apply in the quantum world. So classical analogies are very limiting.
It's basically about energy conservation.
Sadly dont really have facilities to do videos of experiments. But for spring constant take the spring and hang differing weights on it. Make sure you dont go beyond the limit of proportionality or the spring will become distorted. Measure the extension of the spring associated with each weight. Plot a graph of weight against extension. The gradient is k (the spring constant) since F = kx.
No. The EM wave is the source of the varying electric and magnetic fields.
Excellent videos. Would it be possible to do a video on some worked examples on normalisation of some wave functions in quantum mechanics?
constructly helpful !!! what a clear illustration!!
I really love what you do. Thanks a million.
one of the best lectures for this subject!..You are awesome!
Semantics question: Is the first harmonic really equal to the fundamental? From what I understood in my lectures here in Germany, the fundamental wave is the first mode (i.e. L equals one half wavelength) and the first harmonic represents the second mode (where L equals lambda).
I like your videos, the one on Maxwell's equations used a completely different notation and slightly different interpretation than what I learned, so that made everything fall into place in my head.
Sir, you are to be commended on your contribution to my knowledge. You make it easy to understand, some might consider it a gift.
Thanks so much for this, its helped me so much. Just wondering if you could do a video on oscilloscopes , thanks again
You've spoken several times of the significance of the standing wave concept being that it explains why the electron doesn't spiral into the nucleus. However, if we look at the "electron cloud" model of the atom, we see that the electron orbits at widely varying radii from the nucleus and at many times is very close to the nucleus. How does this fact square with the idea of a standing wave preventing the electron from orbiting too close to the nucleus?
Thanks for the video!
speed of the wave is often given as: v = root(Tension)/root(mass per unit length);
I have seen the derivations of it, and the derivations equate v^2/r to Tension/(Mass Per unit length)*r; r is the radius of curvature. I seem to think that they have ignored gravity in the derivation.
I found that video here , so i wanna ask how standing wave of sounds can Levitates light weight in Air ???
do you cover all of physics as topics. I'm taking a unit 2 exam on mechanics, materials and waves. Is it all here?
Very nice video.
I still have one question though. If the electric and magnetic field only oscillate perpendicular to the direction of propagation and there is no medium, how does the electromagnetic wave then propagate?
Thanks for your time in making this video, it really helped. When you spoke about a wave pulse going down a string which is fixed at one end why does it invert when it hits the end? In my book it also says that they don't invert when the end is free (e.g. a ring) but it doesn't say why this is so?
Dear Sir, firstly I'd like to thank you for this video. Secondly, I would like to know that why the incident and reflected wave in stationary case are 180 degree out of phase but not any other values. Where does this come from?
Regards.
Is it possible to create strong standing wave around spherical object?
I am very interested in answer.
Lets say that I would like to stop evaporation gases coming out of holes made in spherical object and keep them around it.
(or to slow them down as much as possible)
I would really appreciate answer on this question.
At 11:55 Sir, you say that there are only two nodes as the ones at the ends are very obvious to stay stationary and thus aren't counted as nodes. But my textbooks say that they too are counted as nodes and there are actually n+1 nodes, if there are 2l/n waves in a string of length l.
explanation of quantum physics was superb
I completely agree! This man is a genius!
If the wave is not really moving, how does it carry information from one point to another?
Thank you once again sir for making this video on my request.. I made my whole class watch your video.. They are the happiest person to have you as online teacher..
Have you seen my video Waves - A Level Physics starting at 31:00 where I deal with refractive index?
No need for geometry to derive the standing wave equation, it comes right out of the sum identities for sin(x+y), sin(x-y).
Great stuff! Very well explained!
what's the difference between a standing wave and first harmonic/fundamental frequency?
Standing waves consist of fundamentals and higher harmonics.
Hi. Your explanations are excellent. However, as a chemist I'm having difficulty conceptualising the standing waves through models based on fixed orbitals in the manner of pilot waves, which I believe comes from de broglie, when we know that these are not the correct models of electron energy levels. I've watched the particle in the box potential energy video, which shows the 1 dimensional solution of schrodinger equation for s electrons. Do you have any videos on three d solutions for p and d electrons rather than standing waves on a fixed orbital. In the absence of the underlying maths I've always been stumped trying to understand let alone explain why we have the 4 leaf clover probabilities for d electrons let alone the dumbbell and doughnut shaped dz2.
Ps. There've need a couple of occasions in videos which refer to centripetal forces on electrons and decay of orbits which I'm having difficulty contextualising with chemical quantum models that deny their existence
Perfect just what I needed.
can a standing still be produced if string is loose (rather than fixed) at end , which means phase change during reflection is 0 degrees ?
Would'nt you consider substracting y1 - y2 (reflection) rather than adding y1 + y2 ?
I woud rader consider an atom as a sfere, not as cirkle. If so, what hapens with electron in other meridians plains? Is it so, when you have 1 electro, he is always in same meridian plain, if 2 of them, they are in diferent plains, or elektrons also tilting in diferent plains, or they are all over the sfere simultaniusly?
since the wave is standing in relation to electron motion then how can be antinodes at the same place all the time?
This equation: 4pi Rv2=sd (v.+)∞(m.c) dt Re2∞ represents the unbroken symmetry of finite matter existing within the backdrop of an infinite universe.
Inward spherical wave's of future probability cascading down from a distance Radius velocity equals Space Density forming electrical potential oscillating volume of mass between antimatter and matter an infinite future and a limitless past compressing+4-0-4+decompressing eXpansion of Time Log+Re2∞ infinity the ref-frames that make up our Universe
Very good and informative videos mate.
Have a look at the first video in my series on electromagnetic radiation for the cause of light waves.
beautiful video .....
I remember watching this 2 years ago when I did my A levels and now Im rewatching because my physics professor @ university is terrible
Could you perhaps do episodes on the physics practicals for different experiments? for example the experiment for finding a spring constant (k) !
:)
Dr.physicsa can you please send me the link for the problem on the standing wave formula. You said that you were going to make a video on how you got 2A sin kx cos wt
+Ranjit Dogra It's simple trigonometry. We, know, sinA + sinB = 2sin{(A+B)/2}cos{(A-B)/2}. Thus, the above result!
Your video's are very helpful! Could you please do a video about refraction of light?
Every expression of Nature negated by its opposite expression 4pi R2= (+m.c2) Re2∞
Two masses are involved: One is +/-mass the other equivalent mass +Mu, of universe acting upon accelerating mass +/-m, from a distance radius.
The inward absorption+/-outward emission EMR forming antimatter+/-matter annihilation electric change and electromagnetic fields.
Each Entangled Wave-Front's Becoming Wave-Center's Compressing+/-decompressing eXpanding sphere's dissipating gravity or dividing time symmetry.
It really helped! Thank You so Much!! :)
I will look at that video now! Thanks!
Can a stationary wave be consisting of two waves with different amplitudes and be travelling in same direction
Stationary waves don't travel. They vibrate between fixed points. But you are right that the wave is set up by the combination of the outgoing wave (from fixed point A to B) and the return (reflected) wave (B to A).
Very nicely explained.......
Im pretty confident that 99% of this video is way beyond the scope of A-Level physics...
Please I wouldnt mind explations with a "coil/ Spring / Spiral" (you know they exists as toys) thanks
Why it is -wt when the wave moves towards +ve x direction ??
Great explanation
we need to know these for AS level ?
how can the standing wave formula predict different harmonic
+oldcowbb Different harmonics depend upon the length of the string and the wavelength, which in turn depends on k, given by the sin(kx) term.
Hey, i totally love your vids. I have one big wish for christmas: Could you be so kind and do video about bloch theorem and band structures? You are my last hope to understand that one day ... ;)
really good!!! thanks for this!!!!
So when we say electrons are waves, that means electrons travel in waves?
No. It means that each electron can be represented as a wave.
If the electron is a wave, then what is oscillating?
+PT Yamin The electron itself isn't a wave. An electron can behave as a particle and a wave. So the electron itself isn't a wave.
thanks, this helped me a lot
Okay I will look at that now, thank you
Hey doc, isn't the equation of the reflected wave -Asin(kx-wt) instead of the positive one. The reflected wave's amplitude is upside down so therefore won't the amplitude have a negative sign?
why does the electron have to spiral in for it to radiate energy?
Its the other way round. In classical physics an accelerating charged particle gives off radiation. So if an orbiting electron (subject to centripetal acceleration) radiates energy it would (classically) spiral in.
DrPhysicsA it can also be accelerating without spiraling in. does it spiral it just because, or is there any proper explanation for it? thanks for the reply btw.
I beleive Atoms and Particle's are a spatially extended spherical rings series compressing+4-0-4+decompressing eXpanding sphere's dissipating gravity.
Spherical cascading down from a distance radius wave's must propagate non-linearly at the central region producing two coupling resonances compressing+/-decompressing, its expression in the two opposing Fibonacci vortex wave motions is negative.
Interchange between these two unbalanced opposites is the basis of all motion in this rythmic Universe.
I love your videos. Please, if you get a chance, could you make some more videos?.
it will depend on what exam board your on
24:57 how is it half a wavelength and it's length 2L?
If you referring to the fundamental Freq diagram shown in the video, then to complete once cycle of the wave you need another equal size of the rope
Thus completing one cycle = 2 times the rope size or 2L
And completing one cycle of will give you one wavelength, length
So Lambda = 2L
Thank you very much.
Why don't the two original waves just cancel each other, surely they are in perfect synchronisation for destructive interference?
May be, because they possess kinetic energy and cancelling waves would mean cancelling their K.E. which I think is not possible and hence the standing waves. However, I too, would like +DrPhysicsA to respond to this question.
Don't talk may be...
And their energy balances it won't destroy/cancel each other
They are also called Antinodes
But L = 2pi r . Where is r?
Listening to this whilst getting dressed .. My exam is today.
NIGHT BEFORE REVISION!
I thought they're called 'antinodes'
Spherical Wave's from all three-dimensional wave-center's of the Universe combine their intensities forming the wave-medium density (space) opposing vorticies at each point of space.
The total amplitude of inward spherical wave's at every point colliding at wave crest's and through's always seek a minimum as trillion's of wave's cancel equally balanced by opposite expansion at interchaning point's the sum of opposite vector's is always zero, this is reason for the symmetry or conservation laws.
This really isn’t what A-Level Physics’ syllabus is about. At least be precise with the content, please. Your channel is really helpful but sometimes it gets harder to understand the actual syllabus.
Yes.
Don't think so, I'm doing AS and none of this looks familiar :P
Wave's from all wave-center's of the universe combining their intensities forming the wave-medium density (space) opposing vorticies at each point of space.
Inward spherical wave's at every point colliding at maximum compression point's forming wave-amplitude at wave crest's amd through's always seek a minimum as trillion's of wave's cancel equally balanced by opposite eXpansion at interchanging point's the sum of opposite vector's is always zero is reason for the symmetry or conservation laws.
thanks .....
I, being a 13 year old, don't think I should be watching A level physics. >-
SWR Standing Wave Ratio
He sounds lime Sherlock Holmes from Elementary
>>>>
Bulls samach ma na hi aarai
My nigga
sexy accent
Not all of it, no.