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 Yearling
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Apr
1
comment Why do wheels spin?
I will mention that the case where a car moves because torque is applied to the wheels and the wheels move the car is almost completely opposite (in a sense) to the case where an external force (the fan) moves the car and the wheels roll in response. To see this you should consider the direction of the friction force on the wheels in each case.
Mar
6
awarded  Yearling
Feb
25
answered Why do we say that there is a voltage drop only when charge passes through a resistor?
Jan
7
comment Distance and pattern on Stern-Gerlach experiment
So yes, the pattern is bigger for the further screen, and no, no one has probably measured it because it is just application of basic Newtonian mechanics and so we know what will happen.
Jan
7
comment A modified Stern-Gerlach apparatus devised by Feynman for a thought experiment
@HolgerFiedler At least non-relativistically are not the same, as Lorentz requires electric charge and velocity of the particles, and the dipole force requires dipole moment and non-uniform field. Anyways, my point is the question is about SG physics and he answers in a useful way using the example of a charged particle under Lorentz force, but doesn't do enough to specify that it is just an example. A young student reading this answer could easily think SG apparatus works because of moving electric charges in a uniform field. Which is wrong. That's my point.
Jan
5
comment A modified Stern-Gerlach apparatus devised by Feynman for a thought experiment
First off, an SG apparatus will use electrically neutral atoms. So in no way is the observed motion due to a Lorentz force or cyclotron motion. It is due to the magnetic dipole moment of the atomic spin coupling with the external field. Secondly, this force on a magnetic dipole is related to the change in the magnetic field, and so your comments about "this argument works with uniform field" is misleading, since an SG apparatus is DESIGNED to have highly non-uniform fields (notice the sharp acute angle of the magnets, it is for exactly that reason).
Dec
17
comment Why are the jets of the “light saber” star slightly curved?
Could it be rotating?
Dec
3
comment Dirac monopole of Berry curvature?
I didn't mean to imply them as such, so I appreciate you pointing that out.
Dec
3
revised Dirac monopole of Berry curvature?
clarification in response to a comment
Dec
3
answered Dirac monopole of Berry curvature?
Nov
14
comment Do electrons actually reside in orbitals?
@Sparkler Well don't you see then? I asked if it was part of your question, you says it is, but the person answering you 50 different ways just above said "No, I don't think so". He doesn't understand your question and so will keep answering whatever question he thinks you are asking. You need to clarify your question.
Nov
14
comment Do electrons actually reside in orbitals?
@Sparkler It seems to me you are asking "What linear combination of atomic orbitals actually describe the typical states of electrons in atoms?" If so, you should make your question more clear, because the answers you are receiving are just clarifying things you may already know.
Oct
19
awarded  Good Question
Aug
11
awarded  Popular Question
May
11
awarded  Revival
Apr
9
awarded  Notable Question
Apr
2
revised Why does the “counting rule” of band theory fail to predict the conduction properties of some materials?
Suggesting a new title which is more to the point and phrased as a question.
Apr
2
suggested approved edit on Why does the “counting rule” of band theory fail to predict the conduction properties of some materials?
Apr
2
answered Why does the “counting rule” of band theory fail to predict the conduction properties of some materials?
Mar
31
comment How can one reasonably theoretically model polycrystalline materials?
Well, depending on the characteristic length scales of the system, 1000-10000 atoms might be more than enough to ensure that each grain contains "periodic" physics in the bulk. I can't say much about about the edge states though. Additionally, x-ray diffraction on powder samples is an extremely common experiment and I think the results are only marginally affected by the lack of bulk crystal (aka the line-widths increase but not much else).