Questions tagged [metals]
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How is absorption integrated in the simple Drude model?
What is the physical process of absorption in the Drude model?
As far as I understood in the Drude model you only consider the electrons as classical particles and frozen ions. No other particles ...
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p- and n- contact metal difference
I'm reading an article about some electronic components and the authors specify that they used p- and n- contact metals, but without giving details about those metals, or what material are they really....
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Why are there electron and hole currents in semiconductor, but only electron current in metal?
Why are there electron and hole current in semiconductor, but only electron current in metal ?
I know that in metal there is an overlap between valence and conduction band,
while for semiconductor, ...
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128 views
Do metals at low temperature follow Ohm's law?
I think metals at low temperature do not follow Ohm's because of superconductivity. Is it true? What about metals at high temperature?
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Can we understand the strong reflectivity of metals from band theory?
I know that solids, including metals, have electronic bands and bandgaps. If we consider some typical metal such as copper, we know that it strongly reflects visible light. From the point of view of ...
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1answer
30 views
Is it possible for aluminium alloys in an explosion to become pure elemental powder particles?
I am making a paper about metals and would like some help with this issue.
If you have some kind of explosion, is it then possible for aluminium alloys to become powder particles?, if yes, can they ...
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Why do (semi-)conducting materials absorb microwaves at their cyclotron frequency? - Cyclotron Resonance Technique
I am currently studying third year physics - more specifically a solid state course.
It was mentioned that in order to determine the effective mass of an electron in the nearly-free-electron model ...
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1answer
53 views
Is it right to conclude that Aluminium has free electrons from this?
I bought Dominos Choco Lava Cake and I had to warm it in my microwave oven. I could see that the cake was wrapped in aluminium foil, I put it in inside the oven and when I switched it on electricity ...
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1answer
27 views
How is an Eddy current separator actually getting the particle fly off?
I am currently trying to understand the eddy current separator on a physical level, but unfortunately I have a few uncertainties to resolve. I don't quite understand what is ultimately the reason why ...
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Quenching a metal spring with coffee
“With” meaning involving, not in. My coffee maker isn’t draining properly anymore, so the drip basket is overflowing. The spring that lets coffee flow out at the right rate seems to have stiffened ...
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85 views
Effective mass for metals
How can I calculate effective mass for of the electrons in $Al$ and $Ca$? I did real from some sources and they were mentioning that it could be evaluated from density of states but how? Also is ...
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99 views
Materials intermediate in density between osmium and neutronium [closed]
The densest elements on Earth are metals. Osmium is the most dense. The densest matter in the Universe is Neutronium which is not an element but degenerate matter. If we put Osmium and Neutronium on ...
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24 views
Can an electric magnet be a substitude for a magnet to test a metall?
For instance I have to check if certain metal is a ferromagnetic metal. Can I use an electric magnet instead of non-electric one?
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Conduction Theory [closed]
Why the conductivity of Metal increase with a decrease in temperature, semiconductor increase with an increase in temperature and alloys remains the same ?
Is it due to the following reasons?
...
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45 views
What happens to atomic spacing when a spring or solid material is deformed?
I am wondering if there is a ever a situation where atomic spacing is decreased when a solid material is deformed? I am aware that atomic layers slide over one another in malleable metals and that ...
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1answer
54 views
Thermal expansion of a rectangular metal shape
This question is inspired by this interesting answer which left me somewhat uncomfortable for the following reasons:
Suppose we have the following notched metal shape:
Following the linked answer, ...
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Why Metal-induced gap states don't apper at the interface of metal-metal?
I'm sorry for the silly question. I'm reading the article of Meta-induced gap state(MIGS) on the wikipedia. It says "MIGS appear when we break the transverse symmetry. At the interface of metal/...
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33 views
Does heating a jar lid significantly expand the metal?
The heat from hot water expands the air inside the jar relieving the amount of negative pressure inside the jar. Hot water may additionally help to loosen any sticky material inside the jar lid from ...
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107 views
Nickel plated steel strip for li-ion Battery pack - Purpose of Nickel Plating?
I am trying to build a battery pack from 18650 batteries, each interconnection is made from steel strip, most '18650 strip' has a steel core with nickel plating.
I have a question regarding the ...
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28 views
Why does brass fracture at a 45° angle?
These images were from a demonstration of a brass sample exposed to intense longitudinal (axial) pressure. Initially it was squashed resulting in some bulging outwards and sideways distortion, but ...
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131 views
Electron and holes in tight binding Hamiltonian on two sublattices
Background
Say that I have a tight binding Hamiltonian (with spinless fermions) of the form
$$H = - 2t \sum_{ij} (c_i^{\dagger} c_j + h.c) - 2\mu \sum_i c^{\dagger}_i c_i$$
where we only sum over ...
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1answer
244 views
What is occurring inside the lattice structure of metal when compression happens?
I was browsing reddit and saw this post. It is a gif of a factory, with a huge press squashing a hot chunk of metal.
I'm specifically interested in the behavior that is happening after the initial ...
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1answer
67 views
Is there a way to inspect thin metal weld (2 mm - 3mm) by ultrasonic testing?
I am working with an ultrasonic device to inspect welds. So far, I have learned that the minimum thickness of the metal sheet for this inspection is 6mm - 8mm. But the product of mine has 3mm thick ...
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1answer
40 views
What has coherence to do with this phenomena?
It reads,"Hardening due to coherent precipitate".Firstly,what has hardening to do with coherence of the precipitate?Why would dislocations shear the precipitate?
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67 views
Does metal thickness change with rise in temperature?
When a metal pipe or metal cylinder is heated uniformly in furness, inner and and outer diameter of cylinder increase and its length also increase but does thickness of the cylinder change with change ...
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Why do metallic Atomic bonds exist? [duplicate]
Articles online say that the outer valence electron orbital shell falls apart and electrons are shared through the bulk Elemental metal. Is there a topic in the physics feel that explains this ...
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1answer
39 views
Unique optical map of a uniform metal object
Given a metal object (let us say a perfect planner uniform surface) that has been exposed to external environment factors such as sun, wind, rain and others for couple of years.
This object has been ...
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2answers
96 views
Movement of free electrons
How can I understand the movement of free electrons in a conductor taking into account the quantam mechanical approach of electrons i.e. uncertainty of position and momentum etc. Does using quantum ...
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19 views
What is the physical meaning of “critical crack length”?
There are two equations that are primarily used in context of the fracture stress one with $\sqrt{\frac{\gamma E}{a_0}}$and the other with $\sqrt{\frac{2\gamma E}{\pi C}}$.I do not understand which ...
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What kind of surfaces can scatter alpha particles? In general, what are the requisites for scattering alpha particle?
What are the properties needed to be possessed by material in order to scatter alpha particles?
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45 views
What's responsible for the different hardnesses between Steel and Aluminum?
Why is the aluminum in a tin can harder than aluminum can? What characterizes their different properties?
Aluminum vs. Tin
https://en.wikipedia.org/wiki/Aluminium
Aluminium (aluminum in American ...
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1answer
154 views
Sonority of metals [closed]
Is there any reasonable atomic theory which can provide a rational reason for the existence of sonority in metals?
Almost all the non-metals do not exhibit sonority. Can it be correlated to the ...
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58 views
What is the meaning of $\tau$=$Gb/l$
What is the physical meaning or intuition of the Shear Stress vs Shear Modulus and Burger Vector over length relation($\tau$=$Gb/l$). I have seen this formula being used to determine length in case ...
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1answer
47 views
How can we see the microstructure of steel samples at room temperature?
When we intend to see the microstructure of a steel sample at a temperature say 950 $^\circ$C they say we quench it in order to freeze the microstructure. However, if we quench it are we not going to ...
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How are the two Stacking Faults namely intrinsic(formed by vacancy agglomeration) and extrinsic(formed by interstitial agglomeration) different?
Stacking Faults and its association with partial dislocations seem to bother me day in and day out.With regard to this I do not understand how Partial dislocations lead to stacking faults and not the ...
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125 views
Should a Bismuth coin slide slowly down a magnetic ramp?
One way to check for counterfeit silver/gold coins is to "slide" them down a ramp made of neodymium magnets. You can see an example here, or just look up "silver slide". I have seen this work for ...
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47 views
How can a metal be magnetic in this way?
I am reading a book about Skyrmions (Skyrmions in Condensed Matter, by Jung Hoon Han), and while reading about the interaction of Skyrmions with electrons (Chapter 5), the following statement was made:...
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1answer
69 views
Does a metal with a strong positive charge decrease its strength?
Does a metal with a strong positive charge decrease its strength? According to the mainstream theory of metal bonds, free electrons form a link between lattices. If this is the case, the removal of ...
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1answer
48 views
In the ground state properties of electron gas, is $V$ the volume of all the metal or the volume of a cell of the lattice?
In the ground state properties of electron gas (Sommerfeld theory), is $V$ the volume of all the metal or the volume of a cell of the lattice?
I thought the latter because the Born—von Karman boundary ...
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1answer
112 views
Does an insulator always contain the Fermi surface in the 1st BZ
I'm looking for a clarification about the classification of metals and insulators;
is it correct to state that if the Fermi surface is contained into the first BZ, then the material is an insulator, ...
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23 views
Metal-Insulator from number of atoms in the basis
I have an issue understanding what A&M means while saying this in chapter 12:
It is a reassuring exercise to go through the periodic table looking up the crystal structure of all insulating ...
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32 views
Can we determine the color of metal from the basic principle of quantum mechanics?
Is there any method by which we determine the color of metal, such as starting from the basic principle of quantum mechanics?
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56 views
Increasing the melting point of metal
I need to know how one can increase the melting point of a metals like steel, tungsten or ... about 500 degrees and without destroying its shape?
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Reflectance and transmittance equations for metal thin film
The Fresnel's equations no long work when the thickness of the metal thin film is thinner than skin depth. For example, the reflectance of a metal thin film is always the same according to fresnel's ...
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2k views
Is the specular reflection on a polished gold sphere white or gold in colour?
My understanding is that all specular reflection is due to Fresnel reflection at the interface which is a broadband effect.
A classic example might be a white reflection on a polished ball (e.g. ...
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271 views
How do knife blades become dull?
Knives are normally used to cut softer objects. So the edge of the knifes blade is harder than the substance it cuts through.
A blades geometry is more complex, but let's simplify it to the blade ...
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1answer
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Radiation emitted from a real melted piece of steel [1800C] VS emissivity
In a lot of questions I read that a good approximation of the radiation emitted from a hot piece of steel is the black body radiation.
Than I search for the value of the emissivity of molted metal ...
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How can electric fields be used to detect cracks in metals? [closed]
My physics teacher brought this up in a lecture and I am not exactly sure what he is saying.
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How to show that the electrons responsible for a current have an energy within $k_BT$ of the Fermi energy?
It is commonly written in textbooks that in metals the electrons responsible for an electric current are the ones that have an energy about $E_F$ and a few $k_BT$ around that energy. See for example ...
asked May 30 '19 at 12:29
thermomagnetic condensed boson
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Are there any crystallographic effects we can see in the reflection of visible light from metal surfaces?
I started thinking about this in a discussion in comments.
One can start by thinking of the reflection of visible light by most metals as similar to the reflection of radio waves in that it's an ...
