Questions tagged [metals]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0
votes
0answers
26 views

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 ...
0
votes
1answer
18 views

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....
0
votes
2answers
77 views

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, ...
0
votes
2answers
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?
3
votes
2answers
72 views

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 ...
0
votes
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 ...
0
votes
1answer
19 views

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 ...
0
votes
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 ...
0
votes
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 ...
1
vote
2answers
35 views

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 ...
0
votes
2answers
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 ...
1
vote
1answer
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 ...
0
votes
1answer
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?
-1
votes
2answers
59 views

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? ...
1
vote
0answers
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 ...
1
vote
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, ...
0
votes
0answers
12 views

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/...
0
votes
2answers
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 ...
1
vote
2answers
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 ...
0
votes
0answers
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 ...
0
votes
1answer
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 ...
1
vote
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 ...
3
votes
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 ...
1
vote
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?
1
vote
2answers
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 ...
0
votes
0answers
25 views

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 ...
0
votes
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 ...
0
votes
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 ...
0
votes
0answers
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 ...
0
votes
0answers
14 views

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?
0
votes
1answer
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 ...
2
votes
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 ...
1
vote
0answers
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 ...
1
vote
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 ...
0
votes
0answers
16 views

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 ...
2
votes
0answers
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 ...
0
votes
0answers
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:...
1
vote
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 ...
0
votes
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 ...
0
votes
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, ...
1
vote
1answer
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 ...
0
votes
0answers
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?
0
votes
1answer
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?
0
votes
0answers
19 views

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 ...
12
votes
1answer
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. ...
1
vote
1answer
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 ...
1
vote
1answer
69 views

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 ...
15
votes
1answer
3k views

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.
2
votes
3answers
221 views

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 ...
2
votes
2answers
72 views

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 ...

1
2 3 4 5
8