Questions tagged [metals]

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Dissipation of sound in a metal

Suppose I produce a mechanical (plane)wave at the surface of a metal. How deep it penetrates into the metal? I have found that the dissipation is small, but how small?
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Understanding electric conduction in tight binding model

Let's consider a system of free electrons moving in a one dimensional lattice with dispersion $\varepsilon(k) = -2t\cos{ka}$, ($a$ is the lattice spacing and $t$ the hopping amplitude). Let's now ...
4 votes
2 answers
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Size of the Fermi surface of hole and electrons

The image below shows the shape of a Fermi surface of Cr metal measured by Angle resolved photoemission spectroscopy. (not important) The question is why does the Fermi surface shrink for the ...
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1 answer
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Fresnel Equations, Refraction, and Metals

I'm trying to make sense of how the fresnel equations apply to metals. Here are a few of the things I believe I understand: All reflections of light occur specularly. When an object appears to ...
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Fresnel Equations and an Opaque Surface?

I'm trying to make sense of what actually happens to light when it interacts with an opaque surface. The fresnel equations give us the proportion of light which is reflected off the surface of a ...
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Vibrating object on optical table

Wikipedia says this about optical tables: Many optical systems require that vibration of optical elements be kept small. As a result, optical tables are typically very heavy and incorporate vibration ...
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Is metallic hydrogen solid or liquid?

If I squeeze hydrogen superhard with 400-500GPa of pressure, it becomes metal so is that solid or liquid? I know gallium melts on my hand and it's metal.
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1 answer
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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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1 answer
648 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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1 answer
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Why/how is this crumpled wad of aluminum foil exhibiting strong magnetic repulsion against everything?

Forgive the extreme, potentially unnecessary, detail, but I'm trying to include all possible info to account for all possibilities, as this has driven me mad here. I lined a baking pan with Great ...
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Richards rule melting enthalpy

I know that Richard's rule states that entropy of fusion is constant for metals, and that it is ~2.2 cal K-1 mol -1. I am struggling to find the origin of this statement, is it empirical? What is its ...
1 vote
1 answer
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Why and How Moly (Molybdenum) can melt at 800°C inside muffle furnace?

I kept a ceramic cylinder wrapped in a Moly sheet. This whole thing was kept on an another Moly sheet inside muffle furnace. I ramped up the muffle furnace to 800°C in half an hour, kept there for ...
3 votes
1 answer
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Would a vibrating metallic and charged surface emit electrons?

Consider a metallic object under an intense electric field so its electrically charged in its surface. If the object is set to vibrate could it emit electrons? Maybe if the frequency is high enough? ...
3 votes
2 answers
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Will an extremely hard material wear away or fatigue if enough very-low energy contacts occur with a softer material?

So let's say that I have a tool that's made of a very tough and hard material, like tungsten carbide or some kind of gem stone. My understanding is, there are limits to every material, that up until ...
1 vote
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Extremely strong peak around 10 eV energy of Aluminum crystal in an x-ray inelastic scattering experiment

I conducted an experiment where I measured Bragg reflection for two different atomic planes (200 and 400) of Aluminum crystal at an energy of 10 KeV. Then, in each of these two measurements I shifted ...
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37 views

Does electric charge have any effect on diamagnetism?

Diamagnetic materials repel magnetic fields because freely moving electrons or cooper pairs within the material can form eddy currents in response to a changing magnetic field. It is natural to wonder ...
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1 answer
795 views

Fermi Gas - Number of Free Electrons at High Temperatures

What I am trying to do is to compute the specific heat of a free electron gas in a conducting metal. I am using Fermi-Dirac statistics as my framework to build off of. Importantly though, I want to ...
1 vote
2 answers
989 views

Is rust a good thermal insulator as opposed to bare steel or hardened clay?

I have no idea, if this is the correct site to find an answer on this topic, but considering it's a question of physical interactions I wanna give it a shot. I am in no way a physicist, just a ...
4 votes
1 answer
618 views

What's the transition from "metal" to "electron-degenerate matter" look like?

Question: Say that we had metallic water and compressed it until it qualitatively resembled the state of matter in a white dwarf: what would that transition look like? Background (revised to be ...
6 votes
2 answers
420 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
1 answer
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Do mirrors (with metal surfaces) show TIR (Total Internal Reflection)?

[Not a duplicate! Also, the answer to a similar question was unsatisfactory] I was digging into why we don't use mirrors in place of fibre optics cables. Majorly, the answers were as follows: It's ...
11 votes
3 answers
2k views

Why does Platinum evaporate if left long enough?

I have been reading into research relating to the redefining the 1 kg weight as the current Platinum-Iridium is becoming smaller. In this article, here, it mentions that the original metal weight ...
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2 answers
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Can someone tell me why there are two values for the dielectric constant from this website?

I have been looking up at available database that had dielectric constants for metals since I need them for my research and wanted to get an idea of what the values were before I focus on actually ...
3 votes
1 answer
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Absolute Seebeck coefficient of metals

Note: In literature, the Seebeck coefficient is most often given to platinum as a reference point, because it is challenging to measure the absolute Seebeck coefficient. It is however possible, this ...
1 vote
1 answer
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Calculate Force Needed to Squeeze a set of prongs together? [closed]

I have an anodizing rack that has hundreds of prongs. These prongs are made of titanium and need to be squeezed together in order to place the parts on the rack. I am wondering how I would calculate ...
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2 answers
2k views

Is there a way to make infrared pass through metals?

I am curious to know a way that will make infrared pass through metals. Metals are good reflectors of infrared,can we manipulate the wave in order to make them pass through metals?.
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2 answers
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How strength of RF coupling depend on the antenna material?

If we place different materials in the microwave owen, they will get hot at different speeds. For instance meals get hot really fast. What material property decides on the strength of the coupling? ...
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Structural notation for multi-element FCC crystal structures

I was wondering if different compound FCC structures share any kind of indicator or structural notation which I could use to find and categorise them. To clarify my problem: the FCC L12 structure, ...
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Question about the elasticity matrix in metals

The most general anisotropic linear elastic material has 21 elastic constants. I am working with an HCP material and I found that it has 5 independent elastic constants. I am programming a subroutine ...
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1 answer
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Relation between Fermi surface and Fermi velocity

Is there a direct relation between the Fermi velocity and the Fermi surface? Can one reconstruct the Fermi surface if the full angular distribution of the Fermi velocity is known?
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1 answer
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Is heat treatment the only means known to man for increasing grain size in steel?

It is well known that steel grains tend to grow larger under heat treatment. Is it possible to enlarge grain size through any other means? I cannot seem to find anything via web search. If steel is ...
1 vote
1 answer
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Metallic behaviour explained by Nearly free electron model

I am having trouble understanding what causes metallic behaviour in context of Nearly free electron model. Is it because 1) In 2d material with fermi level equation is $k_F=\frac{√2πz}{a}$. If for a ...
6 votes
2 answers
10k views

Could airport security possibly distinguish gold and silver coins from other coins?

People usually don't carry pure gold and silver coins in their wallets. If I put some in my wallet, would it be likely that airport security would detect some anomaly with my wallet as compared to ...
3 votes
1 answer
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Are solid materials ergodic systems?

It is stated that a system is considered ergodic if it can access all available states with the same energy in the phase space over long periods of time and that time average and ensemble average of ...
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1 answer
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Why are experimentally obtained specific heat values for different metals higher than the theoretical values?

I have just performed an experimental measurement of the specific heat of various metals by introducing an electrically heated probe and measuring mass and temperature difference with respect to the ...
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1 answer
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Why does gold only glow red after flame is removed?

I was at a jewelry workshop today and saw somebody place a gold ring under an intense flame. Weirdly, the ring looked normal when underneath the flame, but glowed "red-hot" as soon as the ...
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2 answers
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Does a crucible need to be fired in a kiln before use?

Say I made a crucible out of aluminum oxide primarily. Won't it be fired by normal use of it or do you have to pre-fire it? I understand they do that to get a consistent mass measurement. But does ...
1 vote
0 answers
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How does electrostatic field affect liquid metal?

I am currently studying electromigration in liquid metals. According to studies that have been done for electromigration in liquid metals, the metal ions are affected by the electrostatic force and ...
10 votes
1 answer
2k views

What is the physics behind the vibrating feeling you get when you touched an inducted metal surface?

When I was last working on the highway, I stopped to help a motorist parked under high tension power lines. I'm driving a large Ford Transit van, fairly box shaped. My van was parked 90 degrees (...
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1 answer
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What's the densest known material that has been made in macroscopic quantities?

I'm aware that the densest stable element is osmium at 22.61 g/cm3. And that there are unstable elements such as hassium and meitnerium which are predicted to have densities of 41 g/cm³ and 37.4 g/cm³ ...
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1 answer
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What are the north side and south side magnetic metals called?

What are the two metals that cause the repel force of a north side magnet, and the attract force force of a south side magnet?
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2 answers
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Is it possible that only surface electrons of the metal wire conduct electricity at light speed [closed]

Because if drift velocity of electrons is so slow than the actual speed of electricity which is near the speed of light. Then it might be possible that only electrons at the surface of metallic wire ...
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1 answer
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Why mobile electron bond so weak with positive ions in metal?

The mobile electrons move very easily in the metal lattice, which proves that they are very weakly bound to the positively charged ions at the lattice. But why is that?
53 votes
6 answers
138k views

In electrostatics, why the electric field inside a conductor is zero?

In electromagnetism books, such as Griffiths or the like, when they talk about the properties of conductors in case of electrostatics they say that the electric field inside a conductor is zero. I ...
4 votes
4 answers
895 views

Why can't the charge carriers leave the conductor? [duplicate]

I see that electrons are quite small in size, moreover it is moving fast but I have a question why do free electrons not leave a conductor (like a wire) ? but they can only move at the edge of the ...
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0 answers
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Scattering processes in $\rm Au$ and $\rm AuPd$

I'm learning about the transport of electrons in solids (especially based on the Drude model), and I was wondering how the different scattering processes that take place in metals vary with ...
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Why is pyrrhotite LESS magnetic the MORE iron it contains?

Usually, the more iron the better.... Pyrrhotite is an iron sulfide mineral with the formula Fe(1-x)S (x = 0 to 0.2). It is a nonstoichiometric variant of FeS, the mineral known as troilite. ...
4 votes
1 answer
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Landau tubes and Fermi sphere

A question regarding Landau tubes: I cannot understand why pictures of the Landau tubes are in k space as the Fermi sphere, especially considering the fact that $k_y$ ceases to be a good quantum ...
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2 answers
101 views

Why is a charge induced on a grounded metallic plate when another charge is placed near it? Why doesn't the charge flow into the ground?

When we bring a charge -Q close to a plate some positive charge is induced on the near surface of the plate to this external charge and some negative charge on the other farther surface. I believe ...
13 votes
1 answer
937 views

Why is crystalline graphite black yet shiny?

I am unable to find images of pure crystalline graphite with high confidence, but based on various sources I believe that it should actually be both black and shiny, in the sense that it reflects much ...

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