The study of how the properties of matter arise from its structure at all scales and of how processing can be used to modify those properties (often in pursuit of a specific application).

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Is there a substance that doesn't reflect OR absorb light from the visible light spectrum?

Is there a substance that doesn't reflect or absorb visible light but may reflect light from another spectrum? Is there a theoretical substance that would have these properties? EDIT: Sorry I wasn't ...
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1answer
9 views

Question about the way the inner stress in an axially loaded member is defined

When a member is in tension, such as in a tensile test of a piece of metal, its freebody-diagram would show a force of P in both directions. Why then is its internal stress not $\frac{2 \cdot P}{A}$? ...
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1answer
122 views

Energy conservation of permanent magnets engine

How to explain the fact that magnet can attract an object (apply a work W) without losing a (significant) part of its internal energy? How to apply the energy conservation principle? Please think to ...
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1answer
15 views

Adsorption of polar molecules

On any given surface, is there more adsorption if the molecules in a vapor are polar? For example, for a given (approximate) molecular weight would one expect more adsorption onto a surface by the ...
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2answers
541 views

What is the difference between Sapphire and BK7?

What is the difference between Sapphire and BK7 in optics (lenses), is it only about quality?
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2answers
220 views

does the thickness of a rubber sheet affect the tensile strength?

i'm really confused which thickness of rubber sheet i should choose. Does the thickness affect the tensile strength and elongation in any way? is there any relation between them? i would really ...
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1answer
245 views

Force problem related to adhesive and bonding

I have two PCBs (printed circuit board), and they are glued by adhesives, as show in the pictures. And the location of the adhesives are indicated on the picture (please notice that NO adhesive is ...
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1answer
95 views

How does force transmit through a solid block?

If you take a solid block, say, a cube of side length $l$ with density $\rho$, you place it upon a solid floor, and you apply an external pressure of $p(x,y)$ on the upper face ($x$ and $y$ define a ...
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0answers
28 views

The physics of an anvil [closed]

I am trying to understand how an anvil might best be made. An anvil requires two essential characteristics: enough hardness to not be deformed under the blows of the hammer, but as little rebound and ...
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0answers
21 views

Different ways to calculate the bulk modulus

I am trying to calculate the bulk modulus of unit cells of materials with trigonal or monoclinic structure using two different methods: -The first one is by fitting the changes of volume and energy ...
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0answers
29 views

Why do sponges work? [duplicate]

By "sponge" I mean anything used to suck up liquids from surfaces, such as kitchen towels etc. I assume capillary action is a factor, and also maybe surface area and surface energy. What are the ...
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4 views

How is a unidirectional lamina transversely isotropic?

What I don't understand specifically is that if there happen to be more fibers in the $x_2$ direction than the $x_3$ direction, wouldn't that make the material properties in those directions ...
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1answer
27 views

Predicting contact time and COR (coeff of restitution) for a cricket ball and pitch

For real world application, COR --> Bounce produced by pitch, for both spinners & seamers; Contact time --> grip provided by pitch, mainly for spinners Assuming cricket ball to be a sphere and ...
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2answers
27 views

Why do materials show plastic behaviour for large stress?

As the stress is increased, the strain increases proportionally up to elastic limit and the material regains its original dimension within elastic limit. When the stress is increased further the ...
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0answers
22 views

$16~\rm N/mm^2$ flexural strength

This question more relates to construction and architecture but I am sure it will not be the problem to ask and get a good answer here. If we have declared flexural strength of concrete of 16 N/mm2, ...
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2answers
140 views

What is the physical significance of the Curie constant?

What is the physical significance of the Curie constant? I understand it depends on the effective moment of the ion and hence must be some measure of it, but what is it exactly? Like some average ...
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0answers
18 views

Are hardness, strength and toughness of materials not the same thing in a way?

I had to look through several videos and re-read Wikipedia statements about these material properties several times before I could even begin to differentiate them. However, now that I have found out ...
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0answers
20 views

Effective medium approaches - Volume averaging vs homogenization?

In dealing with multiphase two phase systems as an effective medium there are two approaches that can be taken. Volume averaging and homogenization. Volume averaging is very intuitive, just take ...
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0answers
11 views

What is our most complete microscopic theory for the elastic-plastic transition point?

I suppose its all stated in the title. What is our most successful description of the microscopic behavior of material at the elastic-plastic transition point. My condensed matter physics prof was ...
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1answer
34 views

behavior of dissolved ionic compounds in an electric field

Consider the following setup - An open, insulating box is filled with distilled water, into which is dissolved a significant amount of pure NaCl. Two insulated lumps of conductor, one with a large ...
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0answers
51 views

Why should I discard a carafe if it has ever been heated empty? (Can thermal shock permanently weaken materials without causing them to fail?) [closed]

Related to "What pressure or tension occurs in a glass jar when I pour boiling water inside?" I just got a new coffeemaker, and one of the warnings in the manual states that you should discard the ...
3
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1answer
328 views

What factors cause the velocity saturation to occur at different electric fields for different materials?

In semiconductors the velocity of carriers gets saturated after a certain value of electric field. In silicon it occurs at around $10^4 kV/cm$ and in GaAs at some other value. What factors are ...
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0answers
20 views

What's “the” physical explanation of hysteresis in ferrimagnetic materials?

I am wondering what is "the" or "a" physical explanation of hysteresis in ferrimagnetic materials. From what I've read in wikipedia and Cullity's book, there is a simple physical explanation for ...
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4answers
54 views

Same equation, different meanings

I went into a physics classroom today and saw this equation written on the board: $$ E = \frac \sigma \epsilon $$ At first I thought it referred to the electric field $ E $ between 2 parallel plates ...
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3answers
172 views

What can justify the decrease of the electrical conductivity with the increase of light intensity?

I have currently been working with a sample that "appears to" decrease its resistance when I cover it and protect it from light. Basically it presents the opposite behaviour of a photoresistor. What ...
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1answer
22 views

Why are Brillouin zones for graphene and monolayers of transition metal dichalcogenides the same?

The geometrical model of graphene is the flat honeycomb lattice, so the Brillouin zone is also flat honeycomb lattice. However, monolayer of transition metal dichalcogenides is not flat as it consists ...
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1answer
314 views

Malleability in metals

I am trying to understand malleability in metal as a result of the micro structure. I am focusing on the metals of antiquity (in order of decreased malleability): Gold, Silver, Copper, and Iron. While ...
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1answer
4k views

Penetration of armor plate

Is there a simple mathematical expression for the stopping power of a given thickness of armor, given the thickness of armor plate, the radius of a cannon ball, the density of the cannonball and the ...
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2answers
207 views

Why is diamond transparent while graphite is not?

Diamond and graphite are both made of the same atom, carbon. Diamond has a tetrahedron structure while graphite has a flat hexagonal structure. Why is diamond transparent while graphite is not (at ...
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1answer
497 views

Semiconductor problem: how much Boron is required to establish a certain amount of charge carrier density

The problem description is as follows: Boron is used to dope 1 kg of germanium (Ge). How much boron (B) is required to establish a charge carrier density of 3.091 x 10^17 / cm^3. One mole of ...
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0answers
22 views

2D materials with isotropic Dirac cones

The celebrated material graphene has electrons which can be described by the simple 2D Hamiltonian $H = v_F \left( \sigma_x p_x + \sigma_y p_y \right)$, where $v_F$ is a Fermi velocity. Silicene, ...
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1answer
24 views

3D Bravais Lattices in terms of $\mathbb{Z}^3$

I am looking at the definitions of Bravais Lattice on Wikipedia and I find that I can describe many of them in terms of a mathematical lattice $\mathbb{Z}^3$. cubic $\mathbb{Z}^3$ body-centered ...
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0answers
10 views

Spectral Signature

I am interested in studying about spectral signature of various materials. I am working as an electronics engineer intern in a company which deals with Hyperspectral imaging. Working with spectral ...
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1answer
23 views

Thermodynamic / Thermal Property

What is the definition for (i) Thermodynamic Property & (ii) Thermal Property? What are the subtle distinctions in the Thermodynamic Properties and Thermal Properties? ...
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3answers
512 views

Can vinyl LPs store audio above 20kHz and can it be played back? [closed]

If, in the future, humans genetically engineered themselves to be able to hear frequencies significantly above 20kHz (say, up to 100kHz), would they find vinyl LPs a viable method of storing and ...
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4answers
95 views

Can a material made of a heavier isotope of an element become harder or stronger?

I was wondering if any experiments have been done to measure if there is a change in the hardness or strength of a material made solely of a heavier isotope of an element which is a constituent of the ...
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0answers
24 views

Looking for materials with specific magnetic properties

To begin with, I am not a native English speaker and have very limited knowledge regarding magnetism and want to apologize in advance for probable use of incorrect terms. In the picture, M ...
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0answers
14 views

How to measure the two-point function for two phase media?

Given some two phase media, consisting of a random mixture of materials A and B. how does one measure the two-point function? The one-point function is trivial to determine and can be done simply by ...
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2answers
2k views

Why is paper more frangible when it is wet?

My four-year-old daughter asked me why paper tends to fall apart when wet, and I wasn't sure. I speculated that the water lubricates the paper fibers so that they can untangle and separate more ...
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1answer
35 views

why cracks are observed over time in stainless steel vessels? [closed]

We are using stainless steel vessels for long time. But most of the times the vessels made by the stainless steel material are get cracked on its edges. I guessed this would happen due to the ...
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0answers
100 views

Is there a database or a classification of High-temperature superconductors?

I was wondering if there exists a list with all (or most of) the High-$T_c$ superconductor materials. In particular I'd like to know if there are databases or review that classifies them by their ...
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2answers
839 views

Will density of a metal increases during forging?

This question is metallurgical engineering, but I had a similar doubt regarding density of liquids and what causing it. Forged parts refines defects, dislocations will be moved strengthening the ...
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3answers
10k views

What common materials absorb most infrared light?

I'm competing in a simple robotics competition where most of the participants use reflected infrared light to detect their opponent. I'd like to make my own robot as difficult to see as possible. What ...
14
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2answers
592 views

Why would different metals glow red at different temperatures?

According to everything I've been taught about incandescence and black-body radiation, and some quick Googling to confirm I'm not crazy, just about everything, regardless of composition, should start ...
3
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1answer
60 views

Temperature dependence of magnetic domains

Does the size of magnetic domains depend on temperature ? Not able to find any papers on this subject, maybe because there is no such dependence...
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3answers
84 views

How to cut graphene?

How is graphene cut, given that it is similar in strength and hardness to diamond? I assume you cannot just take a pair of regular scissors to a sheet of it and cut out the shape you want?
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2answers
58 views

Elongation and tensile strength of rubber

I want to do some experiments on a neoprene rubber sheet (ex. supplier). When I went to order the sheet I was confused because the listed elongation and tensile strength for all sheet sizes (with ...
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2answers
132 views

Software for analysing SEM or TEM images

I am looking for a software to analyse SEM and TEM images of some PLD experiments because I want to characterize the samples, like calculate the concentration of nanoparticles, size, and do some ...
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2answers
572 views

How much force can bolt cutters exert? [closed]

What's the mechanical advantage of an ordinary, let's say, 3 feet long bolt cutters? How many pounds can they exert? I'm asking because I have a lock which is apparently immune to over 9 tons of ...
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2answers
554 views

Penetration of human skin [closed]

I recently found an answer for the "toughness" of steel http://physics.stackexchange.com/a/16821 and was hoping to get a similar answer regarding human flesh. How much pressure is required to ...