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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2answers
59 views
Equation describing magnetic hysteresis
So when you're looking at B-H curves for ferromagnetic substances, you often see these magnetic hysteresis curves, which occur, I gather, largely because of domain formation which has some reversible ...
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1answer
171 views
Learning roadmap for solid state physics [duplicate]
I am a PhD student in mathematics who knows little more about physics than what one learns in high school. For my research on tilings of space and aperiodic order, every now and then I have to skim a ...
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1answer
82 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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1answer
84 views
Why can we analyse force balance on a dislocation?
Dislocation (like screw or edge dislocation) is not a 'real' thing, while Newton's laws only apply to a real object (no matter macroscopic, like stars, or microscopic, like atoms).
In the derivation ...
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0answers
50 views
Is it possible to increase refractive index at lower densities?
Are there any materials for which the refractive index decreases with density? It seems that for most materials we would expect there to be a positive correlation between density and refractive index, ...
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47 views
Where can I find a complete list of metamaterials up to today?
Where might I find a list of all the metamaterials up-to-date?
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0answers
31 views
AWG chart for Tungsten
This is the American Wire Gauge (AWG) chart page for Copper that I found from Google:
http://en.wikipedia.org/wiki/American_wire_gauge
Is there a similar table for Tungsten/Wolfram available?
Has ...
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0answers
44 views
Is it right to cut a slot on some material before bending?
I made a suggestion to my boss to cut a thin, shallow slot on a metal sheet on the side we wanna make 90°, so that the machine could bend it. However, the outcome was "The metal broke".
My boss was ...
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0answers
123 views
Electrical machines: electrical and mechanical properties of steels and cast iron
I would like to know a good source of information for the common metals (steels and cast iron). Information that I need are basically the mass density and the electrical conductivity or resistivity. ...
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0answers
650 views
What properties of certain plastics make them x-ray transparent? [closed]
I was blown away by the abundance of good info here, and I thought maybe you could help me out with this query. I am in the process of developing a product, and I need to find a clear plastic resin ...
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1answer
386 views
Properties to select suitable materials for making permanent magnets
I have read that soft iron is suitable for making a permanent magnet. Because it is required for permanent magnet to have high coercivity and high retentivity.
Same text also said earlier that soft ...
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2answers
182 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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3answers
3k views
Yield Strength versus Ultimate Strength
What is the qualitative difference between these two:
As seen on the table Typical yield and ultimate strengths.
I am trying to resolve the meaning of the phrase "contact yield stress" from C. ...
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3answers
69 views
Accelerating faster per second than the speed of sound?
What would happen if you were to accelerate one end of a material, say a steel rod for instance, at faster per second than the speed of sound in that material?
For example, if the speed of sound in ...
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3answers
319 views
Liquid crystal shutter with >90% transmission?
Today's liquid crystal shutter glasses, when in the "transparent" state, exhibit only 40% light transmission.
They work using two polarizer layers, one which is liquid crystal and goes {vertical ...
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2answers
423 views
What happen when a gas is being heated far beyond its boiling point?
let's say we pour some water to the Sun. Or boil water on 2000 degrees Celsius on Earth.
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2answers
1k views
Wyckoff positions and lattice coordinations
Many papers use Wyckoff positions and Space Groups to report atom coordinates, making use of the structure's symmetries to save space in the notation (e.g. diamond = Fd-3m, only).
How can I ...
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2answers
191 views
Effect of coarse vacuum on consumer electronics?
What is the long-term effects of storing materials in consumer electronics in a vacuum? Ie, plastics, electronic circuits and optical glasses?
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1answer
46 views
What is tricritical point？
Critical point is the transition temperature of a second order phase transition. But what does tricritical point mean? WIki says that a tricritical point is a point in the phase diagram of a system at ...
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1answer
67 views
Can we make a space elevator/lift?
Is it possible to connect a long rope (excluding the danger of it's breaking) to a geostationary space station and use it to transport food and other necessary item's to the station and then ...
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1answer
41 views
Optical refocusing efficiency
What is the material for optical focusing that produces the less diffraction losses?
Suppose one have a sequence of serial optical elements $R$ that keep refocusing a beam of collimated light, each a ...
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2answers
274 views
Is there a physical reason steel balls are not suitable to play billiards with?
Steel is an elastic matter and is often used when demonstrating elastic collisions. We also make springs from it.
Due to these properties and for its relative low price, it seems obvious to me to ...
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1answer
228 views
Does Polytetrafluoroethylene (Teflon) have low wind resistance?
It is reasonable to assume that covering for example an airplane with Teflon would lead to it having lower wind resistance? The reason why I ask is that Teflon "has one of the lowest coefficients of ...
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1answer
141 views
Why does the d-spacing of a polymer decrease as its crystallinity increases?
I am currently investigating the annealing of a polymer (Parylene-C). In my reading I have found that when the polymer is annealed, there is a decrease in thickness of the film which results from a ...
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3answers
73 views
Hooke's law limitation question
Let's consider a spring. I am a strong man(well, lets assume) and I am pulling the spring. the work I do is being stored in the spring in the form of its elastic potential energy. Then suddenly, ...
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1answer
430 views
Calculation of a bending moment
I'd like to calculate the bending moment of a cantilever, fixed at its base, and submitted to a certain stress on a specific spot, but I can't find the proper definition of this bending moment (first ...
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1answer
85 views
Characteristics of bloch electron in a priodic potential
Effective mass of a Bloch electron in a periodic potential is negative why ?
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1answer
60 views
What are the Electric and Magnetic Properties of Aluminum Oxynitride?
Is Transparent Aluminum (Aluminum Oxynitride) a good conductor of electricity? Also, is it attracted by a magnet?
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1answer
194 views
Are silicone polymers transparent to infrared light?
I know that silicon and even black plastic bags are transparent to infrared light. What about light-colored silicone polymers (take white or green colors)? Are they transparent to infrared light too? ...
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1answer
86 views
What is a good reference for the mechanical properties of materials at cryogenic temperatures?
I want to research various the properties of various materials, namely tensile strength at cryogenic temperatures (~20K). I was wondering if a freely available database of material properties exists.
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2answers
159 views
Behavior of shock waves at relativistic speeds
Suppose I am in a spaceship traveling inertially at a velocity $v$ that is of the same order as $c$. As I pass by a metal bar that is oriented parallel to $v$, someone hits it with another metal bar, ...
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2answers
730 views
Calculation of the maximum load to the bar
Looking for a way of calculating the maximum weight (W) to the rod with the given length (L) where the rod did not break and that only bend for (b) mm.
Need only approximative solution (read: ...
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1answer
398 views
How to calculate the coefficient of restitution for 2 bodies?
I have 2 rigid bodies (from different materials) in a collision.
As you know I should have the coefficient of restitution value to get the velocities after collision.
What is the information/values ...
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1answer
171 views
Nonlinear absorption coefficient and the band gap
How does the nonlinear absorption coefficient depend on the band gap?
How can that coefficient be calculated theoretically? (Preferably with an example)
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0answers
33 views
Material physical properties of a desk related to vibration propagation?
I'm a software programmer (not a physics expert) trying out a smartphone vibration detection algorithm on desks, and I want to measure the impact of the desk's material features on the algorithm. Are ...
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1answer
39 views
What limits the maximum sustainable surface charge density of a sphere in space?
Suppose I charge a sphere and leave it in vacuum for 10 years. After that time, I want its surface charge density to be in the order of 10^5C/m^2. Would that be possible? Would it depend on the ...
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0answers
15 views
Is resilience a measure of power expended upon unloading?
I read the definition of 'elasticity' and 'resilience on Wikipedia:
Elasticity is a property of materials which return to their original
shape after they are deformed.
Resilience is the ...
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1answer
145 views
Acoustic Metamaterials: Negative Bulk Modulus?
In acoustic metamaterials we have simultaneously negative bulk modulus, $\beta$, and effective mass density, $\rho$.
I understand how one can obtain a -ve $\rho$ by constructing a solid-solid system ...
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0answers
77 views
Whats the contact area for elastic contact between a cylinder and a plane surface?
I am trying to determine the contact area between a cylinder and a plane surface of two different materials so that the plane lies tangent to the cylinder. There is elastic contact between the two ...
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0answers
31 views
Does graphene actually remain strong for macroworld engineering?
I heard that people envision strong structural materials made out of graphene, but I heard it may weaken when being stack in layers. Is graphene viable for macroworld structural engineering or is it ...
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0answers
28 views
Piezoelectricity [closed]
I want to do a science fair project in piezoelectricity, any ideas on what I can do?
I want to do the crystals first then perhaps connect them to a lamp. However, I think it's normal. Can anyone help ...
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2answers
335 views
Materials with a high compressive strength to weight ratio
We know about extremely strong materials such as carbon nanotubes. However, this is only in tension. What are some high strength-to-weight materials (both available and hypothetical) in uniaxial ...
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1answer
56 views
Is there real materials have Lieb lattice structure? [closed]
Is there real materials have Lieb lattice structure?
Some examples?
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0answers
111 views
Phase diagram problem for ternary system
For a ternary system, three composites are present.
Temperature is also a variable.
Assuming that pressure is held constant, what is the minimum number of phases that may be present in a ternary ...
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0answers
77 views
Which viscoelastic material that transparent for Infrared light?
I have to work with viscoelastic materials, since I tried to use a silicone polymer (silly putty) which expect to IR transparent properties, however, IR camera shown the black color (means their ...
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0answers
42 views
Terminology Fractional Physics [closed]
I recently read an article about the use of physics in computer graphics. Moreover, the method of "fractional Physics" used to provide the awesome three dimensional effects we've come to enjoy. My ...
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0answers
42 views
Communicating with a long rod / rope [duplicate]
Possible Duplicate:
Is it possible for information to be transmitted faster than light?
If I move a long solid stick can I send message fastest than light?
When we communicate via radio ...
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0answers
193 views
what's the earliest man-made material (that did not exist in nature)? [closed]
I was wondering what would be the earliest man-made material that did not exist previously in nature, e.g. plastic. I was thinking ceramics or glass, but that could occur on volcanic areas and such.
...
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0answers
99 views
Data storage question [closed]
I have been wondering about how a hard drive actually stores data.I have read articles and they all point to tiny magnetized regions being used to store the actual data.If indeed this is how data gets ...
-1
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3answers
321 views
Are we crystals?
Can we say that we are crystals because just like crystals we are made up of very small unit (cell) making up almost the same shape (our body) everywhere.
