Material Definition and 1000 Threads

  1. A

    Fermi Vector in Ferromagnetic Material

    Homework Statement Consider an electron gas of density n_{0} in three dimensions that is completely ferromagnetic: all electron spins point in the same direction. Derive: a) The Fermi wave vector in terms of n_{0}. b) The parameter r as the radius in atomic unites that encloses one unit of...
  2. 1

    More old material planes, normal and parallel vectors

    Homework Statement Consider z = -3x - y + 11 Find a unit vector perpendicular to the plane, and find a vector parallel to the plane. Homework Equations The Attempt at a Solution 1.) 0 = -3x - y + 11 - z -11 = - 3x - y - z Perpendicular vector is then: -3i -j -k...
  3. F

    Mechanics of material shaft coupling

    A shaft of a total length L, connected via coupling C to the engine on the left-hand side, transfers the power P while rotating with n revolutions per second. A gear with pitch diameter D1 and thickness t1attached to the shaft at the distance Lg from the coupling C is in mesh with the driven...
  4. M

    Energy Band structure in Noncrystalline material

    In crystalline material, bands arise due to the interaction of electron waves with periodic potentials. Can anyone please explain the origin of energy bands in non-crystalline material..couldn't find relevant links on Google.
  5. S

    Material tests at quasi static and high strain rates

    Hi, I'm attaching a file which have the stress strain curves of same material at quasi static and high strain rates. See materials on page 1 and page 2. Both are same materials. The curve on page 1 is obtained at quasi static strain rate and the curve on page 2 is obtained at high...
  6. F

    What are the unit vectors of slip for FCC and BCC materials?

    Hey guys I have a few questions to ask: 1.) Why are materials whose yield stresses are highly strain-rate dependent more susceptible to brittle fractures than those materials whose yield stresses do not exhibit marked strain-rate dependence? 2.) How would you define 'toughness' in the case...
  7. F

    Heat generated by particles passing through material

    Lets say you have a stream/beam of electrons, you know the current (I), time (t) and all the dimensional characteristics of the beam. You can now calculate the amount of electrons that pass some material in the amount of time. N=\frac{I t}{e_0}, where e0 is elementary charge. Now each...
  8. M

    What is the strongest known bendable material?

    By "bendable" I mean "you can run it through a pulley and it retains tension", and by "strong" I refer to tensile yield strength. Thanks in advance.
  9. M

    Best material to minimize Impulse?

    Homework Statement Basically I want to know what material (That I could easily access) would be great to minimize impulse in the following situation: A car is placed at the top of a ramp with some angle less than 45 degrees and at its front there is a tracker that measures the amount of...
  10. T

    Core material for electromagnet that doesn't oxidize

    Does anyone know of any electromagnetic core materials that either do not oxidize or who's magnetic and physical strength doesn't change much when it does oxidize? I need to make a room temperature electromagnet for hydrodynamic propulsion experiments. My first experiments used an air core but...
  11. S

    Chemical, material, or electrical engineering?

    hey guys I'm currently a first year engineering student and am at the point in my undergrad where I need to choose which engineering field i would like to go to. I've narrowed my choices to electrical engineering, material engineering, and chemical engineering. Could you please point of the...
  12. E

    Which Materials Self-Decompose in Space Vacuum Conditions?

    Dear all, Does anyone of you know the name of some materials that self-decompose in anaerobic conditions (spontaneus decay possibly) in a reasonable time? I'm researching a possible application for this kind of things. Thank you in advance, Regards, D.
  13. D

    Power of Wavefront Penetrating Dielectric Material

    Homework Statement How large proportion of wavefront's power penetrates dielectric material's surface in a perpendicular collision from air. The only parameter that I have is \varepsilon_r = 16 where \varepsilon_r is the relative permittivity.Homework Equations \varepsilon = \varepsilon_r...
  14. T

    How Can I Download Structural Steel Data for Temperature Ranges?

    Hi, from where can I download engineering material data for structural steel in range of temperature 20 deg C - 1600 deg C ( 68 F - 2912 F). I'm interested in Poission ratio, Young modulus, density, thermal coefficient of expansion, specific heat and thermal conductivity versus temperature.
  15. D

    Need help picking material for shoe sole

    Hi, I am currently working on creating a portable rollable ballerina flat which can be easily transported in a women's purse and utilized as a backup pair of shoes when pain resulting from wearing high heeled shoes occurs. The reason for my inquiry is I am looking for a material to use to...
  16. P

    Measurement of material displacement using recorded material thermal data

    Hello all I am trying to measure material displacement using measured thermal data.7 While the specimen is heated up, I want to measure how much it changes its length at particular points. Is this possible? If you have any further questions or suggestions please do not hesitate to...
  17. Y

    How is the field inside a rod magnet in the presence of ferro magnetic material?

    For a rod magnet, how is the field inside the rod change if another piece of ferro magnetic material is being brought close to one end of the rod? Does the presence of ferro magnetic material increase the field strength inside the rod magnet?
  18. J

    Magnetic field inside a material

    IF a material say a ferromagnet is placed in a magnetic field Bo then there will be an additional field due to ferromagnet which is equal to uoM (M is magnetisation) My doubt is how is the additional field equal to uoM. By considering the units of both this expression is indeed equal to the...
  19. F

    Gauss's Law - Insulating Material

    Gauss's Law -- Insulating Material Homework Statement A slab of insulating material of uniform thickness d, lying between -{d}/{2} to +{d}/{2} along the x axis, extends infinitely in the y and z directions. The slab has a uniform charge density rho. The electric field is zero in the middle of...
  20. C

    Learning Material for General Theory of Relativity

    I am beginner to General Theory of Relativity. Please do suggest any good books, so that I can learn on my own. Anyone, please... If the book is an Indian Edition its very fine.. Thanks in advance to all..
  21. L

    Where to find AP Physics C: Mechanics material?

    Where to find AP Physics C: Mechanics material? So I would like to write the AP Physics exam this year. Unfortunately, my school does not offer AP physics and therefore does not have any material I can look at. So I have gotten myself a textbook, sadly, it does not have much practice material...
  22. O

    Physical laws are they material?

    Physical laws ... are they material?! There was an old question about physical laws , where do they come from? as they are considered separated from the material of the universe. Of course I know that they are produced by the human brain or human consciousness (which is material in turn) , but...
  23. B

    Need help desciding if I am mechanical engineering material. Thanks

    I have worked several different jobs, such as a mechanic for 7 years, logger for 4 years and a welder for 3 years. long stories for each, but i am mechanically inclined. Everywhere i have gone i have been able to look at different things and figure them out quickly, how to fix them and how they...
  24. H

    Core material selection to achieve desired inductance of a coil?

    Hello everyone, I am trying to make a coil with the exact specs as the original. I have all the info I need except the actual core material used. I have all the measurements of the core and coil including: Wire gauge, # of turns and turns per layer,Bobbin dimensions, inductance without the...
  25. C

    Help with material selection - Car Piston

    Hi guys, 1st year mech engineering student looking to get some input on a recent project for my Material Selection class I have to select an alternative material that could be used to make a car piston For simplicity I'll only be forcusing on the piston itself, not the con rods or anything...
  26. M

    Material Science- x-ray diffraction and metal densities

    Homework Statement Consider a metal with an BCC crystal structure and atomic weight 92.91. When monochromatic x-radiation having a wavelength of 0.14 nm is used, the angle of diffraction (2*theta) for the (211) set of planes in this metal occurs at 41.148 ° (first-order reflection)...
  27. F

    Can someone explain why a material that is supposed to be conductive imply?

    Source. Can someone explain what this means? It seems like it would be a big deal if something that should be a conductor, wasn't. But the word "measured" gets me confused. I start think of quantum mechanics, and maybe I am right to do so, but not sure so just a clarification of what's...
  28. lavalamp

    Measuring emissivity of material based on reflection

    Homework Statement I have a university project that involves comparing various paints with regards to how they affect the insulating properties of houses. As part of that I would like to measure the emissivity of the paint for a variety of wavelengths. Unfortunately I can not simply heat...
  29. F

    Saturated absorption: decrease size of material rather than intensity of light?

    In saturated absorption, the decrease in absorption (and corresponding increase in wave transmission) is dependent on the intensity of the incoming wave. But why can't we decrease the size of saturable material, rather than the intensity of light? According to my understanding, saturable...
  30. C

    There is a high concentration of introductory material on wave-particle duality

    (A disclaimer: I'm not an expert, having genuine confusion) There is a high concentration of introductory material on wave-particle duality that claims that the uncertainty principle manifests itself identically to the behavior of waves in the macro world. This however appears to be in direct...
  31. T

    Podcast about Material Science that maybe of interest.

    Thought this podcast may be of interest to you guys. It's from Boise State's (where I went to school and work with now) Beyond the Blue program, which is a podcast series that spotlights various academics from the university. This one is from Amy Moll, who is a professor of material science...
  32. A

    Thickness of material to absorb electron beam

    Homework Statement Beam of electrons (charged particles!) is directed to copper absorber with known energy (E= 10MeV) and intensity (10^8(s*cm^2)^-1) . I need to find the thickness of absorber so that all electrons would be absorbed. Also under what conditions does it happen and what is...
  33. O

    Patenting use of material A instead of B for better performance?

    Hi, I am new to this forum to ask for advice: I have shown experimentally that a very well known material offers great advantages when used as substitute for another material in a range of devices. It is not obvious to use this material and because it requires some very specific knowledge...
  34. H

    How can I find out what kind of core material this is?

    I am working on a project and I need to find out what kind of core material this is... Unfortuantely I cannot ask the person who had it because they no longer have it. I don't think it's ferrite, the thickness is about .125", and the permeability is around 700-1000. It had several coils on...
  35. E

    How to find the right material to change the wavelength of light?

    Hello all, I'm working on a personal design problem and am stuck. I am trying to figure out "how to figure out" what material I would need. I hope that makes sense.For example: I have light of 400nm and I want to change it to light of 500nm. I figured I could just pass the light through a...
  36. C

    Optimization minimize the amount of material used.

    Hi I am having a lot of trouble with this problem. I don't actually know where to begin. A box with a square base and open top must have a volume of 62,500 cm3. Find the dimensions of the box that minimize the amount of material used. Need to find: sides of base cm height...
  37. B

    Extra material for a Mechatronics course?

    Hey guys so I'm enrolled in a Mechatronics/Robotics course next semester and it's notorious for being one of the hardest classes that I can take. I'm a little worried about the difficulty of the class, but I think I can get through it haha. Anyway, I was wondering if there were any online...
  38. T

    How to figure out max voltage from resistance of the material between two plates

    Okay guys, I have a question and I am sure the answer is stupidly obvious but I can't seem to find a equation explaining it. I want to know the max possible voltage of the capacitor based on the distance between the plates, the Area of the plates, and the resistance of the material between the...
  39. D

    What is the Densest Known Material?

    This is a question about something in Sean Carrol's Spacetime and Geometry text. I'll quote here: " ... current estimates of the maximum possible neutron-star mass are around 3-4 Ms, the Oppenheimer-Volkofflimit. Since a fluid of neutrons is the densest material we know about (apart from...
  40. H

    N type material ,solid state physics

    Homework Statement Show that for N-type material the carrier concentration is roughly the donor atom concentration. Explain why a N-type material is conducting at much lower temperature then a intrinsic semiconductor Homework Equations maybe no equations are needed here The...
  41. P

    How does the molecular bonding effect the resistivity of a material?

    Hello all, I want to understand the molecular structure for different electronic components: Conductors - need to have metallic bonding, where electrons are free to move about Dielectrics - are insulators, but ideally atoms need to be polarizable, without charge actually being able to...
  42. N

    Are all material generally covered in Intro to Physics I?

    My professors skipped both chapter 11 & 12, Equilibrium & Elasticity and Fluid Mechanics. I'm worried that I will need to know these chapters for later classes or for the GRE. Has your professor skipped material in your class?
  43. M

    [Electromagnetic Fields] Electrical conductivity of a material

    Homework Statement Two inflnitely long, straight, parallel Wires are embedded in an infmite medium of conductivity 2 Sm-1. The wires are identical, with a round cross-section of radius 0.25 cm. The centres of the wires are 1 cm apart. Find the conductance per metre between the wires. A)...
  44. M

    Neutron star and white dwarf material

    Neutron stars are held together by extremely strong gravitational force. What would happen to a chunk of the star if it had been removed and left to stand alone? Same question for a chunk of a white dwarf?
  45. RonL

    Question about Electron Action and study material.

    I have three books in hand and would like information about how useful they are, or if things have changed that makes them too out of date. From Atoms To Quarks; 1980, James S. Trefil Mirror Matter; 1988, Robert L Forward & Joel Davis Atom; 1992, Isaac Asimov I'm an entry level study...
  46. H

    CD/DVD internal drive case material? Steel?

    Hi, I was wondering if anone knew what an internal CD or DVD drive case is most commonly made of. I was hoping to use it to do some welding so am hoping it is steet but not sure. Cheers
  47. K

    Questions about EM wave in material

    How can I find the induced current density by EM wave in a material? Should I have ma = Fbinding + Fdriving + Fdamping like treating it as a spring? Then the current density should be charge density of the material x velocity (ρv), isn't it? Is there any condition the EM wave cannot...
  48. P

    Entropy of a quantum sized material

    Homework Statement A small material has quantum oscillator energy levels 2E-23 J apart. Suppose the material has a total energy of 34E-23 J and contains 5 atoms. Find the entropy of the material. Homework Equations Entropy = (Boltzmann's constant)*ln(multiplicity) Multiplicity = (q +...
  49. R

    X ray questions:What material is suitable in windows for hard X-rays?

    What material is suitable in windows for hard X-rays? What material would you choose as reflective coating of X-rays mirrors for radiation at 200 eV? Why?
  50. C

    Exploring Normalizing and Quenching for Material Softening

    Hello, there's something that's been bugging me for quite some time now, and i hope anyone can enlighten me on this. So i'll get straight to the point. Can heat treatment be used to make a material softer? In normalising, you can say that the longer the time given for the subject to...
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