Material Definition and 1000 Threads

1- what determines the refractive index of a material? i understand that it is ratio between velocities in vacuum and medium but i want to know about complex refractive index which also accompanies extinction co-efficient. my explanation is that bent and slowing down of light depends on crystal...

i understand that the speed of light slows down in a nmaterial with a refractive index greater than one when compared to a vacuum, but is this merely the speed rather than the velocity decreasing, ie does time actually pass slower? i suppose what i would really like to understand is the...

I would like to study Galois theory by myself (I've already studied group theory). Can anyone suggest any good video lecture or pdf available on the web? thank you in advance

http://www.usatoday.com/news/washington/judicial/2010-06-21-supreme-court-anti-terror_N.htm Interestingly, this case was argued by the Solicitor General, Elena Kagan, who argued: http://www.usatoday.com/news/washington/judicial/2010-02-23-terrorism-law-appeal_N.htm?csp=obinsite The logic...

can you please suggest me good books for material science and metallurgy

Hi, I was wondering how you guys read from a book. Let me be clearer. When reading a paragraph in a book, do you read very slowly with full concentration until you understand every fact in that segment and make relevant notes, or do you read the material a few times, understand all (or...

what really makes a semiconductor? Is it just the presence of a band gap but then insulators and metals also have band gaps or carrier concentration? Or we need to perform Hall measurements and also need to study I-V characteristics? Or do we need all of these parameters to establish a material...

I am attempting to determine how strong a magnetic field will be on the other side of a thick material and then across an air gap. For instance, I have a closed steel cylinder with a steel piston inside it. I plan to affix a permanent magnet to one side of the piston (inside the cylinder)...

Hi, I'm struggling to find a constructive proof (through natural deduction) of the material implication replacement rule (i.e., that (a => b) <=> (~a \/ b). I believe the only possible way would be through contradiction, but I can't seem to get to it. Is it even possible? Thx.

So I am taking intro to stats and probability and I am having trouble understanding something that may be quite difficult to explain in counting. Let me start by telling you what i understand The choose function i.e (6 C 2) will take six elements and create a SET of 15 TUPLE's, in which...

A fluid moves so that its velocity is \vec {u} \equiv (2xt,-yt,-zt) , written in rectangular Cartesian coordinates. Show that the surface F(x,y,z,t) = x^2exp (-2t^2)+(y^2+2z^2)exp(t^2)=constant moves with the fluid (so that it always contains the same fluid particles; that is, DF/Dt=0)...

Dear Engineers I am very curious to know about Piping material specifications (PMs) . How can I select the appropriate material for components which is used in piping? For example we use A106 Gr B for vapour pipes or A105 for flanges and A105/A234 for fittings less/bigger than 2". Now I want...

Plastics is one of the widely used material in the modern world. Almost all the items that we use today are made up of plastics. It is also a major contributor to environmental pollution. Which is the best material that can replace plastics? Ethan

I'm looking for a solid material that will diffuse light throughout it. In particular I would need a thin bar with a light source at one end that will diffuse light to all sides of the bar, however, I don't specifically need a bar as long as the material can be machined. I'm trying to search...

Can someone please explain the difference between Material dispersion and waveguide dispersion?

Hey all, I need a little advice. Are we suppose to derive equations in order to lead to understanding of the material? What is the point of deriving equations? Should I instead read the material first and see how it applies to the problems? I don't do any of this and maybe that's why i have...

hi, i have decided that i want to do research into ; quantum computer (if quantum computer are invented by the time i graduate ) then nanocomputer/nanorobotics more specifically their application in oncology and drug delivery renewable sources of energy ( if possible ) open a...

Hi everybody, I'm focusing on meta-materials. I have recently read Schurig's paper "http://www.opticsinfobase.org/oe/abstract.cfm?URI=OPEX-14-21-9794"). In the article, the components of the permittivity tensor are given by \varepsilon^{i'j'} = \left|\rm{det}(\Lambda^{i'}_{i})\right|^{-1}...

I have built a loading machine for testing material properties. It applies tension at slow rates (ie 1htz) under load control until the specimen fails. One thing I noticed is that if I tap the material as it is loaded, it seems to give off a different pitch noise when it is under higher tension...

i am really wondering does Material engineering has a future. I am wondering this as my friends made a few comments on this subject and i am currently very confuse 1. People who study Material Engineering will most likely very difficult to get a job or the job will be related to radioactive...

Hello everybody, This is just a general question I have, and probably the title did a very bad job at explaining it, so here it goes. Is there any material that is available, or even if its still in research (as long as you have some links), that bends/flexes or contracts in certain...

In class we have been deriving the Fraunhofer interference pattern for a double slit experiment. I now have a question of having to derive it if one of the slits is covered with an absorbing material. I have got the equation out but I am missing a constant K... Homework Statement We have two...

When a dielectric material insert between two plate capacitors the conductivity may increase. Normally we talk that a dielectric is insulator?but how can it increases conductivity?

Homework Statement The refractive index of a material is different for different wavelengths and colours of light. For most materials in the visible range of the electromagnetic spectrum, shorter wavelengths have larger refractive index compared to longer wavelengths. The effect of...

why failure stress depend upon material instead of size and shape?

Can anyone explain the concepts behind dielectric material inside a capacitor. Why is the capacitor able to store more charge exactly? Thanks!

Homework Statement i am trying to work out the required material thickness for a given box. the material i am using is aluminium. i only require the formula - can't find a suitable one on web Homework Equations The Attempt at a Solution M = I σ y M = bd M...

Looking for a flexible plastic, equivalent to TPE shore A 50-60. Finish to be similar to ABS or PC, which mean high gloss, polish finish; that can be injection molded. Can somebody recommend a plastic resin that meet those criteria? -robert

In my project i have solar cells we use are called B50 cells with an efficiency of 21%. Since the cells come in contact with water we are looking for a cover material that is first of all watertight and secondly it should influence the performance as less as possible. Last but not least the...

Hello everyone, I have some difficulties to solve this question in my homework. Homework Statement Picture http://img714.imageshack.us/img714/7953/picz.png Rigid bar ACE connected to rod AB, CD, EF which have same material and surface area A. Calculate tension caused by force P in...

I am currently looking for a particular material that becomes strained under electrostatic or magnetic fields. I am new to the world of solid state physics and I was interested on doing a research project on the studies of the electrostriction effect. Thank You

Homework Statement May i know how to know boom and rod, which is in tension and compression? http://img7.imageshack.us/img7/5728/16203309.gif http://img7.imageshack.us/img7/2595/57134603.gif Homework Equations The Attempt at a Solution

The english version of this book has almost 50 pages more than the french one. Added material or just different type set?

Hi people, Firstly I want to state that it will be my first message in this forum, I am new around here. I am studying electronical engineering, second year student. I am kind of interested in nanotechnology, hence I am trying to add the course whose name is "Material Science and Technology"...

if i have a metal sheet and i cut a hole in its center, and heat the sheet, will the hole grow larger or smaller?? (knowing that the material has a positive therml expansion)? i know that the metal wants to expand, but in which direction, ?? i would think it would grow smaller but that's...

i have done few simple questions by using p = m/v to calculate the mass, volume and density, but for this question, i don't know how to do it. Please help ^^" (a) Define the density of a material. >Density is the mass of the material per unit volume. (b)Brass, an alloy of copper and zinc...

Let's say you have a vision of a material with certain special types of properties. How would I know what the chemical structure and components of that material would be? Is there some way to at least estimate what the chemical structure would be, and its a matter of guess and check? Does it...

Hi, I am Design student at Brunel University London and was wondering if anyone could help. One of my current projects is to design a cheap bottle/container to withhold a carbonated drink. The product must be extremely cheap as it is to be aimed at drink markets in such countries as...

Hello! I'm looking for some introductory materials on the Hamiltonian Treatment of General Relativity; can anybody help with some references?

I am trying to find a thin flexible metal rod that does not have a spring back property and be able to bend 45 deg. per side for 6K cycle. I tried 0.7 mm galvanized steel rod but not getting the cycle needed. Think of paper clip that and be bend 6K times without breaking. Once bend to a...

Hi, Why there are no materials where the net angular momentum is not zero? Permanent magnets have a net magnetic moment coming from the sum of electron spins + orbital magnetic moments. Why the net angular moment cancels out? Or in other words: Is there any material that is not rotating...

Hi, I've got an applications where I need an insulating washer/disk in order to insulate stainless from stainless at 50 degrees Kelvin. I need help in selecting a material to do the job. I.e. low thermal conductivity, durable enough at 50 K to take a compressive static load of approx 40...

What are the reasons that fissile materials are fissile? What makes them fissile?

In my Chemical engineering Course, I have an Engineering Materials assignment, which needs to be submitted by this Monday. It contains questions based on the mechanical design of a binary distillation column that separates acrylic acid from butyl acrylate. I'm required to select a...

1. A conductive sheet of material has a CSA of 10mm x 20mm. Reisistivity of 103 (10 to the 3, 10,000) ohms M. Calculate thickness of the material required to give resistance of 5k ohms 2. Ro = RA/l , where l would be thickness, l = RA/Ro 3. Thickness = 5,000 x 0.2 / 10,000 = o.1m...

is it possible to have a material block high wavelength waves but not low length waves? Gamma rays can pass through objects that visible light cannot. Any thoughts? I was thinking a certain bandgap?

I'm sure this has been asked numerous times so I apologize ahead of time. I have no physics background but have been increasing interested and have read a few books in the recent months and my curiosity has only grown. So far I have read the following. In Search of Schrodinger's Cat - John...

I am in the middle of a large project as an undergrad mech. engineering student and my team and I are having some modeling issues. Here is a description of our task: We must modify the design of a digital spool valve for a company. We have a spool, and 2 electro-magnetic endcaps that the...

Hello, I am a mechanical engineer by education and I am working on a multi disciplinary problem. I regularly work with eddy current dynamometers at work and I am curious about the materials used within the rotor and stator of these dynamometers. First off, this isn't a homework problem per...

Dear all, I got a PhD in computational material science (classical Monte Carlo and molecular dynamics). I'm doing a postdoc but I wonder if I will keep going that way for my next position. I've no idea about what to do afterward if I decide to do something else. I do not know if there are...