What is Band: Definition and 531 Discussions

I am trying to see how to derive the following inequality on page 36 in the proof of Lemma 11.3: https://arxiv.org/pdf/math/0412040.pdf I.e, of: $$\| fg \|_{Lip} \le \bigg(1+\ell \sup_{t\in T} |g'(t)|\bigg)\sup_{t\in T}|f'(t)| , \ \ supp \ f(1-g)\subset S^c$$ My thoughts about how to show...

Homework Statement I am asked to discuss the band structure of diamond. I saw the band structure of diamond has 4 filled valence bands and then 4 conduction bands. Silicon, the same. Homework Equations --- The Attempt at a Solution I'm feeling really silly because I don't understand why it is...

Homework Statement This isn't really a problem, but I wanted some clarification on this topic. In an energy band like the one I drew below, what determines the size of the conduction band and valence band? Etop - Ec and or Ev - Ebot? Is that just a property of the material? Also, how do...

I want to know about RC band pass filter ! more specifically details about the graph of voltage vs frequency.. how the curves goes up and why the curve goes down? I don't understand ... please help me out

I've always struggled with understanding proportional band - even after watching a number of videos trying to explain it. Now I've got a fan regulator that has a temperature sensor and a potentiometer. It works by sending a signal (0-10V) to the fan if the ambient temperature drops below a...

I have an odd question after making a rubber band car. I'm wondering if placement of my pairs of wheels has any affect on how fast or how far my car goes. It seems to be a very impractical design, but I do want to know the science behind it. My question is if I move two wheels all the way to...

Could somebody write the guide for calculate the degeneracy of energy band by group theory? For instance, the valence band of Si and Ge in Gamma point. Thanks a lot!

I want to make my own scope dew heaters, I have 8 meters of nichrome band, with 1,82 ohm/meter resistance. How do I calculate the length for a specific temperature (around 8 Celsius over ambient) and how to wrap it i.e. in a coil or in a series of parallel 320° circles? The circumference of the...

Homework Statement Homework EquationsThe Attempt at a Solution The probability of getting a state with energy ## E_v## is ## \frac { N_v } { N_v +N_c } = \frac1{ e^{-(E_v – E_f)/k_BT} +1} ## ………….(1) Since, ## E_v < E_f, e^{-(E_v – E_f)/k_BT}>>1 ## as ## E_f – E_v>> k_BT ##……….(2) So...

Homework Statement So I've been tasked with designing and band pass filter for my signals class. We're given the specifications that it needs to go from 200-5000Hz, and we need to use a kaiser window as the window function. Homework Equations There are 2 parameters, beta and N, given by these...

Homework Statement How many free electrons are there in the CB? Diamond has a bandgap of ##5.5##eV.Assume the material is at room temperature and that there are ##2 \times 10^{22}## cm##^{-3}## electrons in the material. What does this mean for their use in semiconductor devices? Homework...

Homework Statement Let's put a ball in an empty space with a mass of 280 kg and a radius of 6 meters. Imagine that there is a rubber band around this ball. The initial radial extent of the rubber band is 2 meters. How can I determine the force that stretches the rubber band? And can i say that...

Hi, Lately I've been reading about a lab exercise in which Planck's constant is estimated using LEDs. Every procedure I've encountered states that the energy of an emitted photon (and by extension the potential across the semiconductor's band gap) is equal to the threshold voltage multiplied by...

Hello I am new here, so it's nice to meet you. I study quantum dot lasers and there is something I don't understand about the energy band diagram. Quantum dots are formed with the Stranski- Krastanov method. For example small InGaAs islands of quantum dots are created on a substrate of InGaAs...

I'm interested in the the band theory of solids for semiconductor modeling. I haven't solved the Schrodinger equation for multiple atoms, but I'd like to know some details that experienced physicists might already know. Several texts show how the bands develop from molecular coupling of...

Homework Statement For a stretched rubber band, it is observed experimentally that the tension ##f## is proportional to the temperature ##T## if the length ##L## is held constant. Prove that: (b) adiabatic stretching of the band results in an increase in temperature; (c) the band will...

I was studying about Crystal defects in crystals and came to know that it has huge effect on band diagram.I don't know about their specific impact on band diagram.So what are major impacts of crystal defects on band diagram.?

Hi all, I am working on a rubber band plane (something like this: http://www.instructables.com/id/Rubber-Band-Powered-Aeroplane/) and I got a question regarding to the physics on these plane. As there is only one propeller and one rubber band, when the rubber band untwist, why doesn’t it rotate...

Can anyone help me in what they think would work as far as placing a locking mechanism on a watch band?? I need it to lock onto the wrist. So it can not be taken off by the wearer. I do not want it to need any type of key or source that can be lost. I have been recommended a bluetooth type of...

Homework Statement Homework Equations The Attempt at a Solution [/B] Which is the correct frequency response graph for this question? The first graph or the second one?

0 / 0 Hi all I am trying to find the diameter for a pulley on a drive motor for a band saw the motor turns 2800 rpm the next pulley is 11 1/2" away that is 5" dia on the same shaft is the band saw wheel which is 10" dia and must turn 900 rpm . any help would be great. Doug.

I have a signal that I am able to calculate through an acoustic model for airfoil noise. I am told that the model solves for a narrowband frequency response, however, my measurement data is provided in third-octave band representation. How do I convert my current dataset to the third octave...

I was reading the Feynman lectures and in one of the chapters on thermodynamics it is stated that stretching a rubber band makes its temperature rise. I feel like I understand the thermodynamics of the rubber band and yet this statement is puzzling me. I believe that when you stretch a rubber...

Can anyone help please, I have been searching for vintage valve amplifier circuit diagrams and components. I need help in finding valves, transformers, and diagrams. I intend to build amplifiers for a rock band so i would like to build one with a 3KW output if that is feasible. Thanks for any...

Homework Statement I did an experiment on how stretching a rubber band, affects the range or distance of a projectile shot. Variable list: Independent Variable Amount of stretching Dependent Variable Range or distance I created my catapults on my own and used two different rubbers bands...

Homework Statement [/B] What is the brake torque and the needed force to stop the drum. Photo of problem: https://gyazo.com/5c814dc6791b29362cc2835dacf7005a Data not on photo: Max pressure is 0.7MPa and friction coefficient is 0.2. Homework Equations T=(P1-P2)D/2 p=2P/bD dP-fdN=0 dN=Pdθ The...

Hi everyone, I am just wondering how to calculate electron distribution using tight binding band structure for a system like graphene or any other solid. So the goal is to get |\psi(r)|^2 which \psi is the band state and it is the linear combination of Bloch sum...

I'm working on a finite element simulation of the electrostatic potential V(r) in and around semiconductor nanowires, based on solving Poisson's equation. While the details of the problem will follow shortly, the crux of where I run into trouble is that for nanowires it is important to include...

I need details on this topic ,this is my assignment but my solid state physics is not so good,and don't know much about it but i have to do this assignment ,i have material on reciprocal lattice but for only including in assignment ,not for my understanding,so i directly need any material on...

Homework Statement The conduction band of a hypothetical crystal of one-dimensional Cesium reticular with step a=300 pm (1 atom per cell) is characterized by the ε dispersion law ##\epsilon (k) = V_0 + \frac{\hbar^2}{m_e}(\frac{1}{2}k^2 - \frac{a}{3\pi}|k|^3## where ##V_0 = -4 eV##, is set so...

Homework Statement A uniform thin circular rubber band of mass M and spring constant k has an original radius R. Now it is tossed into the air. Assume it remains circular when stabilized in air and rotates at angular speed ω about its center uniformly. Derive an expression for the new radius...

Hey Guys, through the past years you helped me a lot. But now i have to ask my first question. I am simulating a solenoid, a very easy one, with a core and a coil. And a translational band (2mm). The only problem is, that i cannot put the band correctly because my solenoid is in a housing, the...

in my physics class we have to create a device that will make an egg not break after being dropped from a second story window. my idea was to take a strength training resistance band and use it like a bungee jumping cord and have the egg drop to the bottom without breaking. what are the formulas...

This is schematic band structure for the dxz and dyz orbitals using a 2D square Fe lattice. What is the location in the Brillouin zone of the hole-like Fermi surface and the electron-like Fermi surface?

Stretching a rubber band increase its mass due to e=mcc, but how?

Homework Statement The energy band for two different metals can be expressed as E=Ak2 and E=Bk2, respectively. Suppose A>B, and the Fermi energy is equal for these two metal. Calculate and compare the Fermi velocity for both metals. Homework EquationsThe Attempt at a Solution I'm very confused...

I've tried to summarise the explanation my professor gave. Is it correct or have I misunderstood? It's a highly simplified view of things anyway, but here goes: Taking the simplest 1D case, there are two possibiities for an electron in the lattice: it may be scattered and move back the way it...

I have just read about the Gleamoscope which allows users to dial up visions of the sky in any light that you prefer, for example CMB, Xray, etc. In all of these, the Milky Way shows up as a narrow horizontal band across the middle of theall-sky image. What is it in the analysis that leads to...

In solid state physics you can calculate the band structure of a material, which is effectively the dispersion E_n(k), which depends on the wavevector as well as the band index. What I don't understand is this: Which states are occupied in a band? With this I mean: Which k values correspond to...

When I was 6 or 7 I decided to make a bow and arrow one day. I had never seen or handled one in real life, but it was intuitively obvious to me from TV that they way to do this was to tie the ends of a stretched rubber band to the ends of a stick. This would have worked, after a fashion...

As an electronic engineer I am not an expert on semiconductor physics but I think I understand the basics of energy band diagrams reasonably well. It all fits together fairly neatly with the normal textbook assumption that we are looking at pure N-type or P-type doping. The problem I have is...

Does phonon required a minimum energy in the absorption process of an indirect band gap, and why?

I am studying introduction to solid state physics and it's stated that when germanium is n doped energy states with energy -0.1 ev are introduced, then it's stated that this means that the donor level is 0.1 ev below the Conduction level Does that mean that the Ec is considered 0??

Hi, I was hoping I could get some things cleared up. Recently my Solid State professor mentioned that we could simply, from the chemical formula, predict where the band crossings are going to be. For example, take LaFeAsO. Since La has a valency of +3, Fe of +3, As of -3, and O of -2, he...

My question is more general but I explain it by a simple example i.e. graphene and tight binding method. I solved energy dispersion of graphene with tight binding by the two ways: First, I took graphene as a lattice with the two basis atoms A and B. In the second way, I took graphene as a...

In general, materials are either direct or indirect materials. For direct materials, both the valence band maxima and the conduction band minima are at k = 0. For indirect materials, only the valence band maxima is at k = 0 and the conduction band minima is at some other non-zero value of k. In...

I know how to calculate blackbody radiance in a spectral band from a temperature by integrating (or summing) planks function. How can I do the reverse? For example, I have a Radiance of 1000 W/m^2/sr in the 3-5um band, I'd like to be able to calculate 666.6K.

I've written the following program for drawing the band structure Silicene nanoribbons, but in a zero energy building is a straight line. Can help me to fixed problem. % tight binding calculations for zgnr clear; clc; close all; NU=14; % Number of atoms in unit cell Nbnd=4*NU; % number of...

I have a hazy idea that comes from a few video lectures (see below for example) where the following is stated: The condition for constructive interference (Bragg condition) in reciprocal space is that the wave vector should touch a Brillouin zone boundary. In this case, the standing wave that...

I wants to plot band structure silicene with siesta software so that the K range is 0 to 1 but can not draw a graph in this rang. Can help me to fix the problem.