Band Definition and 481 Threads

Homework Statement Consider a PNP Biploar Junction Transistor uniformly doped in each region. Sketch the energy ban ddiagram for the case when the transistor is biased in a)In thermal equilibrium b)biased in the active region c)biased in the cutoff (depletion) region Homework...

Hello Everyone. It has a year since I have worked with Elastic Potential Energy & I have forgotten the formula to work it out. I have this question and would appreciate it if anyone could tell me how to do it, or tell me the formula of how to work it out. So here it is: Rachel pulls...

What shape does an elastic band describe when hanging from two opposite points and suspending midway a weight W (causing deformation comparable to the droop without W)?

hi ! In a crystal net.When i put 2 or many atom nearly.It's electron's energy will become energy band.(view attached image) why? what is a essential of this phenonmenon? thanks!

Question: A light-emitting diode (LED) made of the semiconductor GaAsP gives off red light \lambda =650nm. what is the band gap for this semiconductor? I know the E=hc/ \lambda so it means the band gap is 1240/650=1.9 ev ??

Hi Folks, Does anyone know about the value of the energy band of Niobium Oxide (Nb2O5)? in eV Great Appreciation:smile:

Hi all, Recently got to thinking about electrostatics and electron densities and band structures. If you have an electrostatically charged piece of material, say for example, a metal, does the density of states of that metal change because of the depletion of electrons? Alternately, if...

Hi, first post! I have a first year exam tomorrow, but I can't find any where which gives a good explanation of the Luders Band displayed in low carbon steel. Can anyone shed any light? Thanks

what does "band gap bowing" means? Hi, i speak spanish, and I've tried to translate the term "band gap bowing", but literally it doesn't have any sense. So, can anyone explain this term to me so i can translate it correctly?? Thanks a lot.

Homework Statement http://www.feynmanlectures.info/exercises/bug_on_band.html An infinitely stretchable rubber band has one end nailed to a wall, while the other end is pulled away from the wall at the rate of 1 m/s; initially the band is 1 meter long. A bug on the rubber band, initially...

So, I'm trying to learn how to do a discrete Fourier transform, with an emphasis on band-pass filtering (for a simple audio wave) Can anyone suggest online resources for this? My boss let me borrow his Bracewell to study the subject but I'm already lost on convolution. I'm still an undergrad...

Homework Statement A barrel of diameter D at 20 degrees Celsius is to be enclosed by an iron band. The circular band has an inside diameter of d at 20 degrees Celsius. It is w wide and t thick. (a) To what temperature must the band be heated so that it will fit over the barrel? (b) What will...

1.in band diagrams, books usually show parabolic bands for the conduction band and the valence band. They will also make note of the acceptor and donor leves in the band gap. However, they always draw straight horizontal lines for these levels. Is that correct? The impurity levels are...

Homework Statement Hey guys, quick EE question for ya. This is the end of a signals and noise assignment and i think I've got it but I am not sure so i thought id check. Attached is the question, doing the 2nd part of 13 The part that isn't shown that we need is that the band pass is between...

First post,a good begin. As far as I know,the band gap is generated from the bragg reflection at the BZ boundary.So I think we just need the special K-point at the surface of 1BZ,and also the band gap(direct or indirect) is at the special K-point on the surface. But it seems not real in most...

Homework Statement I am doing a lab experiment and the objective is to find the efficiency of an elastic band. Distance to ceiling=2.9m Mass of elastic band= 1.85g Force 2.6N (found using Newton meter) Extension: 6.4cm Homework Equations Well I am not looking for a solution, I...

So band structure diagrams are always depicted in k-space (1st BZ -pi/a to pi/a). Is it possible to show them in real space (1st WS cell -a/2 to a/2)? It seems to me that this would be legal. Is it not done because it is not instructive?

I am trying to calculate a photonic crystal’s band structure for a very simply case of a 1-dimentional periodic medium, or rather I am trying to understand the calculations that I am looking at for this situation. The end result of what I would like to do is get some function that I can graph...

I am looking to calculate the energy gap of for starters periodic elements and were wondering how we could get the list and calculation. Is there a table somewhere based on certain temperatures and constants of energy gap level? We would like to get a list of the energy gap energy for valance...

i need some help. i am supposed to design a vehicle that is powered only by one standard rubber band to transport an egg to the greatest possible horizontal displacement without breaking the egg. the vehicle can't have any rotating parts. must be constructed from basic parts (ie not...

Two semiconductor materials have different bandgaps, different work functions, electron affinities and dielectric constants. Let's assume they are lattice matched. The larger bandgap material is doped n-type (or N-type) and the smaller doped p-type. In the heterojunction formed epitaxially...

Would anybody be able to provide me with data concerning the band gap of colloidal CdSe quantum dots against their size?? I am currently using CdSe dots with a ZnS shell, capped with HDA. Any relevant information would be much appreciated. Many thanks, David Cunnah (studying PhD in opto...

im to design something, a plane, or any kind of material to let it stay from the time of release up to it falling into the ground for 13 seconds provided that it is powered by a rubber band... i'm having a hard time thinking about it, having it stay in mid-air longer than usual, and just want...

Seems to be isomorphic to Z, but I can't seem to be able to prove it. Am I right? If I am, how do I prove it?

If you have a rubber band wrapped around a cylinder, how can you tell the tension in the band? What parameters do you need to know?

Why is it that we align the vacuume level (when drawing the band diagram) first before we put two pieces of semiconductor together? (My book talks about how the energy of the two free electrons should be the same when each of them jumps out of its respective material...but it is not entrirely...

I need to prove that the distance of an object launched by a rubber band decreases as its mass increases, algebratically. Can anyone help me? Thanks.

Hi, my name is Hans Lindroth and I have difficulties understanding how to determine the band structure of a chemical substance (in this case rhodamine B) experimentally, given I have the absorption spectrum of it. Is there anybody out there who can help me with this? If you can please help...

In the energy band theory, we are only concerned with two bands - the conduction band and the valance band. Electrons can only be found in one of these bands and they can't have any energy related to the band in the middle - the forbidden bad. My question is that how come there are only two...

Hi all, From Pauli's principles, electrons cannot move into an already filled state. If i assume that somehow I fill in all the energy states in the conduction band (Population inversion :confused: )and then apply an electric field what happens?? Thanks...

Here's a cute problem I came across recently. Suppose you have a rubber band with spring constant k, mass m and unstretched radius r. Now suppose you have a frictionless cone and the angle of the peak is 2 \theta (that is, if you project the shape of the cone onto a plane it looks like a...

Hi all, We say the energy difference between the Top of Valence band and the bottom of Conduction band as the forbidden gap or Band gap. But when we see the fermi level at zero Kelvin, its exactly at the middle of the band gap. Does this mean that there is possibility for an electron to...

Imagine that now i have a can. I poke a hole at the centers of both the bottom and the cover of the can. Then i tie a rubber band onto the holes that it goes across the tin from the hole at the bottom to the hole on the cover. After that i stick some plasticine onto the rubber band. When i roll...

Recently I saw an infomercial for an ionized arm band thing which is supposed to improve your health. It seems like people think its works, and it supposedly has a patent on it, but how it works (if it does at all) was not explained in any detail. Does anyone know anything about this? I could...

Hi, a quick and easy one I hope someone can help me with. What would be the general expression for a DSB-AM modulated signal in terms of the Carrier Signal C(t), Baseband Signal S(t) and the modulation index m? Many Thanks

-Let's suppose we have 2 gases ..one is a "Fermi" gas under an Harmonic potential and the other is a "Bose" gas under another Harmonic potential... in both cases (as an approximation) the particles (bosons and electrons are Non-interacting) then we could write the partition functions. \prod...

I Have A Project To Design And Construct An Active Band Stop Filters I Need Circuit Design Please Thanks

I Have A Project To Design And Construct An Active Band Stop Filters I Need Circuit Design Please Thanks

Hey! I really need to find out how the width of the frequency band rejected depends on the resistance R of the following circuit: http://img418.imageshack.us/img418/8168/rlc2wf.gif I've done the following: Q= \frac{\omega_0}{\Delta \omega} so \Delta \omega = \frac{\omega_0}{Q}...

So, I've just recently got a blues/rock band together, and we need a name. Originally, the guitarist jokingly suggested Mongface, but we've decided to scrap that and have tentatively chosen Insult to Injury. Last night, I had the idea that Natural Selection or The Natural Selection might be...

for a ferromagnetic metal, the there will be splitting of energy band(one for spin up e- and one for spin down e-) under the influence of external magnetic field. the it is known as exchange splitting. here are my questions 1. what determine the degree of splitting? i guess it depends on the...

How delocalization of the states in the valence band occurs. Can somebody explain how many kinds of localization of states are there in semiconductors.

Can anybody explain to me why holes are found at the top of the valence band, whereas electrons are found at the bottom of the conduction band.

Hi all. I have something of a problem in my understanding of a current lab experiment that I am doing in my second year. The experiment is set such that we explore the elastic properties of an elastic band through small and large deformations and measure the force that it exerts on the...

I come across the attached diagram in electrical engineering books quite often and, not being a physics text, they often fail to explain it. I tried to do my homework by spending a couple of hours on google trying to figure out the answer to my question myself, but all I can find online are...

I love this forum...been a lurker for a while...but i have this to say...I have been waiting to hear some music that has not been stupidalized that's right i wrote it stupidalized. If any of you want to hear or see the bridge of the generations check these guys out.I applaud you maybe i'll see...

Set-up: Rubber band modeled as an Ideal chain (polymer) with Nr (links) monomers pointing right, and Nl monomers pointing left each of length l. Find expressions for the length of the band, its statistical weight (iI think that means the multiplicity?) and its entropy, in terms of N[SIZE="1"]r...

Can anybody solve me a problem about electrical conductivity in solid state? I think answer should be quite general: how do holes move within a certain band if they experience an external uniform electical field? I found some trouble when I think about current density, group velocity, crystal...

We've been trying to think of a good band name, and haven't concluded on anything yet, can you help us out? What we've got so far: Fred Zapplin Presents Wookie Translator Population Gravy Plasitc Venture Joanie Loves Chotchie Loves That Blonde From Three's Company... Oh Yeah...

I am trying to find a way to calculate the Ec for intrinsic silicon at room temperature. I can't seem to find anything in my textbook for that. I have searched on line and the closest thing I can find is E_c = E_g + \frac {\hbar^2 k^2}{2m_e} I know what Eg = 1.12 eV for intrinsic silicon at...