Gap Definition and 288 Threads

What democracies existed between those of ancient Greece and the United States?

I have got a trouble with wave concept suppose wave is passing through a medium ( let it ,just started) suppose there are four points in the medium (particles) A,B,C,D as soon as A is disturbed even by an infinitesimally small distance , B experiences a forces (forces act...

Hi, I am currently working on high voltage system, where I need to create an impluse at the primary side of a potential transformer. I am trying to charge my circuit to at least 10kV using a half wave series voltage mutliper consisting of capacitors and diodes, and discharging them through...

The lasers used to "read" CDs, DVDs, and Blu-ray discs operate at 780 nm, 650 nm, and 405 nm, respectively. These are produced through semiconductors. Find the energy gap needed for each laser. (Blue-ray discs can have higher information density because of the shorter wavelength). Ok. I...

a stunt biker is jumping a 45m gap, he is traveling at 20m/s and the jump angel is 30 degrees i need to know if he will make it or not. I am not sure how to go about this problem, if somone could show me the steps taken to solve this i would aprecite it. thanks

What do you do if you have like a 10 or 20 year gap between your MS and your PhD with respect to getting letters of recommendation? I would eventually like to get my PhD, but I'm pretty sure that a good deal of my professors will be retired by the time I'd like to go for it. Are you...

Anyone have a reference or information on longevity and reliability experiments in high power spark gaps? I am looking at the reliability of a 97GW 78Kamp discharge spark gap I would like to know the erosion factor and fouling rate of different configurations.

Came across the following interesting problem : Two explosions take place at the same place in a rest frame with a time separation of 10 s in that frame. A) Find the time between explosions, as measured in a frame moving with a speed 0.9 c with respect to the rest frame according to...

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 ??

Hello Everyone... This is my first post and I would like to tell you my problem seeking your help... I am studying Physics and Mathematics in my own with the help of some pure mathematics professor who offered to give his help to me in parts that I do not understand.. I am already enrolled...

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.

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...

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...

Hello, i am looking for papers about GaN and GaP "history", i mean serious papers or sources, everything will be useful. Thanks. :smile:

in books we have read that there lies a forbidden gap between conduction band and valence band. and electrons can not exist in this gap i.e. probability of electron being found in this region should be zero. BUT the fermi level,which has 50% prabality to contain an electron is found in...

Hello All, I have another set of quick questions that may or may not have a quick answer :smile:. When a simple two-electrode spark gap discharges, what shape do the eclectic and magnetic fields take on? If I were to draw the electric and magnetic field vectors, would they be pointing...

This is a question where the answer is given but I don't understand how to derive it. The answer to the homogeneous eq. is: A cosh(x) + B sinh(x) with no explanation of how it is arrived at and the given answer then goes on to describe how the non-homogeneous part is solved. Diff. eq. ...

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...

Hi, I just get confused on the some definations in the energy gap theory. in the equation \cos {k_1a} \cos{k_2b} - \frac{k_1^2 + k_2^2}{2k_1k_2} \sin {k_1a} \sin{k_2b} = \cos {kd} where \frac {\hbar ^2 k_1^2}{2m} = E \frac {\hbar ^2 k_2^2}{2m} = E - V however the...

Consider a cell in which you have driven the expression of a constitutively active GTPase Activating Protein (GAP) for CDC42, an important Rho-family GTPase. In these cells, CDC42's activity would most likely be: A.Downregulated because activating the GTPase function of CDC42 causes it to be...

Are there any "prime gap" results like this ... I was just reading about "prime gaps" and noticed that most of the results are asymptotic, as in "true if n is sufficiently large". I was just wondering if there are any bounding results for prime gaps that are true for all n, p_n. For example...

I need some clarification on what is meant by the energy gap of a superconductor. From my own understanding, is is caused by the manifestation of cooper pair, and hence can not obey fermi-dirac statistics, but abides with bose-einstein statistics. However, I feel that this reasoning is...

Hi , I have two problem with which I am stuck: 1- Given the family of curves y=1/(x+C). Find the family of orthogonal trajectories. For this problem, I took the first derivative of y---> y'=-1/(x+C)^2. from here, I cannot find the value of C since (x+C)^2=-1/y' which is impossible...

The conductivity of pure germanium increases by 50% when the temperature is increased from 20 degree C to 30 degree C. What is the energy gap E_g between the conduction and the valence bands of germanium? b) For silicon E_g = 1.1eV, what is the percentage change in the conductivity for the...

Try talking about astro phys to *the man in the street*, and there is no interest whatsoever, how can this be redressed ? i can tell you the black eyed peas are more of interest to the GP.

I'm asked to prove that the condition for the existence of an energy gap at the boudnry of the Brillouin zone on a 1D lattice is equivalent to the condition for Bragg refraction. I don't understand this question. Doesn't an energy gap arise solely when there is a potential? Meanwhile, Bragg...

I am trying to costruct a proof relating to the tangent space of SL(n). I'm almost there but all I need to show that if B is an arbitary constant traceless nxn matrix then there exists an A(t) (nxn) with the following properties: i) detA = 1 ii) A'(0) = B. Just a tip in the right direction...

When neurotransmitters are released into the synaptic gap, do they bind with receptors only once and then disengage once, or do they bind and disengage repeatedly? Thanks.

I stumbled across this book while browsing the shelves at my local library. The book is , which I read years ago and which greatly influenced my thinking (it was Sagan who persuaded me to quit watching programs about crop circles and the Loch Ness monster that I was so fond of as a child)...

Hey i was wondering if anyone had any sites on how to build a Spark Gap Radio Transmitter, i need to do this for history to show how marconi invented the radio. Thanks- Andrew

Hi, i live in the UK and currently studying physics at A-level. I have chosen to investigate EMP and its effect on electrical systems for a project. How would i build a generator? Am i right in saying all i would need is a fairly large capacitor and a spark gap? What sized voltage are we talking...

in one of my electronics classes, as a group we have to design and build a transmitter and receiver to transmit and receive morse code. we can only use a tesla coil and/or a spark gap for transmission. since we have 3 in our group... i am making the spark gap, someone else - a tesla coil, and...

Could someone rephrase in a short and casual manner the famous Millenium Problem of the Clay Math institute ? http://www.claymath.org/millennium/Yang-Mills_Theory/ Thank you for help !

Hello, I am in the middle of revising topics for the materials section of myend of year exam. For some reason my department give out past papers but do not give out answers. Any answers to any of the follwing questions would be very helpful. I don't think too much detail is required just a...

http://www.biomedcentral.com/news/20040405/03

I’m not sure if this is the right forum for my question so this was my best guess since it deals with photons. I’ve only gone through my first few physics classes that explain the classic structure of the atom, electromagnetic spectrum and the likes. I’ve also read a few books on physics on my...

This question may sound stupid, but I really don't know what to think. You see, it has been my understanding that energy is just an expression of the movement of physical things (this is simplifying, but it suffices). However, I had also believed that matter was just congealed energy. I hadn't...

This theory is fundamental physics theory.I tried to describe spacetime from new approach.I also tried to link General Theory of Relativity and Quantum Mechanics. I'm really sorry for the wrong translation in the first sentence of the manuscript ... It should be:I think that spacetime behaves...