Gap Definition and 288 Threads

I recently read about the early spark gap transmitter..But I don't understand how the EM waves are generated and transmitted..Induction coil creates sparks in the gap but what produces the waves and how are they transmitted?? Need I study electromagnetic waves in detail??

For a wavefunction at the Brillouin boundary we have: \langle k|H|k\rangle = \epsilon_0 (\vec k) \langle k'|H|k'\rangle = \epsilon_0 (\vec k+\vec G) \langle k'|H|k\rangle = V_G = \frac{1}{L^3} \int e^{i(\vec k - \vec k') \cdot \vec r} V(r) d\vec r \langle k|H|k'\rangle = V_G^* Using...

Hi guys, So in my current situation it is pretty rare to come across people who are mathsy/physicsy, which is why I'm venting here for the advice of some like-minded people. I took a gap year pre-university to work, travel and generally get my head straight but am starting to worry about the...

I am struggling in understanding what the band structure (E vs. k) diagram tells me. Let's say I have the following material: http://www2.warwick.ac.uk/fac/sci/physics/current/postgraduate/regs/mpags/ex5/phonons/indirect_absorption/indirect_absorption.bmp...

Homework Statement Take a steel core (K_m = 2500) electromagnet, bend it into a loop with a small air gap, and determine the B field in the gap. The cross-sectional area of the toroid is 4cm^2, and the air gap is 2.5mm. The current through the coil's 120 turns is 15 amps. The radius of the...

Is there any possibility in silvaco TCAD to introduce Band gap in material. i want to use different energy band gap for different transport direction of a material. i.e.transverse direction one energy gap value and longitudinal directon different energy x-axis one energy value and y direction...

Hi everyone, I am currently a senior majoring in physics and I am scheduled to graduate in May 2015. I am pretty set on going on to graduate school and getting a PhD in theoretical Astrophysics, however, I missed the deadline for the physics GRE and I was consequently not...

Hi Guys, i need your help, where can i download free articles about the band gap of semiconductor materials (like copper (II) oxide). don't mention sciencedirect and arxiv, because i already explore that, and they provide limited research articles. thank you.

Even-though mathematicians regard themselves at the pinnacle or the http://forums.whirlpool.net.au/forum-replies.cfm?t=2330021&p=-1&# of all sciences they too are interested in partaking research areas in physics, e.g. topological quantum field theory, lie groups in quantum systems, ..., etc...

Hi all, I am extremely interested in GR, but somehow feel that the books I read are not really enough. Frankly, I find many question on this site and elsewhere completely bewildering, which makes me think that I don't have a solid foundation, especially in classical mechanics and various...

Could anyone please explain why doped semiconductors show decrease of the bang gap in comparison to the pure semiconductors. Web/literature links to relevant information will be appreciated. Thanks.

Is there any simple justification about graphene having no band gap? How bout its linear E-K? Why bilayer graphene has a quadratic E-K and electric field can open a band gap there? I do not completely understand the broken symmetry argument? Also Why MoS2 which has similar structure, do not...

In part branching off a discussion here, but also a discussion I've always been interested in having. I also want to take some time to answer the question in that thread: axo-axonic gap junctions in the hippocampus are thought to play a role in generating ultra-fast oscillations that have a...

Hello all, Does anyone knows what is the exact energy gap of Titanium Nitride (TiN) film? Is it indirect band gap or direct band gap? From literatures, I've found that the band gap for TiN is around 3.35-3.45eV. . May someone could suggest the specific band gap for TiN? Thanks.

According to solid state texts in Brillouin zone borders where diffraction condition satisfies we have a band gap. However I usually see Band gaps which are located in the center of Brillouin zone. Please correct me if I am wrong.

I am reading about the ionization energy in semiconductors and came across this thing that for Silicon, the ionization energy is lower than its band gap energy. I don't understand how can this be?

For which reason some of materials have direct gap and the other have indirect gap? In other words, what we have to do to convert a direct gap material to indirect one?

In my other thread on choosing a precalculus book for review, I went off topic and into calculus books, and how there seem to be these 3 main categories of books universities and high schools use -> the 1000+page ones with tons of examples, very computational, new editions every other year, etc...

I have a 30" diameter pipe that is supported about every 5-6 ft using bolts in a steel pipe support. As you can see in the attached photo, there is a pretty good size gap between the bolt/nut and the top surface of the pipe support, and also between the two faces of the interface. My question...

I have just completed my undergraduate degree, and will be taking the GRE and applying to graduate school this fall. I'll be applying to terminal master's programs because of my lackluster GPA, a 3.3. This is in hopes of continuing my recent track of improved grades, and hopefully...

I went back to school and so I have a gap between now and my last job. It's a 3 year gap. Should I do anything about it, like put school as one of my 'jobs' in the list to close up that gap? I fear that putting school at the top of the resume will call attention away from my jobs that I...

Looking for some feedback on this. I will have (by next month) completed a BS in physics and a BS in mechanical engineering. I applied to 5 nuclear engineering PhD programs, got into 2 but neither offered funding (tuition waiver + TA/RA). I've decided to work for 2 years. Over the next 2 years I...

My book says smaller the electrode gap,greater the chances of a misfire. The reason stated is that this is because of a smaller activated volume. I understand the meaning of misfire: it is when electricity takes a different path due to electrically conductive residue lying between electrode...

The superconduction gap equation is: 1=VN(0)arsinh(ωD/lΔl). My book says that in the weak coupling limit VN(0)<<1 this will reduce to: lΔl = ωDexp(-1/VN(0)) But how is this obtained. We have: arsinh(ωD/lΔl) = ln(ωD2+√(ωD2 + lΔl2)), but what has the approximation of this got to do...

Hi i have a question regarding the connection between Le chatelier and Waters self Ionization. I'd really appreciate if someone could give me heads up if my understanding is correct, or point me in the right direction if I'm off. Here we go: We know that water self-ionizes from the following...

Hello Friends How to calculate the minimum GAP distance between two electrodes?

Hello, I am currently in my senior year as an undergraduate and plan to apply to physics grad school in a year or two. I feel like taking some time off would help me become more focused and I don't have money to take the physics gre, or to apply for grad school. I also want to explore other...

I was wondering if diffraction of a wave can occur when the gap through which the wave passes is shorter than the wavelength itself. Then I came across this website http://www.talktalk.co.uk/reference/encyclopaedia/hutchinson/m0015966.html Which says that "In order for this effect to be...

of size n can consecutively occur in the sequence of primes.

Hello, For some reason, I need to leave the U.S. and go back to my country for two years once I finish my PhD. I am doing experimental condensed matter. In my country (an unkown place) , there is absolutely no way to do research in this field. I can only work as a lecturer in a university...

Hi, I've worked out that for the particle-in-a-box model (square well) the energy E E = 3h^2/8mL^2 where m is the effective mass of the electron. The next question asks Hence derive an expression for the variation of the effective energy gap in the quantum dot as a function of its...

My book has a discussion of how the Bragg model can explain the origin of energy band gaps in solid. I have attached the relevant part of this discussion. I would very much like if someone could help me understand what it's basically trying to say. Facts: 1) In the free electron model, the...

Hey guys, i really need your help on this. I completed a 3 years BSc in physics in april 2013. However i am not at all satisfied with my preparation (the teachers at my college were hardly interested,yes that's the state of pure physics in my university!). I am planning to take a gap of a...

Hello, I'm new in the realm of numerical analysis. I need to find the local probability density of energy P(E) of a single electron on site i from a self-consistent equation for the energy (mean field equation of energy)...

Hi, Which of ZnS and CdSe will have the larger band gap energy, explain. The answer is given as Zinc sulfide will have a larger band gap energy than cadmium selenide. Both are II-VI compounds, and Zn and S are both higher vertically in the periodic table than Cd and Se. In moving from...

Any ideas on how one can make a small gap (~10-50nm) between two parallel plates and maintain a known distance between them. I have two very flat surfaces and I would like to maintain a small gap (known gap) across them. I searched in the literature but I came up with nothing so if you have any...

I'm just starting back to school as for a BS in Physics and my plan is to follow that up with a PhD. While I can largely get my BS as a part time student over the next 4 years, when it come time to work on the PhD, I'll of course have to do school full time. I do have a plan in place where most...

Is it possible that, in the future, there would be very few people who know how to code, solder and debugging, while PDAs and internet access is available to everyone? I mean people know how to take a picture of themselves in a jacuzzi, apply tons of filter to make those pictures look neat, and...

I would like to do a PhD in a Physics related subject. However, it has been over 25 years since I graduated. I graduated in the UK gaining a BSc (Hons) with a Class 2 Division 1. At the time I was head hunted and received many offers but went on to pursue a career in an unrelated area. I...

Hi all, I would like to know if you guys could suggest me what's the best way to fill my free time (six months) between graduating high school and entering university. I will be taking Bachelor of Science with major in Physics. I also have plan to continue my study further if possible. However...

Can we measure the band energy gap from Fluorescence spectra? If yes, in what way? the excitation spectra or the emission spectra or both Is there a good reference on this subject specifically :smile:

Hey okay, so I have a 12V source which can provide a max of 10 mA, and I also have a switch that can go from open to close in 1 ms, How can I create an inductive circuit that will create a spark gap between electrodes that are 3mm apart? I did the math and found the breakdown voltage to be...

Hello, I'm a very curious EPE student (electrical power engineer) who is trying to figure out why there are variable gaps between joints of large steel structures. Because of this gap the stress seems to be distributed with peak force at the intersection of the bottom plate, why is this...

At what temp does nitrogen becomes plasma? What about oxygen? I am using a spark gap to turn air into plasma, I was wondering what temp is the air that the spark gap is flying through? Does the air in that area keep getting hotter and hotter the longer the spark gap is present?

What are the parameters affects the band gap in a band structure?

What's the purpose of having an air gap in certain gas lasers? Just to be clear, I'm talking about the air filled space between the lasing gas (with glass separating the two), and the partially silvered mirror at the end that let's the light out. Why isn't the partially silvered mirror just at...

Hal Haggard's ILQGS talk should be quite interesting. The plan is to have the slides PDF uploaded sometime Monday at http://bohr.physics.berkeley.edu/hal/pubs/Talks/ILQGS2013/haggard021213.pdf It's potentially helpful to let people look at the slides a day in advance of the Tuesday 12 February...

Is it possible that an electron of the 2s orbit fills the gap in 1s after electron capture? i believe no and it has something to do with the quantum-numbers but i can't find a conclusive explanation. or maybe i am totally wrong.

Dear colleagues, I am trying to deal with quantum-chemical calculations of metal-containing coordination polymers, and I have a question which turned out to be difficult to me: If a system includes copper atoms, which implies that it has 'unpaired' electron, how to describe a band gap in...

Homework Statement Hi, I'm trying to show how the band gap energy changes with the radius as Part 2 of this questions asks us to find: http://screencast.com/t/N7R42aS4l The full solution is here: http://screencast.com/t/y1K3hqOus4H Homework Equations See solution link above. The Attempt...