Dispersion Definition and 261 Threads

MTd2 spotted this paper on arxiv and flagged it for us: Yes! I am very glad to get this one. This paper follows up on a March 2009 video seminar talk Giovanni A-C gave at Perimeter. I'll get the link. Yeah, it's easy to google: just say "Amelino Perimeter". This often works, google...

I understand that as the frequency of an electromagnetic wave increases, its refractive index decreases in a material. According to this, red light would have a higher refractive index than blue light (is my mistake here? why?). Since sinI/sinR = n (where I is the angle of incidence, R is the...

Homework Statement The dispersion relation for a plasma is given by k^{2}=\frac{\omega^{2}}{c^{2}}(1-\frac{\omega^{2}_{p}}{\omega^{2}})\omega^{2}_{p}\:= \frac{Ne^{2}}{m_{e}\epsilon_{0}} Where N is the electron density During re enrty of a spacecraft there was a radio blackout of all...

Hi, In my ignorance of quantum mechanics, which I am trying to address, I had initially assumed that any resolution of the wave-particle duality of photon and electrons led to some sort of common probability equation. Therefore, I am trying to better understand how different dispersion...

Homework Statement Use the dispersion relation to find the group velocity v_group and phase velocity v_phase. Homework Equations omega(k) = [(hbar)k^2]/2m The Attempt at a Solution v_group = domega(k)/dk = [hbar]k/m = h/m lambda = p/m = v This isn't right. v_phase = omega...

To the moderator: I'm not sure if this should go here or in the Computational Physics forum. Please shift it there if you think that's the appropriate place for it. Hi everyone Merry Christmas! I'm writing a computer program in C, to explicitly compute the band structures for a 1D...

What is the main difference between van der Waals forces and dispersion forces? This statement confuses me: "van der Waals forces are nearly the same thing as dispersion forces." Right now, I have an idea that van der Waals forces includes these attractions: 1. permanent dipole - permanet...

Homework Statement white light propagating in air is incident at 45 degrees on an equilateral prism Find the angular dispersion "gamma" of the outgoing beam if the prism has refractive indices n(red) = 1.582 and n(violet) = 1.633. NOTE: "gamma" is just a variable for describing the angular...

What is the dispersion relation in photons? "(Frequency momentum or etc)

I have a few questions regarding the transfer function of a SMF. I'm using the below equation to simulate the effect a single mode fiber (SMF) has on the optical field after some distance \textit{z}. \begin{equation} S_{out}(\omega) = S_{in}(\omega)\exp\left...

Anyone help me What is the difference between dissipation, diffusion and dispersion as CFD point of view?

I've looked around in my basic chemistry books and haven't seen this directly answered, and I'm having trouble with it on the internet too. Wouldn't said force be repulsive just as often as attractive and therefore have no net force?

the link below should take you to a google book called "principles of nano-optics" by novotny and hecht. my question is on the dispersion curve plot they have on page 388/389 figure 12.5 and 12.6. it is describing the surface plasmon polaritons. the part i don't get is this excerpt which can...

I've been working on problems trying to find the dispersion relation of monatomic and diatomic chains. I'm able to find the dispersion relation, but I don't really understand what it is. I'm pretty sure that it's the relation of the frequency to the wave vector. I'm working through Kittel's...

I was wondering how to do the math for a bullet hitting some body armor. Would you just divide the original force of impact by the area of a the circle surrounding the point at let's say 3 inches? So.. let's say I gave a bullet moving 1500 m/s at 1g. so it would be .5(1)(1500^2)=1125kJ...

According to wikipedia below: > Huygen's principle states that each point of an advancing wave front is in fact the center of a fresh disturbance and the source of a new train of waves; and that the advancing wave as a whole may be regarded as the sum of all the secondary waves arising from...

Hey, just a small mathematical enquiry about why temperature tends to average out in, say a box of gases. Let's just use the standard "Partitioned vessel" view of it, with One side having 1 mole of Helium at..say 398k and the other side with 1 mole of helium at 298K. The heat capacity is...

(a) The index of refraction for violet light in silica flint glass is 1.65, and that for red light is 1.61. What is the angle of deviation for the red ray passing through a prism of apex angle 58.4o if the angle of incidence is 51.4o? Units of o (degrees) (b) What is the angular dispersion of...

Homework Statement Multipath dispersion of a pulse of light in an optical fiber. How is this problem solved?

I'm confused as to sources of dispersion in a fibre. Any clarification would be appreciated. Modal (Intermodal) dispersion: pulse spreading due to different group velocities of different modes in the fibre. Each mode has a slightly different n-effective hence the different Vg for each mode...

My homework question is: If the ocean surface is disturbed by a wave, η=η_0 cos(ωt-kx), show that the dispersion equation is given by ω^2=gHk^2+f^2. I have looked every where and while there is a lot of sites with this on they tend to just jump from one to the other saying 'substitue and...

The group velocity of traveling wave is defined as v_g =\partial \omega/\partial k. I am confused about how to actually calculate this. For instance, in the Schrodinger equation, we find that plane waves solve the equation provided that \omega = k^2 \hbar/2m Does this mean that the group...

Material dispersion in optical fiber is defined as D = (-λ/c)×(d²n/dλ²) λ is wavelength, c is speed of light and n is refractive index. I was given a graph of λ²×(d²n/dλ²) against λ, refractive index of core of fiber, index difference and diameter of the core and cladding. What I would like to...

Homework Statement Does London Dispersion Force exist only in molecular compounds, or do they also exist in ionic compounds? Homework Equations None. The Attempt at a Solution I think it exists only in molecular compounds.

This paper which just appeared on arxiv http://arxiv.org/abs/0709.2365 Loop quantum gravity corrections to gravitational wave dispersion Martin Bojowald, Golam Mortuza Hossain 27 pages (Submitted on 14 Sep 2007) "Cosmological tensor perturbations equations are derived for Hamiltonian cosmology...

stuff about gammaray flare observations (dispersion?) http://arxiv.org/abs/0708.2889 Probing Quantum Gravity using Photons from a Mkn 501 Flare Observed by MAGIC J. Albert, et al., for the MAGIC Collaboration, John Ellis, N.E. Mavromatos, D.V. Nanopoulos, A.S. Sakharov, E.K.G. Sarkisyan 5...

Hi all. I have some questions about the dispersion relation in the study of waves. First of all, why do we always assume a plane wave solution when we want to obtain a dispersion relation? Second, is "assuming a plane wave solution" a general way to obtian all dispersion relations? for both...

I know acoustic and optical phonons can interact with one another. Also, longitudinal and transverse phonons can interact with one another. I am wondering can a longitudinal phonon in one plane act with a transverse phonon from another plane to create a third phonon? Or, do these...

Anomalous Dispersion? All I know about anomalous dispersion is that it has a negative second order propagation vector. That would mean the refractive index is negative...how? How do you also "achieve" or get "into" the anomalous dispersion regime?

I am trying to understand 3D Si dispersion relations and reciprocal lattice vectors. My confusion is that when I look at dispersion relations the wave vector typically is normalized from 0 to 1 by a/2pi. I thought the edge of the first BZ was pi/a. Is this correct or is it 2pi/a for a diamond...

In dispersion relation diagrams, where omega is plotted against k, omega is sometimes nonzero at k=0. How is this possible? I thought a wave had to have a nonzero wavenumber :confused:

Hi all. I am referring to the Kdv equtaion as follows: u_t = u u_x + u_(xxx) A fundamental point concerning the KdV equation is that it exhibits two opposing tendencies: 1. "nonlinear convection", uu_x, which tends to -steepen- wavecrests, 2. "dispersion", u_(xxx), which tends to...

Homework Statement Yellow light strikes a diamond at a 47.0° angle of incidence and is refracted when it enters the diamond. Blue light strikes a piece of flint glass and has the same angle of refraction as does the yellow light in the diamond. See Table 26.2 for data. What is the angle of...

Hi, I have a question about the dispersion of white light in prism. Why different color of light have different speed in prism ? What properties of light affect its speed ?

My chemistry textbook states the following: "In general, larger molecules tend to have greater polarizabilities because they have a greater number of electrons and their electrons are farther from the nuclei. The strength of the dispersion forces, therefore, tends to increase with increasing...

hey guys, I'm currently doing a project on laser beam, and just wondering what material i can use to disperse a laser beam so it hit a surface with more surface area. thx Dazza

For those of you who are interested in learning about air pollution dispersion modeling, I recommend that you read the following online articles at Wikipedia: Atmospheric dispersion modeling Air pollution dispersion modeling books Air pollution dispersion terminology Compilation of air...

-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...

Can weever have disperdion of a wavegroup with a unique frequency?

hello Here I a prism with a visible light striking it at 45degree to the normal and the prism has an apex angle of 55.7 degree. It disperse Red, Orange, Yellow, Green, Blue, and Violet color in that order with 1.66 for violet light index of fraction and 1.61 for Red light. I have figured...

I'm studying the phenemenon of band gaps in a experiment, however the stop bands are proving hard to define using just a transmission spectrum dervived from the fft alogrithm. I've heard that it may be possible to define the band region by plotting the dispersion relation of sound waves the...

Hello, I was wondering if someone more knowledgeable in loop-quantum gravity or string theory could discuss a bit about the following topic for me: If there is a lower size limit (or length itself is quantized), does this (or can this) mean that there would be a dispersion relation for light...

Dispersion relations have the tendency to confuse me. In general, I know what dispersion is, but trying to apply it to crystals, I just "can't see the forest among all those trees". :rolleyes: In phonon dispersion, acoustical and optical phonons have quite a different dispersion behaviour...

i need to know what r normal and anamolous dispersion?

what is meant by dispersion in a wave?

i'm getting confused. so when white light diffracts, red light will bend the most and blue light will bend the least. but when white light disperses, blue light will bend the most, but white light will bend the least? I'm not understanding why. and also i read somewhere that the angle of...

(a) A narrow beam of light containing yellow (660nm) and green (550nm) wavelengths goes from polystyrene to air, striking the surface at a 30 degree incident angle. What is the angle between the colors when they emerge? (b) How far would they have to travel to be separated by 1.00 mm? I need...

I need help with a problem in solid state physics: Find the dispersion relation of long-wavelength plasmons in a simple tetragonal crystal in the case of almost empty band built of s-type orbitals. What happens in the case when m_{xx} << m_{zz} ? This is what I did for now (with some help...

Hi, please could someone explain the term dispersion relation to me, particularly for the case of a free electron? Thanks Jayse

Hi I'm studying for a test, and in the suggested reading book review has a few equations that they talk about but I'm not don't really understand how it jumps from one thing to another? the book is very vauge... I've broken the parts i don't understand into A,B,C (I used w = omega) A)IT shows...