Dispersion Definition and 284 Threads

Hi All, In quantum mechanics, related to photon, we have these two equations as valid ones: E = h x f p = h / lambda But we have in vacuum the dispersion relation c = lambda x f. 1) How these relations change when the dispersion relation change ? 2) Is it universally correct to...

Homework Statement In many transparent materials, dispersion causes different colors (wavelengths) of light to travel at different speeds. This can cause problems in fiber-optic communications systems where pulses of light must travel very long distances in glass. Assuming a fiber is made...

In which case would water fall out of the tank faster? 1) If I were to take a tank filled with water and bore a large hole in the bottom of it with some area 2) Riddle the bottom of the tank with small holes that have an area that adds up to the area of the first big hole. In one scenario...

Hi, I'm trying to take this Sellmeier equation, n^2 (λ)=1+ (B_1 λ^2)/(λ^2-C_1 )+(B_2 λ^2)/(λ^2-C_2 )+(B_3 λ^2)/(λ^2-C_3 ) for which i have several sets of constants for prospective glasses, and convert it into a group delay dispersion graph, with axes of fs^2 vs wavelength. How do i...

In a question about dispersion using an equilateral prism, three blackened bulb thermometers were used. One was placed above the red light, one on the green light and the last one below the violet light. The question was ... Give 2 reasons why the highest temperature would be recorded...

Hi, being a skeptical MD (radiology), I'd like to have a physicist's view on a chiropractic mechanical device called the "Activator" (http://activator.com/, http://www.youtube.com/user/drcherok, http://www.youtube.com/watch?v=knM5dx2tFH0&feature=related), which in my view is a worthless and...

Does dispersion of light by a prism have anything to do with how thin films disperse light of different colors at different angles? Could a person imagine the sides as if they were thin films?

Hi. What I'm trying to do is to obtain the energy spectrum from the following dispersion relation: E^4-A·E^3+B·E^2-C·E+D-F·E^2·cos(k·a_0)^2+G·E·cos(k·a_0)^2-H·cos(k·a_0)^2 = 0 where E is the energy, k is the wave vector and a0 the distance between adjacent neighbors in a 1-Dimensional...

Derivation of velocity dispersion from virial theorem?? Hey, Im probably being a bit dim here but could anyone help me derive the velocity dispersion from the virial theorem. I've got 2K+U=0, K/m~sigma^2 and U/m~GM/R. From rearranging I get a negative velocity^2? Or maybe its the...

Let us assume we possesses a line radiator. It's extent is infinite and it radiates 360*. As far as I understand, an expanding spherical wave of order 0 is not dispersive. I assume an expanding cylindrical wave of order 0 would possesses dispersion, however I am not certain. Could any...

Homework Statement White light containing wavelengths from 396 nm to 756 nm falls on a grating with 7300 lines/cm. How wide is the first-order spectrum on a screen 2.15 m away? Homework Equations y=m*L*wavelenth/(d) The Attempt at a Solution using the equation I have found y1 to...

(I would like to put an idea of mine to rest) About one year ago I took a college chemistry course in which I learned about intermolecular forces. The weakest of these intermolecular forces, I learned, was the dispersion force (also called London force). This force was discovered by Fritz W...

Homework Statement Show that c^2 = g/k*(rho1 - rho2)/ (rho1 + rho2) where rho1 and rho 2 are the different densities, k is the constant from solving the PDE (separation of variables). Homework Equations Use the fact that phi(1) --> 0 as y --> neg. infinity and phi(2) --> 0 as y -->...

1. Calculate the velocity dispersion for hydrogen atoms in the solar photosphere, which has a temperature of 5800 K. 2. I know no equations to solve the problem. 3. I have no idea any method of going about solving for velocity dispersion. I would appreciate any guidance. Thanks

Ok so here's another problem that i just completely don't understand at all. Thanks for your help. A linear chain consists of 2N equally spaced identical particles with mass m and speration a, coupled by springs with alternating constands k1 and k2. Use the periodicity of the system to find...

what can be interpret from dispersion curve of phonon?how to find whether a phonon can loose all its energy to a neutron from dispersion curves?are there dispersion curves for other atom apart from phonon?

Hi guys, I just have a short question. A prism splits white light into it component color depending on the wavelength of the color. As the wavelength decreases, the index of refraction increases, so the wave bends more. However according to Snell's law, a greater index of refraction results in...

if i don't want to understand the white light as a pack of waves that when encounter prism the waves start to unpack, but as a photons, but than i can't see how it's working, i mean. what is happening to the photons when they enter a prism? thanks

Hi guys, I don't understand how one would exactly determine a dispersion relation of phonons experimentally. There are two equations, one for momentum and one for energy conservation: \vec{k} - \vec{k^{'}} = \vec{G} + \vec{K} \omega - \omega ^{'} = \omega(K) where...

can some one explain what chromatic dispersion is? and it helps me finding which colour radiates more heat in the given spectrum.

Does light exhibit any type of dispersion in a vacume?

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 Consider the linearized, quasi-geostrophic vorticity equation on the beta-plane, with a mean background flow umean , which allows for vertical structure and propagation of Rossby waves: (d/dt+umean*d/dx)=(nabla2 ψ+(f02/N2)*(d2 ψ/dz2)+bv where ψ is the horizontal...

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...

I'm doing an experiment, in which I have a one dimensional lattice held up by strings. That is I have a series of n masses each of mass M each connected to each other by springs with spring constant C and unstretched length a. Each mass is suspended from the ceiling by a string of length L. I'm...

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...