Modes Definition and 281 Threads

Homework Statement The question is that the decay modes for the ##W+## boson are , ##e^+ v_{e}, \mu^+ v_{\mu}, \tau^+ v_{\tau}, ud', cs' ##, where a ' denotes a anitquark, neglecting the masses of the decay products estimate the branching ratios of the ##W+##? Homework Equations N/A The...

Homework Statement Homework EquationsThe Attempt at a Solution Since it's 3D, I assume there's at least 3 acoustic modes and 3 optical modes? After all, the soundwaves/phonons must be able to travel in all directions. Further on, I know both longitudinal and transverse modes are possible...

I'm a little confused regarding the maths of TE and TM modes. Solving the following system for TE (which derives from Ey(x, z, t) = Em(x) = exp[i(ωt-βz)] ): Asin(px) + Bcos(px) , -d/2 < x <d/2 Cexp(-qx), x>d/2 Dexp(qx), x<-d/2 we conclude in two types of solutions for TE modes: symmetric...

Homework Statement Explain why the number of modes per particle increases with increasing temperature for all gases (except monatomic gases). Homework EquationsThe Attempt at a Solution I am trying to use an energy argument but to be honest, I don't understand the excited state vs rest state...

Homework Statement A room has two opposing walls which are tiled. The remaining walls, floors, and ceiling are lined with sound-absorbent material. The lowest frequency for which the room is acoustically resonant is 50Hz. (a) Complex noise occurs in the room which excites only the lowest two...

I'd like to ask a couple of questions. As a solid object gets bigger, the molecular orbital (combinations of all single atom orbitals) has greater size too? For a one inch square object (of closely packed molecules like crystals), what is its molecular orbital size compared to a one foot square...

hello ; I need some help.I reading about TEM TE and TM Modes for Waveguides. actually I need some equations for Planar wave guide and optical fiber wave guide. I did google search. I don't understand how to write equation step by step for planar wave guide I found this link...

how can we guess the possible decay modes for an element with three given quantities: A, Z and mass difference in MeV

Recently I created a structural vibrations simulation and would like to hear some feedback or suggestions.

Can we say that a point light source (turned off) together with a two slit interferometer and say a photographic plate detector exclude certain photon modes? Light does not go to certain parts of the photographic plate so can we say that the source (turned off), the interferometer, and the...

Why are they important? I've been learning about them quite a bit and have no idea why they are significant. What is the motivation for their discovery, their use, or even their mention in physics for that matter. All I really know is that when you look/have solutions with the same angular...

Good day everyone. I would like to know about the lower limit of the frequency range of active acoustic phonon modes. Textbooks say it can reach zero. But I am curious about whether it can be very small, such as 1 micro volt or the like. Would a phonon mode of so small energy be of any...

Technically I'm supposed to have a total of 8 optical modes but only 4 of them were seen in a solid (by spectroscopy). So I suspect there's some degeneracies and symmetries involved, but I don't know which ones. I have two sets of assigned degeneracies: frequency; degeneracy set 1; degeneracy...

Homework Statement http://imagizer.imageshack.us/v2/275x215q90/661/kIVMcC.png Mathematical pendulum is the part of the oscillating circuit. The system is in a constant uniform magnetic field. Oscillations is small. Find the normal modes of oscilations. Homework Equations ## \begin{cases}...

I'm stumped as to how many optic branches (modes) are present if there are X number of molecules in a unit cell and Y number of atoms in each molecule. I know that each individual atom has 3 degrees of freedom and more generally in a single unit cell, there are 3 acoustic branches (modes) and...

Hey guys, I'm trying to understand the properties of normal modes of the electromagnetic field inside an arbitrary cavity, but I'm having some trouble. By definition, for a normal mode we have \mathbf{E}(\mathbf{x},t) = \mathbf{E}_0 (\mathbf{x}) e^{i \omega_1 t} and \mathbf{B}(\mathbf{x},t) =...

So the equation to obtain the frequency of the modes of a square membrane is something like ω m,n = ∏ [(m/a)^2 + (n/b)^2]^(1/2) This equation can be used to get the frequency for Modes such as (2,1) and (1,2). How do I get the frequency for such modes as (2,1)+(1,2) and (2,1)-(1,2) ...

Modes is usually encountered in physics when we study wave propagation of any sort. Every frequency has n number of modes depending on boundary conditions - I know that much but, find it difficult to relate to so many concepts in which modes get mentioned and they baffle me at times. I want to...

Hello, everybody. I'm trying to replicate plots from Yang et al. 2002. Spatial resonances and superposition patterns in a reaction-diffusion model with interacting Turing modes. Phys. Rev. 88(20) using Mathematica, to explore specifically under what parameter values the pattern of...

Can two degenerate modes have different resonant frequencies? I am asking question in context of resonance in photonic crystal cavities. I am reviewing a paper (I have attached it). Figure 2 (a) and (b) of this paper show modal profile for 2x2PCRR (photonic crystal ring resonator). In...

Why do we need two conducting surfaces to allow TEM modes to propagate through a waveguide? Why can we not propagate TEM waves through a single conducting waveguide?

I don't really understand boundary conditions and I've been trying to research it for ages now but to no real avail. I understand what boundary conditions are, I think. You need them along with the initial conditions of a wire/string in order to describe the shape of motion of the string. I...

Homework Statement The displacement, y(x; t), of a tight string of length, L, satisfies the conditions y(0, t) = \frac{\delta y}{\delta x}(L,t) = 0 The wave velocity in the string is v. a) Explain what is meant by a normal mode. Give the form of the displacement, y(x; t), for the normal...

Hi, I have problems with the following: Number of modes for a 2d crystal with one atom per primittive unit cell. 1. Number of discrete vibrational modes? Should there be 2N of them? That is what I come up with if I think of one transverse and one longitudinal mode for each k. But I am...

Homework Statement a) Write down the Lagrangian and show that the equations of motion are: m\ddot{θ_1}+k[2θ_1-θ_2-θ_3] = 0 m\ddot{θ_2}+k[2θ_2-θ_1-θ_3] = 0 m\ddot{θ_3}+k[2θ_3-θ_1-θ_2] = 0 b) Show that the mode in which θ_1 = θ_2 = θ_3 corresponds to constant total angular momentum...

If the B-mode sky plots could be Fourier transformed what would be a plot of the lowest order B-mode harmonic plotted on a sphere look like? I guess we need two functions of spherical coordinates, one function for amplitude at points on a sphere and one function for the orientation at the...

I wrote it in another thread but it got lost in the middle of the other comments. So, here goes my doubt: In some places I am reading things like the following: For example here: http://motls.blogspot.com.ar/2014/03/bicep2-primordial-gravitational-waves.html#more Where in the whole...

Press Conference on Major Discovery -- primordial B modes? Anyone have more information on this? Any speculation? http://www.spaceref.com/news/viewpr.html?pid=42751

How do you find observable and controllable modes? \[ \mathcal{L}\Big\{\big(\mathbf{A} - s\mathbf{I}\big)^{-1}\Big\} = \begin{bmatrix}...

While reading about whispering gallery modes, I have learned that whispering gallery modes can be seen for "microscopic spheres or toruses" -Wikipedia- , But can they practically be observed in relatively large prisms or glass spheres (m or even cm magnitude) ?

Hi, I am looking into some simulations of rib waveguide structures using Finite Element Method. I particularly solving modes for a 2D cross section of the optical waveguide, looking at TE and TM modes. My questions is about modes called "degenerate" and "hybrid" modes. I haven't found...

Hi, Could You help me with problem mentioned in the topic? I copied translational data (3 column vectors) from modal analysis in Patran (from f06 file). Now I have problem in reproducing the results in Matlab. I am trying to draw normal modes in Matlab, but I haven't got much luck so far...

Homework Statement So I'm given two horizontal masses coupled by two springs; on the left there is a wall, then a spring with k_{1}, then a mass, then a spring with k_{2}, and finally another mass, not attached to anything on the right. The masses are equal and move to the right with x_{1}...

I just want to make sure I understand the normal modes of a vibrating system of particles with discrete spacing. I have tried to drawn what I understand as the lowest and highest frequency mode of the standing waves. Is the drawing correct? Edit: actually I have drawn the maximum frequency where...

Homework Statement A molecule consists of three identical atoms located at the vertices of a 45 degree right triangle. Each pair of atoms interacts by an effective spring potential, with all spring constants equal to k. Consider only planar motion of this molecule. What are 6 normal modes and...

I have a problem about the vibrational modes of a quarts crystal Two vibrational modes are induced simultaneously in a quartz crystal at MHz frequencies via a transducer hooked up to two signal generators it appears as if a third average frequency is also generated but only becomes...

What does one mean by normal mode of an object? Why is it 3n-5 for linear particles, 3n-6 for non linear particle where n is the number of particle.

Hi. I'd like to find the normal modes / harmonics, displayed in a dB - Hz graph, of a given 3D object, namely a wind instrument shaped like a hyperbolic con with holes. I'm trying to perform simulations on Comsol Multyphysics, but I don't know how to do it. Is Comsol the best suited software...

Under the Higgs in wiki it says "Another possibility is for the Higgs to split into a pair of massive gauge bosons. The most likely possibility is for the Higgs to decay into a pair of W bosons (the light blue line in the plot), which happens about 23.1% of the time for a Higgs boson with a mass...

Greetings everyone, I am confusing the definitions in the title of the post all the time. I have books about lasers, yet none of them explain these concepts lucidly and clearly in my opinion. For example, what is our reference plane when we are dealing with semiconductor laser diodes and...

Does amorphous solids support phonons or nomal modes of vibration.?? Can we apply the concept of phonons and Debye Model in case of amorphous and poly-crystalline solids?? http://en.wikipedia.org/wiki/Phonon http://en.wikipedia.org/wiki/Debye_model The links I have attached above...

Hey! So If I have a stretched string of length L fastened at one end, and I am moving the other end sinusoidally, will a standing wave appear ONLY if I move the other end with one of the normal-mode frequencies of the string? If not, will the resulting wave be a moving wave which is a...

I was looking at this page: http://en.wikipedia.org/wiki/Molecular_vibration And saw that they have six different vibrational modes listed for the water molecule. Elsewhere on they page they discuss the "3N-6" rule for determining the number of vibrational modes of a polyatomic molecule...

In calculating the heat capacity of a solid due to the phonons in the low temperature limit, I am given the impression that the idea is to calculate the amount of standing wave modes available for the phonons in the solid. Is this the correct idea? But then in calculating the Debye temperature...

Basically phonons in crystals can either be acoustic or optical according to my book. But then it stresses that a necessary condition for this to hold is that the crystal has more than atom per primitive basis. The optical modes are then when neighbouring atoms oscillate out of phase (i.e. no...

Hello, I've been going through some cavity material and attempted analyses regarding transverse modes. Invariably, they always deal with general solutions of paraxial equation and do not have solutions specific to specific cavities I do know that general solutions to paraxial equation...

Hi all! In Ruth Durrer's book "The Cosmic Microwave Background" there is this picture (Fig. 5.2 page 193) about the E and B mode of the CMB polarization: http://imageshack.us/photo/my-images/11/s7o6.png/ http://imageshack.us/photo/my-images/11/s7o6.png/ They represent the E and B...

Muons and tauons as KK modes?? Hello, everybody: I have (what I think is) a silly question. We all know that μ and τ particles are just as electrons, but with larger mass. Could it be that they are heavier Kaluza-Klein modes of the e in a higher dimensional theory, where the extra dimension...

Hi, I am trying to understand the assumed-modes approach to solving vibration problems. For example, the transverse deformation of a cantilever beam is using two assumed modes is given as ζ(x,t) = ψ_{1}(x)q_{1}(t) + ψ_{2}(x)q_{2}(t) ψ_{1}(x) = (x/L)^{2}; ψ_{2}(x) = (x/L)^{3} In this...

Hi, I'm new on the forum and I would like to start with a question. I've searched for a reply in old posts with no success. If you can help me to find an answer I'll be very glad. Talking about optical modes inside a waveguide. If a waveguide support two different modes, say TM and TE mode...