Propagation Definition and 457 Threads

From reviewing previous posts on the subject, I understand that the E field and B field propagate in-phase through space. From this information, does it mean that at a specific space and time the E and B fields will be zero? If we had an instrument to determine the E and B field at specific...

We have consistently been told that light propagates through a vaccuum. My question is twofold: What is this vacuum vacant of? (Unless we could reach temperatures below -273C, I cannot imagine that there is somewhere that electromagnetic waves are NOT present) Where and when was this bold...

In the electromagnetism theory, the phase factor or constant (usually BETA) in wave propagation for lossy medium has the unit rad/m. I understood that it must be interpreted as the amount of phase shift that occurs as the wave travels one meter. However, differently of the attenuation...

light doesn't cotain any charge then how it fluctulate the electric and magnetic field in vacumn or medium.

Suppose you know the phase of a wave is given by \phi_1 = \vec k \cdot \vec r - \omega t. How can you determine in which direction this wave is propagating? I guess, more specifically, how does a wave described by this phase differ from a wave described by the phase \phi_2 = \vec...

the equation for wave of speed(v) relating tension(F) of string is v= sqrt(F/μ) says that as mass density μ increases, velocity of propagation decreases. but why does sound wave's propagation speed increases in a denser medium like water compared to air?

I'm doing a lab write-up and I've run into a snag. I'm trying to do propagation of error in a product, but one of my quantities that I'm multiplying is 0. The propagation of error formula for z = xy is \left ( \frac{\Delta z}{z} \right )^2 = \left( \frac{\Delta x}{x} \right )^2 + \left...

Hi all: In magnetic resonance imaging such as human brain head image, I select several regions of interest (ROI) with the size of 8 pixel. Thus the average value and standard deviation are computed for each ROI. Now I want to evaluate the average value over different ROIs. For example...

I am working on some interesting topics which relate to the speed at which gravity propagates. My question is this: within the frameworks of special and general relativity (or any other widely accepted theory, for that matter), is it necessary for gravitons/gravity waves to propagate at...

Homework Statement For my lab work, I have created a theoretical model that goes something like: T = \sqrt{\frac{ks^2}{x \sin \theta \cos^2\theta}} where k is a constant, and the variables to be differentiated are x, theta and s. How do I find the error of T? I can find the errors of x and...

The idea of a wave packet is confusing a bit. First let me tell you what I have understood about it. A wave packet is obtained by the superposition of harmonic waves of nearby frequencies which represents a matter wave. It is well known fact that the width of a moving Gaussian wave packet in...

If you connected a DC or AC source to the end of an single, infinitely long, straight wire suspended in free space (separated from anything), would propagation occur along the line?

Hi all.. I am just stuck upon something very trivial.. We know that E and H fields in an EM wave are perpendicular to each other.. I was also told that they are respectively perpendicular to direction of propagation.. Is it correct? are there any conditions for this to hold..??

Homework Statement A wave is sent down a cable. When it hits the end of the cable a reflected wave is sent back. You are given the: - time between the initial and reflected pulse - the amplitude of the initial and reflected pulse. You also know the length of the cable (you may not need...

I am generally an "artsy" person, though I am interested in science, too. I am curious about EM waves, particularly how they get started and what determines their amplitude and direction. I've read that an oscillating charge can generate a magnetic field, though I'm a bit confused about what...

I was watching this E & M lecture -http://www.youtube.com/watch?v=XtHsVSW2W3E&feature=SeriesPlayList&p=C2CEECFD938FD494&index=28 There is a demo at ~45:00 into the lecture, where a structure with metal bars is introduced between 2 waveguides. I am trying to figure out what exactly happens...

all i have under my belt is a high school physics class, so please bear with me. i have a pretty good understanding of light and waves, but this question still gets me. and nowhere can i find a decent answer, or rather, and answer i can comprehend. if EM waves don't require a medium, then what...

I am doing a calculation involving taking three or more temperature measurements and then plotting them against another quantity (dependent). I get a relationship that is pretty linear, so I take the line of best fit to obtain an equation with a slope and an intercept. Now, my question is...

I know my impedance minima and their associated frequencies for a particular coaxial cable. How would I go about deriving an equation that will let me calculate the speed of propagation and the dielectric constant? My only hint is to consider the case for which Z = 0 but I don't know where to...

I am trying to do a simple calculation on radiation propagation using Cs-137 as an example. Cs-137 has the following properties: Activity = 3.400e+15 Bq/kg Decay energy = 188.096e-12 J (1.174 MeV) This results in 639.526e+03 J/s of radiation, which is then inversly proportional to...

Excuse me if this question is obvious. Do mechanical waves propagate through loudspeaker diaphragms (whether they be elastic or rigid) in the same way that acoustic waves propagate through waveguides albeit a different medium? As far as I understand, reflections occur at the boundaries of the...

i have a doubt in wave propagation in solids wave propagation i have studied in school is in continuous medium but real mediums are discreate how will we understnd wave propagation in them -for wave to transfer from one particle to next takes infinitesimial time but since in continuous medium...

Hi, I am trying to represent my data in log2 form rather than "fold change" and I am embarrassed to say I can't remember how convert the error. For example, I have x=3.96 (mean), deltax=0.28 (standard dev). Thus, log2(x)=0.598. But how do I convert the error?? I know how to do it for...

Homework Statement I have conducted an experiment which attempts to calculate the range of the visible light spectrum. Basically white light was shined through a diffraction grating (300 lines/mm) and diffraction theory is applied to calculate the wavelength. So, here are the variables...

Homework Statement The area of a flat, rectangular parcel of land is computed from the measurement of the length of two adjacent sides, X and Y. Measurements are made using a scaled chain accurate to within 0.5% over its indicated length. The two sides are measured several times with the...

Hi, Can somebody point me in the correct direction of learning about Schrodinger Equations in relation to Wave propagation. I came across Schrodinger Equations in some texts but couldn't quite understand some background. Most of the time the author used it from nowhere. Really appreciate if...

This is probably a silly question -- but I have been thinking about it, and I can't convince myself. So, I'd be greatly happy if you could solve my apparent "dilemma". In electromagnetics, for sinusoidal voltages, we use the phasor notation and express a positive traveling wave ( +Z...

I read that capability of electromagnetic signal propagation depends on material or conductor from which it is passed... I want to know How does it effect?... What are characteristics of conductors that result in attenuation for certain frequencies?

Dear topic mates! I'm an electric engineer and physicist student from Hungary. I looking for description of the spherical shock wave propagation in liquids. I need a formula which give the relationship between the propagation velocity and time. Additionally, I wonder the pressure at the...

Homework Statement Consider the multi-path propagation phenomenon discussed in class. Assume the signal from a sender takes 4 paths to arrive at the receiver, and the delay along each path is 3, 6, 9, 21 (in micro-seconds), respectively. Each symbol is 1 bit long. Two symbols can be...

Homework Statement A wave takes 4s to travel form one end of the string to the other. Then the length is increased by 10%. Now how long does a wave take to travel the length of the spring? Homework Equations v = sqrt ( FL/m) F = -kx The Attempt at a Solution If the original...

This came up at mythbusters, a question about the propragation of currrent from a switch that is a long distance from a DC power source. Assume the wires are sufficiently large (capcitance wise): 1 mile long wire connected to positive terminal of DC power source at one end, open switch at...

Homework Statement we are trying to find the x -component of a velocity vector (V*cos\theta) our uncertainty for the velocity is +-.0003 and for the and it is .5(in degrees) how do we propagate the error for this v=.048 while \theta =27 degrees Homework Equations The Attempt...

Homework Statement Given that a puck's velocity is speed v at an angle \theta (measured in radians) with the x-axis, we know that the puck's x-velocity is v\cos(\theta). Given the error in v is \sigma_v and the error in \theta is \sigma_\theta, what is the resulting error in the puck's...

heys, sorry I didn't know where to post this hopefully I will get some responses. well, I had a set of differential equations which I solved using MATLAB and got plots as traveling waves(t=1 to 10). basically, I need to find the velocity at which the wave is propagating and I have no...

1. Homework Statement Estimate the absolute and relative standard deviations of the following calculations. The number in parentheses is the standard deviation of the preceding value. a) z=5.64(s=0.14)*log(138)(s=3) 2. Homework Equations Sx/x =SQRT((Sp/P)2+(Sq/q)2+(Sr/R)2...

I have a perfectly conducting circular waveguide. I want to calculate the time-averaged Poynting vector of a circularly polarised TE mode, ie: H_z = H_0 J_{n}(\rho \chi)e^{in\phi} Where \chi is the appropriate eigenvalue. My result for <S> implies helical energy flow; it has a z...

Homework Statement Given that f=\frac{\bar u \bar v}{\bar u +\bar v} show that e_f=f^2({\frac{e_u}{\bar u^2} + \frac{e_v}{\bar v^2}) where e refers to the error. ok so I added up the fractional uncertainties Homework Equations The Attempt at a Solution and I got this...

Hello everyone, a wave propagates at a speed (group of phase speed), less than the speed of light, no matter what type of wave we are dealing with (electromagnetic, mechanical,...). Why is infinite velocity characteristic of a diffusion process? What does that mean? For something to...

So - if the Sun were to be suddenly altered in a unlikely collision, The Earth would continue it's curved path for about eight minutes before we all became somewhat alarmed.. There is a excellent home-brew demonstration of gravity effect using a torsion balance, done in a University basement...

With: wavelength = 4 meters frequency = 30 cycles/sec period, T, = .033 sec/cycle wave propagation velocity = 120 m/s wave number ,k, = 2pi/wavelength = 1.57 radians/meter angular frequency, w, = 2pi/T = 188.5 radians/sec phase velocity = w/k = 120m/s In the above propagation...

Can anyone validate that phase always decreases in the direction of propagation of wave? Also if i have a sonometre wire in which i develop a transverse wave using a tuning fork and then i immerse the weight into water i.e change the tension, will the frequency also change? I mean frequency...

Hello, my friend: Recently, I encounter a MATLAB program problem on the propagation of the soliton in dielectric . I find that many people use a beam propagation method ( split-step fft ) in order to simulate this procedure. But I cann't get incorrect result. I am eager to...

I'm running a simple limiting case of a simulation with the expression: exp(-i*H*t), where H is the hamiltonian, in this case a 2x2 matrix of zeros. Should this evaluate to 0, or to [ 1 1 ; 1 1] ? Right now my sim uses the latter, which I'm sure is wrong. What do you think? Thanks in...

Hi! Didnt know where to post this.. I was trying to fresnel propogate a spherical beam using the formula U(x,y)=\frac{e^{jkz}e^{\frac{jk(x^{2}+y^{2})}{2z}}}{j\lambda z}\int^{\infty}_{-\infty}\int^{\infty}_{-\infty}{U(\xi,\eta)e^{\frac{jk(\xi^{2}+\eta^{2})}{2z}}}e^{-j\frac{2\pi}{\lambda...

I have a couple of questions about single slit diffraction. It's not a homework exercise - just a conceptual problem. Here it is (with some introductory comments)... I understand that the diffraction pattern from a single slit is the modulus squared of the Fourier transform of the aperture...

Homework Statement If a wave is started up a long rope hanging from the ceiling, it will not climb at constant velocity. Why? Will the wave be traveling faster or slower at the top than the bottom? (Hint: Is the tension of the rope a factor?) Homework Equations v=square root...

Howdy, I'm no physicist, but I am a scientist by trade and some basic physics questions always bug me because I don't have any bases of understanding of the concepts. I apologize if these questions seem a bit abstract: Suppose an event occurs that causes the emission of EM radiation (for...

I am trying to determine the critical crack length of a part using finite element analysis. The software I am using (ABAQUS) has the ability to perform fracture analysis. I model the part, create a crack, and ABAQUS will output the stress intensity factors (modes I, II, and III) and contour...

Hi All, Em waves propagate in varying ground conditons, in the ground the velocity of em waves is reduced since it is dependant on the relative dielectric permittivity, the realtive magnetic permiability & electrical conductivity. This will more than likely make no sense at all? My...