Em Definition and 1000 Threads

1. Can a magnet orbit another magnet (of opposite charge) despite the fact that their masses are insufficient to generate the orbit; i.e., their orbits are caused only by the EM force? 2. Would/could the EM attraction between them generate tidal effects on the two magnets? 3. If you had two...

Why can't EM attraction/repulsion be modeled as spatial curvature the way gravity can be? And for that matter, why can't the strong and weak nuclear forces be modeled that way either? Or can they?

Using differential forms and their picture interpretations, I wonder if it's possible to give a nice geometric & physical motivation for the form of the Electromagnetic Lagrangian density? The Lagrangian for the electromagnetic field without current sources in terms of differential forms is F...

In SM, people say the ##SU(2)\otimes U(1)## theory unify the EM and weak interaction. I understand that the two interactions both originate from the electroweak theory in a mixed way. But does this mean they are unified? Since when we talk about unification like GUT, we require the couplings run...

I recently read Griffiths paper on Hidden momentum, and still didn't found it complete. Following is the short summary. The usual setup of current carrying loop and a charge lying nearby, according to the paper, Shockley and James presented the problem, that is, when we let the current die...

The question is to find the magnetic field at the centre of a current carrying circular loop of radius R, where the current = I Okay so I'm trying to do this by both Amp's Law and Biot Savarts Law, and I can't get my answers to agree. First method - Biot Savarts Law...

Homework Statement An EM wave with frequency 87Mhz travels in an insulating ferromagnetic material with \mu_0 \mu_r = 1000 and \epsilon_0 \epsilon_r = 10 - What is the speed of the EM wave in the material. Homework Equations v=(\sqrt{\mu_0 \mu_r \epsilon_0 \epsilon_r})^{-1} The Attempt at a...

Hello Everyone, This is my first post. Background: I am an audio guy and seek to understand how cables contribute to the sound of my stereo. Issue: Do audio cables such as power cords, interconnects, and speaker cables "break in" as they are used? Typically, with high-end cables, users...

why all EM waves are sinusoidal ? or this is not true at all, i.e., EM waves of other waveforms do exist ? the above 2 questions are among the most vague in classical EM theory, of which i studied many topics in collage as an electrical engineering student, and i liked the subject so i kept...

The record for the number of decimal places of accuracy for the Euler-Mascheroni constant stands at just over 29,000,000,000 decimal places set by Alexander J. Yee & Raymond Chan back in 2009. Does anyone know what function they used to set this record? ***EDIT*** On further searching the...

The Drude model of electrical conduction has the charge carriers being accelerated by an electric field and then interacting with the lattice ions. The cycle is then repeated. An unbound charged particle if accelerated emits electromagnetic waves. Does that mean that a prediction of the Drude...

Hi all I am using the Kalman Filter with an EM algorithm, (schumway and stoffer). From my understanding the log likelihood should monotonically increase. In some instances however I obtain a decrease in the log likelihood, What can I infer from this? Has anyone experience of these...

Okay the question is, given a plane electromagnetic wave in a vacuum given by E=(Ex,Ey,Ez)exp^{(i(k_{x}x+k_{y}y+k_{z}z-wt)} and B=(Bx,By,Bz)exp^{(i(k_{x}x+k_{y}y+k_{z}z-wt)} , where k = (kx,ky,kz), to show that kXE=wB. So I'm mainly fine with the method. I can see the maxwell's equaion...

Would a particle kept in the path of an electromagnetic wave experience a force? Both magnetic and electric field are present, so the equation of motion may be complex, but i have never seen my textbook refer to the the possibility of an em wave causing a charged particle to move.

Hi all- I am working on a hobby project to manipulate top load streamers by applying EM fields to the top load. I cringe to reference it, but think of Red Alert 2 on a much, *MUCH* smaller scale. The streamers are roughly 295KHz at 300kV (9kVA NST supply, 8.5turns primary coil & 1042turn...

EM waves do not need a medium for propagation. But isn't high frequency signal (like USB) flowing in a wire also electromagnetic. How come it needs copper as a medium.

I'm going through my notes and I don't understand how they have included position in an equation to describe an EM wave. The equation is of the form http://upload.wikimedia.org/math/f/6/3/f6386c1751b91ec23c7123b15a11b52f.png [Asin(kx-ωt)]. This equation is just stated in my notes and there is no...

Hi, recently I saw a great video about some scientists levitating small objects in mid air by trapping them in overlapping 180 degrees out of phase sine waveforms. It is easy to see that air is the medium through which sound can travel and sounditself being the vibration of air traps these...

Homework Statement EM Waves propagating through vacuum towards the x-direction approaches a conducting surface at x = 0. Part (a): Prove the following relations. Find the boundary conditions for E and B if charge density σ and current density s exists on the surface. Part (b): Find B in...

Homework Statement (a) Find the capacitance per unit length and find the inductance per unit length of a transmission wire above a infinite conducting plane. I used the image method (b) Show that EM waves can propagate, and find their speed and the characteristic impedance of the line...

I don't really know how to quantify EM waves when it comes to amplitude, but I understand that MRI rf waves are measured in units of tesla. What is the amplitude of a typical microwave oven EM wave in Tesla (mT, uT)??

I was first considering to post this in the GR section on the forum, but as I've understood it, compactification is essential in string theory, so I thought that perhaps you guys know the subject better also in Kaluza-Klein theory. Compactification in Kaluza-Klein theory as I understand it is...

After reading Griffiths' book, I find the explanation from poynting vector to sinusodial EM wave pretty blurred. EM wave has two requirements. 1. E / B = c 2. E and B are sinusodial How could we ensure the Poynyig vector ultimately will produce the form satisfying the two points mentioned? Or...

What does it mean that the electromagnetic field strength includes six degrees of freedom (three for the electric field strength, three for the magnetic field strength), whereas the four-potential includes only three degrees of freedom (two for the photon, one for the Higgs boson)? What is the...

I was wondering if you were to use the em field caused by electricity flowing through a wire or coil to push a magnetic or object would you effect the flow of power in the line. Like if you were to wrap a one phase of transmission lines around a solenoid type device to use the em field to push...

From my understanding, surface plasmons (SPs) are oscillations of electrons caused by incident EM waves. A photon from the EM wave can couple with a plasmon to create a surface plasmon polariton (SPP). Some books/websites use the words SPP and SP interchangeably, so I am confused as to whether...

Homework Statement Show that the E and B field of a plane EM wave are both perpendicular to its direction of propagation in a non-dispersive and transparent medium. Homework Equations Maxwell's equatons.The Attempt at a Solution Well, I know how to easily show that E and B fields are...

Homework Statement Look at the Moire pattern in "Oppgave 5" (assignment 5) in the attached pdf file. The Moire pattern you see is supposed to represent the interference between two plane EM waves whose directional ##\vec{k}## vectors form an angle ##\theta## with each other. Anyway, the main...

Homework Statement The following dispersion relation is obtained by substituting a plane wave solution for ##\mathbf{B}## into $$\nabla^2 \mathbf{B} = \mu \epsilon \frac{\partial^2 \mathbf{B}}{\partial^2 t} + \mu \sigma \frac{\partial \mathbf{B}}{\partial t}:$$ $$\hat{k} = (\mu \epsilon w^2 +...

Homework Statement The magnetic field intensity of an electromagnetic wave that propagates in vacuum is described with the following phasor notation: (H_{z} = H_{0}e^{+jkx}u_{z}) if the previous equation is hard to read maybe this will be easier: Hz=H0e^(+jkx)Uz. Assuming that the frequency of...

Hello everyone, I have been wondering about the quantization of Maxwell's equation in free space, but now suppose that we have a source particle, fermion for example, now the field equation is a mixture of both fermion field and photon field so my question is whether you can get out of this by...

What effect does water have on electromagnetic waveforms? Does metal attract or reflect EM waveforms (specifically rf)?

Homework Statement Derive from Maxwell's equations these Hill equations for 's' and 'p' mode waves; s\hspace{3mm} modes: E(r,t) = \Psi_{s}(z)e^{i(\beta x - \omega t)}y \\ \hspace{10mm}Hill\, Equation for\, \Psi_{s}(z)\\ \hspace{17mm} \dfrac{d^{2}\Psi_{s}(z)}{dz^{2}} +...

First of all, I understand that an EM wave is created by a charged particle that is moving. What I don't understand is how it propagates itself when traveling through a vacuum as there is no medium for it to interact with. Can this be explained by anything other than photon theory? I really...

Do quarks cause EM waves?

Can anyone please provide an intuitive explanation of why phase shift of 180 degrees occurs in the Electric Field of a EM wave,when reflected from an optically denser medium and also why the phase remains same on reflection from a denser to rarer medium? please try to explain on an atomic/sub...

I'm going to start by asking about an example from class and then hopefully use that to work on the problem I need to solve. Here is an example: Let's say we have a multinomial distribution $x \sim M(n;.5+.25\theta,0.25(1-\theta),0.25(1-\theta),0.5\theta)$. The likelihood function of $\theta$...

Hey guys, I am wondering whether there is any book out there that approaches EM field using differential form and on the same or more advanced than Jackson, I have a solid knowledge of differential form and algebraic topology, thanks :D

Are gravitons and gravitational waves analogous to photons and EM radiation?

Hi all The reflection and transmission of a pressure wave at a boundary depends on the relative impedance of the two media. I'm pretty new to acoustics but the textbook I've been looking at doesn't seem to specify that the such calculations are only valid when the medium is at least a few...

Energy Of A "Single" Photon In Em Radiation? Is the energy of all photons in em radiation same? That is, say light differs from radio waves only in the number of photons per second

Hello, I was reading articles about EMR and health and I realized I never got how "output power" is related to frequency. Let's talk about energy, the rule is: the higher the frequency (shorter wavelength) the higher is the energy transported by the wave. Now power, power is the energy...

It is known that the electric field component of the EM wave is given by E=E_{0}cos(kx-\omega t) How do I arrive at such a form? It is quite different from the standard sinusoidal equation of y=Acos(\omega t+\varphi) Any guidance? What does the kx-\omega t describe physically?

Do we have any understanding as to why em waves have same speed in all inertial frames?

Just a thought because of the anomalous Planck satellite cmb data, and the second largest continuous structure in our solar system that almost fried the pioneer probe... Jupiter's magnetosphere which is known emitting radiowaves.

I have a short question about the derivative of a given EM-Tensor. ##\rho## = mass density ##U^\mu## = 4 velocity ##T^{\mu\nu} = \rho U^\mu U^\nu## Now I do ##\partial_\mu## Should I get a) ##\partial_\mu T^{\mu\nu} = (\partial_\mu \rho) (U^\mu U^\nu) + \rho (\partial_\mu U^\mu)...

Homework Statement Solve the equations of motion ##\ddot{y}= \omega \dot{z}## and ##\ddot{z}= \omega (\frac{E}{B}-\dot{y})## Homework Equations The Attempt at a Solution Integrate the first equation to get ##\dot{y}=\omega z + c_1## and plug into equation 2: ##\ddot{z}=\omega...

i think I've asked this a number of times on different posts stemming from various discussions but i don't think this question was in the wrong thread. so I've decided to make a new thread for this. so what 'IS' an EM wave? i understand that the acceleration of charges could produce a wave...

i always hear about the frequency/wavelength, and the speed of the wave, but i never heard about the actual amplitude of the wave itself? how would one derive this? I'm not referring to intensity... intensity deals with the number of photons being captured by a detector... I'm referring to the...

for RF, how does this mechanism work? http://i.imgur.com/Crx4Amx.png how does the conductor do this? and why does the unpolarized RF not seep through the spaces between the conductive bars?