Em Definition and 1000 Threads

I would like to do some reading about how EM waves interact with each other via internet. Upon googling "EM wave interaction," I got some general links about EM radiation and some book titles but I didn't see any websites. Does anyone know one or more good online sources that give an overview...

Frequency & Wavelenght of EM wave! Hi..on some other thread i found this link showing animation of propagation EM wave: http://www.molphys.leidenuniv.nl/monos/smo/index.html?basics/light_anim.htm it has cleared my one doubt, because i used to think that EM wave is like an invisible line...

You have a coil of wire inside a solid cylinder of iron or some other magnetic material. There is a DC current going through the coil of wire so you have an electromagnet. If you were to spin the outer shell, would the coil also spin in the same direction. My first thought when approaching...

Consider a narrow beam of EM waves that propagates in the Z direction and is concentrated near the YZ plane, so its intensity fades rapidly as we move away from the YZ plane in the X direction. Let the E field be in the X direction. Consider a cube with edges parallel to the X, Y and Z axes...

Hi, I've not posted on here before but I'm trying to keep on top of work over the summer and I'm having some real problems with this question Homework Statement Consider the plane polarised EM wave in a source free vacuum with magnetic field B = (1,1,0)B0cos(kz-wt) where B0 = 0.001T. Find...

[EM] Scattering by a rod Hello everyone :) I'm interrested by the diffusion of an electromagnetic field by a rod with rectangular section i.e. a parallelepiped with one infinite dimension. Does anyone know if that's already been done ? If it is even possible analytically ? Thanks in...

The instructions are to calculate the odds of winning if you are dealt King and 9 of clubs, what are the odds of winning? I am finding myself spending more time trying to figure out texas hold em (never played before) than writing the program. So far I found a list on wiki that breaks down the...

hey, I was asking myself a few questions about the selection rules for EM dipole radiation which occurs if electrons "jump" into lower bound states according to the selection rules. now I know that the full explanation about matrix elements of the dipole operator comes from fermi's golden...

Hi, I have a few queries regarding the flow of electric current through (sea)water... In general, can the flow of electricity through seawater be treated the same as through a metal conductor? I am wondering whether the fact that it is ions rather than electrons that carry the charge has...

I remember my teacher saying that the medium that light travels through is the EM field , is this correct , if so then what is the medium that the electron , or neutrino or gluon travels through . Or what is the medium that a gravitational wave travels through .

Let us consider the Electric field components of a polarized EM wave . [PLAIN]http://www.cdeep.iitb.ac.in/nptel/Electrical%20&%20Comm%20Engg/Transmission%20Lines%20and%20EM%20Waves/graphics/CHAP%204__255.png. Now if we fix the value of z (for convenience take z=0) and consider the locus of...

i know that einstein explained it in terms of particles but can maxwells EM waves explain the photoelectric effect aswell?

Are potentials appearing in the Maxwell equations the components of a contravariant vector or a covariant vector? Let us be specific. metric is (+,-,-,-) . Let us write the potentials which appear in the Maxwell equations as \Phi and \vec{A}=(A_x,A_y,A_z) Is it then the case that...

Goodday. In my introductory course of Physics, we use Serway. I've typed over a little piece from the book that I find quite vague. It is giving an example of (after deducing the plane wave EM equations) EM radiation. It uses the following antenna: The positive and negative sides are...

its my exam question.. i am not so sure... but i put it can't because sound is a wave of vibration which it can diffract but not interence... but i don't know.. can sound wave interference? cheers

Hi, I have to find the 'stationary position' of a particle of mass m and charge q which moves in an isotropic 3D harmonic oscillator with natural frequency \omega_{0}, in a region containing a uniform electric field \boldsymbol{E} = E_{0}\hat{x} and a uniform magnetic field \boldsymbol{B} =...

Hi, I'm having difficulty understanding exactly how the reciever loop detects the EM waves in this experiment and I can't find any definitive information online. My understanding is that since EM waves are transverse, to be absorbed by the receiving electrodes, the length of the molecule chains...

Can someone give me an example of a non polarized EM wave? I've heard that a light bulb would produces EM waves not polarized because the E fields of each waves aren't in the same direction. This I can understand. But in the case of a single EM wave, how do one gets a non polarized wave? I...

Hi everyone, I've dealt with resonance (normal modes of a system) in a fair amount of detail, but it was in the context of a mechanics course. Now, I'm trying to extent this concept to electromagnetism, particularly LRC circuits, and I'm having a really hard time wrapping my head around it. I...

I've read that even before the 20th century physicists realized that light carries momentum, and that - although experiment is the ultimate arbiter in science - one can arrive at this conclusion by studying Maxwell's equations alone. If this is the case, could someone give me an outline of the...

Homework Statement Describe the sum of two EM waves that have the same initial phase and same amplitude but different frequencies such that \omega _1 >> \omega _2.Homework Equations E=E_0 \cos (kx -\omega t + \alpha).The Attempt at a Solution I summed them up and reached, after an...

Homework Statement Show that the superposition of three waves with frequencies \omega _c, \omega _c + \omega _m and \omega _c - \omega _ m and same amplitude are equivalent to another wave of frequency \omega _c which is modulated by a sinusoidal wave with frequency \omega _m, i.e. E=E_0 \left...

I have come across a problem I am trying to understand, and hoping someone here has some insight. Basically, when writing down different solutions for an EM field from given sources, there seems to be a problem from the standpoint of time symmetry. From my understanding, if you reverse time, the...

In the case of plane waves, E is orthogonal to B and they're both orthogonal to the direction of propagation, call it k. I'm not sure I'm picturing well what such an EM wave is. For instance I know that E and B oscillates with respect to time. Without looking to quantum electrodynamics that...

About whether energy is stored in the charge or the field, in Griffiths EM textbook, i found this: "...(for electrostatics) it is unnecessary to worry about where the energy is located. In the context of radiation theory it is useful(and in General Relativity it is essential) to regard the...

When a neutrino and an anti-neutrino collide they produce a photon , from what field does this photon come from. Photons are excitations of an EM field correct. or what about neutron anti-neutron collisions .

Quick question from a complete science ignoramus. The electromagnetic spectrum is described as a continuum, correct? So, given the scales of frequencies that our science is familiar with, The high end would be gamma rays, with frequencies of 300 EHz, the low end being extremely low frequency...

EM fields. Angular Momentum seems not to be Conserved! Hi everyone.. This is a paradox which as been stated in Feynman Lectures 2 (Chapter 17-4). What Feynman is telling is, there is a plastic plate which is free to rotate about an axis passing through the center of the disc, there are...

I've been wondering about this for a long time. The little black box that you plug into the wall so you can power your electronic devices contains a general run-of-the-mill transformer. But if the power is completely shut off to the device: not draining any current waiting for a power button...

Are all the frequencies of the Electromagnetic spectrum in a beam of light before being filtered by the Earth's ozone? Beyond ROYGBIV though.. so like infrared rays, microwaves, xrays, etc

In general the electronic susceptibility, χ, is a function of frequency and is complex for a dielectric medium. So what are the implications of this for the propagation of EM signals in a dielectric medium? Since the electronic susceptibility varies with refractive index, and the refractive...

Homework Statement Using the expression below for the stress energy tensor of the em field, show that it has zero trace. Homework Equations T^{\mu\nu}=F^{\mu}_{ \alpha}F^{\alpha\nu}+\frac{1}{4}\eta^{\mu\nu}F_{\beta\gamma}F^{\beta\gamma} F is the faraday tensor and eta is the...

Hello. Just a noob question about electromagnetic waves. An electron "wiggles" and sends out a change in electric field, which creates a change in magnetic field, which creates a change in electric field etc etc. My question is, because the photon travels to virtually infinite distances...

Hello everyone. I have tried to do as much research as my layman mind will allow on how an electromagnetic wave propagates in relation to how a sound wave for example does. I understand that an acoustic wave is longitudinal and works on compression and that a light wave is a transverse wave...

We were taught in the vibrations and waves lecture course that the solution to the wave equation for traveling waves is of the form ψ(z,t) = Acos(wt-kz). In the Electromagnestism course we learned that EM waves are traveling waves and have the solution E = E0cos(kz-wt). I know that changing...

If you have a 3 dimensional perfectly conducting body the conditions at the boundary for the EM field is as follows: \boldsymbol{E}_{\parallel} = 0, B_{\perp} = 0, E_{\perp} = \frac{\sigma}{\epsilon_0}, \boldsymbol{B}_{\parallel} = \mu_0 \boldsymbol{j} \times \boldsymbol{\hat{n}} where \sigma...

Are there any sets of basis functions that are particularly useful for Maxwell's equations? I was thinking about Fourier just because it is the first basis I always think of, but I don't know that it would actually be a convenient basis. For example, I don't know that curl or divergence would...

Homework Statement A 1.10m long FM antenna is oriented parallel to the electric field of an EM wave. How large must the electric field be to produce a 1.28 mV voltage between the ends of the antenna? Homework Equations u = EoErms^2 I = uc Intensity = Power / area The Attempt at a...

I did not quite understand the "stimulation" part. How does the photon coming near the excited atom force this atom to emit another, identical (from the physical properties point of view) photon? More precisely, how do the stimulating photon and the atom interact?

Is EM theory in curved spacetime the same as "unification"? I am wanting to learn about classical EM theory in curved spacetime (just curious) and I found this old thread containing some references https://www.physicsforums.com/showthread.php?t=3950 Is simply talking about the EM field in...

Hi,all, problem is: in Electromagnetism, we introduced a scalar potential psi, such that: E = - grad Psi and In Newton's law, there is also a scar potential U, such that: F= -grad U My question is, one is the gradient of a scalar field give a field and a force?! Can anyone...

Sorry if this isn't the best forum for this question; putting it here due to a gut feeling cos my brain wouldn't tell me where to put it. I'm thinking of an idea for an art project. I'd like to somehow depict what a boring, every-day scene might look like if our eyes could see more of the EM...

Does it work like that.. that a changing EM field in-phase (actually, like.. 180 degre (spell?) out-of phase) with the incoming photon would absorb it? .. when sound waves of 180 degre.. (spell) out of phase with each other would cancel each other out. The same thing would happen with EM...

I know for spherical or plane EM wave, there's relation E=cB, and we can prove it by the explicit expression of these two kinds of wave. But does E=cB hold for all EM waves, e.g. all possible wavelike solutions of maxwell's equation?

What is the difference between EM Waves and EM Pulses and how are they related to one another? When trying to look up info on this, I always get a full article on either just one or the other so that no comparison is ever made between one and the other, the definitions alone seem a little...

I'm learning that in the electrodynamics of circuits and charges, an E-field is very different from a B-field. But in Maxwell's equations for a disturbance in the electromagnetic field, where a changing electric field causes a changing magnetic field, which in turn causes a changing electric...

Homework Statement a) A microwave transmitter T and receiver R are placed side by side facing two sheets of material M (aluminium) and N (hardboard). A very small signal is registered by R; what can you deduce about the experimental set up? b) When M is moved towards N a series of maxia and...

Homework Statement What is the dB loss for a 3GHZ EM wave traveling through 2 meters of a medium with ϵ=1.5ϵ_0 and loss tangent = 9E-4? Homework Equations Umm...I'm actually not sure. I can't find anything really relating these things at all. The Attempt at a Solution My first...

Can man-made EM waves produce physical vibrations of objects? Can man-made EM waves vibrate powders like sand or talc? I'm trying to understand if any types of electronic frequencies can cause physical vibrations...thanks.

I've been trying to search for this seminal paper on EM waves in stratified media. 'Investigations on the propagation of sinusoidal electromagnetic waves in stratified media', by F. Abeles Ann. Phys. (Paris) 5, 596, 706 (1950). I cannot find it in any database. Can anyone please tell me...