Em Definition and 1000 Threads

I was wondering, if two EM waves of the same freq could add via superposition ON THE SAME ELECTRON or atom (at the same time) to become ionizing? For argument's sake say if each wave was just below UV I remember E = hf, which would indicate no, I don't see how the energy would not add...

Hi! Does electromagnetic waves induced emf or current in the coil or inductor due to faraday law as the magnetic field is continously changing in em wave?

According to this review: http://lanl.arxiv.org/pdf/quant-ph/0508202v1.pdf A classical EM plane wavefunction is a wavefunction(in Hilbert space) of a single photon with definite momentum(c.f section 1.4) , although a naive probabilistic interpretation is not applicable. However, what I've...

Homework Statement Consider 2 conductor hollow spheres that share the same center, of radii a and b (a>b). The hollow sphere of radius b is at zero potential while the hollow sphere of radius a has a potential of the form V(\theta, \phi ) =V_0 \sin \theta \cos \phi. Where V_0 is a constant and...

Why is it that a radio wave or a microwave is not affected by a magnetic field from a electromagnet or bar magnet? I know they are self contained and so no outside force should effect them but that I can't get my head around. The idea I have is that since the Electromagnetic field is...

A plane wave normally incident onto a perfectly conductive surface moving in the normal direction with constant velocity comparable to the speed of light. How do I solve such problem? If I treat the conductor as static, and the source of plane wave as a moving source, do I only need to consider...

We all know that the wave vector of a propagating plane electromagnetic wave indicates the direction of propagation. What does it mean by the "in-plane" wave vector of that plane wave?

The continuous version of the Lorentz force is \mathbf{f}=\rho\mathbf{E}+\mathbf{j}\times\mathbf{B} but what does f mean? In the discrete version F is the force on the charged particle appearing on the RHS. So if x is the position of the charged particle we have that its equation of...

I know that if you have alternating current in a wire, it will produce electromagnetic waves since the electric and magnetic field change direction continuously as the wave propagates, and that the wave direction, orientation of the E component, and orientation of the B component will all be...

My M.S. school is using Schwartz for EM instead of Jackson. I've heard horror stories about Jackson so I'm very happy at this news right now. However, does this mean I'm "missing out" and would need to do Jackson for a 2nd round of EM if I were to go to PhD in Physics at a different school that...

Have viewed PF, first time post (have searched for this question on forum): The energy of EM radiation can be described by the Poynting vector S = E x B (insert conversion factor for cgs, MKS, etc). For a traveling EM wave, what happens to the instantaneous value of S when E and B are...

Homework Statement It's example 3.8 in the Griffiths book in case someone has it. Basically the problem involves a uncharged metal sphere in a uniform field in the +z direction. Naturally, there will be induced positive charges on top and negative charges at the bottom. The question asks for...

I was wondering whether, making a comparison between the propagation of electric current through a conductor and the propagation of an electromagnetic wave through a dielectric, one could establish the following correspondences: Ability of a material to facilitate the propagation of the...

Hello, I have a loop antenna I have been messing around with for a few years and I understand most of the physics behind it, especially with regards to Faraday's Law of Induction; however, I'm trying to work backwards now to determine a source voltage at a distance. For example, if a...

All: This is a weird question. I'm trying to find a video or TV program, I'm hoping someone else saw this and can tell me what it was. There was a mouse or frog in a box or cylinder. They were experimenting with EM fields, very high energy and they were shaping the fields. I think this...

Given $20$ pairwise distinct positive integers each less than $70$. Prove that among their pairwise differences there are at least four equal numbers.

Homework Statement The electric field of a spherical electromagnetic wave in vacuum can be written in the form of: E(r,θ,phi)= A(sin(θ)/r)*[cos(kr-ωt)-(1/kr)sin(kr-ωt)]phi Show that E is consistent with ALL of Maxwell's equations in vacuum and find the associated magnetic field...

Hello! My book here states that for a medium where the index of refraction n increases with increasing frequency (or wavenumber), "the group velocity is less than the phase velocity". This is stated for a wave which is the sum of two waves with equal amplitude and differing frequency...

Derive the relation Δn.Δσ ≥ 1/2 where n is number of photons in an EM field and σ is phase Using heisenburgs uncetertainty principle? Tried subbing in frequency into heisenburgs uncertainty principle to get to the number of photons and to get rid of mometum is this the right line? Dont...

Homework Statement You and a friend are sitting in the outfield bleachers of a baseball park 140m from homeplate. The temperature is 20*C. YOur friend is listening to radio comentary with headphones while watching. There is a microphone located 17m from home plate to pick up the sound as the...

What is the difference between classical EM at the undergrad and graduate levels? Is it just the math that's harder at graduate levels, or are there any new concepts that are not covered in undergrad, that's covered in graduate? Thanks.

Homework Statement A point charge q is a distance a>R from the axis of an infinite solenoid (radius R, n turns per unit length, current I). Find the linear momentum and the angular momentum in the fields. (Put q on the x axis, with the solenoid along z; treat the solenoid as a nonconductor, so...

OK, so i understand that wave functions have something to do with something...i'm clueless, please help on this one. First, what ARE wave functions? i haven't an answer that i can understand, explain this to me dumbed down please. Second, what do they do exactly in the double slit...

I am assuming the answer to my question is no, but what am I missing? My reasoning is very basic: E=hf, therefore as the universe expands the wavelength of all the far traveling radiation is increased and due to constant velocity c their frequency must decrease which translates into them losing...

Homework Statement See figure attached. The file attach isn't working so here is a link to the problem statement, http://imgur.com/FhoIe The answer is given in a red box. Homework Equations The Attempt at a Solution The file attach isn't working so here is a link to my...

If you go to the relativistic Hamiltonian, what allows us to go from \dot{\vec{P}} = - \frac{\partial \mathcal{H}}{\partial \vec{x}} = e (\vec{\nabla} \vec{A}) \cdot \dot{\vec{x}} - e \vec{\nabla} \phi to \frac{d}{d t}\left(\frac{m \dot{\vec{x}}} {\sqrt {1 -...

In a single photon at a time double slit experiment. Is it the wave function or electromagnetic wave of a photon that is interfering? If both, what is the contribution of each? Remember that the electromagnetic wave is not the wave function of the photon. In a single photon, it has wave...

So, I have been doing a lot of reading. I have an 8 year old girl that has renewed my interest in physics, chemistry, biology, etc. I find it interesting that we say that Electromagnetic Waves travel through a vacum. We know that mechanical waves like those propagated in liquids and gas...

Hello all, I'm curious as to the opinion of some people here about what is more important: Complex analysis or EM II for someone interested in going into theoretical physics (mainly particle theory). I have a hectic workload for next semester. I'm taking particle physics, EM II, grad...

Hi, I have a question about destructive interference. Suppose I have two very closely spaced EM sources, e.g two RF emitters. At a point far away from the sources the arbitrarily orientated magnetic field due to source one is: B1(t)=sin(ωt) and source two: B2(t)=sin(ωt+pi) so the total field...

Is this the correct form for a Dirac electron in a Higgs field with scalar potential \phi and an electromagnetic field with vector potential A_\mu i \gamma^\mu \partial_\mu \psi = g \phi \psi + e \gamma_\mu A^\mu \psi where g is the coupling constant to the Higgs field and e is the...

For censored data. Random sample X1,...,Xn Censored such that x1,...xm are observed but xm+1,...,xn are not - we just know they exceed T. fx = exponential = theata exp(-theta.x) L = ∏ (from 1 going to m) f(x;theta) ∏ (m+1 - n) 1 - F(T;theta) Using F = int f I get L =...

So I'm trying to understand how the Higgs field and Higgs boson are different from the EM field and the photon. Firstly how I understand the photon is that It is the quanta of energy that an electromagnetic field oscillating at a certain frequency can give to some other system. The photon is the...

I have known for many years that the speed of sound (usually quoted ≈340 m/s) and the speed of light (usually quoted ≈3*10^8 m/s) are vastly different. Doing some reading, I would seem to conclude that part of the reason for this is the fact that sound is a mechanical wave, propagated through...

How can I find the induced current density by EM wave in a material? Should I have ma = Fbinding + Fdriving + Fdamping like treating it as a spring? Then the current density should be charge density of the material x velocity (ρv), isn't it? Is there any condition the EM wave cannot...

Homework Statement A 50cm wavelength EM wave in air has 50mW/m^2 of energy. what is the frequency? what is the average E field? What is the B field strength? What would be the λ in water? Homework Equations I found the λ. How do I find it in water The Attempt at a Solution...

Homework Statement Homework Equations Savg = Em * Bm / (2*μ0 * c) The Attempt at a Solution I solved for S avg without calculating inside the cos, but I got it right. The z and t is given, but is there the reason why you don't solve inside the cos, or is it the bug? it's...

The setup: I am reading the review: arXiv:hep-th/0004098 (page 9-10). In Einstein-Maxwell theory, the gravitational field equations read: \begin{equation} R_{\mu \nu} - \frac{1}{2} g_{\mu \nu} R = \kappa^2 \left( F_{\mu \rho} F^{\rho}_{\;\;\nu} - \frac{1}{4} g_{\mu \nu} F_{\rho \sigma}...

Homework Statement Hi In Griffiths (chapter 9) he states that any wave can be expressed as a linear combination of sinusoidal waves, f(z,t)=\int_{-\infty}^{\infty}{A(k)e^{i(kz-\omega t)}dk} = e^{-i\omega t}\int_{-\infty}^{\infty}{A(k)e^{ikz}dk} Is it correct to say that this in principle...

Hi all, I've a hamiltonian that describes the coupling of electrons in a crystal (bloch electrons) to an EM field described by a vector potential A \begin{equation} \mathscr{H} = \frac{e}{mc}\left[\mathbf{p}(-\mathbf{k}) \cdot \mathbf{A}(\mathbf{k}, \omega)\right] \end{equation}...

Why is a magnetic field "a field-of-force in space" while a gravitiational field is "not a field in space, but a curvature of space itself"? Why can't we describe and explain EM repulsion and attraction the way we explain gravitational attraction? Why don't we say that the presence of a charge...

It is my understanding that electromagnetic radiation is absorbed by an electron and then emitted at another angle. So why does particle size affect scattering when the phenomenon involves electrons? Also, why does the size of the wavelength of the light relative to the diameter of the particle...

Maxwell's equations use four dimensions. But wouldn't we need more dimensions to completely describe the EM force. I'm thinking of polarization and twist. So how many mathematical dimensions are necessary for a complete description? That is, how big do the matrices need to be and how many...

Alternating current produces EM Wave. What determines the frequency(or wave length) of an EM wave related to current or voltage?

Hi I don't understand the polarization of EM waves. I have same questions about that. 1-) As you know, EM wave is consist of both electric and magnetic field/wave. And there is 90 degree between them. Is that possible to separate these two fields or waves? I mean is that rule: If there is...

Homework Statement Show that in vacuum the magnitude of the momentum density vector of a plane electromagnetic wave is equal to the energy density divided by the speed of light, c. Homework Equations \vec{S} = \vec{E}x\vec{H} The Attempt at a Solution This doesn't seem too hard if you know...

I was just reading about EM wave propagation and had two questions I would appreciate an answer to. 1-I read how the electric and magnetic fields of an EM wave oscillate sinusoidally and perpendicular to each other and the direction the wave is traveling. Is there any significance or special...

Can radio waves penetrate steel? What about titanium? Maybe a characterization of what they can't penetrate would be more informative? ...Or a way to figure out what materials they can penetrate. Thanks, Jake

Homework Statement The plastic rod of the length L=1 m has a non-uniform charge density λ=cx where positive constant c =2x10-6 [some unit]. What unit does c have? Find the electric potential at the point on the x-axis 1 m to the left from the left end of the rod. Find the electric...

Homework Statement Hi I wish to Fourier transform the following expression P(t) = \int\limits_{ - \infty }^\infty {dt_1 dt_2 \chi (t - t_1 ,t - t_2 )E(t_1 )E(t_2 )} What I do is the following \int\limits_{ - \infty }^\infty {P(\omega )e^{ - i\omega t} } = \int\limits_{ -...