Electromagnetic Definition and 1000 Threads

Hello. I need help! is it possible to create a box/cage (ive seen the faraday cage etc) to give one 100% protection from all/some the electromagnetic spectrums - and from electrical pollution? "Nothing enters and nothing leaves" style, so it but cut out all that comes outside of it, and blocks...

I am in search of an electromagnet which has high magnetic remanence (or retentivity) even when the current through the electromagnet is zero. Can someone provide information about such a material?

How exactly is the EM field tensor related to the proper orthochronous Lorentz group?

In texts on geometrical optics I have read that an image is formed where light rays converge -- without an explanation of why. Thus I ask, why are images formed where light rays converge? In particular, what is the answer to this question in terms of the wave theory of light (Electrodynamics)...

hello engineers, i have a question . what effect would a recovery station that is power at 20 KV and 50 hz from the local power line would have on the immediate area around it? i mean i know it will produce some electromagnetic field around it, and that is not that good for the rezidents living...

Hello, For reasons I’ve read here in this forum, some material (let’s say PVC or paper) are not transparent to light. But light is an electromagnetic wave. If I lower the frequency, that material is now transparent, even if I cannot detect it with my eyes but must use special equipments, the...

Homework Statement A sinusoidal electromagnetic wave from a radio station passes perpendicularly through an open window that has area of 0.700m2 . At the window, the electric field of the wave has an rms value 2.30×10−2V/m . How much energy does this wave carry through the window during a...

In nMRIs the strong magnetic field plus the radio wave aligns protons. 1). Which protons? Just the proton ions (actually H3O+) from water; or protons in all molecules that contain hydrogen atoms such as water, fats, carbohydrates, proteins? 2). The relaxation phase does what? As the protons...

Is there a way to determine the profile of the field around a charged closed loop - particularly on the direction normal to the plane of the loop, both front and back? For generic values of V, I, B, H, etc., and any dimensions of the loop, any particular formulae possible to obtain? Thank you...

Homework Statement For an electromagnetic wave with an electric field given by \mathbf{B}=\mathbf{i} E_o cos (kz-\omega t)+ \mathbf{j} E_o sin (\omega t - kz) where Eo is a constant Find (a) its direction of propagation (b) the magnetic field (c) Poynting vector (d) energy density, i.e., the...

In a Superman comic Superman drops a bomb into a sun eater and outruns the explosion, which is 50 times the size of Kepler's supernova. He is hit by the electromagnetic shockwaves but manages to fly out of the way of the wall of radiation. What type of energy did he absorb? What do...

So, I'm trying to show that by duality B_{i}\rightarrow E_{i}, using tensor notation. I've done it in a different way, and it works (starting from \overline{F}_{ij}, the dual of F_ij), but I would like to get it from B_i directly. Where am I going wrong? This is what I did...

I have read this wikipedia article, but I still don't understand: http://en.wikipedia.org/wiki/Near_and_far_field Why can EM radiation only be transverse waves? Why can't it travel as a longitudinal wave? If I have two charges in a vacuum, with the straight line between them called 'x...

Suppose that we have the four-vector potential of the electromagnetic field, [texA^i[/tex] The wave equation is given by $$(\frac {1}{c^2} \frac {\partial^2}{\partial t^2}-\nabla^2) A^i=0$$ Now the solution, for a purely spatial potential vector, is given by $$\mathbf{A}(t...

Did James Clerk Maxwell Ever Draw a Picture of an Electromagnetic Wave in any of his notebooks? Who was the first one to draw one? Would love to find the first picture representing it all! I am looking for the first example of a drawing looking like this showing the perpendicular sinusoidal...

I’ve read that the particle responsible for the transmission of the electromagnetic force is the photon. Another way to say this is that the photon is the carrier of the electromagnetic force. Having that in mind, let’s suppose that we have an electron resting in vacuum, and suddenly an electric...

Why is light viewed as both wave energy and particle motion, whereas other forms of electromagnetic radiation is only seen as waves? Light is just a small part of the spectrum, so, surely all electromagnetic radiation should be viewed in the same way.

Maxwell's equations solutions in vacuum - is a free electromagnetics waves. Such solutions can be obtained even without knowing anything about the charges and currents. Does this mean that such waves is the essence , not related charges, e.g. free electromagnetic waves? Moreover, the Maxwell's...

If light is a quantum object, then what are electromagnetic waves that Maxwell predicted?

Consider two frames: S and S', with S' moving to the right along the positive x-axis or S at a relative velocity v. The origins of S and S' coincide at t = 0. A spherical electromagnetic wave leaves the origin of S the moment S and S' coincide, or at t = 0. If we consider the transformation...

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) =...

Caution: I'm new at this stuff. On page 573 of Gravitation (Misner, Thorne, Wheeler), they write down what I think is the electromagnetic wave equation for a discussion on Optics, "Next insert the vector potential (22.25) into the source-free wave equation (22.19d):" I am wondering if the...

Homework Statement Show that the solution \textbf{E}=E(y,z)\textbf{n}\cos(\omega t-k_xx) substituted into the wave equation yields \frac{\partial^2 E(y,z)}{\partial y^2}+\frac{\partial^2 E(y,z)}{\partial z^2}=-k^2E(y,z) where k^2=\frac{\omega^2}{c^2}-k_x^2 Homework Equations See above. The...

hi to everyone L=T-V as you know it is the lagrangian equation the effective Lagrangian of the electromagnetic field is given by following relation in gaussian units. L=(1/8pi) (E^2-B^2) how is must calculate this relation? (the energy density of electromagnetic fields is given by u=(1/8pi)...

My textbooks says in a region where there is no charge or current Maxwell's equations read divergence of E=0 Curl of E=-dB/dt all d are partial Divergence of B=0 Curl of B=ue(dE/dt) I get the math of showing that there are waves, but I don't get some of these conditions. 1st don't you...

Two parallel electromagnets situated symmetrically on either side of the straight section of an oval track propel a wheeled trolley along the track, so that the trolley is in continuous motion, as long as the current is supplied to the electromagnets. Is this workable? Does the entry and exit...

so suppose i have a wire given parametrically by C(t)=x(t),y(t),z(t), and i run a current of I amps through it. to find the total B field i would sum up the contributions over the length of the wire, and (please tell me if I am wrong) the total B field due to the wire at point p=xp,yp,zp would...

Hi! In classical electromagnetic theory the energy of an electromagnetic wave is proportional to its amplitude squared. In contrast, the quantum mechanical equation ##E = \hbar \nu## states that the energy is proportional to the frequency of the wave (photon). Now, according to the...

I recently saw an technical instrument that uses electromagnetic field to capture and move small objects. For example it can be used to capture and unscrew nut(female screw). How this instrument can be named right to find its description in the Internet?

Hello all. I have been searching for information on wave beats in light but haven't been very succesful. I have found a lot of information on beats but most of it refers to sound or to waves in general without referring to EM waves. I think that when EM waves are dispersed at normal incidence...

Hello, I am trying to design a way to move a platform that is inside a container without any direct connection to the platform. I hope to have a linear guide outside of the container with an electromagnet attached. When the electromagnet is energized it will couple with the platform...

creating force with sound Hi, I am currently building a device for the company I work for to open molds that have been plasticized together using sound. The idea is to produce a frequency that will either vibrate the lid open or push it open, but I am stumped on what calculations I need to use...

Is it possible to solve these partial differential equations directly, relating to Antenna Theory; ∇^2 E - μ_0 ε_0 \frac{∂^2E}{∂t^2} = -μ_0 \frac{∂J}{∂t}. AND ∇^2 B - μ_0 ε_0 \frac{∂^2B}{∂t^2} = -μ_0 ∇ x J. I don't like the idea of having to make up fields that don't exist in order to make...

Hello, I am at present analyzing the electromagnetic interaction of a layer of paritcles in air when illuminated by an electromagnetic wave. This can be done by considering the layer of particles as an interface with surface current (as opposed to a 'normal' interface with Fresnel...

Hi PhysicsForums, I was wondering if this youtube was a correct representation of a photon traveling through space with time. What I am trying to grasp is that, is the photon creating a trail of static Efields and Bfields as it moves through space as shown in the youtube, or does the...

At the core of the quantum concept by Planck was the black-body radiation, then: electromagnetic waves, whose amplitudes are electric and magnetic fields, but when one follow the developments and one comes to the Schrödinger waves, now their amplitudes are not of that kind but related to...

Hi guys I just want to know why changing magnetic flux in a coil induces emf? Thanks in advance.

How would one go about figuring out what to dope a diodes pn junction with in order to create a desired electromagnetic wavelength ?

I was just thinking about the "changing magnetic field through a loop induces an EMF" and thought of a conceptual question I'm having trouble with. So, imagine you have an open surface where there's a changing magnetic flux that you know (say its a plane of magnetic field coming toward you...

This is from Wikipedia: 1. What is really meant by "self-propagating", how it works? 2. How many electric and magnetic fields are in one wave? 3. What is the strength of those electric and magnetic fields? 4. What does -q and +q represent in the above diagram? 5. Why would...

Hi all For a recent project, I am looking to simulate a metallic object moving through a magnetic field (think modeling the motion of a solenoid core inside of a coil of wire). I've tried out simulators such as MaxFEM and meep, but I can't seem to figure out how to simulate the motion of an...

Why is it that the boson for the electromagnetic force does not have a charge? I apologize if this question is rudimentary, as all of you guys are WAY out of my league. Thanks!

I stumbled on it while searching for electrodynamics textbooks for undergrads but this seems more advanced than Griffiths. Has anyone else used this book by Marcus Zahn? Is it a worthwhile read for an electrical engineer about to start sophomore year?

I’m not asking about the duality particle/wave behavior. I just want to know when did the notion of light being an electromagnetic wave first came up. Was it before or after Maxwell’s calculations of the speed of waves? I am currently reading a book that explain the process by which Maxwell...

Dear All, Can anyone explain me if light is an electromagnetic wave then why a charge does not experiences an electric force(or magnetic force) due to electric field component(or magnetic field component)of electromagnetic wave? this is a very challenging question asked by my friend to me...

In Heaviside's Electromagnetic Theory (1895) he says that "The second law of thermodynamics itself needs to be established from electromagnetic principles, assisted by the law of averages..." I attempted to Google whether or not anyone has derived the second law via electricity and magnetism...

I am talking about electromagnetism.. Can we construct a system with no power consumption.. I ve an idea... 1 we can construct rail route surrounded by dome shaped copper (actually cu strips to avoid eddy current) 2 rail on which permanent magnet is fixed will allowed to move on this...

https://www.physicsforums.com/showthread.php?p=2881300#post2881300 According to the quoted thread above and according to textbooks and Wikipedia the phase between the E and B fields of an electromagnetic wave propagating in free space is zero. This assertion is based on the Maxwell equations...

*Edit: I noticed I may have posted this question on the wrong forum... if this is the case, could you please move it for me instead of deleting? thanks! :) Hello, I am having problems on building my electromagnetic tensor from a four-potential. I suspect my calculations are not right. Here are...

Hi Everyone I am wondering about something. As everyone here knows, electromagnetic waves obviously possesses an electrical component and a magnetic component. Firstly, can electromagnetic waves be considered to be a sort of complex wavefunction? If yes then do the two components of...