Electromagnetic Definition and 1000 Threads

Hi Much of what I am going to write in this post is based on what I have read and understood (with very, very limited knowledge of the subject) on the Internet. So, if I have been misinformed or I have misunderstood anything, please don't hesitate to correct me. I would appreciate it. As...

When a magnet is pushed into a solenoid an induced emf occurs. So if it is a closed circuit then an induced current will flow. But if it is an open circuit then an emf will still be induced but no current this time. So will any poles be formed to repel it? What do they mean by the current...

What will happen when I push a magnets into a solenoid with constant speed throughout? I understand that when the magnet leaves and enters an induced emf will occur, but in the middle no emf will occur. Why is this so? I thought that the magnetic flux linkage changes as it moves in the solenoid?

I have heard that the strong nuclear force is stronger then the electromagnetic force at short ranges, "Up to two and a half times the proton diameter". Ok, so i have an approximation of the length it dominates over the electromagnetic force, but i don't know where the force starts from; is it...

Homework Statement I attach a word document with the equations because I don't know how to write them on the post. My question reads: Show that Maxwell's equations Eq (1) is equivalent to Eq (3).Homework Equations The first term of Eq 1 reads: F sub alpha beta comma gamma. That means partial of...

Can anybody tell me the basics of EM waves...like what constitutes EM wave...what is displaced...what are electric and magnetic field components...?

Bohr model had a flaw that electrons would emit EM radiations and would spiral into the nucleus - but he just said that it wouldn't happen providing no reasons Do the modern models of atom explain - why electrons won't emit EM radiations?

Hi What was the evidence that led Maxwell to conclude that light is an electromagnetic wave? How do we measure the strength of the electric and magentic fields of a light beam ? TIA

I'm trying to use some home-made electromagnets to lift a small object. I am a college student, but this is a personal project, so while I may reference something from a textbook, its not a homework problem. I know that I can get some iron bar, coil it with wire, run some current through it...

I like to know if electromagnetic waves pass through a medium (Glass) and if this medium were in contact with two other mediums in its boundary which the first one with same optical dense (Glass) and the second with less optical dense (air). Is there any tendency or priority for wave to pass...

I have to simulate the motion of particle in an electromagnetic device which deflects particle using electric and magnetic field. Those field are arranged in such a way that the electric field is inside the magnetic one. Moreover the electrodes begin at the center of the magnetic field ad their...

Einstein stated in a paper concerning the discovery of the quantization of electromagnetic force that an object emitting electromagnetic radiation will lose its inertial mass. If this is the case, then why does the gravitational force of the sun not weaken and the sun not become less massive as...

Basically I couldn't understand Maxwell's equations during my college days mainly because I didn't understand divergence and curl intuitively. I need some good book on Electromagnetic Fields (such as Gauss Laws and so on) and also I want to learn about Maxwell's equations. I want to...

What keeps the current in an electromagnetic coil from moving between the touching conductors and instead go through the conductor? Is it the resistance being much higher between two touching sections of the coil? Is there a small amount of current "leaking" between each loop where they touch?

In 2-5, an analogy is given for electromagnetic field: two corks in water, and the effect of jiggling one cork on the other (probably the up and down motion). Now, that sounded more like water is a medium propagating the energy. But the electromagnetic waves require no medium for propagation...

Repulsion's got a nice, 'this emits that, hits this; see Newton's third Law' explanation. Attraction. I found one thing. It says this: A virtual particle with momentum p corresponds to a plane wave filling all of space, with no definite position at all. It doesn't matter which way the...

I've always thought that photons and electromagnetic waves are one in the same. And I still do, but I'm trying to get a better grasp on the idea and am finding it difficult. 1) As I understand it, they are the same. But an electromagnetic wave with definite frequency is a perfect sine wave...

An electrically charged particle has an electric field centred around itself that extends far into space. That field has an energy density proportional to the electric field squared. By Einstein's E=mc^2 that energy density is equivalent to a mass density. Thus, as a charged particle...

Homework Statement The diagram below shows two pith balls, equally charged and each with a mass of 1.5 g. While one ball is suspended by a thread, the other is brought close to it and a state of equi- librium is reached. In that situation, the two balls are separated by 2.6 cm and the thread...

This was a question on an online homework for a modern physics class. I had two chances to answer it, but I was wrong both times, so I'm simply curious what the answer is. Homework Statement The Attempt at a Solution (a) Quarks attracted to one another is the strong force (b) A...

Biot-Savart's law of magnetic field " electromagnetic fields" Homework Statement A rectangular loop carrying 10 A of current is placed on z=0 plane as shown in figure . Evaluate H at a) (2,2,0) b) (4,2,0) c) (4,8,0) d) (0,0,2) Homework Equations the used...

Homework Statement A charge q is released from rest at the origin, in the presence of a uniform electric field and a uniform magnetic field \underline{E} = E_0 \hat{z} and \underline{B} = B_0 \hat{x} in frame S. In another frame S', moving with velocity along the y-axis with respect...

If two magnets, equally but oppositely charged, were placed one on top of the other, such that they repel each other, but the weight and shape would not allow the top magnet to slide off, what energy is generated by the relative weight (gravity acting on the mass) of the top plate overcoming the...

best book for "Electromagnetic Theory & Transmission Lines" We've this subject of "electromagnetic theory and transmission lines" this semester..and i wanted to know which books deal the content properly ...mastering this topic may require that one cool book (and ofcourse, regular effort)...and...

Would it just be the energy of the wave (i.e. E = hf)?

I need some help with properties of electromagnetic fields in the presence of microwaves. specifically will a electromagnets field, powered by an external power supply, function normally in a microwave chamber? Will the magnetron induce a current in the copper coil? Would the external power...

Hi all, I'm trying to understand exactly what the physical meaning of conductivity/current is in relation to waves. if we have a wave traveling through a conductor, we find that it decays exponentially, i.e. e^{-\alpha z} where \alpha=imag(k)=\omega\sqrt{\frac{\epsilon\mu}{2}}...

I understand that electromagnetic induction is determined because of a moving electric charge in a magnetic field, but why is the motion necessary? Why is it that motion causes electromagnetic induction and it isn't possible without motion?

Hi! In some texts (Sakurai - advanced qm and others) I found this expression for the lagrangian of an em field: L=F_{\mu \nu}F_{\mu \nu} but I'm a bit confused... L must be a Lorentz invariant, so I would write instead: L=F_{\mu \nu}F^{\mu \nu} \;\; Which form is the correct one? Or...

Homework Statement Using the transform of the electromagnetic tensor F between frames, F'=RFR^{T} verify that: i) the perpendicular component of the magnetic field in the frame, S', moving with velocity v with respect to the frame S, can be found from the transform of B_{\bot} in S...

Hello everybody! For a physics project, I'm trying to create an electromagnet exposed to varying current, determined by a sensor. This sensor will measure the distance between a magnet under the electromagnet and the electromagnet itself, and then we'll need to convert this distance to the...

The Dirac electron in the Higgs vacuum field v and an electromagnetic field with vector potential A_\mu is described by the following equation: i \gamma^\mu \partial_\mu \psi = g v \psi + e \gamma_\mu A^\mu \psi where g is the coupling constant to the Higgs field and e is the coupling...

Hello everyone, First to preface I am not a scientist and have the heart of one (I purchased the heart from eBay... jk). Anyway I have a lingering question regarding Europa: Ok, I get the science about the tidal forces on Europa that flexes the rocky portion of Europa heating up the...

Would electromagnetic coupling between an electron with charge e and an electromagnetic field with scalar potential V_em add to its mass in the same way as its coupling to the scalar Higgs field? i.e. mass_electron = g V_Higgs + e V_em Somewhere I got the picture that a left-handed...

Please teach me this: How can we unify electromagnetic and weak interactions?Is it correct that the SU(2) symmetry(flavor symmetry of fermions) is spontaniously broken(by Higgs Field) and the symmetry(be broken) ''become'' U(1)xSU(2) symmetry that is the symmetry of electroweak interaction...

Hi everyone I have a question that has been bothering me for a while now. I have basically built a Faraday cage using wire mesh. I know there is a relationship between the mesh hole size and the wave suppressing ability of the cage. As I understand it an electromagnetic wave can be thought of...

In the picture below http://www.geo.mtu.edu/rs/back/spectrum/e_mag.gif a bulb is placed on a wire parallel to the direction of the electric field. The bulb is directly on the x-axis where the two waves cross each other. 1. Would the bulb glow when the wire is parallel to the direction...

The general formula for the electromagnetic four-vector produced by a moving charge is the Lienard Wiechert formula, which involves the retarded position of the charge. However, in the special case where the motion of the charge is a uniform velocity motion, the result becomes extremely simple...

Homework Statement Hi In Griffiths it is stated that any possible wave can be written as a sum of plane waves f(z,t)=\int_{-\infty}^{\infty}{A(k)e^{i(kz-\omega t)}dk} This is a sum over spatial frequencies. In another book I have, they write the H-field as H(r, t) = \sum_n{C_n H_n(r)\exp...

You know how a microwave oven has a mesh on the door so visible light gets through but not the microwaves? Can such a thing be done with infrared radiation too? Is it possible to block heat from getting through a mesh but not visible light?

Homework Statement http://dc10.arabsh.com/i/03594/qn9gr42q192z.png What is the direction of current in ring 2 if : a) ring 2 moves towards ring 1 b) ring 2 moves away ring 1 The Attempt at a Solution I used Fleming right hand rule but I'm not sure if it is true, a) the...

Hi, I am looking for clamping circuit for electromagnetic waves. I have a wave which has amplitude of 5 and -10. is it possible to clamp it to 1 and 0 respectively. I want a positive side clamp to be +1 units and negative side clamp to be 0 units. is it possible to realize using any...

how can microwaves heat food?

What determines the wave length.

Both are energy right? I'm asking cause I'm trying to understand the double-slit experiment and I'm just wondering how they can be sure to treat the electron as a particle. Could it be performed with for instance whole atoms or maybe the cores or something else that's more obviously matter...

Hello, Recently I have learned that magnetism causes the Lorentz force. The electric force makes sense to me in terms of virtual photons. But how do virtual photons give rise to magnetism and the Lorentz force. Is it because when the charged particle moves through an magnetic field it comes...

I have skimmed relevant links in wikipedia, and some external links regarding electromagnetic fields, but would like a simple (I'm no physicist) answer to the following question that I have. When one, for example, takes two strong permanent magnets and aligns so that there is repulsive/or...

My first posting after joining today so starting off "light" - I know a terrible pun but please be kind as I will ask a lot of basic and seemingly dumb questions from my simple mind in my quest to learn a lot as quickly as I can! I will try to word this as best I can but, how exactly do EM...

Hello all! I am getting into the electromagnetic waves section in my optics class and in some of these derivations, they are using expressions that I cannot remember how they were derived or the context of them. My book from my E&M class I took awhile back is currently at my house and I am at...

I'm having some trouble understanding visually the propagation of an electromagnetic wave. I'm self-studying electrodynamics so I've never had someone explain this properly to me. I understand an electromagnetic wave is a propagating disturbance in an electromagnetic field. Originally, I...