Electromagnetic fields Definition and 76 Threads

I recently posted a comment about the properties of electromagnetic fields in an article about electric fields in the library. But it was deleted, could someone please point out the errors in the article so I can refine my understanding of this phenomena? The article is written below and...

Homework Statement The angular momentum density in the electromagnetic field is defined in terms of the momentum density (3.6, BELOW) by \textbf{L}_{EM} = \textbf{x}\times\textbf{P}_{EM} = \textbf{x}\times(\textbf{E}\times\textbf{B})/\mu_{0}c^2 Show that if the continuity equation for...

Can someone provide a qualitative description of how electromagnetic fields behave differently when one uses the Proca equations rather than Maxwells equations? That is, if I start with a nice classical EM problem like a plane wave, a moving charge, or an antenna, and then I gradually increase...

I'm having some trouble getting a good understanding of how the EM fields are working in a circuit. Essentially, Maxwell's equations and boundary conditions at a perfect conductor are confusing me. If, in a perfect conductor, the E and B fields are zero, then how does a voltage appear in a...

The nuetron has a known substructure of three charged quarks with net charge 0. Still, these quarks cannot occupy the same space simultaneously, so neutrons should have an electric field surrounding them. Has any work been done to find the properties of this field? For example, what is the...

According to the http://en.wikipedia.org/wiki/Biot-Savart_Law" , the equation for the magnetic field around a charged particle moving with constant velocity is \mathbf{B} = \frac{1}{c^2} \mathbf{v} \times \mathbf{E} But then...

Problem: Iv been trying to prove that the energy reisdes in the magnetic field in a good conductor and equally in both electric and magnetic for an insulator. My problem lies in the time averaging part of the problem...i can't seem to find out how they do it! The time averaging formula used...

Hello to all: Suppose we have two photons that are 180 degrees out of phase. We can assign one unit of energy to each photon. When we superpose the two photons, the combined electric and magnetic field goes to zero as does the Poynting vector and the energy density. So where does the...

Homework Statement A laser beam, having a power of 100 MW and a diameter of 1mm, passes through a glass window of refractive index 1.59. Find the peak values of the electric field and magnetic fields of the laser beam (a) in the air and (b) in the glass. Homework Equations P = ε_0...

Hi all, I have a few odd questions. 1. Can electromagnetic fields influence electrons orbiting around a nucleus? 2. Would it be possible to squash an electron "cloud" into a ring or saucer shape by the application of magnetic fields (think of Saturn and its rings, Saturn = nucleus & rings =...

Ok, everyone knows what an electromagnet is--the most obvious example being wire coils around a nail through which a charge is passed. If you had a hollow cylinder, and the coils were wrapped around the outside; how would the magnetic field be shaped? Illustration (Please assume that there...

What are the differences between these three types of fields or are they all interrelated and the same.

Hey, Former physics student here a bit rusty on his electromagnetic and quantum theory. I recall that an electric field in one frame of reference has a magnetic field component in another frame of reference, so E and B field are ultimately products of the same phenomenon (photon exchanges...

A week or so ago, my high school physics teacher sent us all summer work - we have to write an article explaining the processes by which electromagnetic fields (particularly low frequency electromagnetic fields) could effect the human body. Since then, I have been wading through the large wealth...

ScienceDaily (May 2, 2008) — The electromagnetic fields produced by incubators alter newborns' heart rates, reveals a small study published ahead of print in the Fetal and Neonatal Edition of Archives of Disease in Childhood. It is not clear what the long term effects might be, but this could...

What event creates and sustains natural electromagnetic fields? And what do they mean when they say a photon mediates the electromagnetic field?

Homework Statement What is the magnitude of the force on the proton in the figure? View Figure Homework Equations F=q(E+v*B)The Attempt at a Solution Ive tried just putting the numbers into that equation provided and it doesn't work so I am guessing there is some more that I am missing. I've...

Hi. All the books I read depict the electric fields and magnetic fields in electromagnetic waves as being in phase - meaning they reach their max or their min at the same time. The books also say that the changing electric field creates magnetic field and changing magnetic field creates...

an electromagnetic wave contists of an electric field and a magnetic field oscillating perpendicularly to each other and to the direction of propagation. also, a polariser only let's through light of one particular orientation, so if the polariser is parallel to the direction of the oscillation...

I am having a little trouble with this. To attack this problem (I reckon anyway) is to recognise that the current density vector J(x) can be written it terms of the number density and the velocity. But I'm not sure how to incorporate the Taylor expansion with the cross product. If somebody could...

I am stumped, and googled out. I am interested in knowing whether or not anyone knows of a chemical in liquid form, that will glow or emit light when it is excited by electrons, or more specifically an electromagnetic field. If I am generating an electromagnetic field and want to be able...

electromagnetic fields (nucleus & electron) An interesting conundrum is the nature and makeup behind the electromagnetic field. Quantum Mechanics was developed, for many reasons, but one perhaps, to greater introduce the notion of particle-particle interaction. More precisely to explain each of...

Is the light we see just wave of a certain frequency in an electromagnetic field?

I have been having some difficulty in trying to understand the difference between inductive and radiating electromagnetic fields. When an alternating current is present in an electrical conductor , two types of fields are observed an inductive field and a radiating field . The inductive...

Electromagnetic forces are transmitted by photons, according to the widely accepted theory. Is there any way to block these photons, a sort of magnetic shielding? There may be a very common and obvious substance that does this (of which, alas, I am ignorant) or such a thing may be...

I can see how you can attract conductive objects with an electric field, but I'm wondering if it's actually possible to use some sort of electromagnetic phenomena to repel objects, like in Star Trek, or something Also, how does a Tokamak fusion reactor keep the plasma in place with magnetic...