Electromagnetic field Definition and 235 Threads

hi i just read this article,which discussed about getting the Schroedinger's equation for a particle in a em field by transforming the psi, http://www.vttoth.com/gauge.htm .can anyone please tell me if we can get the dirac's equation for a particle in a em field by transforming the psi thanks...

Is there any deep reason for introducing the electromagnetic field tensor other than the fact that Maxwell's equations can be written in a very succinct form in terms of it? Would it be possible to write down a lagrangian involving a normal kinetic term for A^{\mu} that reproduces the physics...

Can somebody tell me how can i create a powerful electromagnetic field using magnetic wires. I don't want it to be big. The diameter of the circle should be as big as an average water bottle. It can be really thick but the height should be about 1 to 2 inches. I guess i can buy some other...

There was a question several days ago related to visualizing the electro-magnetic field. I reminded me of a great passage from the Feynman Lectures on Physics. I won't quote the whole thing, but it is in section 20-3, "Scientific Imagination" (unfortunately I don't think the lectures are...

What is a field? Say, a velocity field or an electromagnetic field. How we actually define a field? I think the most precise definition is mathematical: a set of numbers associated with each point that can describe some physical properties on that point, namely, a function with respect to space...

I have some specific, related questions, for which I haven't been able to find answers: 1. At any instant in time, is the physical size or extent (e.g., length, width, diameter) of the electromagnetic field of a single photon (of a given wavelength) traveling through a vacuum determinate...

How does an EM field, with both an electric and a magnetic component, each of which "disappears" produce an apparently steady photon? A point charge has an electromagnetic field it creates...A stationary observer with respect to the charge sees and electric field; an observer in motion sees...

Four interesting questions: 1: Is there a maximum range of a given electromagnetic field? 2: Is there a maximum strength of an electromagnetic field? 3: If the maximum electric field or magnetic field different from each other? 4: Can you make an electric or magnetic field so strong...

An EM Field is described as follows : The electromagnetic field is a physical field produced by electrically charged objects. It affects the behaviour of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the...

Hi all, I am designing vending machine to be used outdoors in a train station. I am a mechanical engineer and i don't know much about electromagnetic fields. The fact is based on what I have read, in train stations in which the train is working with electric power, the power lines are high...

What is the importance of dual electromagnetic field tensor? Generally this is not included in the action. What will be the advantage/disadvantage if I include terms like F_{\mu \nu}\tilde{F}^{\mu \nu}, \tilde{F}_{\mu \nu}\tilde{F}^{\mu \nu} in the action? (The tilde denotes the dual tensor.)...

[SOLVED] Geometric Algebra: Signs of electromagnetic field tensor components? Here's a question that may look like an E&M question, but is really just a geometric algebra question. In particular, I've got a sign off by 1 somewhere I think and I wonder if somebody can spot it. PF isn't...

How is the electromagnetic field different from aether? if there is an em field why is it not considered to be at absolute rest

Can a medium tension electromagnetic field cause permanent damage to LCD tvs? I am about to buy a LCD to my living room, but the builder said that, because of the electric cables in the wall having medium tension, it could cause an electric field that can ruin a LCD screen. Is this true...

As the title suggest, does this PEMF therapy crackpottery? I have been browsing the FDA website, and from what i read, manufactures do seem to provide adequate evidence to show that PEMF does help bone growth such as fractures and such. But do PEMF help will pain relieve, that i am not that...

Inspired by another https://www.physicsforums.com/showthread.php?t=176823", where the discussion drifts toward the (Schroedinger) wave function of photons, I rather like to focus on the electromagnetic (EM) field and its relation to photon(s): What actually is the relation between an EM field...

I will be very happy if you answer me. I tried several times on google to search about this but I didn't find anything. So please answer me, if you know the answer. Thank you.

An photon has mass zero by virtue of its momentum canceling its energy in m^2c^4 = E^2-p^2c^2 But in electromagnetism a field configution only has momentum when both a magnetic field and an electric field are present, e.g. in an electromagnetic wave. Now when there is only an electric or...

Homework Statement A 1400 nF capacitor with circular parallel plates 1.0 cm in diameter is accumulating charge at the rate of 25.0 mC/s at some instant in time. What will be the magnitude of the induced magnetic field 9.0 cm radially outward from the center of the plates...

Homework Statement Trying to magnetize water in a test tube so that it will move or pick up iron shaving(s) Homework Equations none The Attempt at a Solution Wrapped test tube with magnetic wire (500 turns) wire is connected to DC current of 122 volts. It will pick up iron...

I have created an external electromagnetic field by using DC current connected to magnetic wire that is wrapped around a small test tube. I put water in the test tube. I have increased/decreased the gauge of the wire, increased the volts of the DC current, tried AC current and I still cannot...

A while ago someone asked on s.p.relativity how a black hole can accelerate in a gravitational field, given that the round trip time to the event horizon is infinite. This seems easy enough to understand -- given that there's no background metric, what else could it do? But I realized that I...

Hello, What is the precise form of the electromagnetic field generated by a single charge q at a given point P and time t1, if the movement of q is described by M(t). I have seek the precise answer to this question in many books of physic, without success. I think it must be relativistic...

A charges cork ball of mass 1.00g is suspended on a light string in the presence of a uniform electric field has an x compenent of 3.00 x 10^5 N/C and a y component of 5.00 x 10^5 N/C, the ball is in equilibrium at \theta = 37 degree. Find: (a) the charge on the ball (b) thetension in he...

Greetings, I am currently working on an interesting experiment on crystalized metal and I need to find a way to get a detailed map of an electromagnetic field when current is induced into a metal sample. I found the basic 2D approach of using conductivity paper and Ag ink to be useless as it...

I have a problem understanding the meaning of magnetic field strength, denotet H. I have the following example from a textbook: 1. The path of magnetic field strength developed in a conductor loop is given by the formula H = (I*N*R^2) / (2*sqrt(R^2+x^2)^3) I = current N=number of turns...

This is an experiment which might prove interesting. We know , thanks to the work of Oersted and Ampere , that the field around a wire carrying a current and the field around a permanent magnet are identical. Both of these fields are caused by moving charges , although the field around a wire is...

Hello, i had a question (as many do on these forums, it appears ;). I know E_{k}=F_{0k} I also know B_{k}=(1/2)*(\epsilon_{klm}*F_{lm}) EM field tensor F^{uv} defined as: (I put tildes (~) into make it more like a matrix form) 0~~~~E_x~~~E_y~~~E_z -E_x~~~0~~~~-B_z~~B_y...

Consider the electromagnetic field in a linear medium with material properties \epsilon \ \ \text{and} \ \ \mu . Calculate \nabla \cdot \mathbf{S} for the energy flux \mathbf{S = E \times H} . My work: \nabla \cdot \mathbf{S} = \nabla \cdot \frac{1}{\mu}(\mathbf{E \times B }) =...

Why is it that as a particle propagates through an electromagnetic field, the electric and magnetic forces are perpendicular to each other? (through the straight line of the particles motion) What effect does this have on the particle's motion, wavelenght and frequency? Thanks

The QED Lagrangian is given by \mathcal{L}_{\hbox{QED}} = \bar{\psi}(i\partial - m)\psi - \frac{1}{4}(F_{\mu\nu})^2 - e\bar{\psi}\gamma^\mu\psi A_\mu What is the purpose of the middle term. I know that it represents the energy of the E and B fields. However is that due to the external...

For question 3, i don't know ho to differentiate the electromagnetic field. Can someone help me?

Is the electromagnetic field "real"? This is sort of a mix of classical and quantum so I put it here ... In our current view of the universe, is the electromagnetic field "real", or is it simply a manifestation of the true underlying causes behind the electromagnetic force? It seems to me...

hi, electromagnetic radiation is a combination of oscillating electric and magnetic fields...if a transmiter sends a cmplex elctro magnetic signal into space and then shuts down, there is no longer a source of information to the signal, how does this oscillating electromagnetic field keep its...

can't an electro-magnetic field be used to separate two liquids? For example: petrol and water(as they have different magnetic properties) i'd be grateful if someone helps me with this.