Electromagnetic Definition and 1000 Threads

Let's suppose that on Earth I have two devices which permits me to detect the gravitation produced and electromagnetic waves (photons) emitted by the Sun. Then, the Sun suddenly disappears. Which of the two devices will notice first that the Sun has gone, i.e. which wave propagates faster, the...

Homework Statement The figure below shows a plane electromagnetic sinusoidal wave propagating in the x direction. Suppose the wavelength is 56.0 m and the electric field vibrates in the xy plane with an amplitude of 20.0 V/m. (a) Calculate the frequency of the wave. (b) Calculate the magnetic...

Hello I am new to this forum and wanted to ask a question on em induction. I know if a current passes through a wire a magnetic field around the wire is produced and can be amplified by having a coil of wire. If that is then placed in a magnetic field (like between a north and south pole...

Apparently for emf to be induced in a coil, the magnetic field (or part of it) has to act along the normal to the coil face. So does this mean that the coil moves side-ways through the magnetic field? where instead of moving through its length (its longer side), it moves through the coil face...

I haven't been able to find any literature that answers this question in a pleasing way. Also, all sources on the internet are contradictory. If electromagnetic waves (out of phase since they are emitted by the gaseous atoms in discharge tube) sent through a diffraction gitter interfered with...

Homework Statement Two metal rods are placed on two parallel smooth conducting rails , under uniform B field lines . The metal rod on right-hand side is initially moving at a constant velocity of 3 m/s , while the other one is initially at rest . What would be the subsequent motions of the two...

Homework Statement Q1: explain how the setup shown in the diagram acts as a break? Q2: Electric and hybrid cars use regenerative breaking. At high speeds, the car can be slowed by reversing the direction of the electric motor so that it acts as a generator. Explain how this system...

Say I were to shine a laser in a particular direction and quickly turn it off. After a certain time, the radiation passes through a region of space. Some force field (e.g. electric or magnetic; assume gravity is negligibly small) is then turned on as the radiation passes, such that no mass or...

Imagine that an electron is traveling with velocity +v inside a uniform sphere of charge at potential +V. In the rest frame of the electron the charged sphere has velocity -v. Thus in the rest frame of the electron, inside the charged sphere, there is a vector potential A given by A = -...

A while back (thread) you guys helped me understand why \tilde{F}=m\frac{d\gamma\tilde{v}}{dt} (3-vectors) as it follows from \bar{F}=q\Psi\bar{v} (4-vectors) and \tilde{F}=q(\tilde{E}+\tilde{v}\times \tilde{B}) (3-vectors). However, I had the impression that one also uses...

As I understand it, there are these categories: radio microwave infrared light visible light ultraviolet light X-rays gamma rays It seems that microwaves are really just radio waves that happen to have a very short wavelength, with the distinction that radio & microwaves are waves...

i have gone through that photon is force carrier of em force..but in macroscopic level as far as I studied I know em force is designated with field in macroscopic rather than a particle like interaction.so how can they justify that em force is managed by photon.If photon is more plausible is it...

dear all, I have a question about Electromagnetic field tensor. As I was reading introduction to relativity by Hobson, I saw this sentence: "in order that the rest mass of a particle is not altered by the action of the erforce we require the latter to be a pure force, so: u.f=0 1) what does it...

we know light bends and loses energy when it travels in gravity..what abt influence on light when it travels in EM field..similarly can anyone trace out what happens in weak and strong force fields as welll.I guess its complex..

Hi fellow members! I have a serious confusion for light being an electromagnetic wave? since the we know that electromagnetic wave is produced due to the motion of charged particle.Light reaches us from the sun due to nuclear fusion reaction but light is produced due to the heat or energy...

Scientifically, it doesn't make sense why you can't just wind up wire without really much air in the middle. In order to get more wire closer to the magnetic flux, why wouldn't you just wind up the coil tighter? I keep seeing ferromagnetic or air cores. Why not a tightly would wire so more...

Hi everybody! Please explain to me how can we consider static electromagnetic field in point of view of Quantum Field Theory.Because varying electromagnetic field can quantize to photons,so we can consider varying electromagnetic field like a ''set'' of photons. Thanks very much in advance.

Homework Statement img341.imageshack.us/img341/1338/scanpic0001a.jpg This is the picture. Sorry i can't add a link cause i do not have 10 posts. The part that i don't understand is why the aluminium ring takes a longer time to fall when an alternating current is used The Attempt at a...

This isn't a homework problem - I can't understand a particular statement in my professor's notes. As such, I hope it's in the correct forum. Homework Statement The Hamiltonian for a charged particle in a potential field A is \hat{H} = (1/2m) ( -i \hbar \nabla - q A)^{2} The square...

How Eddy Currents Produce Attractive Electromagnetic Forces--Maglev Hello, I am working on a paper about maglev systems and am trying to describe attractive electromagnetic suspension systems, but I am having a little trouble exactly visualizing how this works, which from what I have read is...

I was just thinking about electromagnetic fields and magnetostatics. Magnetostatics is the study of magnetic fields where they do not change or very little. I was wondering if a static magnetic field is still considered part of a Electromagnetic field? Since the magnetic field is not changing...

I am having trouble understanding how a light wave travels through a medium, such as the Earth's atmosphere when emitted from a light bulb... I have read some topics on the difference between transverse and longitudinal waves, but I am having trouble understanding how they exist. I can imagine...

I have trouble understanding the concept of electromagnetic waves. my textbook has the following explanation for electromagnetic momentum. It's not very clear to me. [ light reflecting from a perfect reflector will leave the surface with its initial momentum, thus having twice its initial...

So what i understand from my professor about the electromagnetic waves is this : an electric charge has an electric field E a moving electric charge induces a magnetic field B The electromagnetic wave produced is due to the moving charge which has both components E and B... But my...

Homework Statement I have a question for homework which is. "Chemical rockets are unsuitable for travel beyond close planets. Describe a method of propulsion based on electromagnetic induction which could be used for long distance space travel beyond the nearest planets." Homework Equations...

1. A closed loop is held stationary in the magnetic field between the north and south poles of two permanent magnets held fixed. Can we hope to generate current in the loop by using very strong magnets? well, my doubt is: as magnetic field is a vector and since we have two pairs [one...

What is electromagnetic duality for Maxwell's equations in free space without sources? Is this symmetry valid when there are conventional sources? If not, what hypothetical additional sources are needed to restore duality symmetry?

Hi There is lots of text, but it is actually just a presentation of facts and thoughts to explain where I am in all this. There are two main questions: 1) Are the incident waves from a very distant source, say a star very far away, interfering with one another to create one or more resulting...

I understand the relationship between velocity and wavelength when the refractive index changes but I can't fully understand why frequency cannot change. What would happen if it did? why can't the speed of light stay constant as frequency and wavelength change to keep it. Is it because of...

Electromagnetic fields mostly have a stress-energy tensor in which the trace is zero. Is traceless stress energy tensor always implies Ricci scalar is zero? If yes how to prove that?

Hello everyone, I have the following problem understanding electromagnetic induction. THis is not a homework question but it's a thought experiment I seem to not succeed in doing. Let's take the situation where you move a rectangle shaped plate with a speed perpendicular to a homogenous...

Homework Statement Find the electromagnetic energy and momentum density and their ratio. \\Determine the instantaneous values of the energy density, momentum density, intensity, and stress associated with the electromagnetic fields for the following cases. Also, identify these cases. Assume...

I took a physics competition recently and found I missed 6 questions on electromagnetic induction and the like. I've always been shaky here, so I'm wondering if anyone can give me an online resource, or just explain to me exactly how it works (i.e., Lenz's law, etc., etc.)? I'm sorry for not...

Hello everyone, How are you doing? I have a doubt about electromagnetic induction, in three particular cases. I need to confirm that I have the right concepts, so I ask for your help. The main problem: Imagine that you have a permanent magnet, axially polarized and rotating on its...

Is there any mathematical relation between the value of charge(ie proton/electron) and radiation which is being emitted? I m sure energy is conserved in this process so does that mean electron decelerates in process of radiation ?

Hi, I'm trying to work through something and it should be quite simple but somehow I've gotten a bit confused. I've worked through the Euler Lagrange equations for the lagrangian: \begin{align*} \mathcal{L}_{0} &= -\frac{1}{4}(\partial_{\mu}A_{\nu})(\partial^{\mu}A^{\nu}) \\ &=...

Dear all - I am new here so please be gentle :smile: I have searched the site for a few days but alas still have a few questions on something i am hoping to make...so with your kind help - here we go! I am looking to make a type of electromagnetic piston, basically i want to have an...

Hi, I'm wondering if there has been any actual experiments done to measure the speed at which magnetic fields propagate?

I recently read an article online stating that electromagnetic radiation is 'a form of energy emitted and absorbed by charged particles'. This isn't always correct, is it? I mean, I know that charged particles that are accelerating can emit bremsstrahlung and synchrotron radiation, but my own...

Homework Statement If I move a SQUARE conductive layer in a forward direction, with a magnetic field pointing vertically upward why is an EMF only induced in the left-right plane NOT the forward-backward plane??Homework Equations The Attempt at a Solution I would have thought that as BOTH...

Hello, why the electromagnetic waves move up and down instead of just travel straight? When an electron go in a lower energy level it relases a photon, but where does this photon came from? Thank you!

Homework Statement Hey guys, I am trying to draw out the electromagnetic absorpton vs frequency graph for a known dielectric constant ε in a medium but I am kind of stucked. I am studying from the Griffiths' book if you can catch me up from there, equations are on pg. 394, in chapter 9.4...

By Maxwell's equations, electromagnetic waves seem to come about by means of magnetic fields generating electric fields and in turn electric fields generating magnetic fields (the loop continues.) But how is this not perpetual in the context that energy is not conserved? It seems as if a...

I have been searching the internet for a simplistic equation which is capable of calculating the force of an electromagnet. I think I have found one at http://www.ehow.com/how_5969962_calculate-force-electromagnet.html however am not entirely sure this is a correct equation (don't really trust...

Homework Statement You are holding a conducting loop of copper and looking at its circle. Behind it is a long current-carrying wire carrying the current from left to right. As you pull the loop toward you, what is the direction of current flow if any? A)No way to tell B)Counter-clockwise...

Homework Statement A quantum of electromagnetic radiation has an energy of 0.877 keV. What is its wavelength? The speed of light is 2.99792 × 10 8 m/s, and Planck’s constant is 6.62607 × 10−34J · s. Answer in units of nm Homework Equations E=hf v=fλ ... λ=v/(E/h) The Attempt...

Physics is not my forte, but I need some answers re EMFs. I want to buy a 30-ft sailboat that has an electric engine. (I have attached a link to the exact model for reference.) Further, my intent is to live aboard. I have been planning on making my permanent bed right over the top of the...

How much stronger is the strong nuclear force compared it to the electromagnetic force beyond what could be accounted for by the inverse of the distance squared?

Homework Statement A plane monochromatic electromagnetic wave with wavelength λ = 2.2 cm, propagates through a vacuum. Its magnetic field is described by \vec{B} = (Bx\vec{i} + By\vec{j})cos(kz+ωt) where Bx = 1.8E-6 T and By = 3.8E-6 T, and i-hat and j-hat are the unit vectors in the +x and...

In a nuclear reactor, what kind of energy is produced when the radioactive isotopes go through fission? How much of it is in the form of electromagnetic waves? Are the waves mostly in the UV and Gamma Ray region of the electromagnetic spectrum?