Em Definition and 1000 Threads

I am studying EM wave and transmission lines. I see both derive equations for propagation constant \gamma: Plane wave velocity is 1/\sqrt{\mu\epsilon} and \eta = \sqrt{\mu/\epsilon} Transmission line velocity is 1/\sqrt{LC} and Z0=\sqrt{L/C}. From that the book just to say the velocity...

I have heard many things about electromagnetic induction, but I have got still more questions than answers. For example if a magnet is closing fast to a coil, a current will be induced in a coil. This also means, that part of the momentum will be given to those charged particles. If we count...

I am trying to review some basic physics, purely for my own interest, and have been looking at particle physics in the form of the Bohr model and EM theory in the form of Maxwell’s equation. While I still have a way to go on these topics, I was wondering if anybody is in a position to help me...

Show that the electric field: E = Emsin(kx-ωt) and magnetic field: B=Bmsin(kx-ωt) satisfy the following equations: -\frac{\partial B}{\partial x} = \mu_{0}\epsilon_{0}\frac{\partial E}{\partial t} and \frac{\partial E}{\partial x} = -\frac{\partial B}{\partial t} I have no idea...

Homework Statement this integral owned me, can anyone tell me what to do to solve it/ how to solve it or a step by step solution. from 0 to h, 1/((h-r)^2+r^2))dr Homework Equations The Attempt at a Solution Im thinking partial factions or trig sub...

Hey all, I am an undergraduate taking a particle physics class and we just learned that the EM force was caused by charges "spitting" virtual photons back a forth. In like second grade we learned that the EM force was dependent on the two charges involved (keeping this simple) and the distance...

Round em up, send em to GITMO! I'm watching CNN and YET AGAIN another CEO is spending wild sums of money (1.3 million) to redecorate his office. He spent 14k on a waste basket. Over and over, all these CEOS are scum bags. I mean jesus christ, how disgraceful.

Anybody knows if there is a rule for EM radiation cross over materials ? The wavelenght in comparison the size (or structure) of molecule is determinant ? Ex. why infrared pass through the concrete but not metalics ? Thank you.

Hi I hope this is the right place to post. I have some questions regarding EM wave amplitudes. There are some other posts in the past regarding this and some people replied by saying that amplitude of a light wave is equal/close to wavelength of the wave. This is deduced from the fact that...

I know that in free space, the general solution of the wave equation about electric field is of sine and cosine form. One can also write it in complex form as E = E_0 \exp(i\vec{k}\cdot\vec{r} - i\omega t) I have two queations about this solution 1) If consider the polarization, how...

I love Star trek and I was thinking, how to create a warp drive. I have read a discusion about EM waves on this forum, there was written that they do not need any medium for propagation and : “In a simplified sense the oscillating E field sustains the oscillating B field which sustains the...

On the boundary (surface) of two regions, the tangential components of electric fields on above and below surface are continuous. I wonder if it is also true for displacement \vec{D} and polarization \vec{P}? That is, can I say: the tangential component of \vec{D} or \vec{P} on above and below...

In EM wave polarization. Where is linear polarization where \gamma =0 or \pi . \gamma = +/- 45 deg and amplitude of Ex and Ey are equal to give circular polization etc. My question is why there are different angle of \gamma on the first place? If you set the reference at x...

Speed of EM travel through the good conductor is \omega/\beta I know the speed of signal travel in stripline is c/\sqrt{}\epsilon_{}r_{} My symbols don't look very good but I think you get what I mean. Obvious they are different. I am confuse because in both case EM wave travel in good...

Alright first time poster here with a question that has been eating at me for a while. I am curious to know if there is a substance that when one part of the EM spectrum is passed through it, it would come out as another. I know that if you are to shine a lightbulb on some black cloth you would...

I am trying to derive the electromagnetic wave equations from Faraday's law of Induction, and the Ampere-Maxwell law. But, I am having a problem with the 1/c^2 disappearing. This is what I am using: \nabla\times\vec{B}=\mu\vec{J}+\mu\epsilon\stackrel{\partial\vec{E}}{\partial t}...

Homework Statement 1. The expression F = [x,y,z] defines a vector field. Given the parametric representation of a surface S:[u cos v, u sin v, u^2] = r (u,v), where the parameters cover the ranges 0 ≤ u ≤ 2 and 0 ≤ v ≤ 2π, calculate the flux F through the surface S.Homework Equations How do i...

Homework Statement Find the velocity of EM waves as a function of \epsilon_{0} and \mu_{0} 2. The attempt at a solution E = E_{0}cos(kx-\omega t) Using v= \frac{\omega}{k}

I know undergrad QM fairly well. There they use the EM potential to introduce EM fields into the momentum. What should I study to understand the connection between EM fields and actual photon particles?

The maximum I have found about contact force is very roughly this: it is nothing but electromagnetic force, meaning that, if two bodies collide, the electrons of the atoms of the outer shell of each body repel each other, those atoms displace towards their neighbours and repel them in turn, thus...

Homework Statement Sketch in 3D, the following waves. (both E fields are in x direction E_1 = 3*exp(-j*8*Pi*z) E_2 = 4j*exp(-j*8*Pi*z) (where j=sqrt(-1)The Attempt at a Solution I know how to sketch E_1, but my question is how to treat the imaginary amplitude, 4j in E_2. here is my stab at...

Hi, i am working in a motion capture project one of its parts is a sensor i need a formula of the voltage generated in the coil due to moving in electromagnetic Field from an inducer i think it depends on ( B , cosθ , µ , N , L , r ) i post this thread in another forum but no one answer...

EM field and its sources... hello forum, a simple question about EM field and its sources. In a time-varying situation, maxwell equations tell that the E field has the time-changing charge density rho as a source, while the B field has the time-changing current density J. But both...

Homework Statement Basically, the problem states that a cavity at temperature T is emitting EM waves isotropically in all directions (with frequency distribution of Planck's Law). If the time averaged density is <e>, find the value of d<S>/dw where w is the solid angle and the quantity is the...

Does a stationary charge emits electromagnetic radiation? Does a moving charge in magnetic field emits electromagnetic radiation?

Homework Statement Difference between EM wave & a Matter wave ?

Hi all, I have brave hopes of modeling the following problem: Imagine an antenna transmitting an ~50V 100kHz sine wave. Imagine a receiving antenna placed three or four feet apart, with an amplification and detection circuit. First, measure the amplitude of the received wave. Next...

I've been trying to obtain the EM stress energy tensor... but I'm not sure if what I got is correct. In all the websites I googled, I found T^{\mu\nu} =- \frac{1}{4}g^{\mu\nu} F^{\alpha\beta}F_{\alpha\beta} + F^{\mu}\,\!_{\lambda}F^{\nu\lambda} However, is this with the sources or without...

Homework Statement Demonstrate (qualitatively) that an electron in a linearly polarized EM beam that is driven transversely at \omega will also oscillate longitudinally at 2*\omega (due to the B field, apparently). Homework Equations I want to use a phasor form for the fields...

Homework Statement When an EM wave propagates, the E and M field at a point are perpendicular. If E and M at a point are NOT perpendicular to each other, can it be that an EM wave is passing through that point?Homework Equations The Attempt at a Solution Consider a linearly polarized light...

Hello, Is there any empirical evidence that electromagnetic radiation produces gravitational fields? I understand that as a form of energy it is expected to induce a spacetime curvature, but has this prediction of GR actually been tested? Is it at all subject to any controversy? Thanks, Armin

What are the ways (both natural and artificial) in which em radiation is generated? Here is one of the methods: We take a point charge (or more practically a charged sphere with uniform charge distribution) such that we can voluntarily fluctuate the amount of charge on it. We fluctuate the...

Ok my question is pretty simple and is in two parts. 1. say you created an em field what would have to an em wave the is propogating towards it. 2. what would would to an em wave if it went through an em coil. If you could would you be able to point me in the direction a...

There is a EM radiation of frequency suppose x Hz.Let it has to travel a distance of y m.Now what's the time required for the radiation to travel the distance?The question seems to be very easy, but my confusion is in how can the frequency,distance,speed and time can be related? Can someone give...

OK so I'm familiar with the idea that EM radiation propagates through space in straight lines at a uniform speed, that of light. The idea that light moves in waves, that each wavelength carries a uniform energy and that the wavelength differs yet because the same speed is maintained each...

In short: Is a class based on the Jackson text necessary to truly understand electromagnetism? In length: I have heard many people (some on this forum) state that the Jackson text is more of an exercise in mathematical physics and/or is the “hazing” that one must endure to be a PhD in...

Hi, Something has been bothering me about deriving the wave equation for a plane EM wave. We were showed this derivation in class and had to reproduce it but something is not making sense to me... The derivation is as follows: Suppose you have a plane EM wave (in a vaccuum) traveling in the...

Hi, i was wondering Sorry if i don't have the right words, i study in France Why are Microwaves better for heating up food ? I mean since E=hv, these should contain less energy Right now, i know vaguely, that atoms absorb photons where the energy can make it go from one of its characteristic...

Hi I was wondering how can antennas capture + receive Electromagnetic waves I was thinking, in particular of FM Transmitters Antennas, and Fm receiver Antennas. And also, how come metals act as a shield to EM Waves I know that antennas have a resistance, and that they consume Energy by...

In GR, gravity is seen as property of the geometry of spacetime (curvature) as opposed to a force field. Does this theory extend to electromagnetics ,i.e. could EM be described as a property of spacetime, or is EM strictly dealing with fields? Do light waves and gravitational waves travel in the...

Quote from Organic Chemistry, L.G. Wade, Jr.: "Not all molecular vibrations absorb IR radiation." "One of the component of an electromagnetic wave is E field. This field alternately stretches and compresses a polar bond." "If this alternate stretching compressing of the bond occurs at the...

Hi, I understand that EM fields have energy and they travel at c. Light is an EM field so it travels at c as well. So say you run a current through a wire - an EM field is generated, propogating outwards at c. Since an EM field is generated, and EM fields have energy, that energy has to come...

Particle energy and momentum are obtained from the wave function as eigenfunctions of the spatial and time derivative operators. Is this true of ElectroMagnetic fields? In other words are E and B eigenfunctions of a differenial operator? I can see that E and B could be interpreted as a...

I have just read, in general, weak interactions, have the lowest Q values; meaning they have the smallest cross sections, which means they control processes in stars at some time in the early universe. What would be the next relative strength? Cheers

Homework Statement I've derived the EM wave equations from Maxwell's equations, and I now need to show that the E and B components are both perpendicular to each other and to the direction of propagation. The textbook I've been using attempts to show why this is, but it isn't particularly...

When playing poker at a 10 person table, each player obviously has a 10% chance of winning. This means that, when a person is the first player to act at the table, he should only play hole cards that are in the top 10%, in terms of non-losing percentage (ties count as wins here). [In any...

So, accelerating charges produce EM waves, and I understand that the greater the acceleration, the shorter the wavelength of the EM waves. It is also my understanding that when one charge is attracted to another, EM waves are somehow exchanged between the two. Now, let's say you have a unit...

Another noobish question: Let's say there is an electromagnetic wave of constant wavelength and constant peak amplitude that travels a known distance. Let's say that we also know the total energy of this EM wave. Is there some formula that can tell us what the peak value of the electric field is...

Hi everyone, (nb: I posted this in the introductory physics section, but maybe it should be here? I'm not exactly sure how to divide physics into introductory and advanced. I hope this isn't against the rules - it's only my second post!) I am trying to understand my EM course again, and I...

can anyone help me derive the poynting vector from energy density of electromagnetic waves? and how we obtain average value <S> thanks