Em Definition and 1000 Threads

Homework Statement Given the following EM wave propagating in vacuum, find the direction along which the electric field oscillates and the direction of propagation of the wave: \vec{E} = (-3\hat{i} + 3\sqrt{3}\hat{j}) 10^4 e^{i[\frac{\pi}{3} (\sqrt{5}x + \sqrt{5/3} y10^7 - 8.1246 *10^{15} t]}...

When I studied EM we always treated EM fields as being "individual" autonomous fields generated either from the separation of charges or induced by other phenomena. However, I'm reading that modern physics is treating the zero-point energy as fluctuations in THE EM field. Susskind clearly states...

Let's say there is a conducting plane of conductivity \sigma. Boundary conditions for above and below such plane are: E_1^t = E_2^t (D_2 - D_1 ) \cdot n = \rho i.e. tangential components of E field are continuous and perpendicular components of D are discontinuous because of surface charge...

Assuming, of course, that we simply rescaled our color perspectives so that longest wavelengths = red, shortest wavelengths = violet. Are there any such pictures?

Homework Statement two long cylinders (radii a and b) are separated by material of conductivity (sigma). if they are maintained at a potential difference V, what current flows from one to the other, in a length L? Homework Equations Please see the attachment The Attempt at a Solution...

Suppose you have two coherent microwave beams, one beam at 45 degrees to a reflecting wall and the other one at 90 degrees, with the two beams pointing to the same point on the wall. If the two beams are 180 degrees out of phase and destructively interfere at the point on the wall, will the...

Homework Statement A particle of mass m and charge q is attached to a spring with force constant k, hanging from the ceiling. Its equilibrium position is a distance h above the floor. It is pulled down a distance d below equilibrium and released, at time t = 0; Under the usual assumptions...

When an EM wave goes in a conductor it says that the B field component lags the E field component, What causes this? I looked in Griffiths and I couldn't find the answer. Does it have something to do with the fact that when the EM wave enters the conductor it is moving the free electrons in the...

I was always told that EM radiation is a far field effect. Does this mean that the light emitted from the accelerating electron is not right next to the electron but a little further out. And also how do you calculate the frequency of the light coming off. When I looked through Griffiths...

I understand the classical view of EM fields as being (theoretically) continuous. What I don't quite get is how this can be reconciled with the QM view of photons coming only in fixed frequencies (The electromagnetic field may be thought of in a more 'coarse' way.). Is the number of possible...

When an accelerated charged particle is shot into an electromagnetic field such that the accelerated particle comes to a complete stop in the field, we naturally have loss of energy from the charged particle. But what is this energy converted to? And where? Does the particle release radiation...

¿ Can diff. EM frequencies create diff. magnetic fields with diff. properties ? I understand that a magnetic field is generated via moving charged particles . Electricity and magnetism are linked through electromagnetism . Electromagnetism can be in different wavelengths and frequencies but...

I would like to know whether Kelvin or KJs matter when it comes down to a material radiating and / or conducting its heat.

why electromagnetic waves are represented by complex numbers?

The cytoskeletal structures were considered responsible for the elementary cellular intelligence in the past. (For example, see the articles from Albrecht Buehler. http://www.basic.northwestern.edu/g-buehler/FRAME.HTM.) Microtubules are pipe-like structures made of two kinds of proteins...

I am an ameteur physicist (i actually have my degree in meteorology), and i have some questions about the EM properties of liquid metals or ferrous liquids when in spherical form. I understand if you are too busy or if i sound off, but if you do have the time to answer a few questions, it would...

Hi all, I know that the electric field generated by a dipole is given by \mathbf{E}= [1-i(\omega/c) r]\frac{3 (\mathbf{p}\cdot\mathbf{r})\mathbf{r}-\mathbf{p} }{r^3}+(\omega/c)^2\frac{\mathbf{p}-(\mathbf{p}\cdot\mathbf{r})\mathbf{r}}{r} e^{i(\omega/c)r} where \mathbf{p} is the dipole's...

Homework Statement Show that the electromagnetic wave equation \frac{\partial^{2}\phi}{\partial x^{2}} + \frac{\partial^{2}\phi}{\partial y^{2}} + \frac{\partial^{2}\phi}{\partial z^{2}} - \frac{1}{c^2}\frac{\partial^{2} \phi}{\partial t^2} is invariant under a Lorentz transformation...

In another recent thread it was being discussed whether there is energy in the field of an electron according to U = \frac{1}{2}\epsilon_0 E^2. I began by saying "yes", then changed to "no" because of the way the equation was derived. (It was derived by bringing together N=2 or more charges...

Why does a moving particle particle emit EM-radiation?

is it possible to make am em wave of length 5(lamda)...lamda=wavelength of em wave...

Assume a infinite depth good conductor block with width in y and length in x direction. Boundary is at z=0 and air is at z=-ve and conductor at z=+ve. Let a voltage apply across the length of the block in x direction so a current density established in +ve x direction. We want to look at the EM...

My understanding from the book about EM wave that E and B is perpendicular to the direction of propagation only in medium that is charge free so \nabla \cdot \vec E = 0. What cases when E and B not perpendicular to the direction of propagation? Thanks Alan

I just noticed that we tend to call EM wavelengths shorter than visible light "rays" while we call we call those that are longer "waves". Why is that? Did we ever think that "rays" and "waves" were physically different?

If photons "carry" visible light, and light is just a specific frequency of EM radiation... who carries radio waves? [PLAIN]http://www.antonine-education.co.uk/physics_gcse/Unit_1/Topic_5/em_spectrum.jpg And can an EM radiation at specific frequency be changed to a different frequency? I...

Organisms radiation EM energy. I am aware of the brain and nervous system as a source (because of electrical currents, etc) and that we have a lot of IR radiation. Is the majority of the energy due to blackbody radiation, a by-product of chemical reactions, or something else?

Okay I have a really odd question that might be difficult to answer. I have searched for an answer in several physics books and websites and don't think I have come across a specific answer for this question. Suppose I were to send a negative electromagnetic charge through a solenoid and want...

Since a changing current creates a magnetic field, and if there's a wire near by, the magnetic field will induce a current in that wire. What is needed / what does it take to turn that magnetic field into EM radiation such as a radio wave? Or is it purely just the frequency of the current, so...

OK, so recently I have learned that in the early 20th century, while Max Planck was attempting to explain the quantum nature of light, two men named Philip Lenard and Heinrich Hertz discovered the photoelectric effect. They found that an electron must absorb a specific amount of energy...

Can anyone explain why cranes in construction sometimes experience induced currents from antennas radiating from distances of up to several Kilometers. I have looked into the phenomenon several times, and have not been able to find a study or baselines to follow. I have a basic understanding...

Hi, From what I've learned so far, Lorentz transformation meets certain criteria, such as the constancy of EM wave propagation speed in vacuum, &/ casuality, among others. My question is, why would it/would it not be applicable to phenomena that have nothing to do with EM interaction? In...

Hi there PF How does on calculate the field strenght of the electromagnetic field (from Maxwells equations) and of the gravitational field (from general relativity). I want to relate this to particle physics, where the relative strenghts of the fundamental interactions are calculated here...

Homework Statement So I'm trying to show for a specific, given EM plane wave in vacuum that kx - \omega t = k' x' - \omega' t' but I'm running into some difficulties. I'm hoping someone can show me where I'm going wrong. Here's the setup: In the lab frame K, a plane EM wave traveling in...

Hello: Many many years ago I walked away from community college with an associates degree in physics, and despite my fondness for the subject, I had to put it aside for other things. I recently happened upon something that lead me to realize how much I had forgotten, and so I've decided to...

Homework Statement Problem: Sea water has k = 80 in the low frequency limit. Yet its refractive index is around 1.34. Explain the discrepancy Homework Equations For a non magnetic dielectric medium, the absolute refractive index in the low frequency range, is given by : n = √k...

Guys, I found this Downfall parody video about how much Hitler hates Jackson EM book: Apparently, even he can't stand Jackson after one full semester of EM course. :D

Aight, so I have this problem where I think about something and then I understand it, but then instead of stopping thinking and understanding it, I keep thinking and stop understanding it. Unfortunately then my poor brain is so confruzed that I am unable to backtrack to understanding, and I...

Hi everyone, I have a specific question regarding the nature of electromagnetic waves. I understand he basics of EM waves (frequency, amplitude, wavelength, etc.) and that 'it' is a pair of oscillating fields; one electric and one magnetic, perpendicular to the direction of travel. What I...

Hi, I am not a student of physics, asking the question as it came to mind as I read certain articles: 1. When EM Waves is emitted by a source say star it spreads in vacuum. How does the waves Stretch? What fills in the gaps as the sphere of spread grows? If light emission is continuous...

Perhaps this is going in the wrong forum, but the Math and Science Learning Materials forum would not let me create a new topic. I am not necessarily worrying about a specific question; in fact I am able to use the equations and formulas relevant to electromagnetic waves in my physics course...

My understanding is that the EM field at r.t generated by a radiating source can be described as the amplitude of the EM fields at r, at time t. Is there a corresponding photon associated with that wave? A unit surface area at large r from the source will have less energy passing through it...

hi, i have a problem understanding why the wave equations are as such if wave is moving left, it is f(z,t) = Acos(kz + wt - d) if wave moving right , f(z,t) = Acos(-kz -wt + d) finally i don't know what this represent f(z,t) = Acos(kz - wt + d) where A is constant , k is wave...

I am deeply confused about the following and I'd really appreciate it if anyone could help! Consider a charged hadron such as a proton. Amongst the state-independent properties that define a proton are strong isospin Iz=1/2 and charge Q=e. Now, the total Hamiltonian for a proton is Hs...

Discussion continued from this post on another thread... Bell's proof does not involve any notions of "particles" or "waves" whatsoever, it only involves observed experimental results combined with the idea that the theory generating them is local realistic. Again, do you agree or disagree...

I find EM waves very intriguing. But i get more confused and new questions pop up in my head every time i read something about it. I have a few basic questions. 1. Wavelength: As wavelength is distance between two peaks, how can we measure this distance in cm, meter etc. as physically there...

For an EM wave in vacuum, we know the energy density is given by1/2 e E^2 for the electric field, with a similar expression for the magnetic (e is permittivity of vacuum). E^2 implies that the energy oscillates as a cosine squares function if we represent the E field as E_0.cos [ kx -...

What's the main difference between the concepts of aether and that of the EM field? They both seem, to my unpracticed eye, to be everywhere and the medium that allows light.

Firstly, I'm a bit confused about EM wave propagation. Take the picture you see everywhere illustrating the perpendicularity of E and B in a traveling EM wave (like this http://web.onetel.net.uk/~gdsexyboy/em_wave.jpg) -- does that actually illustrate the magnitudes of E and B at a particular...

My father-in-law uses a USB internet stick for his internet since he lives in The Middle of Nowhere where there is no cable nor DSL. His problem is that reception from his basement office is very poor. However, reception from the second floor of his house is okay... I don't understand this...

Homework Statement The helium-neon lasers that we use in lab produce light waves with an average power of 0.85 mW. Suppose that at a distance of 1.0 m from the laser the beam has a diameter of 1.1 mm. a) What is the average intensity of the laser beam 1.0 m from the laser? b) What is the...