Em wave Definition and 214 Threads

Can someone give me an example of a non polarized EM wave? I've heard that a light bulb would produces EM waves not polarized because the E fields of each waves aren't in the same direction. This I can understand. But in the case of a single EM wave, how do one gets a non polarized wave? I...

Hello everyone. I have tried to do as much research as my layman mind will allow on how an electromagnetic wave propagates in relation to how a sound wave for example does. I understand that an acoustic wave is longitudinal and works on compression and that a light wave is a transverse wave...

We were taught in the vibrations and waves lecture course that the solution to the wave equation for traveling waves is of the form ψ(z,t) = Acos(wt-kz). In the Electromagnestism course we learned that EM waves are traveling waves and have the solution E = E0cos(kz-wt). I know that changing...

Homework Statement A 1.10m long FM antenna is oriented parallel to the electric field of an EM wave. How large must the electric field be to produce a 1.28 mV voltage between the ends of the antenna? Homework Equations u = EoErms^2 I = uc Intensity = Power / area The Attempt at a...

I'm learning that in the electrodynamics of circuits and charges, an E-field is very different from a B-field. But in Maxwell's equations for a disturbance in the electromagnetic field, where a changing electric field causes a changing magnetic field, which in turn causes a changing electric...

Homework Statement a) A microwave transmitter T and receiver R are placed side by side facing two sheets of material M (aluminium) and N (hardboard). A very small signal is registered by R; what can you deduce about the experimental set up? b) When M is moved towards N a series of maxia and...

Homework Statement What is the dB loss for a 3GHZ EM wave traveling through 2 meters of a medium with ϵ=1.5ϵ_0 and loss tangent = 9E-4? Homework Equations Umm...I'm actually not sure. I can't find anything really relating these things at all. The Attempt at a Solution My first...

Is it possible to polarize an EM wave in the time direction as you would in any of the spatial dimentions?

Vacuum polarization is when an EM field causes the virtual particle pairs around it to become polarized like a dipole. The most common example is with an electron in vacuum, but a transmitting radio antenna could do it as well. But, if this was with an oscillating signal, it would create waves...

i read this "in electrodynamics, polarization characterizes em waves, such as light, by specifying the direction of the wave's electric field" in a book. i really didn't get it clear & does the magnetic filed nothing to do with polarization?

Since light is a type of EM wave, wouldn't that mean that when you flash a beam of light on a system of charges, you're exerting electric and magnetic fields onto the system?

Even in simple circuit, there must be some "turning point", for example the electric wire is bent somewhere. Therefore when electron pass through there is centripetal acceleration. I have heard that accelearation of electrons emits EM wave, so will EM wave be emitted from these positions?

I am trying to code a java applet to give a physical representation of an EM wave, and how it will react in a resonant cavity. However, I am having a very hard time finding a good physical representation of what an EM wave actually looks like. For example, If I take a 2 meter wave, place it...

Why does the strength of an electrical field diminish with distance from its source whereas the amplitude and frequency of a beam of light do not vary, regardless of distance?

I am generally an "artsy" person, though I am interested in science, too. I am curious about EM waves, particularly how they get started and what determines their amplitude and direction. I've read that an oscillating charge can generate a magnetic field, though I'm a bit confused about what...

Hey guys and gals, Here are two of a vast sea of sources that say a passing EM wave will disturb charged particles: http://books.google.com/books?id=jC4...age&q=&f=false "...a wave passing over a row of electrons; the arrows indicate the magnitude and direction of the electromagnetic...

Hi, Let E(r,t) = E(r)exp(-ikz)exp(iwt) be a plane wave in time domain, propagating along Z direction. I wonder how to find the spectral representation of it (i.e. E(r,w))?? I know, for a finite intensity field (i.e. |E(r,t)|^2 < infinity), we can give...

AC Circuits II: AC Power Generator Homework Statement A An AC generator supplies an rms voltage of 110 V at 60.0 Hz. It is connected in series with a 0.300 H inductor, a 5.80 μF capacitor and a 236 Ω resistor. What is the impedance of the circuit? B What is the rms current through the...

So I am trying to work through the proof why why the direction of proporgation, the E field and B field are all orthogonal to one another. What i have is... E=E_{0}e^{i(k\ \bullet \ r-\omega t)} B=B_{0}e^{i(k\ \bullet \ r-\omega t)} \nabla \times E= -\frac{dB}{dt} \Rightarrow k...

I have a simple question about reflecting EM waves at dielectric boundaries. To best illustrate my question, consider normal incidence. The incident wave has the wavevector k positive, and the reflected has k negative. Since B = k x E , and k has changed sign, B must also change sign. This is my...

I am trying to understand why it is not possible to produce an EM wave through interference that is completely different from the source waves. For example why can't 2 or more EM waves outside the visible spectrum add up to produce light? I haven't had any physics since high school and I don't...

Homework Statement The E field in an EM wave has a peak of 22.8 mV/m. What is the average rate at which this wave carries energy across unit area per unit time? Homework Equations S = e_0*c*E^2 The Attempt at a Solution where e_0 = 8.85*10^-12 c = 3*10^8 E = 0.0228 V/m S =...

Does it removes either the electric wave of magnetic wave component of the EM wave? And if so, won't the wave exiting the polariser not a EM wave anymore? More like an E wave or M wave. If the above argument is correct, won't the speed of light become\frac{1}{\sqrt{\epsilon_{0}}} or...

Homework Statement How much energy is transported across a 1.15 cm^2 area per hour by an EM wave whose E field has an rms strength of 36.5 mV/m? Homework Equations E=hv? The big problem I'm having is that I don't know what formulae to use. The Attempt at a Solution I know what V/m...

I have been desperately trying to find an equation (or a set of equations where I can derive an equation) that shows a relationship between the energy in an electric field and the wavelength or frequency of an electromagnetic wave. I am trying to show a relationship between Wavelength and...

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...

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...

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...

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}...

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?

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...

Homework Statement Difference between EM wave & a Matter wave ?

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...

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...

hey..while looking into the consequences of the invariance of light...we see that time needs to be slowed down in order to incorporate it in all the appropriate condtns..normally every body( in most of the books) gives an example...if we are in a space ship(moving horizontally with a speed of v)...

1. If you took a positively charged antenna and shook it up and down 500 million times a second, would it emit a radio wave. If so, why? If not, why not? I would say, the EM wave that it emit is heat due to friction with the air. anyone have any other suggestion. 2. Electric charges are...

I read that em waves get generated by oscillating and/or accelerating charges. I am confused on how this occurs. Doesn't this violate energy conservation? Say 2 charges( a +& a -) are separated by a certain distance. So they have potential energy. Then you let them go. The potential energy is...

Why microwave frequencies are more affected due to rain? How does water actually affect microwaves?And lower frequencies have more diffraction.Why is it so?

Hello All, this is my first post, and while I'm a newb to the forums I'm not a newb to Optics. However, I have a very light background in low level electromagnetics, I'm more of a network design person. I'm working on a very very long term personal project to understand optics better and I've...

Hi, I'm rather new here. I've got a question that's bothering me, and therefore decided to ask here. Why is it that in a lift/elevator, radio signal usually gets weakened? And, as far as i know, FM radio operates on the radio wave band, as well as cell phones. But why is it that mobile...

Homework Statement energy density in a laser beam is 9.5x10^-8 J/m cubed. the laser beam is cylindrical, and it delivers a power of 15W to a certain area. What is the radius of this circular area? Homework Equations Intensity : S=cu and S=Power/Area Area of a circle (or possibly the...

How an em wave propogates?? i understand that an em wave can be produced due to an oscillating electric field or oscillating magnetic field... but how does this wave move forward at the speed of light??

How does Electromagnetic waves travel in vacuum ?

Can a monochromatic plane EM wave exists in a plasma when \omega is less than \omega_p (the plasma frequency)? If so, is it attenuated? I read in a text that a wave incident on a plasma with \omega < \omega_p is completely reflected, but does this mean such a wave can't exist in a plasma? If...

Here is the question i am working on: An AM radio station broadcasts with average power 4000 W in all directions. A dipole receiving antenna 65 cm long is at a location 4 miles from the transmitter. Compute the amplitude of the emp that is induced be this signal between the ends of the...

Hi, if someone could help me figure this out I'd really appreciate it. Estimate the average power output of the Sun, given that about 1350 W/m^2 reaches the upper atmosphere of the Earth. I know the answer is 3.8 X 10^26 W but I don't know how to get there. I've tried different equations...

Suppose I have an eliptically polarizied EM wave, whose electric field can be written as \vec{E}=A\cos(kz-\omega t)\vec{e}_x+B\sin(kz-\omega t)\vec{e}_y, where the constants A and B are amplitudes of the x and y components of the beam, respectively. How would I report the amplitude of the...

I'm not sure if this belongs here or in the relativity forum but associated with an electromagnetic wave is a magnetic field B and the force of this field on a charge q with velocity v is qv x B. Since any charge will be moving with speed c relative to the wave, will the magnetic force on a...

I've read in a book, that if you had a standing electromagnetic wave between two metal plates, only nodes would be at the metal plates. This is due to the infinite high conduction of metal, the book says. Why is that so?