Electromagnetic waves Definition and 322 Threads

Below is the Wikipedia URL shows the shape of EM wave. http://upload.wikimedia.org/wikipedia/commons/3/35/Onde_electromagnetique.svg" Electromagnetic laws say that' "changing magnetic field produce electric field and changing electric field produce magnetic field" In the...

Homework Statement Hi there! I am currently taking physics and we are in the process of learning about electromagnetic radiation. I am a bit confused as to how exactly an electromagnetic wave is produced. I understand that a periodically oscillating charge produces and oscillating magnetic...

Lately I'm thinking about the question of how to convey how Maxwell was able to derive from first principles how fast electromagetic waves propagate. How is that possible at all?In Maxwell's time it was already well known, of course, that the electric field and the magnetic field are very much...

"mass" of electromagnetic waves Consider the stress energy tensor T^{\mu\nu} of a particle. Integrating the trace T over space gives the invariant mass m of the particle. For electromagnetic fields, T=0 which fits with the quantum picture where a photon has zero invariant mass. However...

We all know that Earth is rotating. So every particle on it is accelerating. So all the charges present on it are accelerating. So why there is no production of elecrtomagnetic waves by them? (As accelerating charges produce EM waves)

I want to know in details what is the main origin of electromagnetic waves? and thanks a lot in advance.

Can I assert that any charged particle vibrating at a certain frequency produces an electromagnetic wave with the same frequency? Considering this, do elastic waves generate electromagnetic waves?

Boundary conditions & time domain electromagnetic waves: does classical model fit? Consider two propagating media: a lossy dielectric medium and a lossless dielectric medium. Thus, the interface that separates them has two tangential components of electric field, one for each medium. One of...

Could we have electromagnetic waves (light) that if depicted 2D look like 2 half circles from all directions?

-Why do electromagnetic waves not readily penetrate metals? Also a question occurred in class, and they asked -"The sun emits most of its electromagnetic wave energy in the visible region of the spectrum with the peak in the yellow-green. Our eyes are sensitive to the same range, with peak...

based on this picture if light is made up of little tiny massless particles called photons what are radio waves made of? what are microwaves made of? what are infrared waves made of? what are ultraviolet waves made of? what are x-ray waves made of? gamma rays are made of electrons and...

I've two electromagnetic waves (light) with amplitudes 1x (normal) and 2x (double) amplitude. And I want to pass these two waves through a "normalizer" expecting 1x amplitude for both waves. Question is: Is such a "normalizer" possible and/or exists. I'm not looking for any electronic...

I am following Engineering Electromagnetic by H. Hayt, And there, we derived, the speed of Electromagnetic wave in good copper is just around 3.2m/s. Sure, this can't mean it takes 1 second for a light bulb 3.2 m away to glow if I press a switch? I have experience that this is almost...

Homework Statement Not really a homework/coursework problem, I'm just trying to make sense of some class notes from our chapter on special relativity. I'm trying to find the expression for electromagnetic wave propagation in a reference frame S' that is moving at a constant velocity with...

Hello! Not sure if I've posted here before... (in the intorductory Physics section, that is!) Anyway, I don't have a particularly good understanding of physics, and I have just started looking at waves recently. However, I have a quick question regarding electromagnetic waves. I have read that...

Homework Statement Suppose Maxwell's displacement current was left out of the Maxwell equations. Show that , in a vacuum, the magnetic field has to have the form B = grad f(r,t), where f is any function which satisfies the Laplace equation. Homework Equations curl E = - dB/dt curl B = 0...

If we have case \rho=0, \vec{j}=\vec{0} then we have this equations \Delta\vec{E}-\frac{1}{c^2}\frac{\partial^2 \vec{E}}{\partial t^2} \Delta\vec{B}-\frac{1}{c^2}\frac{\partial^2 \vec{B}}{\partial t^2} Particular solutions of this equation \vec{E}=\vec{E}_0...

When we heat a metal, the positive kernels begins to vibrate.Will this vibrations produce electromagnetic waves ?

Hello, could you please help to clarifly the following. Do electromagnetic (e.g. light) and gravitational wavefronts caused by e.g. a supernova both appear at the same time seen from a distant observer perspective? Thank you!

Hello. In most texts I have read, EM radiation is depicted as sinusoidal in shape. I understand why this would be the case, as the oscillating fields are often the product of circular generators or alternating current, but is this always the case? For example, is the light we receive from stars...

Homework Statement Consider a plane-polarised electromagnetic wave in source-free vacuum, with magnetic field B = (1,1,0)BoCos(kz-wt), with Bo = 0.001 Tesla. Find (1) the direction of propagation of the wave, (2) average energy density carried by the wave, and (3) the fraction of this...

Hi, My doubt is how can the EM waves interact with an electron, i.e., electron is a particle with negative charge.. have EM waves any charge to attract or to repulse an electron ? :confused: An example is the microwaves oven when waves interact with water molecules. Thanks :smile:

In what direction does the magnetic component of an EM wave oscillate? Is there a lateral end to the interference pattern created in the double slit experiment, and if so, what defines it? How fast do EM waves expand laterally? In the double slit experiment, what makes the interference...

If electromagnetic waves loose energy as the increase their distance, is there an equation that reflects the loss of energy?

Can anyone tell me what Maxwell said is the source of electromagnetic waves? I read that accelerating charges produce EM waves; are there any other sources?

Hi I've looking into path loss for electromagnetic waves and it's quite straight forward to figure out how it works in free space by looking at the free space path loss formula (http://en.wikipedia.org/wiki/Free-space_path_loss). It has not been that easy figuring out how another medium...

Until now I've learned that light is electromagnetic waves. I haven't learned about photons yet, but I'm guessing that photons are waves according to the electromagnetism theory (or quantum mechanics?, or both?). My question is "when do you consider photons as particles"? Particles in the...

Hi, I come across these 2 questions on a website: 1. Why are the antenna on TV and Radios about the same length 2. Why is the antenna on the cellphone (i.e. the older versions) smaller than the Radio antenna? My answers to these 2 questions are: Firstly, the waves that the cellphone...

Homework Statement The electric components E1 and E2 of two coherent electromagnetic waves are given as follows : E_1=E_o\sin (\omega t-kx) E_2=E_o\sin (\omega t-k(x+\delta)) These two waves superpose each other at a certain point . Derive the amplitude of the resultant wave in...

How does the electromagnetic waves store information, what makes these waves to store. (this may be a stupid question but i need to know how) Thanks.

There is one thing that’s bugging me. I read about electromagnetic spectrum. It says that light is, by its nature, electromagnetic wave just like radio signals, microwaves, X and gamma rays, infrared waves etc. The only difference between these waves is their frequency, right? Now imagine...

I am interested in naturally occurring electromagnetic waves, is there a reference that lists wavelength, frequency, electric and magnetic fields, etc.?

electromagnetic waves are created or produced by accelerated charge. but EM WAVES are chargeless? how is it? please clarify folks... thanks in advance

Since the combined speed of electormagnetic waves can be 'c' and that they travel in space at 'c' leaves no component for time, hence the time on a watch on a beam of electromagnetic wave does not change at all. With this understanding, assume two stationary mobile phone users U1 and U2...

I'm a bit confused, when drawing the diagram for oblique incidence, how do I choose which way to draw the electric field? For example, I know the direction of the wave is in the plane of incidence and the wave vectors are simply arrows in the direction of the wave that I draw - and that the E...

I don't really know how to put my doubt in words but I will try. Electromagnetis waves of various frequencies are used for communication.Also there are EM waves from other sources, for example even sunlight is eloctromagnetic wave.Now all these waves are out there in space. So at...

Homework Statement What differences are there in speeds of electromagnetic waves Homework Equations None The Attempt at a Solution None

I am confused regarding the heat properties of electromagnetic radiation. Wiki states "Any electromagnetic radiation can heat a material when it is absorbed.". Does this imply radiation with wavelengths in the visible light region can also heat a material, that is, increase its temperature? From...

Homework Statement Given the electromagnetic wave traveling in the y direction at velocity c: B = +cEo sin(k y − ω t) ˆi. a) What happens to the ratio of the electric to magnetic field if the angular velocity ω of the wave is decreased? Does it decrease, increase, or remain the same...

I understand that they come from objects with high temperature. But to me it makes no sense because from what I understand temperature is measuring the small molecules moving around, I do not see where the relationship is between the two. Do I have an idea mixed up?

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...

Homework Statement The 2.0-cm-diameter solenoid in the figure passes through the center of a 6.0-cm-diameter loop. The magnetic field inside the solenoid is 0.20 T. What is the magnetic flux through the loop when it is perpendicular to the solenoid? Φ1 = Wb What is the magnetic flux...

Hello there my fellow physics fact finders, As the title suggests, I was wondering if we use infrared and radio waves to communicate information because they're the only waves that can carry information, or just because they're the safest. Which actually brings me on to another question, how...

Homework Statement Homework Equations For a plane polarized electromagnetic wave traveling along the z axis, with its E vector parallel to the x-axis and its H vector parallel to the y axis, Faraday's law \nabla\times \textbf{E}=-\frac{\partial \textbf{B}}{\partial t} gives that...

Hi all. I have heard that cell phones heat up the brain, when you are talking in one because of the EM-waves at ~800-900 MHz. Now the transmitter of a radio station at e.g. 100 MHz sends out EM-waves at a frequency of 100 MHz in all directions. Does this mean that all our brains are being...

Hi I have two questions 1-How electromagnetic waves transfer information? 2-Could you give me the physical and mathematical contexts that are needed to make a helicopter or an airplane? thanks a lot

Hi, This may ultimately be an opinion question: When thinking about electromagnetic waves semi-classically, how appropriate is it to describe the waves as propagating through an electromagnetic field? If it is appropriate, how appropriate is it to describe the electromagnetic field as a...

Homework Statement Public television station KQED in San Francisco broadcasts a sinusoidal radio signal at a power of 316 kW. Assume that the wave spreads out uniformly into a hemisphere above the ground. At a home 6.00 km away from the antenna, what is the average density of the...

So I've been told that electromagnetic waves oscillate like flicking a rope up and down or a ripple in a pond. In the first example, from a side view, the rope can be considered to be a line, or 1-dimensional. However, once the ropes starts oscillating to represent waves, width must also be...

Homework Statement Which electromagnetic waves travel the fastest in a vacuum? a. Violet light. b. Red light. c. Ultraviolet light. d. Red, violet, and ultraviolet light travel at the same speed. ok so i thought that in a vacuum every wave traveled at the same...