Electromagnetic Definition and 1000 Threads

My teacher told us energy at a point of a progressive wave is proportional to square of amplitude, it is true for both mechanical and electromagnetic wave. But in the other lesson, he also tols us the energy of the EM wave is equal to hv, where h = Planck constant, v = frequency of the wave...

All electromagnetic waves carry energy. We kno that most of the electromagnetic radiation escapes the boundary of the "physical(corporeal) Universe". Therefore, much of the energy is radiating out to the voids spreading beyond material universe. Thus, a great amount of energy is lost...

In the double slit experiment, a wave is forced to go through a tiny slit. I do not understand what is stopping it from going through the barrier. After all, we can think of an electromagnetic wave as just the electric/magnetic fields of a sinusoidally oscillating particle, evaluated using...

Homework Statement When a third charge is placed at the origin, it is found that the force on it is zero. Find alpha? Two charges Q and 5Q are located as shown in the figure below. https://chip.physics.purdue.edu/protected/GiordanoEMimg/chapter17/17prob16.jpg If possible, please...

Hello friend. I am working of design of Electromagnetic Disc Brake system. I have performed some calculation. which you can find on following links. https://rapidshare.com/files/3568781938/untitled_folder.zip https://rapidshare.com/files/2134776724/untitled_folder_2.zip Please have a...

Hello, I have been playing around, making my own electromagnets. As I am out of my depth, I am experimenting with 1.5 to 9 Volt battery packs. I am hoping to have a setup where two electromagnets, around the size of a AA battery placed about an inch apart can noticibly repell each other a...

Hi, First post on these forums, but I've lurked a bit in the past. I'm doing a project on the Faraday Cage, and I have a quick question... I was wondering why a Faraday Cage can block electromagnetic radiation like a radio wave (which, as far as I can tell, is a "mix" of a magnetic field...

I will appreciate any contribtion to the question below. > You have a system that consists of a coil and magnet. The magnet, which is resting on a spring, is free to move up and down in the coil. This system can be modeled as a simple mass-spring-damper system with a...

Dear friends, I have a 5 minute presentation to give on the dependence of electromagnetic mass on its velocity for my physics class. This could be a very broad question to answer, but all I ask is to direct me to some useful links. I have troubles with that because I keep finding regular...

Hmm, not sure if this is the right place to be asking this. I am wanting to understand what effects electromagnetic energy can have when injected into the combustion process of hydrogen and oxygen? Can anyone tell me or point me what effects can occur or point me in the right direction to...

Hi all I am wondering as this diagram shows. Which way is the electromagnetic field(s) moving? http://www.biophotonicsresearchinstitute.com/Picture1.png Thanks.

hi, i have to build an dc electromagnetic buzzer for school project, but I'm having tons of trouble! can anyone offer advice to help me out? (like good websites with instructions or pointers?) i have most trouble with the connect/disconnect part of the buzzer! i have this nail that is fixed in...

I am currently reading and trying to solve most of the problems in Carroll's Geometry and Spacetime. I am generally okay at the math (I've done some mathy Riemannian Geometry type stuff), but am not overly good at some of the higher-level physics. Homework Statement (Chapter 1, Question 13)...

I have recently found a circuit schematic that can pick up radio signals without the need of a battery. Is this an example of electromagnetic induction? If so, how much voltage/current is induced? Does it change the properties of the electromagnetic wave, e.g. energy, wavelength, etc...

I'm having hard time understanding how exactly current that passes through inductor transforms energy into magnetic field and then into voltage, with 90° phase shift. I drew schemes representing sinusoidal imput current, its magnetic field and voltage relation. Is it correct? Would...

According to EM theory,in the absence of any interaction with matter, destructive interference in one location will always be balanced by constructive interference in another location keeping the law of conservation which means that there is no local conservation law for energy flux regarding...

Homework Statement The positron and the electron each have a rest mass of 9.11 x 10-31 kg. In a certain experiment, an electron and a positron collide and vanish, leaving only electromagnetic radiation after the interaction. Each particle is moving at a speed of 0.20c relative to the laboratory...

What is the mechanism for explaining the different effect of repulsion and also attraction due to the exchange of virtual photons in the electromagnetic forces? For example, the electrostatic force between two point charges, for both when they are oppositely charged and like charged?

Homework Statement The average intensity of sunlight at the top of the Earth's atmosphere is about 1400 W/m^2. What is the maximum energy that a 20 m × 30 m solar panel could collect in one hour in this sunlight? Homework Equations Not sure what equation to use The Attempt...

Hi PF Are there an interaction between an electromagnetic wave and a charge source? For example, does an electromagnetic wave get attracted by a charge source, the same way the Earth attracts the moon? Or is something else going on?

i really want to understand the lesson so bad i read the lesson 10 times and the lesson is like 50 pages and i still don't get the concept of how electromagnetic waves were originated?? and what about polarization? please with all the details you have and thank you

Homework Statement A laser beam of power P and diameter D is directed upward at one circular face (of diameter d < D) of a perfectly reflecting cylinder. The cylinder is levitated because the upward radiation force matches the downward gravitational force. If the cylinder's density is ρ...

the title is pretty clear, so we have this F=q( E+V/c X B) the force for a point charge q in an electromagnetic field. and we have the formula to the hamiltonian of electromag force: H= (P+ q/c.A)/2m _ e\phi. the question is how can I get the F from the hamilton principle, using the...

Hi Guys, I came across this article by Jikang Chen and it is of importance to me to know what measure of credibility this concept holds in the general physics fraternity. I do not have the background to make sense of the mathemetics or physics cited. I would appreciate your comments. The...

Homework Statement Hello there! I have a couple of questions regarding light(EMR) and how it behaves when moving from one medium to another. From what I understand, the frequency of any light wave, when it moves from one medium to another, stays the same. As a consequence of this, the velocity...

Hello, Perhaps my wording is a bit off so excuse me for that. I think it best to explain by way of a thought experiment. Say there is a device that counts the amount of photons with the same wavelength for all possible wavelengths. What is then the intensity vs. wavelength curve that I would...

Hi everyone, So I feel sort of stupid posting what you'll probably find is a very elementary question but physics really isn't my best subject and I'm completely stumped. Thanks so much! Oh, and there's also the possibility that this question is just really badly worded. Homework Statement...

Hi, In electromagnetic wave, electric field take the form E(z,t)=A q(t) sin(kz) where A is a constant, k is a wave number, and q(t) is a time dependent factor having the dimension of length. This mean that q is a position..but position of what ?? Is a position of the wave ?

Suppose a single wire (in a horizontal position) falls toward a pole of a magnet. Does the wire slow down? A diagram is attached.

Homework Statement Hello all; i am trying to calculate the potential, inside a non conductive sphere of radius equal to a, in a point at a distance r from the center of the sphere. Homework Equations i know that: where E and s are vectors; and that the Eletric field inside the...

Homework Statement In my notes i have the following two equations written with no explanation where thehy came from... can someone help please!? L=(u, x )= -mc\sqrt(u^{\beta} u_\beta)-\frac{q}{c}A^{\alpha}u_\alpha, L(v,r, t) = -mc^2(1-\frac{v^2}{c^2})-\phi +\frac{q}{c}vA L is...

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...

Hello all. I'm trying to figure out how to determine the correct sign of paths and surfaces defined for calculating quantities in electromagnetic problems. For example, say there's a wire in the shape of a rectangular prism along the z-axis with some current density, \vec{J} . Then the...

Ok, so my class has spent about a day on the topic of electromagnetic induction and I really you help on this subject because tomorrow i have a quiz. I don't need you to explain it in a super detailed way but in a fashion where the teacher will realize that i actually understand these topics...

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...

If it can block portions of anti-matter I am assuming. Could it possibly be true, that it can deflect asteroids?

Hey everyone, I am trying to develop a small electromagnet to pick up (relatively) large amounts small shavings which are roughly 70-80% Fe in composition and are roughly 10-40 microns in size. This device needs to be powered by a maximum of two D-Cell batteries (maybe we can look into alternate...

Homework Statement Instead of sending power by a 850 kV, 1100 A transmission line, one desires to beam this energy via an electromagnetic wave. The beam has uniform intensity within a cross-sectional area of 80 m2. The speed of light is 3×10^8 m/s and the permeability of free space is 4×10^-7...

Homework Statement Find the energy densities of an electromagnetic wave separately for the contribtions arising from the electric and magnetic field components Homework Equations The Attempt at a Solution How does one do this? Is it just the usual derivation for a continuous...

The electromagnetic power radiated by a nonrelativistic particle with charge q moving with acceleration a is: P = \frac{q^2 a^2}{6 \pi \epsilon_0 c^3} If a proton is placed in a cyclotron with a radius of 0.500 m and a magnetic field of magnitude 0.350 T, what electromagnetic power...

we have studied electromagnetic induction that takes place in coils, solenoids, or wires forming geometrical shape, but my question is can electromagnetic induction occur in a single straight wire by changing B the magnetic field that crosses the wire? would there be electromagnetic flux and...

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...

Homework Statement I have a few homework questions that ask for the direction of induced current for ex a loop of wire. I can't figure out how to find it .

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)

Show that the "plane wave" is a general solution to the electromagnetic wave eqatuion Homework Statement Show that the "plane wave" E=Eocos(k.r-\omegat) is a general solution of the electromagnetic wave equation. (you must derive this first)Homework Equations we were given Maxwell equations...

For quite a while I have been wondering if the quantization of light may be due to the emission process. In that case, at first sight there seems to be no reason for radio waves (created with LRC circuits) to be quantized. But perhaps I overlook something? And would there be a way to test...

What practically obtained experimental evidence could be used to distinguish between the location of electromagnetic energy density given by these contending terms, E^2+B^2 vs. \bar{J}\cdot \bar{A}+\rho \phi \ , where A is the magnetic potential, \rho is charge density and \phi is...

Hi all physics lovers, please bear with my question as its like a kid wondering about something :) Energy can neither be created nor be destroyed. So when I switch off an electric bulb, there is darkness. So where does the electromagnetic energy go? :confused: Thank you.

Currently working on a pet project, looking to build a model for accelerating a relatively large mass on a short straight track type system. Can't find much information about the way "Maglev" trains accomplish their propulsion or the way the electromagnet systems work to keep the train...