What is Electromagnetic: Definition and 1000 Discussions
Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles. The electromagnetic force is carried by electromagnetic fields composed of electric fields and magnetic fields, and it is responsible for electromagnetic radiation such as light. It is one of the four fundamental interactions (commonly called forces) in nature, together with the strong interaction, the weak interaction, and gravitation. At high energy, the weak force and electromagnetic force are unified as a single electroweak force.
Electromagnetic phenomena are defined in terms of the electromagnetic force, sometimes called the Lorentz force, which includes both electricity and magnetism as different manifestations of the same phenomenon. The electromagnetic force plays a major role in determining the internal properties of most objects encountered in daily life. The electromagnetic attraction between atomic nuclei and their orbital electrons holds atoms together. Electromagnetic forces are responsible for the chemical bonds between atoms which create molecules, and intermolecular forces. The electromagnetic force governs all chemical processes, which arise from interactions between the electrons of neighboring atoms. Electromagnetism is very widely used in modern technology, and electromagnetic theory is the basis of electric power engineering and electronics including digital technology.
There are numerous mathematical descriptions of the electromagnetic field. Most prominently, Maxwell's equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents.
The theoretical implications of electromagnetism, particularly the establishment of the speed of light based on properties of the "medium" of propagation (permeability and permittivity), led to the development of special relativity by Albert Einstein in 1905.
Homework Statement
Hi
In Griffiths it is stated that any possible wave can be written as a sum of plane waves
f(z,t)=\int_{-\infty}^{\infty}{A(k)e^{i(kz-\omega t)}dk}
This is a sum over spatial frequencies. In another book I have, they write the H-field as
H(r, t) = \sum_n{C_n H_n(r)\exp...
You know how a microwave oven has a mesh on the door so visible light gets through but not the microwaves? Can such a thing be done with infrared radiation too? Is it possible to block heat from getting through a mesh but not visible light?
Homework Statement
http://dc10.arabsh.com/i/03594/qn9gr42q192z.png
What is the direction of current in ring 2 if :
a) ring 2 moves towards ring 1
b) ring 2 moves away ring 1
The Attempt at a Solution
I used Fleming right hand rule but I'm not sure if it is true,
a) the...
Hi,
I am looking for clamping circuit for electromagnetic waves. I have a wave which has amplitude of 5 and -10. is it possible to clamp it to 1 and 0 respectively. I want a positive side clamp to be +1 units and negative side clamp to be 0 units. is it possible to realize using any...
Both are energy right?
I'm asking cause I'm trying to understand the double-slit experiment and I'm just wondering how they can be sure to treat the electron as a particle. Could it be performed with for instance whole atoms or maybe the cores or something else that's more obviously matter...
Hello,
Recently I have learned that magnetism causes the Lorentz force. The electric force makes sense to me in terms of virtual photons. But how do virtual photons give rise to magnetism and the Lorentz force. Is it because when the charged particle moves through an magnetic field it comes...
I have skimmed relevant links in wikipedia, and some external links regarding electromagnetic fields, but would like a simple (I'm no physicist) answer to the following question that I have.
When one, for example, takes two strong permanent magnets and aligns so that there is repulsive/or...
My first posting after joining today so starting off "light" - I know a terrible pun but please be kind as I will ask a lot of basic and seemingly dumb questions from my simple mind in my quest to learn a lot as quickly as I can!
I will try to word this as best I can but, how exactly do EM...
Hello all!
I am getting into the electromagnetic waves section in my optics class and in some of these derivations, they are using expressions that I cannot remember how they were derived or the context of them. My book from my E&M class I took awhile back is currently at my house and I am at...
Say one had three intense laser pulses and one weak reference pulse coming together on the surface of a thin nonlinear medium as if coming from the corners of a square. The three intense laser pulses mix, and there will be the third order mixing k1+k2-k3 or k1-k2+k3 or whatever coming out in the...
I'm having some trouble understanding visually the propagation of an electromagnetic wave. I'm self-studying electrodynamics so I've never had someone explain this properly to me.
I understand an electromagnetic wave is a propagating disturbance in an electromagnetic field. Originally, I...
I am having a problem understanding a thing in a electrodynamics problem.
Imagine we have a wall at x=0 made of a perfect conducting material. Imagine now we have an electromagnetic wave traveling perpendicular to the wall with the electric field polarized in the y direction and the magnetic...
Homework Statement
When we place a magnet in a long coil of wire the emf will be maximum when the magnet is at either end. What would happen when the magnet lies in the middle of the coil (i.e: the same amount of flux is interacting with the coil at all times). Would we have an induced EMF...
Are the amplitudes of the electric and magnetic components of an electromagnetic wave proportional?
Or is the amplitude of the electric portion unrelated to that of the magnetic portion?
Homework Statement
Electromagnetic waves contain time varying electric and magnetic field perpendicular to each other and also to path of progression. The phase difference between electric field vector and magnetic field vector is zero
Homework Equations
The Attempt at a Solution...
Homework Statement
Electromagnetic Railgun consists of two parallel, distant from the horizontal, very long rails, after which moves perpendicular to the rails, linking them to the metal bar of mass m.
The rails are in a vertical magnetic field intensity B. What is the speed limit the...
Can someone please tell me why the magnetic field makes the electrons flow round the coil in a generator? Does the force of the magnetic field have to go in the same direction as the coil?
A standing wave can be produced in a guitar string where the wavelength of the wave is the same length as the string (I believe this is referred to as the first harmonic) and where the string is an exact multiple of the wavelength of the wave (referred to as the second and subsequent harmonics)...
Homework Statement
So here is the Problem :
I am Modelling an interesting problem for a project i am busy with. I need to find out the force exerted on a single busbar in a 3 phase system, with each phase carrying 3300A.
This is mainly so that i can deduce what size of busbar supports i...
Homework Statement
If I take a magnet and drop it though coil then the graph would have an increasing voltage until a maximum and then a reducing emf (until 0) and then a further reducing emf until a minimum and then an increasing emf again
graph looks like this...
[Solved] Find electric and magnetic field amplitudes in an electromagnetic wave
Homework Statement
Find the electric and magnetic field amplitudes in an electromagnetic wave that has an average energy density of 1 J/m^3
Homework Equations
u = Energy density
u = (1/2)(e0)(E^2) +...
The electrical circuits in a house run on alternating current. This is a current of electrical charges that oscillates back and forth at a frequency of 60 Hz. Do these currents produce magnetic fields? Explain. Do these circuits radiate electromagnetic waves? Why or why not?
I don't have any...
I have been wondering why photons can't go through matter and electromagnetic fields mostly unaffected while neutrinos can. Neither of them have an electric charge as a particle, and the basic description I see about neutrinos is always that "they are unaffected because they have zero electric...
A classical electromagnetic field requires you to know how far away from the source of the field you are, if this requirement is carried over to QED, how is the EM field of a particle known when we only know the probability of this particle being in a certain place?
I know that light is a form of electromagnetic radiation but I know that all electromagnetic radiation is not light. I know that light has four basic properties:
1) Light travels in straight lines.
2)Light can reflect.
3)Light...
From EM, the energy of electromagnetic wave in unit volume is \varepsilon_0 E^2. Does that mean the number of photon is \varepsilon_0 E^2/\hbar\omega ( \omega is frequency of wave)? In 1-D, E=E_0cos(\omega t+kx), then the number of photon in average is \frac{1}{(2\pi/\omega)}\int_{0}^{2\pi...
13.
A plane electromagnetic wave is traveling in the negative y direction. At t=0, the magnetic field at the origin has its maximum magnitude of 5.300×10-7 T and points in the positive x direction. Which axis does the electric field lie along? Answer with a single letter: x, y, or z. WARNING...
Hello,
This is not homework, as I'm not in school :)
I was wondering if there are any standard equations for electromagnetic waves interfering with each other. For instance, can I change the frequency of a wave by hitting it with another wave of a different frequency? I can find info on...
Suppose a spaceship is at 1 light year distance by Earth and it sends a message back home through an electromagnetic wave, we choose a frequency so that the wave will be a radio wave which requires little energy to produce.
How do i know if the wave will reach the Earth? and what characteristics...
Greetings all!
I'm completely new to Quantum Mechanics (my PhD research is in Computer Vision) and I am planning to apply some concepts to my research.
I would like to know whether it's possible to get the Wave Equation over the components of a \mathbf{B}=(B_\phi,B_r,B_z) field induced by...
Hey!
I stumbled across this problem while reading Wald's "General Relativity", but it belongs to Electrodynamics. In problem 3 of chapter 6 one has to find the general form of a static, spherically symmetric Maxwell tensor, which is clearly F_{ab}=A(r)(dt)_a \wedge (dr)_b+B(r)r(d\theta)_a...
Looking at this in a weapon point of view, what would be the more effective one?
Say we have a 155mm projectile traveling and hitting a hard target(metallic), lightly and heavily armored, at different times, both with an impact energy of 530 MJ.
Also say we have a very short IR laser pulse...
From: http://answers.yahoo.com/question/index?qid=20090223155307AAgqbWk
Question: Why are electromagnetic waves transverse waves?
Answer: "Because they are generated by the rapid vibration of elecrons, which go side to side, perpendicular to the direction the waves travel (very very rapid...
Anything that occupies space creates a 'distortion' to a certain degree in the space time fabric and hence will experience gravitational force.And we know radiation does experience gravitation , this would directly imply that it occupies 'space' or 'volume' . The question now is .. how much volume ?
point charges in an electric field
Homework Statement
Problem: A +8.75 micro C point charge is glued to a frictionless table. It is tied to -6.5 micro C point charge by a 2.5 cm string (weightless and nonconducting). A uniform electric field of magnitude 1.85*10^8 N/C is directed parallel to...
Hey everyone,
Im doing this research and reading this http://science.hq.nasa.gov/kids/imagers/ems/gamma.html" it had a diagram of the depth of penetration of different wavelengths into the eaths atmosphere...
my question is, How come x-rays penetrate deeper than visible light - what is the...
Homework Statement
see attachment/picture
im having problems with fields inside matter. i get the left side of gaussian surfaces/ampere loops. but for example this first equation's right side i can't understand.
The Attempt at a Solution
i would think the right side should be
I
since...
consider first , an induction motor... a rotating magnetic field is applied to an electrically conductive rotor, and the eddy currents induced will oppose the change in magnetic field experienced by the rotor, hence the rotor gets torque
in an induction motor the rotating magnetic field is...
Homework Statement
B field = xt in z direction in Cartesian Coordinate, t is time.
Homework Equations
obtaining the remaining field expression together with charge densty "rho" and conduction current J, so that all Maxwell's equations are satisfied. There is no unique solution.
The...
Hi,
I suppose I'm a little late to start here, but I just got hung up on the following: The field quanta in E&M is the photon and it comes from the gauge potential in QED A(x)
A(x)=\int \frac{d^3 p}{(2\pi)^3 \sqrt{2\omega_p}}\sum_{\lambda=1,2}\left[...
Hi Guys,
I have a doubt. When we think of a modulated wave, consider frequency modulation for example, does the wave contain photos of gradually changing energy (or frequency)?
If EM waves are pumped into a resonant cavity at it's resonant frequency will each incoming wave add it's energy to amplify the wave(s) in the cavity?
I know that if you pulse a light source into a circular wave guide and you pulse the light source each time the light wave returns to it's...
Sorry for a naive question.
In EM textbook and QM path integral textbook, the action and Lagrangian in electromagnetic interaction are
S = L dt = e(\phi – A v) dt ---equ.(1)
But in QFT textbook, the action and Lagrangian density are
S = L d^4x = A J d^4x ---equ.(2)
As I...
If you have a 3 phase 4 wire distribution where the 3 phase conductors and 1 neutral is inside a pvc conduit, how would you model the force of the electromagnetic field at a certain distance away from the conduit?
Assuming the loads are balanced, the currents would sum to zero on the...