Electromagnetic Definition and 1000 Threads

Basically as the title says. I'm interested in the naturally occurring EM waves, and I would like to know the strongest EM waves out there. I'm not talking about "strong" as in energy per photon that is proportional to the frequency, but about the overall energy transported by the wave that is...

Alright the attached picture has the two physical layouts I'm considering for the chuck, however I'll admit that looking at the math involved to determine the construction of the individual magnets and a knowledge gap in how best to manipulate the construction of such a thing to have the...

Hi, I wonder why with electromagnetic radiation, there's some radiation that penetrates with Earth atmosphere such as visible light, while other can't like gamma radiation. What does the penetration of any em radiation on any object depends on

Homework Statement I am trying to reproduce MTW's ADM version of the field Lagrangian for a source free electromagnetic field: ##4π\mathcal {L} = -\mathcal {E}^i∂A_i/∂t - ∅\mathcal {E}^i{}_{,i} - \frac{1}{2}Nγ^{-\frac{1}{2}}g_{ij}(\mathcal {E}^i\mathcal {E}^i + \mathcal {B}^i\mathcal {B}^i) +...

The energy density of an electromagnetic field with a linear dielectric is often expressed as . It is also known that energy can be found by . Using the latter, the energy density is found to be , as is well known. If you integrate the latter only over free charge and ignore bound charge, you...

at a point they become plain waves, how much will they be attenuated when 'received' by a spiral log periodic antenna Vs another dipole? Would an H field created by a loop antenna have less attenuation?

I assume this forum to be the appropriate one, since the real problem is about covariance rather than electromagnetism. In electrodynamics in a curved background, the relation ##F^{\mu \nu} = A^{\mu , \nu} - A^{\mu , \nu}## stays in terms of ordinary derivatives. So, in particular ##F_{,\mu...

Is there a difference between the meaning of charge conjugation in Relativistic Quantum Mechanics and its meaning in Quantum Field Theory? In chapter 4.7.5 of "Thomson Modern Particle Physics" the charge conjugation operator is derived without changing the electromagnetic field Aμ. This...

Homework Statement I have been stuck on this for weeks Homework Equations ∫E.dl = -dφ/dt The Attempt at a Solution Total EMF (V) = -dφ/dt (Where φ is the magnetic flux through the loop) ⇒V = -A(dB/dt) (Since Area remains constant) ⇒V = -Ax (x=dB/dt) ⇒V = -2xl^2 I do not know how to proceed.

Homework Statement Two coils P and Q are placed close to one another. P is connected to a power supply whereas Q is only connected to a voltmeter and no supply (see attached diagram). The current in coil P is constant. An iron rod is inserted into coil P. a) Explain why during the time that...

Hello, In the sources I have looked into (textbooks and articles on differential geometry), I have not found any abstract definition of the electromagnetic fields. It seems that at most the electric field is defined as $$\bf{E}(t,\bf{x}) = \frac{1}{4\pi \epsilon_0} \int \rho(t,\bf{x}')...

If a source emits high frequency electromagnetic wave, for example gamma rays, does it imply that it also emits all the waves of lesser frequency?

When there is electric charge, then there is an electric field in space aorund it. Or when the electric charge is moving (without acceleration), then it is produced magnetic field in a space around it. Both of these fields permeated to infinity according to Maxwell theory. But how fast...

Consider equation (2.7.8) page 42 in the book Gravitation and Cosmology by Weinberg F' αβ = Λαγ Λβδ Fγδ Now consider the time reversal Lorenz transformation Λμν = 0 if μ ≠ ν, 1 if μ = ν = 1..3 and -1 if μ = ν = 0 then F' 00 = 0 F' 0i = -F 0i F' ij = F ij Using equation (2.7.5) of the same book...

Hi! I'm trying to solve a problem and I'm lost. Would someone kindly help me with the solution, please? 1. Homework Statement A plain electromagnetic wave with a 20GHz frequency moves in the positive direction of the Y axis and its magnetic field is oriented along the Z axis. The amplitude of...

This is an example from "Noether's Theorem" by Neuenschwander. Chapter 5, example 4, page 74-75. He gives the Lagrangian for a charged particle in an electromagnetic field: ##L=\frac12 m \dot {\vec{r}}^2+e \dot{\vec{r}} \cdot \vec{A} -eV## And claims invariance invariance under the...

Hello all again, I was just thinking again about another aspect of electromagnetic waves: Assume we have a planar wave. How "broad" is it or how far does the electric field of it reach? For instance if we have a single planar wave, assume the k-vector in the direction of propagation and then the...

Hello all, after thinking about properties of electromagnetic waves, especially concerning the electric field of them, I ran into some serious understanding problems: 1) photons are electromagnetic waves and vice versa and they convey electrical force. Let's now do a thought experiment: let's...

I'm working on a project and came across electromagnetic braking recently and I'm really curious to know if it's really feasible. The project in brief is a vehicle on a monorail at speeds of +600km/hr needs to be stopped. The monorail is made of an alloy of aluminium. I have no background in...

Homework Statement Homework Equations Right Hand Rule The Attempt at a Solution I am not understanding why the force is left. I can only figure out that the current in the solenoid is moving clockwise because of the right hand rule. From there, I see that the induced current might be...

Hello, I am working on a science project to generate electromagnetic fields. From what I understand, the simplest way to do that is to coil copper wire around an iron core. My initial goal is to create a magnetic field with a maximum strength of 500 microtesla. Can this be accomplished if I...

Homework Statement The figure below shows a small circular loop of wire in the plane of a long, straight wire that carries a steady current I upward. If the loop is moved from distance x_2 to distance x_1 from the straight wire, what will be the direction of the induced current in the loop and...

Per the maxwell equations, we know that em waves travel at the velocity of light, but that is not a sufficient condition to say that electromagnetic waves are light. How do we know that electromagnetic waves are light? They could just be something that has the same velocity as light. Any...

As I understand space time fabric is exclusively the Gravitational field according to Einstein.So every field wave or interaction is contained in the Gravitational Field.This fabric of spacetime(gravitational field) is having properties of inertia and elasticity that is why gravitational waves...

Suppose a point charge is slowly oscillating simple harmonically. Does it emit an electromagnet wave and if not why not ? How does its field change with time. Does anyone know of a good animation ? Thanks.

And if it does what is the mechanism and can it be used in astronomical spectroscopy?

Hello, I've been reading up on this topic and have a couple of questions. This videos shows what I am referring to: 1. What makes the electromagnetic waves from a dipol antenna spread out? There would have to be some type of force that pushed them outwards, right? 2. When the electromagnetic...

Homework Statement Consider an electromagnetic field in an empty space in the region ##0 \leq z \leq a## with the following non-zero components: $$E_x = -B_0\frac{\omega a}{\pi}\sin\left(\frac{\pi z}{a}\right)\sin\left( ky-\omega t\right)\\ B_z = B_0\frac{ka}{\pi}\sin\left(\frac{\pi...

Is Quantum Electrodynamics relevant to every electromagnetic field?

There are some things that confuse me about electromagnetic waves, and I haven't found good answers anywhere. Consider the following equation: E=E0 e i(wt-kx) (here E and E0 are vectors, I couldn't find the right symbols). The things that confuse me are the following: 1° We say that the power...

I mean by the best the one that use the least energy to produce the grater force capable of carrying weights . Say you have a pulley attached to a ceiling with height of 3 meters, around the pulley is a string that attached to a 30 kg weight and on the other side of the string you want to use...

http://web.mit.edu/sahughes/www/8.022/lec01.pdf So I'm trying to understand how to get from F = ∫[(Q*λ)*dL*r]/(r^2) to F=∫q*λ*[(xx+ay)/(a^2+x^2)^(3/2)]*dx Like I don't understand why the x and y components of r are negative, or why "The horizontal r component is obviously zero: for every...

Title says it all. Also, if the frequency of electromagnetic radiation is limited, why? My guess is the wavelength is limited to the Planck length, and when I plug those numbers into the calculator, I get 1.855 * 10^43 Hz. The maximum (Edit: observed) frequency of a gamma ray is 3 * 10^20 Hz...

I recently learned about Electric displacement field and capacitors, and I have a question that how was the formula derived shown below (blue circle part)? Thanks!

So I'm kind of confused. The way I understand it, an electromagnetic field is just a regular electric field viewed from a relativistic point of view, meaning that since we see the charges moving relative to us, we feel like the particles and the fields created by them come closer together (I...

I have learned about the electric fields of static charges and those of moving charges. From what I gather(although I have not really learned the specifics) when charges are accelerated they emit electromagntic waves which are essentialy an electromagnetic field progagating through space. My...

Homework Statement A plane electromagnetic wave travels upward. At t = 0, x = 0, its electric field has the value E = 5 V/m and points eastward. What is the wave's magnetic field at t = 0, x = 0? Homework Equations B=B init. sin(kx-wt) E=E inti. sin(kx-wt) E=cB The Attempt at a Solution I am...

Hi to everybody ! I was thinking about something which confuses me about wave emission. The question is simply the following: Does an electron emit light when it accelerate? or just during its deceleration? or maybe when acceleration and deceleration alternates in some order? I'm not really...

Let us say I have a moving charge. At each point x,y,z in it's path from understanding there is a transverse electromagnetic wave being radiated (could also be viewed as a photon). The electric field at any point x1,y1,z1 in the path is disturbed. The moving charge does the same thing all...

Do electromagnetic waves have potential and kinetic energy like springs, strings, etc. If so how are they calculated, inter-related? What is the total energy? Are the energies fluctuating over time? I am a physics hobbyist so generally the first answers should come with the least mathematics...

I'm not really sure if this is even scientific but while calculating how much energy is stored in electromagnetic coils and capacitors, pretty much the same formula is used: For electromagnetic coils it's U=0.5LI2 For capacitors it's U=0.5CV2 Why I think they're the same is that in a sense L to...

I want to create a small pad consisting of two electromagnets that repel and attract each other, this can give the feeling that something is pushing up against your skin if held. Is this a practical idea?

Hello everybody, I am new here :) what exactly is the energy of the wave? how to think about it generally, in electromagnetic waves and in relation to amplitude? I can think about the kinetic or potential energy that a particle can get from that kind of wave or the sum of all such energy in all...

Homework Statement The correct answer is D Homework Equations The Attempt at a Solution The current is clockwise( in the first picture at least) due to right hand rule. The magnetic flux is changing, the direction of the induced emf depends on the direction of change (increase or...

Homework Statement [/B]In this question, it asks for the magnetic field associated with the electromagnetic wave. Homework EquationsThe Attempt at a Solution The magnetic field is perpendicular to Electric field but it can be in either x or z direction...how do I choose the direction.I

A 2000-turn solenoid is 2.0 m long and 15 cm in diameter. The solenoid current is increasing at 1.0 kA/s. (a) Find the current in the 10-cm-diameter wire loop with resistance 5.0 $\varOmega$ lying inside the solenoid and perpendicular to the solenoid axis. (b) Repeat for a similarly-oriented...

Homework Statement The problem is state in the attachment. Homework Equations None to add. 3. The Attempt at a Solution Struggling with this problem because of the phasor part of it. Perhaps this is justified because the angle is very small and so that relates to a low frequency? Is it...

Homework Statement An EM wave from air enters a medium. The electric fields are --> ^ E1 = E01 cos(2πv(z/c-t) x --> ^ E2 =E02cos(k(2z-ct)x in a medium ,where the wave number k and frequency v refer to their value in air.the medium...

Electromagnetism gives the energy density ##\frac{\epsilon_0}{2}E^2+\frac{1}{2\mu_0}B^2##. It does not include frequency ##\nu## or ##\omega## at least explicitly that QM or photon needs. For an example static electric field has nothing to do with frequency but has energy. How should I...

Homework Statement A cell phone sends and receives electromagnetic waves in the microwave frequency range. Explain the physics of how an oscillator creates these waves. Homework Equations n/a The Attempt at a Solution An electromagnetic wave is created by the functioning of the oscillator...