Electromagnetic Definition and 1000 Threads

Some site I've looked at are https://www.sciencedaily.com/releases/2000/10/001016073704.htm and [Link to garbage site removed]

I think my main question is pretty much summarised in the TL;DR. I have another related question: Is it possible for one to "create" two fermionic particles of the same charge but a different spin (using creation operators ## \hat{a}_{ \downarrow , + }(x,t)\hat{a}_{ \uparrow , + }(x,t) |0...

In Griffith's Introduction to Electrodynamics, chapter 12, he discusses how electromagnetic fields transform when we move from one inertial reference frame to another. On page 553, he claims He then considers how the electric field inside a conductor made up of two parallel rectangular plates...

So I was watching this video containing DIY experiments on electromagnetic induction . At minute 4:45, the dude pretty much creates a transformer without using an iron core. He runs 30-50 kHz AC in a coil (forming the primary circuit) and then brings another coil with its ends attached to a...

My guess is that the force per volume is: $$ \vec F_V = \rho \alpha x \hat x + \vec J \times \beta x \hat y$$ but I'm not sure where to go after that. I'm not given a value for either the charge density or the current density, so I can't simplify the relation much. Further, I'm not sure if my...

Hello, I am still trying to fully grasp the general idea of the EM field, which always travels at the speed of light regardless of the reference frame, and is represented by a tensor with 16 components in relativity theory. My understanding is that, depending on the observer's frame of...

Mission: create a pair of electromagnets which always connects (angel) perfectly together. Initially, I design with the following 3 ideas, could any design possible to achieve? 1) First idea is to separate 5 iron core, all close to the edge and connect to the battery source. this attempt is...

why does an electrical motor produce an induced back emf which is equal to V-It when terminal speed of electrica, fans or electric drills is reached

Let me preface this by saying I have no background in physics or any of the above other than hours and hours of reading. Could someone explain why (if a method was developed) we couldn't use EFA as a thrust system for a rocket? My reasoning is instead of using fuel to fight gravity and push...

Hello! This is probably a silly question (I am sure I am missing something basic), but I am not sure I understand how a Hamiltonian can be a scalar and allow transitions between states with different angular momentum at the same time. Electromagnetic induced transitions are usually represented...

Does the electric and magnetic fields of electromagnetic radiation remain perpendicular in the presence of an intense gravity field? If not, what is the physical ramifications of this?

I am trying to answer exercise 5 but I am not sure I understand what the hint is implying, differentiate with respect to ##p_\alpha## and ##p_\beta##, I have done this but nothing is clicking. Also, what is the relevance of the hint "the constraint ##p^\alpha p_\alpha = m^2c^2## can be ignored...

When the ##\psi(2s)## particle decays also the following two transitions are observed $$\psi(2S) \rightarrow \gamma + \eta({1}^S_0)$$ $$\psi(2S) \rightarrow \gamma + \chi_{c0}({3}^P_0)$$ The branching fraction for the first decay is about ##3.4*10^{-3}## while it's ##9.7*10^{-2}## for the...

I've attached my attempt at a solution below, I thought integrating it would be the best way to go but I'm just getting so confused and could use some help. This isn't my first attempt at a solution either I've been working on this for just under two hours now.

I am interested in showing a visualization of water molecules in a time-varying electric/magnetic field as part of my PhD work. I would like something like this visualization: , but with an external time-varying field applied. At first, I thought of simply animating water molecules...

ans is opt4

Hello to all, In a short pulse laser emission setup, can a pulse be emmited with beam length shorter than one wavelenght? (can a pulse have a duration shorter than its period?) Lets say a laser emmiter shoots a quarter cycle pulse, what would happen to this short beam? (lets supose the...

1. |ε|=dΦ/dt B=μ0I×cos(0-cos180)/4πr =μ0I/2πr dΦ=BdS=μ0I×(vdtxdr)/2πr ΔΦ=(μ0I×(vdt)/2π)x∫dr/r=(μ0I×(vdt)/2π)xln(b/a) *the intergral goes from a to b |ε|=dΦ/dt=(μ0I×v×ln(b/a)/2π) i=ε/R=(μ0I×v×ln(b/a)/2πR) 2. dI/dt=-50 B=μ0NI/L ε=-dΦ/dt=-BdS/dt (*) =-NBS/dt (wait what?)...

Would you be able to transfer a "current" through rings of conductive and paramagnetic material? As in, have a current, which causes a magnetic field to pop up in the ring, which fluxes, and causes the next ring to have a current? I am curious because this is a research project for FLL. (There...

What does a measure of 2000 µW/m² electromagnetic radiation by "Hf35c Rf Analyze (800mhz – 2.5 Ghz)" radiation meter mean? Is it too high? see this link: https://www.electrahealth.com/hf35c-radio-frequency-meter.html it shows that “1000 or more µW/m²” in the meter is “Extreme Concern”, does it...

Hello, I'm trying to make an electromagnetic shaker but I'm not sure if this is possible? Basically I want to wrap an iron core with a solenoid and use AC to shake a magnet at some distance away. I'm not certain on the approach at the moment but I'm kind of looking at the feasibility at the moment.

I'm wondering if plants are sensitive to electromagnetic (EM) waves? Of course I'm not speaking of light but in the low frequency domain, say from 0 Hz to 100 kHz? I looked up the web but couldn't find anything, only experiments with EM waves above the range of 300 Mhz. Has there been any...

no need of equations

How was it discovered that electromagnetic radiation is electromagnetic? -- Jeff, in Minneapolis

I have an infinite sheet (in lossless, homogeneous medium) of time-harmonic current in ##yz##-plane at ##x=−d##. The current density on this sheet is given by $$\mathbf{J}=\hat{z}J_0\delta(x+d)$$ ##δ(x+d)## is delta function. Moreover, there is a perfect electric conductor (PEC) half space at...

We're trying to prove this: There exists 3 distinct regions: Region 1 has index of refraction 1 and lies before light hits the coating. For simplicity, define the position of the interface between the air and the coating z=0. The second region is the coating, which has index of refraction √n. At...

As a prior physics major (had to stop at my 3rd year of undergrad due to children and financial difficulties), there was something I was always extremely passionate about - finding feasible ways to travel faster than light. Obviously, the only feasible way seems to be to bend space-time, but I...

I found equion ##T^{\mu\nu} = \frac{1}{\mu_0} \left[ F^{\mu \alpha}F^\nu{}_{\alpha} - \frac{1}{4} \eta^{\mu\nu}F_{\alpha\beta} F^{\alpha\beta}\right] \,.## from wikipedia page https://en.wikipedia.org/wiki/Electromagnetic_stress–energy_tensor . it's (0,0) component should be electromagnetic...

If an up quark has 2/3 of positive charge and down quark has 1/3 of negative charge then why don't they add together by their electromagnetic force?

What's the most used type of electromagnetic potential? Is it the retarded potentials?

In David Tong's QFT notes (see http://www.damtp.cam.ac.uk/user/tong/qft/qft.pdf , page 131, Eq. 6.38) the expression for canonical momentum ##\pi^0## is given by ##\pi^0=-\partial_\rho A^\rho## while my calculation gives ##\pi^\rho=-\partial_0 A^\rho## so that ##\pi^0=-\partial_0 A^0##. Is it...

Homework Statement: The rod is moving on a second rod with speed of v in the magnetic field perpendicular to rod. I know its resistance per meter. I am expected to omit megnetic field created by the current and resistance at the point where rods touch each other and calculate current. I...

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I want to simulate 2D TM scattered fields (microwave range) for austria profile. Austria profile has 2 circles beside each other of certain dielectric and one ring below the circles. So basically I have three dielectric objects in the domain of interest and also positions of Tx and Rx are known...

Homework Statement: A radio station on the surface of the Earth radiates a sinusoidal wave with an average total power of 50 kw. Assuming that the transmitter radiates equally in all the directions above the ground, at a distance of 100 km from the antenna (ε0 = 8.85 10-12 C2N-1m-2) Homework...

What are the best resources (books/lectures/articles) to learn Classical Electromagnetic Scattering (forward and inverse modelling)? I am an Electrical Engineer so I would prefer some resource which is from an applied perspective. My specific research topic is related to modeling and analyze 2D...

When an object is hot its particles are moving faster than when is cold, right? I've searched that particles are electrons and protons, so it means that if we warm a object the electrons will be moving or even accelerating. Every charge accelerated creates Electromagnetic Waves (or light)...

Electromagnetic waves are oscillations of the electrical/magnetic field which propogate through space. So one might predict that the presence of a magnet/charged particle would effect their propogation somehow, like distortion or interference (eg, light might get refracted in a magnetic field or...

I am studying a beginner's book on QFT. In a chapter on electromagnetic form factors, the authors have written, using normalized states, $$\begin{eqnarray} \langle \vec{p'}, s'| j_\mu (x) |\vec{p}, s \rangle \ = \ \exp(-i \ q \cdot x) \langle \vec{p'}, s'| j_\mu (0) |\vec{p}, s \rangle...

Summary: Does a static magnetic field affect a weaker pulsed magnetic field close by? If you have a static magnet close to a low level pulsed electromagnetic field, will the static magnetic field influence the pulsed field if the static magnetic field is the same strength or stronger than the...

is there some physical limit on the wavelength of electromagnetic radiation? Can there be radiation shorter than gamma rays?

Attempt at a solution: $$ -\gamma^{\mu}\gamma^{\nu}D_{\mu} D_{\nu} - im\gamma^{\mu} D_{\mu} + im\gamma^{\nu}D_{\nu} - m^2 =$$ $$ -\gamma^{\mu}\gamma^{\nu}(\partial_{\mu} + ieA_{\mu})(\partial_{\nu}-m) - I am \gamma^{\mu}(\partial_{\mu}+ieA_{\mu})+im\gamma^{\nu}(\partial_{\nu}+ieA_{\nu}) - m^2...

Summary: Mathematical and Physical queries in regards to Electromagnetic Fields and their manipulation of Space-Time. I recently started looking into Einstein's Field Equations, to get a better understanding of how mass distorts and curves the plane of Space-Time, however from doing this I...

Light is said to consist of photons or electromagnetic waves. I'm not asking which view is correct, what conditions make one view or the other more useful, or advantages and disadvantages of each view. I am assuming the two views are compatible to the extent that the wave character of light can...

I am trying to find the correct formula for the electromagnetic stress energy tensor with the sign convention of (-, +, +, +). Is it (from Ben Cromwell at Fullerton College): $$T^{\mu \nu} = \frac{1}{\mu_0}(F^{\mu \alpha}F^{\nu}{}_{\alpha} - \frac{1}{4}g^{\mu\nu}F_{\alpha\beta}F^{\alpha...

Like what are the chances that dark matter can be described with electromagnetism instead?

I am searching information about the interplanetary magnetic field,e.g, what is its strength? Does it vary with time? (I guess so) Are there statistical model to predict its variation in space and time? ... At the moment I have not a specific question in my mind, but I am looking for some...

do electricmagnetic wave moving in upside down form? So the highest position is wave crest and the lowest is wave trough?

gotta be honest I am really struggling