All Questions
Tagged with electromagnetic-radiation conductors
40
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Confusion regarding phase
As far as I know about phase if the phase difference between two waves is positive, the former is leading..and the latter is lagging. Then why has D J Grifith stated this?
If the phase of the magnetic ...
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1
answer
117
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Why is the Poynting flux not conserved across the interface between two conducting materials?
This question is part of my attempt to use an answer to another question I've posted on this site.
If I have two materials with complex indices of refraction, $\widetilde{n}_0$ and $\widetilde{n}_1$, ...
- 123
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Confusion about EM waves in a conductor, AC in wires, and skin effect
I am trying to get my head around these different points:
From Maxwell's equations we find that an electromagnetic wave in a conductor decays in amplitude with a characteristic length of about 1 cm in ...
- 197
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64
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Can cell phones send message in the elevator?
From Gauss's theorem, a closed, hollow conductor shields its interior from fields due to charges outside, but does not shield its exterior from the fields due to charges placed inside it. So my ...
- 267
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How are neutral conductors neutral even though they microscopically aren't?
When dealing with electromagnetic waves inside conductors we take $$\nabla \cdot E = 0$$
and I believe we use the fact that conductors are neutral to do this. However, even though conductors on ...
- 320
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What happens in a conductor when the electric field has a plasma frequency?
The complex index of refraction for a conductor is given by the equation: $$N(\omega)=n+ik=\sqrt{1- \frac{\omega_p^2}{\omega^2+i\gamma\omega}} $$ where $\omega_p^2=Nq_e/\epsilon_0m_e$ is the plasma ...
- 41
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How to derive intrinsic impedance of parallel plate transmission line?
I've been Googling variations of this for hours but I can't seem to find any information on it and the formula my professor provided just seems to come out of nowhere and he provides no explanation or ...
- 2,327
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Induced charge density on perfect conductor
Assuming there is a perfect conductor at $x=0$ in $\mathbb{R}^3$ and a plane EM wave $\vec{E}_i(\vec{x},t)=\vec{E_i^0}e^{i(kx-\omega t)}$ is coming from $x=- \infty$. We know, that the wave $\vec{E_r}(...
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Does microwaves nevertheless pass through smaller slits?
It is known that the Foucault currents prevent the microwaves to leave a microwave oven (MWO). The waves can not pass tru several times smaller openings than their wavelength because the grid of the ...
- 651
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306
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Why do we use wires/conductors to transport energy?
I am currently studying Maxwell equations and I learned that copper wires are essentially just wave guides for EM waves. Why do we not use an insulator to guide the wave and transport the energy which ...
- 225
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Turntables in Appliances and Standing Waves
I am just confused on a concept - maybe someone could correct me if I am wrong? I was just wondering why do some appliances contain a turntable.
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Is EM radiation released when metals, that have free electrons, are accelerated? [duplicate]
I have read that charged particles, when accelerated, emit Electromagnetic Radiation. This was the basis for rejection of the Rutherford's atomic model. But is this statement complete?
Metals have ...
- 65
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Reflection at a conducting surface Boundary Conditions: Not sure if I am understanding this correctly or not
In Griffiths Introduction to Electrodynamics (4th edition), when discussing the boundary conditions for a dielectric to (imperfect) conductor interface for a monochromatic plane wave, Griffith claims ...
- 75
31
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8
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11k
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If air is a bad conductor, how does fire heat up a room?
If air is a bad heat conductor, how does fire heat up a room?
Could someone help me, as I really don't get this?
- 451
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What causes the phase difference between electric and magnetic fields of an EM wave in a conductor?
When an EM wave travels inside a conductor , we find that there is a phase difference between the Electric and magnetic fields within the conductor. The magnetic field lags behind the E field and ...
- 1,581
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396
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EM-wave equation in conductors with source terms
The traditional modified Maxwell's equations to express em wave inside conductors that I have come across are:
$$
\nabla\cdot\mathbf E = 0
\\\nabla\cdot\mathbf B = 0
\\\nabla\times\mathbf E = -\frac{...
- 6,636
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529
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Do induced currents in a conductive surface result in significant electromagnetic fields outside the surface?
Consider the situation of a plane electromagnetic wave in vacuum incident normally on an interface with a good conductor. Within the conductor there is a small transmitted electric field (proportional ...
- 133k
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Electric and magnetic fields boundary conditions
For a perfectly conducting and perfectly dielectric interface, I understood that tangential component of electric field is zero and continuous. But I have read that the normal component of magnetic ...
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Effect of an electromagnetic field on an open metallic body
I have read on my book (I do not put its title since it is not in English) the following sentence about a metal body which receives an external electromagnetic wave (with Js we mean its current ...
- 1,319
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484
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Coaxial cable and faraday cage: why those shielding properties precisely?
The magnetic field produced by a coaxial cable outside of the outer shell is $0$. Indeed, integrating $\nabla \times \mathbf{B}=\mu_0 \mathbf{j}$ along a circle outside the outer shell, the inner ...
- 1,450
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377
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Electromagnetic waves in a conductor
I am trying to understand the solution for electromagnetic plane waves in a conductor. I understand the derivation of the wave equation:
$$\nabla^2 \boldsymbol{\mathrm{E}} = \mu\epsilon \frac{\...
- 2,122
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111
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Are these forms for effective permittivity equivalent?
I was browsing through a book and noticed the following form for effective permittivity (Eq. 1.14.2 of this book):
$$\epsilon(\omega) = \epsilon_d(\omega) + \frac{\sigma_c(\omega)}{j\omega}$$
...
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Perfect Electric Conductor with applied voltage source
Let’s consider a perfect electric conductor which is connecting the terminals of an ideal voltage source (it is a short circuit in practice). What happens from an electromagnetic point of view?
We ...
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Conductors and non-optical photons
While there seems to be plenty of information available about the photoelectric effect and the emission and absorption of photons by conductors (metals) at optical frequencies, I’ve been searching for ...
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Why are 'low frequency' EM waves attenuated by a single layer of kitchen foil?
Can someone explain why my am radio doesn't work when covered by a layer of foil that is less than one 'skin depth' at the appropriate frequency?
According to wikipedia and other websites on the ...
- 57
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2k
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Skin Effect Explanation
I do not understand some things about the Skin Effect.
Its Wikipedia definition is:
Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor ...
- 1,319
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140
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Do conductors reflect Wifi signals? If so why?
I know electric field can't pass through conductors, but I have seen people surround their wifi router by soda can (not entirely) for better signal strength. I want to know what really happens there.
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2k
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Difference between bound and free charge/current in a perfect conductor
For the case of charge, it seems clear that in a perfect conductor the free charge refers to the excess charge that has been dumped into the conductor, while the bound charge refers to the charge that ...
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Is there a way to make infrared pass through metals?
I am curious to know a way that will make infrared pass through metals. Metals are good reflectors of infrared,can we manipulate the wave in order to make them pass through metals?.
user197535
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How do you tell whether charges oscillate in the antenna because of an electric or magnetic field?
The electrons in a receiving antenna oscillate, can we establish if they respond to an electric or a magnetic field?
How can we know if there is an electric field apart from the one caused by the ...
user137879