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-1 votes

What happens to the charges in an inductor when you induce a voltage?

If you connect to an ac source you have an ac current in the second wire , same as in a larger transformer ,if you connect to a dc source you have no effect on the second wire except in the first ...
trula's user avatar
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1 vote

Is First-Class Constraint Generator of matter Gauge Symmetry in EM example?

The solution to OP's problem is to include a pertinent matter sector in the E&M Lagrangian (3) (in OP's case: a complex scalar $\phi$). This produces the source term in the first-class secondary ...
Qmechanic's user avatar
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1 vote
Accepted

Can plasmas have eddy currents?

Yes. Induced currents in plasmas can be useful. The poloidal field in a tokamak is an eddy current induced by a magnetic field that threads the torus.
John Doty's user avatar
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0 votes

Why the frequency component is not included when the energy of a wave is described?

According to particle theory, the energy of a photon depends on frequency which makes sense. But in classical theory, how is it included? I am not seeing it. Energy density vs. energy flux One has to ...
Roger V.'s user avatar
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2 votes

Is First-Class Constraint Generator of matter Gauge Symmetry in EM example?

From @Andrew's comment, I know how to solve it. In scalar QED, EM field would couple to current $J^{\mu}(x) = \phi^{\star}(x)\partial^{\mu}\phi(x) - \phi(x)\partial^{\mu}\phi^{\star}(x)$, and the ...
Ting-Kai Hsu's user avatar
0 votes

Why the frequency component is not included when the energy of a wave is described?

This really depends on the wave. If it's a wave in rope, there is kinetic energy associated with the velocity of the rope moving up and down, and in the linear limit: $$ v \propto A\omega $$ which has ...
JEB's user avatar
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8 votes
Accepted

From what equations is magnetic field uniquely determined for a given current distribution?

The domain is important. The solution is given by Biot-Savart if it is the entire $\mathbb R^3$ space, with some assumptions on the regularity and decay of $B$ (e.g. $L^2$). In this case, you can ...
LPZ's user avatar
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3 votes

How to avoid the ordinary Coulomb solution in QCD?

First, I think your proposed current would break gauge invariance, but that's a relatively trivial problem in that I think you could reformulate your question getting around that issue. The bigger ...
Andrew's user avatar
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0 votes

Diffraction when the wavefront is not parallel to the plane

This is how you derive Snell's law: https://ocw.mit.edu/courses/3-024-electronic-optical-and-magnetic-properties-of-materials-spring-2013/480e12b984eb21a5e88b8ee5cc051ef8_MIT3_024S13_2012lec22.pdf ...
ABetheGammow's user avatar
0 votes

What effect do two perpendicular magnetic fields have?

Maxwell's equations are linear, that means: The magnetic field of two loops of currents is then sum of the magnetic fields of each loops of current.
JEB's user avatar
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1 vote

How is a steady current maintained in case of motional EMF if net force on electrons is zero?

if they are slowed down or are sent in random directions once they encounter resistance in the wire then how should a steady current keep flowing? If the rod is isolated, only then electric charge ...
Ján Lalinský's user avatar
4 votes

Gauge theory of Electomagnetic Potentials - 2nd order derivatives

The Gauge fixing condition must be (1) accessible (This is addressed in Gabriel's answer), and (2) it must uniquely fix the gauge. In E&M one way to see that you get the gauge degree of freedom is ...
Josh Newey's user avatar
1 vote

How is a steady current maintained in case of motional EMF if net force on electrons is zero?

Indeed there is no current in the rod once the force on the electrons become zero. While the rod was entering in the magnetic field , the magnetic force acted on the free electrons to produce a ...
CP of Physics 's user avatar
1 vote

Gauge theory of Electomagnetic Potentials - 2nd order derivatives

This is only a partial answer to your question. What you say about X and Y being linear is not necessarily true, as I have seen other guage choices like the Weul gauge, $A_t=0$, used in QFT, or the ...
Gabriel Ybarra Marcaida's user avatar
0 votes

Understanding Symmetries and Invariances in Electrostatic Fields

The concept of symmetry plays an important role in all branches of Physics, and electrostatics is a good playground for developing an intuition on how symmetries works. A little disclaimer: I do not ...
Giovanbattista Favorito's user avatar
0 votes

What is the relation between the Faraday effect and the Zeeman effect?

Most magneto-optic effects, such as the Faraday or Kerr effect, are classical phenomena. You don't need to explain things in terms of photons or atoms to understand these effects. The Zeeman effect ...
ABetheGammow's user avatar
0 votes

Would a gauss rifle based on generated magnetic fields have any kickback?

There is one questionable assumption that the pro-recoil camp is making. A normal firearm PUSHES the projectile down the barrel. The force applied is from a single direction horizontal to the user. A ...
IDave's user avatar
  • 1
0 votes

Directionality of EM Waves in Double Slit Experiment

The diagram on the left is in the xy-plane and you can liken it to a contour map taken at an instant of time, like a photograph. Initially let me assume that the incoming light is plane polarised in y-...
Farcher's user avatar
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3 votes
Accepted

Analog between Electromagnetism and Gravity

In electromagnetism, if you have a $$ \mathcal{L} = -\frac{1}{4} F^2 + A_\mu J^\mu $$ where $F^2=F_{\mu\nu}F^{\mu\nu}$ is the Maxwell term ($F_{\mu\nu}=\partial_\mu A_\nu-\partial_\nu A_\mu$), the ...
Andrew's user avatar
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1 vote

Friction and electromagnetic force

I disagree with Bob D that there is no underlying relationship. Instead, what I'd say is that friction is applied electromagnetic forces. Electromagnetic forces dominate interactions between atoms. ...
Cort Ammon's user avatar
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0 votes

Is magneto-optic Kerr effect discernible for material with natural optical activity?

From an experimentalist's point of view: If the material's chiral structure is independent of the external field or magnetism, then the sample's optical activity will be calibrated out of the result ...
ABetheGammow's user avatar
1 vote

Difference Between Plasma Potential and Floating Potential in a Plasma

The floating potential is the potential a metallic body acquires in the plasma when it is not connected to any electrode, so that the charged fluxes arriving to it have no where to go but to change ...
Gotaquestion's user avatar
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-2 votes

Can photons interact with one another?

Most of the time they interact by changing a medium which changes the properties that the photon sees. But another possibility is HOM interference, in which the possible outcomes of the different ...
Steven Sagona's user avatar
3 votes

Can photons interact with one another?

Photons can interact with each other. However, the interaction is very weak in the vacuum. I'm not sure this can be explained using a simple explanation from wave-particle duality. The full ...
Josh Newey's user avatar
0 votes

Quick question regarding Larmor precession and bar magnets

https://en.m.wikipedia.org/wiki/Ferromagnetic_resonance: ‘ Ferromagnetic resonance, or FMR, is coupling between an electromagnetic wave and the magnetization of a medium through which it passes. This ...
my2cts's user avatar
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4 votes

Why is the length of a Faraday cage's lattice relevant to what wavelengths it blocks?

Think of each hole in the Faraday cage as a very short waveguide. If the wavelength of the radiation is short enough (roughly $\lambda < 2d$ where $d$ is the diameter of the hole), then that ...
The Photon's user avatar
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0 votes

In a simple battery + resistor circuit, what form of energy is lost from the electrons upon exiting the resistor?

I was writing an answer to a very similar question that was closed and merged in this one, so excuse me if I repeat the other answers. The particularity of this other answer is that it called for an ...
Alfredo Maranca's user avatar
1 vote
Accepted

Flux change through a loop

This comes from Faraday's law. I believe it is only valid in quasistatic (no radiation generated) situations. Faraday's law in differential form is $$-\frac{d\Phi_B}{dt} = \varepsilon.$$ If you have a ...
mike1994's user avatar
  • 978
1 vote
Accepted

Permittivity real and imaginary parts with similar value possible?

Since the right side of the second figure is not clear because of the inappropriate scale, I will only analyze the left half of the frequency range. Obviously, the imaginary part of the permittivity $\...
et al.'s user avatar
  • 111
3 votes

Why electric field increase near the cable connected in AC 220V socket even current is zero?

The electric field depends on the potential difference (voltage) between the wires in the cable, not on the current going through the wires. The electric field will be strongest inside the cable, ...
Philip Wood's user avatar
1 vote
Accepted

Magnetic field for a cylindrical shell in which current flows

If you construct a circular loop around the cylindrical axis and argue by symmetry that the magnitude of the field is constant on that loop then Ampere's law can only tell you about the $\phi$ ...
ProfRob's user avatar
  • 133k
0 votes
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Maxwell stress tensor on a capacitor late given a dielectric

I figured out the answer to my question! Although I couldn't find any reference to the Maxwell stress tensor in a dielectric in my normal Griffiths textbook, I found that "Electrodynamics of ...
asyndeton256's user avatar
0 votes

How do I find the wavelength of an EM wave derived from an accelerating electron, given its acceleration?

The Larmor formula gives the Poynting power of radiation coming off a classical charged particle in accelerated motion. It does not give distribution of frequencies in this radiation. Acceleration ...
Ján Lalinský's user avatar
0 votes

How to solve Relativistic Lorentz Force equation if $\gamma$ is not constant?

As stated in answers (see Ján Lalinský answer) to other similar questions the way to go is to evaluate the ALD force on the trajectory without the radiation particle reaction. Following this idea,the ...
ZMD's user avatar
  • 1
0 votes

What's the difference between conduction current density and source (impressed) current density in an $RC$ circuit?

Kirchhoff's first circuital law is about currents $I$, not about current densities. Thus we have $I_i=I_c$, but it is not necessary to have $j_i = j_c$, because cross-section of the source and of the ...
Ján Lalinský's user avatar
0 votes

Comparing Electric Potential Energy of two Charges

From your picture the potential has by approximation left-right symmetry and top-down antisymmetry. Therefore the potential difference V_A'-V_A=V_B'-V_B. If the charges are equal then the ...
my2cts's user avatar
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0 votes

Comparing Electric Potential Energy of two Charges

The change in electric potential energy for a positive charge going from position $A$ to position $A'$ is the same as the change in electric potential energy for a positive charge going from position $...
Farcher's user avatar
  • 97.9k
0 votes

Comparing Electric Potential Energy of two Charges

You can calculate the energy of the charges explicitly. For simplicity, let us reduce the problem to a one-dimensional case. Take fixed charges $-Q$ at $z=-a/2$ and $+Q$ at $z=a/2$. These act as the ...
CompassBearer's user avatar
1 vote

Comparing Electric Potential Energy of two Charges

In the case that A and B both have the same positive charge: remember that potential energy associated with a position (it is not defined as something that requires two positions e.g. A and A') is the ...
Marius Ladegård Meyer's user avatar
0 votes
Accepted

What is the impressed current density?

$\mathbf{J}_e$ is the "impressed current density" in the source/external battery, etc. (Ohm's law need not hold in the source, so in the general discussion, there is a reason not to express ...
Joshua's user avatar
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0 votes

Why the $T_1$ recovery & $T_2$ decay are independent?

When you say the videos "show them dependant on each other", perhaps your confusion arises because they both evolve with time. I think a simple classical explanation is best, so I won't go ...
Dr. Nate's user avatar
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1 vote

How do you convert from Townsend Unit $\rm Td$ to $\rm kV/(cm bar)$?

An educated guess by an insider. Everything rob says is correct and everything calculated in the question is correct. I have been making calculations with E/N values and I also have to convert from V/...
tom's user avatar
  • 6,958
1 vote

Most generic form of refractive index tensors

Symmetry: In non-magnetic media, the real part of the refractive index tensor is typically symmetric due to energy conservation principles. This symmetry is related to the reciprocity theorem in ...
ahri's user avatar
  • 21
3 votes
Accepted

Why the $T_1$ recovery & $T_2$ decay are independent?

The first thing you have to note is that: no, the transverse $M_{xy}$ component does not exchange energy with the longitudinal $M_z$ component for the magnetization $\vec{M}$ to return to equilibrium. ...
hendlim's user avatar
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3 votes

Why the $T_1$ recovery & $T_2$ decay are independent?

They are indeed independent. I don't know what animations you're referring to, but this independence is clear from their defining equations, which do not depend on each other: $M_z(t)=M_z(0)(1-e^{-t/...
Sam's user avatar
  • 123
0 votes

Straight wire in moving uniform magnetic field induced emf

First, it is useful to make clear what EMF is. For any curve $\gamma$ (open or closed), it is $$ \mathscr{E} = \int_{\gamma} \mathbf E^* \cdot d\mathbf s, $$ where $\mathbf E^*(\mathbf x)$ is net ...
Ján Lalinský's user avatar
0 votes

What is the net macroscopic electric field at any point inside a dielectric?

You both are correct. The external field should be produced by some other charges whose influence are already included in the part $\vec{E}_{out}$. Because $\vec{E}_{out}$ is the field due to outside ...
Argha Modak's user avatar
1 vote

Straight wire in moving uniform magnetic field induced emf

First : scenario 1 and two are not the same in scenario 2 B moves relative to the full loop not only relative to the green rod, so there will not be any emf induced, same as if moving the whole loop ...
trula's user avatar
  • 6,362
8 votes

Can a satellite generate electricity by using a planet's magnetic field?

The Earth's magnetic field is very weak compared to that produced by a magnet you might '[slide] next to a coil' and the time over which the field will vary is long (> ~90 minutes for one orbit), ...
Penguino's user avatar
  • 2,976
0 votes

Volume distribution of charge in a wire in a DC circuit

In electrostatics, if there is net charge in a conductor it's distributed on the surface. While electric current flows in a wire, the wire is electrically neutral, $\rho = 0$. There are some negative ...
basics's user avatar
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