Questions tagged [dipole-moment]
Dipole moment is the electrostatic moment generated by two opposite charges taken together, far away from the charge's locations
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Absorption Cross Section for Two-Level Spin System in an AC Magnetic Field - Photon Picture
For a two-level spin with a energy difference of $E = h f$, where the two levels have zero dipole electric coupling and can only be driven by a magnetic field, how do I calculate the absorption cross ...
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Meaning of electric dipole moment
what is the meaning of electric dipole moment?
Or why do we need to define electric dipole moment?
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Intuition for magnetic dipole moment
The definition of the electric dipole moment of a system of charges makes sense intuitively -
$$\boldsymbol {\bf p} = \int_{V} \boldsymbol {\bf r} \rho (\boldsymbol {\bf r})dV$$
describes the overall ...
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Multipole expansion, same charges
I know dipole is defined with 2 opposite charges. That's why in EM dipoles exist, while in gravity they do not.
However, I view multipole expansion as a way to describe how the distribution of charges ...
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Understanding polarization and magnetization intuitively?
I am trying to develop a more intuitive understanding of the field produced by magnetization and polarization.
I have the following image, and I can derive it from Maxwell's equations what the fields ...
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Dipole moment and Branching ratio relation
I am looking for a good derivation of relation between dipole moment of transition and Branching ratio of the transition, is there a good textbook for this?
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Larmor precession with an oscillating field?
With a non-polar molecule like CO2, presumably Larmor precession doesn't apply.
However, CO2 has a mode of vibration that induces an oscillating dipole moment.
Could something similar to Larmor ...
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What does centre of mass of charge mean?
I am unable to understand what does this centre of mass of positive charge and centre of mass of negative charge mean??
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What does centre of positive and negative charge separated by a small distance mean? [duplicate]
I dont understand the meaning of this statement that centre of positive and negative charge is separated by a small distance??
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Why do we make a dipole a ideal dipole?
My question is that why do we make a dipole a ideal dipole ($q\to\infty$ and
$d\to 0$) …i mean i want the reason behind to take this and what is the problem of taking a charge with some magnitude (not ...
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Density of current in a Elementary Dipole
I can't understand this formula from my textbook, I'm trying to understand why the Density of Current is I*ΔZ(ΔZ is the lenght of the dipole) i mean a density of current would be I/Δs (with Δs the ...
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How do i determine the dipole moment of a charged conducting sphere in a uniform electric field?
What bugs me the most is that since there is net charge, i dont know two things, how would that charge distribute across the surface (even though my intuition says that one of the sides will have more ...
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How do degenerate states affect molecular absorption?
Molecular absorption of light is related to the transition dipole moment according to the equation from Hilborn, 1982:
$$\sigma(\omega)=\frac{\pi \omega}{3\epsilon_0\hbar c} \frac{g_2}{g_1}\mu^2\rho(\...
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Does this basic example of two bar magnets preserve angular momentum conservation?
Let's say I hold two bar magnets side by side both vertically aligned ($z$-axis). I don't want to worry about their shapes, so let's approximate them as dipoles. I will use the dipole formula rather ...
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Why does spin break time reversal symmetry but electric dipole moment does not break time reversal symmetry?
I wasn't able to get a proper reason behind this and the only thing I could find were classical analogies for spin which (when I asked my prof) were not to be relied upon.
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Can ideal dipoles be associated to a covariant four-current?
I am trying to check if the classical electromagnetic sources from a point electric/magnetic dipole do form a true four-current. In this SE post, it is shown that a point electric charge do transform ...
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Dipole operator in a lattice model
If I have a lattice Hamiltonian, say for example the Hubbard model
$$H = \sum_{j,k, \sigma} t_{j,k} \hat{c}^\dagger_{j \sigma}\hat{c}_{k \sigma} + U\sum_{j} \hat{n}_{j \uparrow}\hat{n}_{j \downarrow},$...
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Understanding the Landau–Lifshitz–Gilbert (LLG) equation discrepancy in literature
Background, I am a masters student in microelectronics trying to perform some micromagnetic studies.
In some literature, the $\gamma$ in the LLG equation is said to be just the gyromagnetic ratio of ...
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Why in an isotropic, linear and homogeneous dielectric, the average electric moment can be expanded as a series of electric field $\mathbf{E}$? [duplicate]
As I was reading this classic 1939 document by Kirkwood The Dielectric Polarization of Polar Liquids. It is stated in the text that the average electric moment in an isotropic liquid can be expanded ...
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Confused by validity of torque on a magnetic dipole
I'm not quite understanding the concept of a magnetic dipole.
From what I've seen, we can treat a given conducting loop as a magnetic dipole ONLY in the approximation where we consider its potential (...
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How does the the Landé g-factor change?
In my statistical physics book, it is said that, when a particle with total angular momentum $\vec J$ is placed in a weak external magnetic field, it has a dipole magnetic moment equal to $$\hat {\vec ...
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Dipole moment operator for many a electrons wave function
From textbooks (such as Optical Spectroscopy of Inorganic, Henderson, 2006) I know that the electric dipole moment operator is defined for one electron as:
$$
\hat{\mu} = e \hat{r}
$$
But then suppose ...
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What is the covariant version of the dipole moment?
Magnetic dipoles in a rest frame behave as a mixture of dielectric dipoles and magnetic dipoles in another moving frame. However this is sometimes controversial due to Mansuripur's paradox (see ...
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When deriving work from an uniform electric field and dipole why do we need to integrate it?
If the force is constant in a uniform field wouldn't that mean you dont need to integrate to find work?
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What is the difference between paramagnetic and ferromagnetic?
What is the difference between paramagnetism and ferromagnetism?
Before answering, I want to note my difference between the rest of the similar questions on this website: from what I think I know, ...
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Quadrupole magnetic trap principle
I read that, the principle of the magnetic quadrupole trap confining is that an atom, with a magnetic dipole moment, subjected to a inhomogeneous magnetic field, is driven towards the point where the ...
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Why does a transition between 2 $s$-orbitals work for cesium's clock transition?
I have a small question about the cesium's clock transition. According to the information on the Wiki: https://en.wikipedia.org/wiki/Caesium_standard, the chosen transitions are two hyperfine ground ...
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Question about "like dissolves like"
I know the rule of thumb of "like dissolves like". However, I'm not totally certain about the following scenario. Please check if my thinking is correct.
Suppose we have a non-polar molecule....
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Coupling of electrc field with electric dipole moment in the hamiltonian
I'm studying linear response theory from "Fundamentals of many body physics" by Nolting. We want to study electrical AC conductivity, so what happens when we apply a spatially homogeneous ...
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Shouldn't the electric dipoles (and thus dielectrics) increase the net electric field?
We know that the magnetic field is almost always greater in a medium, apart from diamagnetic media, than in vacuum. And the reason is, of course, that the magnetic dipoles align with the external ...
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Infinite integrals in calculation of dipole potential
The Situation
Assume that a point dipole is positioned at $z=D$ and is pointing in an arbitrary direction so that its dipole moment is $\textbf{p} = p \cos \alpha \, \mathbf{\hat{r}} + p \sin \alpha \,...
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How to get electric dipole moment formula from a unbalanced dipole?
The potential due to the electric dipole moment is given
$$
\Phi_{dipole}(\vec{x}) = \frac{1}{4 \pi \epsilon_0} \frac{(\vec{x} - \vec{x'}) \cdot \iiint_V \rho(\vec{x'}) \vec{x'}\, d^3 x'}{|\vec{x} - \...
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Earth magnetic field, WMM/IGRF
I am studying about World Magnetic Model (WMM) and International Geomagnetic Reference Field (IGRF) models. It is well known that, to a first approximation, earth magnetic field is a field of dipole. ...
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What does electric dipole moment really mean?
Electric dipole moment is mathematically defined as,
$p = q\cdot d$, where $q$ is the magnitude of the charge and $d$ is the separation distance between the charges.
I was introduced the term "...
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Dipole matrix elements for Bloch wavefunctions?
Suppose we have a one-dimensional periodic system with lattice constant $a_0$. From Bloch's theorem, we can express the wavefunction for an electron in band $m$ with crystal momentum $k$ $\left\langle ...
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If torque is a form of moment, then why is the word 'moment' used for the 'magnetic dipole moment', NiA, for a current-carrying loop?
I thought torque is a form of moment:
If the moment makes the object rotate, we call it torque; otherwise we just use the name moment.
However it seems the electric & magnetic dipole moments are ...
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Has been the spin magnetic dipole moment value of the free electron to be Lorentz invariant ever experimentally verified?
As far as I know all experiments measure the rest value of the spin magnetic dipole moment of a free electron either indirectly at relativistic speeds near the speed of light measuring for example the ...
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Is the spin magnetic dipole moment of the free electron not at rest the same as its rest value?
As far as I know all experiments measure the rest value of the spin magnetic dipole moment of a free electron indirectly (i.e. apparently there is yet no method or apparatus to directly measure this ...
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Does an initially accelerating electron introduced inside a homogeneous magnetic field reduces its spin magnetic dipole moment?
Due to the Lorentz force we know that such an electron will be forced to a helical forward trajectory and given enough time inside the magnetic field it will experience also a continuous diminishing ...
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What would it mean for a dipole moment not to be constant?
It is fairly easy to show that, for a neutral the electrostatic force on a neutral charge distribution with a dipole moment $\bf{p}$ is given by
$\bf{F}$$ = $$(\bf{p}$$\cdot \nabla)$$\bf{E}(r)$ if we ...
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Work done in bringing a test charge from infinity to center of dipole
Potential at Equatorial point of dipole is given 0 in my book(after putting angle = π/2 and cos(π/2) = 0 in formulae
V = (K p cos(x)/r2)
x = angle made my ...
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Question regarding understanding Dipole Moment
I am trying to understand the meaning of the term Dipole Moment,every definition or physical explanation involves some kind of hand wavy explanations ,I would like some concrete intuitive explanation ...
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Quadrupole moment being tensor in electromagnetism
I was reading "Lectures on Electromagnetism" by Ashok Das and he says that because the moment of a monopole is a scalar, the moment of a dipole is a vector then the quadrupole moment is a ...
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What kind of experiment could measure the total sphericity of the electron's monopole charge $E$-field? [duplicate]
As far as I know this was never experimentally undertaken with a high precision measurement, probably by measuring the $E$ interaction field around the monopole charge of an isolated electron (i.e. ...
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Why magnetic field doesn't do any work on moving charge?
As we know the Lorentz force $F=qv\times B$ never does work on the particle with charge $q$. But it does work on a dipole.
My question is, doesn't a moving charge behaves like a dipole? I mean an ...
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Can we calculate dipole moment about infinity?
If $Q_{net}$ is zero:
can we calculate dipole moment about infinity?
if yes, is the dipole moment the same as about origin dipole moment is calculated?
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Two molecules with different polarizability in a EM field
If I have two molecules with different constants polarizabilities $\alpha_1$ and $\alpha_2$ and I send and EM field first on the molecule no.$1$ and then on the molecule no.$2$ so that the two ...
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I can't seem to figure out a way to compute a gradient without reference coordinates
I'm not sure if this question is better asked here or in Mathematics but here it goes:
I'm studying electric dipoles, and this exercise I'm working on asks for the energy between 2 dipoles, given by $$...
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Doubt regarding an approach to derive the potential energy of two parallel dipoles
For a system of two dipoles of dipole moment $|\vec{p}| = p = qd$ each, separated by a distance r, parallel to each other, the Potential Energy of the system comes out to be $ kp^2/r^3$ when ...
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Magnetic field of dipole derivation
How can we derive the following formula:
$$\vec{B}(\vec{r})=\frac{\mu_0}{4\pi}\left[ \frac{3(\vec{m}\cdot\vec{r})\vec{r}}{r^5} - \frac{\vec{m}}{r^3}\right]\; ,$$
I want to derive it as a limit of a ...
