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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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Sign issue deriving SHM of Electric dipole in external uniform electric field

If we have an electric dipole as shown: Net torque on system = $Fdsin\theta$= Rate of change of angular momentum = $I \ddot \theta $ For small displacements along line of E field, $sin\theta \...
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Vectors, their representation and dipole moment

I know that the length of an arrow representing a vector gives represents the magnitude of that vector, now consider a force vector. $\vec{F}$=m$\vec{a}$ , therefore in space a force vector ...
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Divergence and rotation of ideal dipole field at d --> 0

I am working on an assignment in vector calculus where we are supposed to find the divergence and the rotation of the electric field caused by an ideal dipole when the distance d between the charges ...
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Electric dipole and collisions

An electric dipole consists of 2 oppositely charged particles (having the same magnitude) separated over a small distance. Now if opposite charges attract each other then wouldn't 2 charges making a ...
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Dipole Inside Cavity of A Spherical Conductor

Consider the following case: There is a short electric dipole placed arbitrarily inside a spherical cavity inside a solid,uncharged conducting sphere We need to find electric field at a point ...
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How to prove that the limit of surface integral exists?

My book "Electromagnetic Fields" says in $\text{Section}\ 3.4$: Question Why does the limit in equation $(3.42)$ exist (convergent)? Why is the contribution from $(S-S_{\delta})$ remains ...
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Question related to electric dipole moment via QFT

My question is related to the following post: Extracting Electric Dipole Moment from Matrix Element via Form Factor There, it is said that the electric dipole moment (EDM) is giving by a term that ...
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Direction of dipole moment is different in different case [closed]

Why is it that the direction of dipole moment is different in Physics and Chemistry? I mean how can the same quantity have different directions in different subjects. A simple answer is definitely ...
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Considering nontrivial $\mathbf \nabla \times \mathbf P$

For the following image: I am told that this solid cylinder is essentially a bar electret, which has a uniformly distributed $\mathbf P$ throughout its volume. There are no free charges, I will posit....
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Polarisation inside neutron

What happens to a neutron when it is placed in an electric field? Does polarisation take place inside the neutron (As it consists of charged quarks) in a similar way as that of neutral atom?
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Applications of multipole expansion in gravitational problems [closed]

I want to know what exactly are practical applications of multipole expansion in some problems concerning gravitation. I have also read in Subtle is the Lord by Abraham Pais that Einstein had ...
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Do positrons have electric dipole moments?

Is there experimental evidence checking to see if the positron has an electric dipole moment at rest? Or has an experiment measured it’s magnetic dipole moment at rest?
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How can Torque act on an electric dipole if an electric dipole is not a rigid body?

According to my knowledge of physics, torque can only exist on a rigid body and an electric dipole is defined as a "system of charges" (equal in magnitude, opposite in sign) separated by an ...
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Looking for an understanding of Toroidal Moments [duplicate]

The wikipedia page is not so enlightening Apparantly the Neutrino, if it is a Dirac particle, has a Toroidal Moment. Does this mean the Dirac neutrino would interact electromagnetically as well as ...
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Why do spinning electrons generate magnetic dipole moments?

Can the spin of electrons generate currents? If not, how does it create magnetic dipole moments?
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Electric quadrupole moment and electric octupole moment

From a Chinese electrodynamics textbook, first we take a $1/r$ Taylor expansion into the electric potential equation and simplify it, then we get the final equation, and we call each term different ...
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Why is it that when the atom has inversion symmetry, its dipole moment vanishes when the atom is in an eigenstate?

I am now reading my lecture notes on dipole moment and there's a point which confused me. It says that: Let us consider the $|1s\rangle$ and $|2p_x\rangle$ states of a hydrogen atom. The atom has ...
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Why is electric dipole moment represented by “p”?

I recently came across a text where the electric dipole moment was represented as "d" instead of the more commonly used "p". The reason behind using "d" here is probably that "dipole moment" begins ...
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Does ammonia emit microwaves?

Ammonia has an electric dipole moment which means that there is a charge located on one side of the molecule. The molecule can also exist in an inverted form with the charge located on the other side ...
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Direction of the permanent dipole moment of the NH$_3$ molecule

What is the direction of dipole moment in a molecule of $\rm NH_3$? Is from hydrogen to nitrogen? Also do we take into account the dipole moment of the lone pair with hydrogen? When we must take into ...
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Griffiths Multipole Expansion and $Q$ going to zero

Griffiths states that given the multipole expansion: $$V(\vec{r})=\frac{1}{4\pi\epsilon_o}\sum_{n=0}^\infty\frac{1}{r^{(n+1)}}\int(\vec{r}')^nP_n(cos(\theta')\rho(\vec{r}')d\tau'$$ for large $r$ the ...
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Question on force between dipoles [closed]

Two point dipoles of dipole moment $p_1$ and $p_2$ are at a distance $x$ from each other, and $p_1$ is parallel to $p_2$. The force between the dipoles is? I’m not understanding what does point ...
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In the case of the Dirac Equation,what forbids the free electron to absorb a photon? (electron magnetic moment)

It is straightforward to show from relativistic kinematics that a free electron cannot absorb a photon, as shown in this previous thread. However, It is also known that using the Dirac equation, you ...
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Is there an electric dipole moment in an electron?

I just read an article in Science News (p7, 11/10/2018, link here) where researchers looked for an electric dipole moment in an electron. They spoke of charge separation between the positive and ...
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What is the potential inside a hollow conducting sphere with multipoles uniformly surrounding it?

If considering a hollow conducting sphere with a surrounding uniform charge distribution, for example, it will have a constant and uniform potential throughout the inside of the hollow sphere because $...
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What Standard Model extensions are getting constrained by today's new measurement of the electron's EDM?

As published today in Nature: Improved limit on the electric dipole moment of the electron (free to view) and summarized on Live Science. They improve on the previous measurements by an order of ...
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How to derive the $\frac{4\pi}{3}\vec{p}\delta^3(\vec{r})$ element for the dipole field, from its potential?

This might be a bit more general question about how to figure out what is the appropriate (delta) expression in singular points, but e.g. for the dipole, we can derive its potential by a taylor ...
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What is the physical significance of Dipole moment?

What does dipole moment physically signify? I know it is the product of 2 charges and distance between them. Like momentum is the product of mass and velocity, but physically it shows the quantity of ...
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What is the mechanism by which light induce polarity in tiny particles?

I understand that the electric field in light induces polarity in tiny microparticles for example. Can someone explain the mechanism of how the vibrating electric field in light induces a dipole ...
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Why torque and force between two electric dipoles are not equal and opposite, is it violation of newton's 3rd law?

so, here are two dipoles distance $r$ apart i have calculated following: (i)$\vec {F_{p_{1}}} $ (force on $p_{1}$ due to $p_{2}$)$=0$ (ii)$\vec {F_{p_{2}}}$(force on $p_{2}$ due to $p_{1}= -\dfrac{...
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Is a dipole vector directly dependent of the dielectric constant in vacuum?

Supposing to have a little gas particle of diameter d surrounded by an electric field that varies sinusoidally in time $\vec{E} = \vec{E_0}sin(\omega t)$ such that $d << \lambda $, I want to use ...
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Does Natural SUSY predict any deviations in the Electron Dipole Moment?

There are projects underway that measure the Electron Dipole Moment (EDM). So far these experiments have ruled out some parameter space of some SUSY models. See here https://www.researchgate.net/...
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Electric dipole moment when charges are not symmetrically opposite each other [closed]

In the above figure, I want to calculate the net dipole moment. I know that dipole moment is a collection of equal and opposite charges. But, according to that concept, the above figure cannot be a ...
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Special relativity constrains massless electric dipoles, but not massless magnetic dipoles?

Discussion in comments on the two questions linked below leaves me confused about the following point. We expect a magnetic or electric dipole to make a field that has some universal transformation ...
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Electric dipole moment of electron: about what point is the moment taken?

There is a lot of experimental research activity into whether the electron has an electric dipole moment. The electron, however, has a net charge, and so its dipole moment $$ {\bf \mu}= \int ({\...
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Does the dipole moment depend on the choice of origin?

Does the dipole moment depend on the choice of origin if the total charge Q is not zero? for a system of charges neutral overall? How can I show that mathematically? Also I need some drawings to ...
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Multipole expansion of two moving charges…Dipole moment is zero, but time derivative should not be?

I am reading Zangwill's Modern Electrodynamics (2013) on the topic of Cartesian Multipole Radiation. Specially, in equation 20.150 (page 745), he uses the zeroth order approximation (with respect to ...
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Real QM cause of magnetic dipole moment

I have read these questions: Relation between magnetic moment and angular momentum -- classic theory Why is the electron magnetic moment always parallel to the spin for an electron? Does a magnetic ...
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Orientational averaging of dipoles

I was reading a research paper where Quantum emitters with random dipole orientations are placed around a spherical nanoparticle. Then during calculations averaging over orientations is performed ...
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Existence of an electric/magnetic dipole of a molecule

I have a molecule with a symmetry group $S_3=D_3$. I have to determine if it has a non-zero electric and/or magnetic dipole moment using the representation theory. I'm using the book of Jones "Groups, ...
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Resolution of dipole moment into components [closed]

In the derivation that involves finding the electric field due to a dipole at a general point on a plane in which the dipole lies, the following procedure is followed: Resolve the dipole moment into ...
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Can an electromagnetically induced dipole be explained with photon interactions?

An incident electromagnetic wave will cause a dipole moment in the medium it passes through, displacing positive and negative charges in accordance with the EM field. How much of this interaction (if ...
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Electric field due to a short dipole at a point $A$ on the axis

There is a short dipole $ X,Y$ of charge $+q$ and $-q$ placed along the x-axis and then we consider the point at $A$ which is far away from the dipole and lies on the x-axis. The electric field $E_\...
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Direction of dipole moment and electric fields seem to create an issue

If the direction of electric field is from positive to negative, how is it considered that when two equal (in terms of magnitude) but opposite charges are placed at a distance of $r$, the the dipole ...
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How would we calculate the dipole moment of a charge combination (of 3 or more charges) whose magnitudes are different but net charge is zero?

How would we calculate the dipole moment of a charge combination (of 3 or more charges) whose magnitudes are different but net charge is zero? As a special case, what if the net charge is not zero? ...
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How do I graph a magnetic field?

For a school project, I'm trying to graph a magnetic field. I found this page on the NASA website with spherical coordinate equations for a dipole field, but I'm having trouble interpreting the page. ...
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magnetic and electric interactions in atomic level

From what I understand Van der Waals (VDW) forces are the primary source of inter-molecular interaction. There are three different possible origins for van der Waals forces: permanent dipole-permanent ...
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What is the meaning of the Wilson coefficients $C_{S,P,T}$ in the electron-nucleon interaction?

I am doing a project on electric dipole moments in supersymmetry. My background is in high energy physics, so I am having trouble fully grasping the nuclear interactions. Part of that includes ...
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Direction of dipole moment

How do you find out the direction of the dipole moment in a charge distribution? For example a sphere with charge density $\rho$ in northern hemisphere and $-\rho$ at southern hemisphere? How can you ...
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Integrals with azimuthal symmetry

The dipole moment is given by $$\textbf{p}=\iiint \textbf{r'}\rho(\textbf{r'}) \;\mathrm{dV}$$ let's say that the charge configuration is a sphere with radius R and that the charge density is $\rho$ ...