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2
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2answers
87 views

Why is there no electric dipole term in the Hyperfine Hamiltonian?

I have been looking a several discussions of hyperfine structure. (For example: here and in the explanation for eq. 2.1 here It seems that the hyperfine interaction can be explained almost entirely ...
0
votes
2answers
32 views

Why electric potential at equatorial point of a dipole is 0?

Well ok I know that electric potential at equatorial point of a dipole is 0. It is a derived conclusion. Q1. But how this can be explained "theoretically"? Another question that electric potential ...
0
votes
2answers
120 views

dipole-dipole interaction

U= -p(vector of one dipole)*electrict field due to the second dipole does this equation give the energy of one dipole due to the electric field due to the second one, if so is the total ...
5
votes
1answer
180 views

Near Energy In the Null of a Hertzian Dipole

Since $\mathbf E = -∇Φ - ∂\mathbf A/∂t$ one expects an oscillating $\mathbf E$ field even in the null of a Hertzian Dipole unless the two right hand side terms cancel -- which they do in the far field ...
1
vote
1answer
102 views

Question about Gauss' law and dipoles

I've got a question about dipoles and Gauss' law: Consider an electric dipole $p=ql$ in free space, centred at the origin of a Cartesian reference frame. Using Gauss’s Law, discuss if the electric ...
0
votes
1answer
46 views

Doubt in derivation of electric field at axial snd equatorial point

Firstly, in derivation of electric field at an axial point due to a dipole we have to determine the Electric field at a point P on the axial. So there are two electric fields acting on this Point P, ...
0
votes
1answer
77 views

Dielectric heating - does EM field transfer energy to polar molecules?

In AC field, polar molecule are trying to align with external field. At high freguencies, changes of field are so quict, that molecules cannot align with it. This leads to increasing kinetic energy of ...
0
votes
1answer
62 views

Change in work done by dipole

How would you explain the intuition behind the equation $dW = -\tau d\phi$ for an electric dipole?
-1
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1answer
352 views

difference between magnetic dipole moment and torque on a magnetic dipole?

I am a bit confused. What is the difference between magnetic dipole moment and torque on a magnetic dipole ?
2
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0answers
59 views

Connection: Work on dipole <-> optical absorption

If I consider a two-level system with a ground and an excited state, I can compute the instantaneous rate at which work is being done on the dipole $\mu(t)$ by an electric field $E(t)$: $\dot{W} = ...
2
votes
0answers
95 views

Mie Scattering for spheres with constant dipole moment

I was wondering whether there exists a theory that describes Mie Scattering for spheres that have a constant dipole moment. Since there are theories that describe Mie scattering in the case of a ...
1
vote
0answers
15 views

General expression for electromagnetic toroidal moments

I'm reading about this third family type of multipole moments (independent from the usual electric and magnetic moments), called "toroidal multipole moments". The first multipole term in the expansion ...
1
vote
0answers
23 views

What makes an insulator good for polarizing?

Water in an electric field become polarized easily, since the natural dipoles twist and turn to align with the field. In non-polar insulating materials, a redistribution of charge can happen in the ...
1
vote
0answers
83 views

Why do “virtual states” in Raman spectroscopy have absorbance profiles distinct from either the ground or excited states of an absorbing material?

Do virtual states in Raman spectroscopy have distinct and observable dipoles that can interact with and/or induce dipoles in other molecules (over extremely short femtosecond timescales)? This notion ...
0
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0answers
32 views

Is my definition of a dipole and its dipole moment correct?

Assume that we have a dipole affected only by an applied magnetic field where only 2 possible orientations for its dipole moment are possible: "up" and down". A dipole is simply an object with a ...
0
votes
0answers
18 views

What is a surface dipole? What is an interface dipole?

I often see the these two terms in solid state physics. However, I couldn't find any explicit definition for them. Are they simply dipoles that happen at a surface or at an interface or is there more ...
0
votes
0answers
29 views

Half wave antenna

I need to calculate the magnetic field intensity at a distance $x$ and angle $\theta$ for a half wave dipole antenna. I know the length of the antenna is $$ l = 333.33mm$$ and the magnetic field ...
0
votes
0answers
37 views

Calculating instantaneous field strength for known signal source

I was referred here from electronics stackexchange. Suppose I have a time varying signal source V = Vm cos(wt). This source is fed to a half wave dipole antenna which in turn radiates electromagnetic ...
0
votes
0answers
26 views

If magnetic force (hence torque) does no work, how does a dipole placed in a magnetic field have a potential energy associated with it?

If potential energy equals negative of work done and magnetic force does no work what force does the work?
0
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0answers
23 views

strength of each dipole charge

If I have a two dimensional dipole whose line charges are located on the y axis, I know that the electric flux through a gaussian pill box containing both the charges will be zero, that is ...
0
votes
0answers
30 views

Series expansion of potential due to a dipole displaced from the origin

I learn that we can expand the electric potential in an infinite series of $\rho$ and $\cos(n \phi)$ when solving the Laplace equation in polar coordinates. The problem I want to consider is the ...
0
votes
0answers
47 views

Electric field of a dipole in cartesian

I have the function that describes the electric field of a dipole in cartesian coordinates: $$E_z= \frac{p}{4\pi\epsilon_0} \cdot \left(\frac{3z^2}{r^5}- \frac{1}{r^3}\right) $$ and ...
0
votes
0answers
41 views

Direction of polarization in dielectrics

Our teacher just taught us polarization in dielectric materials. I have some doubts that he wasn't able to clear. Is the direction of polarization, for any non-linear dielectric, in the direction of ...
0
votes
0answers
11 views

What's the contribution from nuclei and electrons in molecular infrared absorption process?

  I'm very glad to post the first question on this StackExchange forum. It's wonderful to discuss the sientific problems with experts, researchers, teachers and students on the website. Even my ...
0
votes
0answers
46 views

The dipole moment P in a metallic sphere

A metallic sphere is in a homogenous field $\vec{E}=E \cdot \vec{e_z}$. Put a dipole moment P at the origin, so the total potential is constant on a surface of a sphere with radius $a$. Which $p$ is ...
0
votes
0answers
35 views

forces between two dipoles, one of them oscillating

so, imagine we have two dipoles A and B, A is fixed at the origin and B is free to move on the X axis. Suppose we make the dipole A oscillate, say reversing it's direction every one second, then B ...
0
votes
0answers
131 views

Finding Magnitude and Direction of Dipole's Electric Field at a Point

This question pertains to finding the magnitude and direction of a dipole's electric field. Specifically, I am trying to figure out why we are using both the hypotenuse and $\sin\theta$, and not the ...
0
votes
0answers
31 views

How do I evaluate this general magnetic dipole equation for this given setup?

This shouldn't be too hard a question (mostly focused on vector multiplication) but I'm still not confident in my answer. Basically, I am looking at the force between two magnetic dipoles and using ...
0
votes
0answers
84 views

The approximation of the potential field of a half wave dipole antenna

I'm currently deriving an approximation of the potential field of an dipole antenna in the far-field in two dimensions, and I have some troubles. Since using two methods give two different answers. ...
0
votes
0answers
64 views

Explicit Ewald equations for dipole-dipole interaction in a simulation

I'm starting to work with spin ice simulations and I found that it is usual to use the Ewald method for the long-range interactions computation (dipole-dipole in this case). Although I've been reading ...
0
votes
0answers
52 views

Why doesn't a quantum pairwise Hamiltonian couple states in which more than one interaction occurs?

This question is about the standard quantum mechanical pairwise interaction Hamiltonian. I'll phrase it in terms of an example using Rydberg atoms, but you could just as well imagine spins (for ...
0
votes
0answers
25 views

If an common metal is induced with a static dipole moment, won't the the positive side be weaker?

To my knowledge, common metals with metallic bonding is formed through free electrons within its lattice structure. If say we are to shift the free roaming electrons to one side and therefore minutely ...
0
votes
0answers
286 views

Calculation of Magnetic Field Lines

I am doing some research on how to calculate magnetic field lines for a bar magnet. So far I have found the following equations: \begin{align} \frac{B_r}{B_\theta} &= \frac{d_r}{rd_\theta}\\ ...
0
votes
0answers
47 views

Are there examples of “loss-less” Forster Resonance Energy Transfer (FRET)?

When I think of a Forster Resonance Energy Transfer (FRET) process, I typically imagine the initial excitation of an absorbing chromophore with a photon followed by the subsequent emission of a lower ...
0
votes
0answers
112 views

Is this picture of the electron dipole moment correct?

It's the electron spinning on its axis, and a magnetic moment shoots up. The direction of the North-South is opposite what I thought it should be. Why is the vector arrow pointing from North to ...