# Questions tagged [dipole]

The tag has no usage guidance.

384 questions
Filter by
Sorted by
Tagged with
7k views

### Why there is no dipole gravitational wave?

I have read that "thanks to conservation of momentum" there is no dipole gravitational radiation. I am confused about this, since I cannot see the difference with e.m. radiation. Is this due to the ...
3k views

### Why is dipole the simplest source in electrodynamics?

I see this sort of statement in many materials, for example this: The smallest radiating unit is a dipole, an electromagnetic point source. and this: The simplest infinitesimal radiating ...
3k views

### In the Lennard-Jones potential, why does the attractive part (dispersion) have an $r^{-6}$ dependence?

The Lennard-Jones potential has the form: $$U(r) = 4\epsilon\left[ \left(\frac{\sigma}{r}\right)^{12} - \left(\frac{\sigma}{r}\right)^{6} \right]$$ The (attractive) $r^{-6}$ term describes the ...
1k views

### Do neutrons exhibit momentary small charges due to the movement of its quarks?

So in a similar way to electrons moving in atoms, causing induced dipole-dipole interactions, can neutrons momentarily attract or repel?
762 views

6k views

### What is the origin of the Dirac delta term in the dipole electric field?

I am a bit lost how one has deduced the formula for electric field with electric dipole because of some inconsistency between different sources. The Wikipedia article contains a delta function in the ...
2k views

### Meaning of the phrase “dipole moment of the combination”

Here is a question I came across in a book: Three point charges $-q$,$-q$ and $2q$ are placed on the vertices of an equilateral triangle of side length $d$ units.What is the dipole moment of the ...
2k views

### Will there be any force of attraction or repulsion between an electrified body and a non-electrified body?

Up to my knowledge an electrified (charged) body can attract a non-electrified (neutral) body. I thought this because, when we bring a charged (suppose negatively charged) body near a neutral one. ...
331 views

### Is there a finite-sized charge distribution whose electric field is *exactly* that of a point dipole?

This kinda gets lost in the telling when electric dipoles are introduced in textbooks, and it ends up causing a good deal of confusion (as in e.g. this recent example). Point electric dipoles, and the ...
391 views

### How do you fit a dipole in an electron?

Experiments used to observe particle spin properties (such as Stern-Gerlach) rely on a varied magnetic field and a dipole-like reaction in the particle, deflecting it in one direction or another. In ...
88 views

### Definition of electric polarisation and the potential due to a polarised body

I've two questions, the second one depends on the first. $\mathbf{1}$ How exactly is polarisation defined? Griffiths says $\mathbf{P} \equiv$ dipole moment per unit volume How exactly do we go about ...
19k views

### Force between two point dipoles

What would the force between two parallel point dipoles be? I was thinking of doing it the way force between two point charges is found out, by finding the field and then the force but I am not able ...
146 views

### Direct detection of the electric field of an electromagnetic wave from an oscillating dipole

The principle behind the detection of gravitational waves is that stellar-mass sources can act as coherent oscillators, producing a gravitational wave with a well defined, and relatively slowly ...
4k views

### Difference between a “source dipole” and a “force dipole”

I know quite well what a dipole is and in general what multipole moments are (in the context of, for instance, electrodynamics). What I find myself confused by is something called a "force dipole" in ...
364 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 ...
4k views

### What do we mean with magnetic monopole and dipole?

What do we mean with magnetic monopole and dipole? I can not find a way to relate magnetic monopoles and dipoles with electric ones. I do not understand their outcomes. Also,what is their role in ...
111 views

### Energy of magnetized vs not magnetized ferromagnet?

A ferromagnet conststs of many, many microscopic magnetic dipoles that can be pointed in different orientations. If the ferromagnet is not magnetized by applying an strong external magnetic field, the ...
5k views

### Derivation of Interaction energy of Dipole - Induced Dipole Interaction

I see that the formula giving the potential (interaction) energy of a dipole and an induced dipole is $$V=-\frac{C}{r^6}$$ where $$C=\frac{\mu_1^2 \alpha'_2}{4 \pi \epsilon_0}$$ and that the formula ...
201 views

### What is a neutron's polarizability?

It is undergraduate textbook level knowledge that atoms are polarizable – that is, they become electric dipoles in electric fields due to the deformation of the electron wave function(s). ...
101 views

### A Classical model for diamagnetism

I'm trying to derive a classical model to describe diamagnetism, and I'd like to understand if it is possible to understand the basic properties of diamagnetic materials with it i.e.: ''A diamagnetic ...
179 views

5k views

### Why does the field of an electric dipole drop off as $1/r^3$?

Electric field of a point charge drops off inverse squarely but that of a dipole varies as $1/r^3$. Why the field drops off more quickly for a dipole?
211 views

### 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 ...
2k views

### Why does the dipole moment depend on the distance?

Why does the dipole moment of an electric dipole of different charges depend on the distance from the origin? Physically, I don't understand why something that measures how much of a dipole something ...
2k views

### What is the charge density of a pure electric dipole?

I've only found two definitions of the charge density of a pure electric dipole: $$\rho(\vec{r})=\vec{p}\cdot\nabla\delta(\vec{r}-\vec{r}_0)$$ and \rho(\...
349 views

### Intuitive explanation of difference in $r$-dependence between dipole and monopole

For an electric monopole, its potential scales with $\frac{1}{r}$, where $r$ is the distance from the point of interest to the charge. However, for a dipole, its potential scales with $\frac{1}{r^2}$. ...
This question came in my physics test: Charge density in a one dimensional space is given by $\rho=Q[\delta(x-x_0)-\delta(x+x_0)]$. The electric field due to this charge distribution at point (2$x_0$,...