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2answers
33 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
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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
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1answer
20 views

Since a dipole has some potential energy,it should be able to do some work !? What is it?

We say a dipole has potential energy.What work can a dipole do ?.For eg : A ball on a shelf has a PE because it has the potential to fall down and do some work on the ground if shelf wasnt there.What ...
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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
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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 ...
6
votes
1answer
60 views

How do temporary dipole-dipole interactions work in quantum mechanics?

The standard presentation of temporary dipole-dipole interactions (in high school at least) is classical: the electrons in an atom/molecule 'orbit' around its nucleus/nuclei. As a direct result of ...
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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
1answer
41 views

Dipole in electric field

An electric dipole is placed in a uniform electric field at some angle, say 90 degrees. The dipole consists of 2 charges, one negative and one positive. The charge which is positive will have a torque ...
0
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1answer
61 views

Electric potential of dipole

We have proton and electron and distance between them is $d$. If we choose $z$ axis along this dipole, net electric potential created by dipole on the point A is equal to summation of the electric ...
1
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1answer
61 views

Total dipole moment of three charge system [closed]

Consider three charges located on the $z$ axis: two $+q$ charges are located at $\vec{r}=\pm{a}\hat{z}$ and the third charge of $−2q$ located at the origin. I am trying to find total dipole moment of ...
1
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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
2answers
54 views

The Strength of the Tangential and Radial Components of a Dipole Magnetic Field

I am following along well several textbooks (Geophysics) that helps me understand the in-depth physics behind the magnetic field of a dipole magnet. I understand that the basic magnetic potential ...
0
votes
1answer
25 views

Dipole-dipole field

Assuming that we have two parallel and exactly identical electric dipoles. How does bringing them together change their frequency? What would such field look like (how would they interact)? In fact, ...
18
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2answers
1k 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 ...
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
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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?
1
vote
1answer
66 views

Figuring out the orientation of a dipole and its distance from a point charge

The problem assigned is this: A dipole is centered at the origin of a coordinate system, and a small charged sphere is some distance away along the perpendicular bisector of the dipole. The particle ...
1
vote
1answer
26 views

Vanishing dipole radiation of equidistant point charges on a ring

I learned that if I distribute point charges uniformly on a circle and let them run along the circle with the same constant speed, the dipole radiation of that configuration vanishes. However, moving ...
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
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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 ...
2
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2answers
224 views

Physical meaning of electric dipole moment [closed]

I am reading about the electric dipole moment. What I can't understand, and seems that no one cares to explain, is what is the physical meaning of it. To my understanding everytime that dipoles are ...
0
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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 ...
1
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1answer
41 views

Where does the net charge on a hemisphere appear to act from?

I was wondering if, like centre of mass, there is anything called "centre of charge".
2
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4answers
594 views

Dipole in a spherical cavity in an infinite dielectric

In this example the assumption is made that inside a spherical cavity (with an infinite dielectric) with a dipole placed at its centre, the potential takes the following form: $$\phi_{in}= \frac{p ...
0
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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
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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 ...
2
votes
0answers
46 views

Lorenz Gauge Dipole Potentials Formulation In SI Units? [closed]

After hunting in vain* for a documented closed form solution (ie: no integrals or differentiation in the formula) for $\phi$ in terms of A under the Lorenz condition, of an electrically short dipole ...
0
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0answers
14 views

Charge distribution [duplicate]

a) There's a radially symmetric charge density $\rho(r)$ centered around the origin. Determine the dipolemoment of that charge density. b) Let $\rho(r)$ be an arbitrary charge density now. ...
2
votes
1answer
97 views

Do Dipole Moments Obey Superposition?

Essentially, I have two surfaces which I know how to find the dipole moments for. I realize that $V_{dip}(r) = \frac{1}{4\pi \epsilon_0 r^2} \mathbf{\hat{r}} \cdot \int \mathbf{r'} ...
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
2answers
245 views

Why is the potential energy of a dipole in an electric field zero when the dipole points perpendicularly to the field?

I have read that potential energy of a dipole in an electric field is taken to be zero at 90 degree as they say that it is a reference. But there must be some reason behind it?
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 ...
2
votes
1answer
150 views

Vector Potential Oscillating E Field of the “Null” Field of a Hertzian Dipole?

The vector potential of a Hertzian dipole falls off spherically as $1/r$. The polar axis of the dipole is a "Null" field -- meaning no electric and magnetic field. The absence of magnetic field is ...
0
votes
1answer
100 views

Spontaneous radiative decay due to electric dipole radiation

In my textbook, we calculated the rate at which an electric dipole radiates energy to be $Pwr = \frac{1}{4\pi \epsilon_0}\frac{2}{3c^3}\left(\frac{d^2 p}{dt^2} \right)^2$ where p is the dipole ...
0
votes
1answer
35 views

Help with this question (Eletric Fields, Dipole) [closed]

The answer in the textbook in the solutions manual is the following: I didn't undestand the last step. He said he did a binomial expansion, I just can't figure out! Appreciate any help.
1
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2answers
86 views

Entropy reversal in magnets

Entropy is an irreversible phenomenon without any energy supplied to reverse it. I was reading about paramagnetic substances and how dipoles align inside them on application of magnetic field. My ...
0
votes
1answer
362 views

Are muscle cells electric dipoles?

I'm wondering how we can detect the electrical activity of a muscle cell. My initial thought on this question was that the membrane potential, around $\Delta V_{\text{membrane}} = -80mV$ across the ...
0
votes
2answers
127 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 ...
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 ...
2
votes
2answers
378 views

What is meant by 'a perfect dipole'?

Question What is meant by a perfect (electric) dipole? Additional information I came across the term in this question Force from point charge on perfect dipole and also in a textbook (which does ...
0
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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 ...
2
votes
3answers
389 views

Why does the Electric Field of a dipole have no $x$ component?

According to the solution $2E\sin(\theta) = E_{net}$. I understand how the dipole works but I don't understand why the x component would be 0?
-1
votes
1answer
353 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 ?
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 ...
1
vote
1answer
204 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?
0
votes
0answers
65 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 ...
1
vote
1answer
129 views

How does one calculate or even approximate the force observed by a magnet as its dropped inside of a diamagnetic cylinder?

How does one calculate or even approximate the force observed by a magnet as its dropped inside of a diamagnetic cylinder? Wikipedia and Google does not provide much information on this topic. ...
2
votes
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
1answer
358 views

dipole field on axis twice the field on perpendicular bisector

Why is the dipole field on axis twice the field on perpendicular bisector? For the perpendicular bisector: Lets assume -q is right from of the origin and +q is left from the origin, both a distance a ...