# Questions tagged [dipole]

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### Electric potential and force in terms of Rydberg

Given charges +Q and +q, separated a distance r[nm], find the electric potential and repulsive force. I am given a solution to a problem that is evaluated in terms of the Rydberg energy, but I don't ...
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### Physics of an electrostatic water pump, is it even possible?

I have been trying to figure out how to approach this problem. Imagine a cylindrical shell made of insulating material. The top surface has a hole in its center, with a pipe extending up. The bottom ...
• 5,113
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### Calculate the force acting on a dipole at an electric field [closed]

I have the following question: There are two electric charges at $(-a,0,0)$ and $(a,0,0)$ with the charge $Q$. A dipole with dipole moment $\vec{P}_{el}$ is placed at $(0,0,0)$ and is oriented in the ...
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### Is there a similar process like hysteresis for dielectrics/dipoles?

Hysteresis is shown in the following image from hyperphysics: Does a similar curve exists for dipoles? For example given a dielectric medium inside a capacitor, the electric field will induce a ...
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### DC Bias Characteristic of Ceramic Capacitors under Transient

It's pretty well documented that many ceramic capacitors will "shed" capacitance with increasing DC bias. Seems that the mechanism is pretty well outlined too. (The physics behind DC voltage ...
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### Confusion about exact electrostatic potential of a pure dipole [duplicate]

I asked a version of this question before but the phrasing was unclear, so don't mind me please. Suppose you have a physical dipole with equal and opposite charges Q and -Q, with a specified dipole ...
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### Electrostatic potential due to a pure dipole

For a pure dipole, is the electrostatic potential given by the dipole term in the multipole expansion exact for all $r$ (position vector from the origin)? Or is it exact only far away from the dipole? ...
• 331
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### What will happen when external magnetic filed disappear suddenly in Larmor precession?

Larmor precession is a phenomenon that when we place a magnetic dipole in the external magnetic field, the magnetic dipole will rotate around the direction of the magnetic field. But I am not quite ...
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### Charge density of Hertzian dipole

I am wanting to find the charge density of an infinitely thin Hertzian dipole, but am struggling evaluating the Dirac delta functions gradient. $$\vec{J} = I_{0}\cos(\omega t) \delta^3(r) \hat k.$$ ...
• 3,705
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### Force between two dipoles [closed]

I am extremelly confused with this question: Basically suppose we have two electric dipoles, parallel to each other, as follows in the figure: I am supposed to show that the force is attractive and ...
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### About applicability of Gauss’ law in electrostatics

While reading about Gauss’ law in electrostatics, I saw that we do not apply this law to evaluate the fields generated by dipoles, quadrupoles etc. It is only applicable to cases where the fields fall ...
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### Multipole Expansion Intuition

So my intuition of the multipole expansion is that we have a certain charge distribution, and the ME tells us that we can approximate that distribution as a superposition of monopoles, dipoles, etc. ...
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### Griffiths and Multipole Expansion, what is each variable in the equation?

Griffiths defines the formula for the multipole expansion as $$V(\mathbf r)=\frac{1}{4\pi\epsilon_0}\sum_{n=0}^\infty\frac{1}{r^{(n+1)}}\int(r')^nP_n(\cos\alpha)\rho(\mathbf r')\,d\tau'.$$ But I am ...
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### Is an expression of a quadrupole as an expansion of dipoles possible?

Would it be possible to express a quadrupole as an expansion of dipoles? Because a possible definition of a quadrupole seems to be: an electric field equivalent to that produced by two electric ...
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### Why should a dipole have zero net charge?

Why can a dipole not have two unequal charges separated by a distance? Is there any significance for the dipole being defined as electrically neutral?
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### Line integral across perfect dipole

In problem 4.7 of Griffiths' "Introduction to electrodynamics, 4th Edition", we are asked to find the potential energy of a dipole in an electric field, $\vec{E}$. In the solution, the ...
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### Electromagnetic energy from a dipole antenna

Looking for references on previously done analytical development of the radiated field very close to a dipole antenna. I am not interested in a spherical coordinate system-based analysis, because that ...
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### Why can a magnetic dipole have an energy in the magnetic field?

It is well known that the energy of a magnetic dipole in the magnetic field is given by $$V = - \vec \mu \cdot \vec B$$ But I wonder how there can be a concept of energy at all. You can imagine the ...
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### Why half-wave dipole is the most efficient one in comparison to other electrical lengths?

I have a problem on the understanding of a half-wavelength antenna. Namely, why is the half-wave antenna has a highest power emission. Considering Far Field factor F($\theta$), which is known from the ...
1 vote
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### Electric dipole moment of a ring of charge [closed]

In my book dipole moment is defined for two charges. But I got a hw question to calculate dipole moment due to a ring. I tried two different methods to solve this problem but I don't think that any ...
According to this paper, the potential of any point on the surface at a distance '$h$' from the center of some simple conducting geometric shape is given by For a Sphere: V(x)=Mh^2\frac{xcos(\alpha)+...