All Questions
Tagged with electric-fields dipole
116
questions
2
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Dipoles as vectors
A triatomic molecule $X_2Y$ has plane structure as shown in figure. Due to difference in electronegativity, charge acquired by each X atom is $q$ and charge on Y atom is $- 2q$. The bond length ...
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2
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Potential of an electric dipole
I'm currently working my way through Griffith's Introduction to Electrodynamics (4th ed).
In chapter 3 section 4, he shows that we can take the equation for the electric potential of a continuous ...
2
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2
answers
378
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Dielectric and dipole
When a molecule of a dielectric material is placed in an electric field, the molecule acquires an electric dipole moment. Why?
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0
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17
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Time average of product of 2 function with same frequency
Hi I'm Reading a notebook on "light atom interactions"
There is this calculation I don't understand of average power -
$$P=\overline{-\boldsymbol{E} \cdot \frac{\mathrm{d} D}{\mathrm{~d} t}}=...
2
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0
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57
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Do neutral atoms have an electric field? [duplicate]
The charge of an atom is the sum of its nuclear charges (protons and electrons). If a atom is neutral, does it mean it does not have an net electric field?
I thought about this a lot, here is some of ...
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1
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What's the Lagrangian of an electric dipole in an external electric field?
I took electromagnetism a while ago, but now that I took Lagrangian and Hamiltonian mechanics, this question came up to me when I imagined an electric dipole in the presence of a uniform electric ...
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How did the scientist measure the dielectric constant? Does the dielectric constant relate to an alignment with the electric field?
I heard that the dielectric constant of water is around 78. When we think about the way we get the $\kappa$ of water,
Can we get the $\kappa_{water}$ by putting the water molecules on the $\vec{E}_{...
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3
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78
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Why can't the two charges in an electric dipole exist independently in an uniform electric field?
Why can't the two charges in an electric dipole exist independently in an uniform electric field? What I mean is, why should they behave as if they are connected together by a rod between them? What ...
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Potential energy of an electric dipole without any external field
What is potential energy of an electric dipole without any external field?
If its 0 then why? Wouldn't the charges get attracted thus do work so they must have some potential energy.
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2
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$\vec{E}$-field in toroidal polarized dielectric
In an electrostatic situation, imagine a dielectric torus that is permanently polarized with polarization given by:
$\vec{P} = P(r, z) \hat{\phi}$
(Here cylindrical coordinates are used with the $z$-...
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2
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660
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Dipole approximation
I am studying the "dipole approximation" as is defined in quantum optics. (See, for example Introductory Quantum Optics by Gerry and Knight, pages 24–25.) In this situation, we have the ...
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98
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In Maxwell's equations concerning dielectric materials , does the electric field represent the external electric field or the net electric field?
Let's assume we have dielectric material and we apply an external electric field that acts on it (let's call it Ex ) . As a resault we get dipoles who in turn create another electric field (let's call ...
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66
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Electric Field Lines - Why do we draw such lines for dipole?
In a dipole case (1 proton / 1 electron), we draw $E$ field lines such as they go and move into the negative charge. If we take an example point near negative charge's upside vertically, we see there ...
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1
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223
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How and why potential energy is stored in a dipole in uniform electric field?
I learnt that potential energy is stored in a dipole in uniform electric field when it is rotated from theta = pi/2 to any other theta, and the magnitude of stored potential energy can be found out by ...
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251
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Electric field of dipole antenna
I have seen that the electric field of a dipole antenna detaches and propagates.
For a section of the detached electric field, will the antenna experience recoil if the detached field moves a charged ...
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3
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124
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How do I renconcile electric potential and field of a dipole along its perpendicular bisector?
It's been a while since I've studied electrostatics and is my first time posting here, so please forgive me if I'm missing something basic.
According to my reference book, the electric potential of a ...
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99
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When deriving work from an uniform electric field and dipole why do we need to integrate it?
If the force is constant in a uniform field wouldn't that mean you dont need to integrate to find work?
user361546
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1
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A rigorous derivation of the EOM for a charge in a dipolar field
I've given the following question (and solution) to a class I am TAing for. The question is from Zangwill (Prob 4.5) and, for further reference, Zangwill cites R.S. Jones, American Journal of Physics ...
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1
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53
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The intepretation of $d$ in $p=qd$
In Griffiths Example 4.1, the author derived the polarizability of a uniformly charged spherical cloud with radius $a$. For an external field $E$, the electron cloud will shift to the left with a ...
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105
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What is the $\frac{1}{r^2} $ term in the electric field of a Hertzian dipole equations?
Taking common equation for the electric field of a Hertzian dipole from Wikipedia:
$${\displaystyle {\begin{aligned}E_{\theta }=i{\frac {\zeta _{0}I\delta \ell }{4\pi }}\left({\frac {k}{r}}-{\frac {i}{...
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239
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In General Relativity can electric field-induced tension in a Bose-Einstein Condensate reduce the energy needed to create an anti-gravitational field? [closed]
This is my theory showing how an electric field can create an anti-gravitational field. It is based on Einstein's General Relativity (GR), and the ability of an electric field to induce tension in ...
2
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2
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I can't seem to figure out a way to compute a gradient without reference coordinates
I'm not sure if this question is better asked here or in Mathematics but here it goes:
I'm studying electric dipoles, and this exercise I'm working on asks for the energy between 2 dipoles, given by $$...
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0
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33
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What is the shape of the electric field lines of a pair of newly formed charged particles?
I am trying to visualize the field lines of the spontaneous creation of a pair of oppositely charged particles. Initially, I imagined that they would look like those of a dipole with the two charges ...
user338734
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On Problem 2.2 in Griffiths' Introduction to Electrodynamics
In part (a) we were asked to find the electric field at a distance $z$ above the midpoint between two equal charges of magnitude $q$ that are a distance $d$ apart. I obtained the correct answer:
$$\...
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359
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Dipole potential and sphere grounded
Find the electrostatic potential arising from an electric dipole of magnitude $d$ situated a distance $L$ from the center of a grounded conducting sphere of radius $a$. Assume the dipole axis cross ...
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2
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461
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Electrostatic potential of a dipole in a non-uniform field
There are numerous derivations for the potential energy of a dipole in a uniform field as:
$$
U = - \boldsymbol{p}\cdot\boldsymbol{E}
$$
But does this hold also for non-uniform fields? Are there any ...
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0
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124
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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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2
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139
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How does zero electric field look like?
Imagine if we have an electric dipole inside a cube (a conductor). The net electric charge inside the cube is zero. Hence, using Gauss's law, the net electric flux coming out of the cube must be zero. ...
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Direction of electric field
When we place a positive test charge near a positive charge, it moves away from it. If there is a negative one instead, it follows a curved path. That is, the field of positive charges originates from ...
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Energy of dipole using the electrostatic energy of all of space
I was watching my online lecs, and we were considering the electrostatic energy of a dipole. First, doing the torque-in-uniform-field calculations, and derived that $U_{rot}= - \vec{p} \cdot \vec{E}$. ...
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Dielectric constant of crystals: Feynman's mistake?
Feynman mentioned in his lecture that we can, in some way, obtain dielectric constant of crystals by summing up the electric field due to dipoles. For example, equation (11.33) from above link shows ...
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435
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Doubt in the interaction energy of the dipole in an electric field
Consider a dipole ($\vec{p}$) in an electric field ($\vec E$) making an angle $\theta$ with the field.
We can see that $V_1-V_2=Ed\cos\theta$
In books, the derivation for the interaction energy of ...
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732
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What does "weak-field limit" mean when it refer to dipole and atomic polarization?
In Griffiths' book, Introduction to Electrodynamics 3rd, problem 4.3,it requires me to find the condition on ρ(r) such that equation $p = αE$ will hold in the weak-field limit. The answer gives $ρ（r）=...
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142
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Can a dipole keep rotating with increasing angular velocity?
Let's say, we have a dipole and we know if we keep it in uniform electric field it allines it self along the electric field direction.so can we some how make an arrangement to rotate it indefinitely ...
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What does this variable coefficient represent of electric field of dipole?
$V:=\text{potential at point P}$
$V=\frac{2Qd\cos(\theta)}{4\pi \epsilon_{0}r^{2}}$
$E_{r}=-\frac{\partial V}{\partial r}$
$E_{\theta}=-\frac{1}{r}\frac{\partial V}{\partial \theta}$
The problem for ...
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How to interpret bound charges geometrically?
Conceptually, it makes sense to say that when there is an electric field along $E=E\hat{n}$, then given a polarization $P$, the amount that $P$ aligns with the electric field is simply the dot product ...
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1
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101
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Uniform electric field formation in motional emf induction
Why is the electric field $E$ across the ends of a conducting rod, when it's moved with a uniform velocity $v$ in a magnetic field $B$, uniform? Wouldn't it vary non-linearly, since there are opposite ...
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358
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Electric field due to a dipole sheet
The potential due to a dipole sheet, $S$, having dipole moment density, $\vec\tau$ (per unit area), is given by
$$
\phi(\mathbf r) = \frac{1}{4\pi\epsilon_0}\int_S\frac{\vec\tau(\mathbf r')\cdot(\...
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Confusion over Gauss' law for an ideal electric dipole
To find the charge density of an ideal electric dipole centred at the origin, I can evaluate the divergence of $\vec{E}(\vec{x})$ which equates to evaluating the laplacian of the potential.
Working ...
user161157
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1
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54
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Would this be divergenceless?
If I were to put two charges of opposing polarity next to each other (a finite distance away but not superimposed on each oter) and would then take the divergence of the whole $E$-field, would that be ...
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How possible is using complex variables to model the electric field system of a dipole? [duplicate]
If one considera a dipole system, is it possible to model the system using complex variables and if ao, how can we use complex analysis to model it? I have the idea that we can model dipole moment as ...
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33
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How do I calculate the electric field of a dipole after passing through a collecting lens with a given NA?
How can I make the (far field) electric field of a dipole dependent on the numerical aperture of a collection lense it is passing through?
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253
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A Dipole in an External Electric Field
We can derive that, the potential energy of a dipole in an external electric field is
$$U=-\mathbf{p}\cdot \mathbf{E}$$
And Work done by the field on the dipole is
$$W=\mathbf{p}\cdot\mathbf{E}$$
Here,...
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Why is an electric dipole neutral overall and still has energy?
We are taught that only charged particles have an electric field in their vicinity and a neutral object does not. But a dipole is neutral overall and still produces an electric field. Why?
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245
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Do neutrons in a strong electric field show a small dipole behaviour?
As neutrons are neutral an electric field should not attract or repel them. However, as they are composed of a positive and a negative part, called one 'up' and two 'down' quarks, shouldn't those ...
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84
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How do we take angles in the limits of integrals in Physics?
I am looking at the following derivation of the potential energy of a dipole in a uniform electric field, paraphrased from phys.libretexts.org:
Consider an electric dipole $p$ placed in a uniform ...
2
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1
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916
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Angle between dipole moment and electric field
I was learning the potential energy of a dipole because of torque from Halliday Resnick. In the given diagram, it said that if we move the system anticlockwise then the amount the Work that was done ...
user265103
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4
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Potential Energy of a Electric Dipole
I am trying to derive the potential energy because of torque in a dipole placed in a uniform electric field. But the answer I am getting is different from the answer I saw everywhere. So could someone ...
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Electric field in matter- Bound Charges why the term $\rho_b$ exist?
I am reading the book of Griffiths, Introduction to electrodynamics, and he explains in this chapter about the bound charge densities $\sigma_b$ and $\rho_b$
but I do not understand how is it possible ...
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Electric field outside a conductor
Say there is a conducting cylinder in a uniform external field. The charges on the cylinder surface will distribute and create a surface charge density.
Is there any reason the charge density would ...
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