Dipole Definition and 796 Threads

Homework Statement A dipole of moment ##\vec{p}## where p is fixed, moves with velocity ##\vec{v}## though a magnetic field ##\vec{B}##. Show that the force on the dipole is ##\vec{v}\times(\vec{p}\cdot\vec{\nabla})\vec{B}+\dot{\vec{p}}\times\vec{B}##. Homework Equations...

Homework Statement An electric dipole with charge ±q is separated by distance d. This dipole is enclosed in a spherical space of radius r = a such that the center of the dipole is located at the origin and the entire dipole in encased in the space. In other words the charges are at ±d/2 and a...

Homework Statement Hello everyone, I am new here and have a question regarding method of images in my electricity and magnetism class. I need help to even get the ball rolling. The question is as follows: a) What is the image of a dipole, oriented toward the center of the conducting sphere, if...

So, I'm trying to plot a 3D "dipole" (an arrow with a small torus around it basically) in mathematica, and want to rotate it according to Euler angles... I use this code for the rotation matrix: rot[a, b, g] := RotationMatrix[g, {1, 0, 0}].RotationMatrix[b, {0, 1, 0}].RotationMatrix[a, {0, 0...

Homework Statement Two identical co-axial rings ,(radius R each) are kept separated by a small distance d, one of them carrying a charge +Q and the other a charge -Q. The charges are uniformly distributed over the respective rings. A point charge q is kept on the common axis of the rings, at a...

Homework Statement A dipole is centered at the origin, with its axis along the y axis, so that at locations on the y axis, the electric field due to the dipole is given by E vector = 0, 1/4πε0 * 2qs/y^3, 0 V/m The charges making up the dipole are q1 = +6 nC and q2 = -6 nC and the dipole...

In a uniform electric field if a dipole is slightly displaced from it's stable equilibrium position it executes angular SHM. What if a dipole is slightly displaced from it's unstable equilibrium position ,will it execute angular SHM?

in this video from time 1:20 to 1:24 he says we can treat the system of three charges as a dipole ignoring middle charge .I want to know why ?I mean just because r>>a how we can ignore the middle charge ?How is it relevant?

(2) Hi. I am having a problem with understanding how to approximate 1/R in the forms of equations written above. I took this equations from a blog, and it tells that I can use talyor polynomial. but I don't get there somehow.

Homework Statement Problem 3 from the attached photo Homework Equations p = qd The Attempt at a Solution I know the magnitude of the dipole moment is p = qd, where d is the distance between the 2 oppositely charged particles. I know the direction of the dipole moment vector is from - to +. My...

1. the problem goes like this : The energy of interaction of a classical magnetic dipole with the magnetic field B is given by E = −μ·B. The sum over microstates becomes an integral over all directions of μ. The direction of μ in three dimensions is given by the angles θ and φ of a spherical...

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 expansion for the potential due to a 2D line dipole (two infinitely-long line charge separated by a small...

Hi, I was wondering why dipoles are singled out as a separate section in my physics textbook. For instance, after discussing electric fields the textbook specifies what a dipole is, dipole moment, and the electric field for a dipole. Finding the e-field for a dipole would be the same as finding...

Note: Post edited by moderator: 1. Homework Statement Homework Equations I can't use voltage, nor polar coordinates (got to stick with cartesian). Cartesian vector form of Coulomb's Law The Attempt at a Solution

Homework Statement 2. Homework Equations [/B] Given in the question. The Attempt at a Solution [/B] For part a I obtained an expression for the the dipole moment: ##P(t)= P_0 cos(wt)## And therefore, for part b, I obtained the expressions ##\frac{dP}{dt} = -wP_0 sin(wt)## and...

Hello everyone! I'm stuck at an Electrodynamics problem and would be happy for some guidance 1. Homework Statement A magnetic dipole \vec{m}(t)=\vec{m}_0cos(\omega t) at the origin can be described by the current density \vec{j}(\vec{r},t)=-\vec{m}(t)\times\vec{\nabla}\delta(\vec{r})...

Dipole moment is the measure of strength of electric dipole and is equal to product of either charge and distance between two charges. P=ql but as we know when charges are close the force b/w them is strong n when they are far away force decrease. But in above equation strength increases with...

Homework Statement A solid sphere, radius ##R##,is centered at the origin. The "northern" hemisphere carries a uniform charge density ##\rho_0## and the "southern" hemisphere a uniform charge density ##-\rho_0##. Find the approximate field ##\mathbf E(r,\theta)## for points far from the sphere...

Homework Statement Evaluate the electric field of a hollow sphere with a dipolo , in a dialectric. See left figure.. Homework Equations $$\alpha \vec{p}$$ The Attempt at a Solution I don't understad why at the field electric "in" there is a term of form $$\alpha \vec{p}$$ , and term $$\beta$$...

Homework Statement Find the equation of motion of a chain of atoms in 1D with alternating magnetic dipoles At stationary equilibrium the atoms of mass m are separated by d , all displacements are small compared to d Homework Equations U=μBx=2μ2(μ0/4π)(1/x^3) F(x)=-dU/dx The Attempt at a...

Hello, a dubt arose while doing some exercise. If I have a charge q at a distance d from the above-mentioned plane, i can find the solution to the laplace equations (thanks to the uniqueness theorems) finding a collection of image charges that satisfies the boundary conditions. These conditions...

In the books of electrodynamics by Griffith, He explain the physical view of the polarization inside of the dielectric matter. He try to make a picture polarized charge being offset near one. However, I wonder how the chage can be offset with other molecular but not with own proton. Definitely...

Homework Statement A square wire loop of size 2a by 2a lies in the x- y plane with its center at the origin and sides parallel to the x and y axes. A counterclockwise current I runs around the loop. (a) Find the magnetic field on the z axis. [Answer: Bz = 2μ0Ia2/[(a2 + z2)(2a2 + z2)0.5]] (b)...

Is an oscillating dipole of a molecule the periodic motion of the atoms in the molecule (the oscillating back and forth of a more negatively charged atom and more positively charged atom), or, is an oscillating molecular dipole just oscillations in electron density? I just can't get a clear...

Homework Statement This is problem 6.5 in Griffiths EM. I can't understand why dipole moment does not depend on coordinate systems. Homework EquationsThe Attempt at a Solution

Homework Statement You have been hired by Brockovich Research and Consulting (BRC) to research a new water purification device that uses seeds from the Moringa Oleifera trees.1 A protein in the seed binds to impurities causing them to aggregate so that the clusters can be separated from the...

Homework Statement Homework Equations Total electric field = Electric field caused by Q_1 + electric field caused by Q_2 ##\vec{e} = \vec{e_1}+\vec{e_2}## Dipole moment = ##P = Ql## The Attempt at a Solution **For Part A** ##\vec{E} = \vec{E_1}+\vec{E_2}## The charges are opposite so it...

Homework Statement Find the electrostatic attraction force F between a point dipole and an infinite metallic conducting plate. The dipole moment p is perpendicular to the plate and the distance from the dipole to the plate is h. Find the work that has to be done in order to move dipole from...

Homework Statement A dipole consists of charges +e and −e separated by 0.57 nm . It is in an electric field 2.6×104 N/C . What is the work required to rotate the dipole from being oriented parallel to the field to being antiparallel to the field? Homework Equations PE = (dipole...

According to the wikipedia article about the transition dipole moment: When an atom or molecule interacts with an electromagnetic wave of frequency , it can undergo a transition from an initial to a final state of energy difference through the coupling of the electromagnetic field to the...

I am "continuing this thread" in hopes of asking questions that deal with the meaning of the question. https://www.physicsforums.com/threads/griffiths-e-m-3-33-write-e-field-of-dipole-moment-in-coordinate-free-form.359973/ 1. Homework Statement Show that the electric field of a "pure" dipole...

I'm trying to build a high gain TV antenna. I'm looking to achieve a 75 mile minimum range under most weather conditions. I do have a signal amp board I striped from an OK antenna, that I plan to use as well. I'm trying to specialize the antenna for my viewing market, UHF channels 17-38 (489.25...

Consider a dipole antenna that is radiating at it's resonant frequency F. Consider an observer approaching this dipole antenna, in a direction perpendicular to the axis of the dipole, at velocity 0.6c. According to the relativistic doppler shift, the frequency perceived by the moving observer...

Homework Statement find the electric dipole moment of the system shown in figure Homework Equations In the simple case of two point charges, one with charge +q and the other one with charge −q, the electric dipole moment p is: where d is the displacement vector pointing from the negative...

The E and B field lines of a dipole radiating EM waves looks like that (sorry for the poor quality) : What I wonder is how can we see that the amplitude of the fields decrease as 1 / r? When you look as such a picture it actually feels likes the amplitude should rises. The E field gets...

Hello, friends! I read that, if a dipole is centred on the origin, with the ##+q>0## charge in ##a>0## and the negative ##-q<0## charge in ##-a##, the field in a point ##(x,y)## of the plane is $$\mathbf{E}=k\frac{3pxy}{(x^2+y^2)^{5/2}}\mathbf{i} +k\frac{p(2y^2-x^2)}{(x^2+y^2)^{5/2}}\mathbf{j}$$...

Hi, friends! I read that the torque exerced by a uniform electric field ##\mathbf{E}## on a dipole with moment ##\mathbf{p}## is ##\boldsymbol{\tau}=\mathbf{p}\times\mathbf{E}##. Then the book, Gettys' Physics 2, explain that the work made to rotate the dipole around a fixed point is...

Hi all, I'm trying to understand how to calculate the time dependent expectation value of the atomic dipole moment for a superposition state, and I have a good guess to check with you. Say we have \psi = \frac{1}{\sqrt{2}} \left[ \psi _{100} + \psi _{310} \right] at t = 0. Then, for t > 0: \Psi...

Homework Statement A 45-m long wire is coiled so that it makes a coil containing 100 circular loops, one on top of the other. If the wire carries a current of 13 A, what is the magnetic dipole moment of the coil? 21 A·m2 6.7 A·m2 3.3 A·m2 2.6 A·m2 1.2 A·m2 Homework Equations B(z) = u0/2pi...

Homework Statement ; attempt and equations[/B] Many times I face problems with a wire loop with some current (which may or may not depend on time, which may or not move) "flowing" in it. And I'm asked to calculate the radiation due to it. So using the multipole expansion I know that the dominant...

Do mono-nuclear molecules have dipole moment? If yes then, what type of dipole moment? why do they have (or do not have) dipole moment?

It is NOT a homework question. I am doing my revision and get stuck at this question. I am confused with the angle θ shown in this link: http://www.physicspages.com/2013/10/06/mutual-inductance/ Professor who wrote this solution stated that θ is the angle between unit vector z and unit vector...

http://www.physics.sjsu.edu/becker/physics51/images/28_03_Earth_magnetic_field.jpg If this is your magnetic dipole and you start at the north end and follow a field line to the south end, is the magnetic field equal in magnitude the entire way through?

For some reason, I'm having trouble with what I feel should be a relatively simple derivative to take. Feynman is differentiating the potential to find the z-component of the electric field. He has: -\frac{\partial \phi}{\partial z} = - \frac{p}{4 \pi \epsilon_0} \frac{\partial }{\partial z}...

Do temporary dipole moments require energy to form? I'm talking about Van der walls and London forces. If temporary dipole moments don't require energy to form then consider the free electrons in a metal plate, temporary dipole forces in the metal act on the free electrons causing them to gain...

Why is the dipole moment directed from negative to positive ?

I am looking for a reference describing the far-field electric and magnetic field of a dipole. However, I want a general formula for an arbitrary scalar function, and not specifically the usual formula which assumes a continuous sinusoid: $$ \mathbf{B} = -\frac{\omega^2 \mu_0 p_0 }{4\pi c}...

Hello Everyone, I have been recently calculating the static electric dipole polarizability αD of a polar diatomic molecule, but I was wondering how to calculate the components of the dipole polarizabilities αParallel and αPerpendicular of diatomic molecules? Any help is really appreciated...

Are photons emitted from the stationary protons in a dipole antenna? The protons don't accelerate at any point but their electric field does contribute to the electromagnetic wave.

Hi Ok I have a contradiction in my mind: Patch antenna is called a leaky wave resonant cavity because of the magnetic slots which radiates. We all agree on the fact that they are standing waves with clearly identified max and min as a characteristic of a specific mode inside this cavity...