Dipole Definition and 796 Threads

I'm going to explain my understanding about a bit of a contradiction I can't resolve, and I was hoping somebody could help me understand it. Sorry about the bombardment of vector components! There appears to be two methods we can use to calculate the force (effectively the same in fact, but...

Why aren't positive and negative charges attracted to each other?

Homework Statement An electric dipole with -q at the clouds of height h, and +q beneath the surface with height -h. Given q=200 C, and h=6000m Electric discharge occurs with electric field of 3000 V/m near ground level, and 200 V/m above the clouds. Find the ranges where discharges are...

In one moment in time you have a charge going about in a circle of radius r. in another moment in time the charge goes in the same circle but faster, where Δv is the difference in speed. i want to find the change in the magnetic dipole moment Δm.if magnetic dipole moment m=IA (assuming uniform...

Hi, I have been trying to get the expression for the transition dipole moment of hydrogen but I am not able to get the expression. Hope someone can help me with that. I want to evaluate \vec{d}(v)=<v|\hat{r}|0> where v is the free state and 0 is the 1s wave function for hydrogen...

Homework Statement An electric dipole consists of a pair of equal but opposite charges, +Q and -Q separated by a distance d. What is the electric potential at the point that's midway between these source charges? Through using the formula electric potential = kQ/r, I found the electric...

Hi all, Just a quick theory based question regarding the Zeeman Effect. The effect of the applied magnetic field in the Zeeman effect separates the possible angular momentum states (each of which has a magnetic dipole associated with it) into different energy levels. However, if the...

I just wanted something to play with so I thought of this problem and solved it but now I have questions about it. Consider a charged particle with charge q and mass \mu which is constrained to move on the surface of a sphere of radius R. There is a magnetic dipole with moment \vec m=m \hat z...

Are there any experiments or theories about the relation between magnetic dipole moment orientation and velocity vector of free electrons?

Why do we take Θ=90° for calculation of potential energy

When the dipole makes an angle with an electric field, its potential energy is given as the work done in bringing the dipole from the position, when it is aligned with the electric field direction, to a desired position, i.e W = pE [-cosθf -(-cosθi)] ...eq(1) p = moment of the dipole...

I'm developing a classical model of a dipolar ion in an external electric field. It consists of two charges ##\delta_+## and ##\delta_-##, located at a fixed distance from each other. For the special case I'm considering, I end up with the potential energy $$ (\delta_+ + \delta_-)...

So, I've got a charge distribution given by: \begin{equation} \rho(r,\phi,z)=\frac{q}{2\pi R}\delta(r-R)\delta(z)\cos(2\phi) \end{equation} This, if I'm not mistaken, translates into a circular charge distribution located in the z-plane, a distance R from origo. Thus \begin{equation}...

In a dipole, p = qd is the dipole moment. q is the magnitude of either charge, while d is the distance of separation. I was just wondering what differences in properties would be evident if both charges in the dipole were not the exact negatives of each other. For example, if you have a positive...

Homework Statement I have a dipole in the electric field of a parallel plate capacitor. The plates are circles with radii r and they are at plus or minus d on the z axis. The coordinate system thus has the origin directly below/above the centres of the plates with x and y axes. I have to...

I've been trying to answer the following question, without success. Can someone help me here? A \lq\lq pure \rq\rq dipole is located at the origin and is directed to the +z-axis. a)Calculate the force on a point charge q at (0,a,0). b)Calculate the force on q if it is at (a,0,0). c)Calculate...

The PE of an electric dipole in an external E-field is U=-p.E where p is it's dipole moment. I was under the impression I could find U, and then easily determine the force on the dipole using F=-∇U, to obtain Fx=px∂Ex/∂x+py∂Ey/∂x+pz∂Ez/∂x Fy=px∂Ex/∂y+py∂Ey/∂y+pz∂Ez/∂y...

P.W. Anderson in his essay "more is different" said that: "no stationary state of a system has an electric dipole moment". He used an example of NH3 to illustrate that. I then checked online and found that, Chemists said there is dipole moment in NH3 molecule, but (nuclear) physicists claim...

From what I have been learning recently, a dipole is a separation of electric charges and in chemistry, a dipole refers to the separation of charges within a molecule between two covalently bonded atoms (which is caused from one atom having a higher electronegativity) What I don't understand is...

Homework Statement The Earth's magnetic dipole moment is 8.0 x 1022 A m2. (a) What is the magnetic field strength on the surface of the Earth at the Earth's north magnetic pole? You can assume that the current loop is deep inside the earth. 6.17e-5 T (b)How does this compare to 5.0 x...

Homework Statement The ammonia molecule (NH3) has a dipole moment of 5.0×10−30C⋅m. Ammonia molecules in the gas phase are placed in a uniform electric field E⃗ with magnitude 1.0×106N/C. What is the change in electric potential energy when the dipole moment of a molecule changes its...

In "An Introduction to Electrodynamics", Griffiths gives the following equation for the dipole moment: p=\int r' \rho(r') d\tau'. My question is, in general, what volume am I integrating over? It seems a bit arbitrary to me. I assume I'm integrating over whatever volume is enclosing the charge...

Homework Statement An electric dipole has opposite charges of 6.55⋅10−15C separated by a distance of 0.65mm. It is oriented at 54.0° with respect to a uniform electric field of magnitude 10.0⋅103N/C. Determine the magnitude of the torque exerted on the dipole by the electric field...

2 particles of charge q are placed at 2 vertices of an equilateral triangle of side a. An electric dipole is placed at the third vertex with its dipole moment orientated parallel to the opposite side of the triangle. a) Determine the magnitude of the torque on the dipole due to the electric...

Homework Statement Two identical permanent dipoles, each consisting of charges ##+q## and ##-q## separated by a distance ##s##, are aligned along the ##x## axis, a distance ##r## from each other, where ##r >> s.## a. How many external forces act on each dipole? Homework Equations...

Does anyone know how to calculate the magnetic field or flux of a uniformly moving magnetic dipole with magnetic dipole moment \vec{M} pointing along the direction of motion? Thanks

Homework Statement Build the lagrangian of a set of N electric dipoles of mass m, length l and charge q. Find the equations of motion. Find the corresponding difference equations. Homework Equations Lagrange function L=T-V Lagrange's equations \frac{d}{dt}\left(\frac{\partial L}{\partial...

i do not know why. does the magnetic moment of an atom come only from the spins of the electrons?

I just wondered how I transform electromagnetic dipole moments. For example assuming I have magnetic dipole moment μ in a frame without E dipole moment. Then I boost orthogonal to μ. Now I would like to determine the electric dipole moment. I could use the magnetic potential and transform...

This problem is originally from Wopho and its goal is to describe the trajectory of a point mass charge around a dipole. http://img18.imageshack.us/img18/2676/fvac.png First we have to calculate the radial and tangential electric fields made by the dipole (this I've done as well) but...

I have a dipole such as: \rho(\vec{r}) = q \delta(\vec{r} - \vec{a}) - q \delta(\vec{r} + \vec{a}) with \vec{a} = a \vec{e}_x. I have to show that the energy in a constant external field \vec{E} is: V = - 2 q \vec{a} \vec{E} My calculations so far: With the formula...

Hello, I have this matrix element \langle n', l', m'| x |n, l, m \rangle where x=rsin\theta cos\phi in spherical polars Which I write explicitly as: =\int \int \int R_{n', l'} R_{n, l} A_{l', m'} A_{l, m} P^{m'}_{l'} P^{m}_{l} e^{im\phi} e^{-im\phi} rsin\theta cos\phi r^{2} sin \theta d...

Hi, I an reading an interesting chapter of Feyman where he explains the basis of light-matter interaction with wave theory: http://cua.mit.edu/8.421_S08/Reading/Feyman_refr_index.pdf I didn't understand there one thing... to explain it he says that all the dipoles on the plate ''feel''...

Homework Statement 1. A wire of length L and carrying current I is bent into a square loop to form a magnetic dipole. This dipole is then oriented in a uniform magnetic field of magnitude B such that the dipole is in its lowest energy state. What is the value of the dipole's energy with this...

I had to clear this up since there were many threads with the wrong analysis of this problem. Lone pair electrons DO have and affect on dipole moments. Lone pair electrons do have an effect on the net dipole moment of a molecule. A dipole moment is the product of the magnitude of the partial...

Hi, I know that to receive or inject a signal into a rectangular waveguide (I'll just call it a waveguide from now on with the assumption that I mean rectangular waveguide), you can get a dipole of some sort, and poke it into the waveguide. What I'm wondering about is, if I got a dipole...

Homework Statement A point charge, Q, is "nailed down" on a table. Around it, at radius R, is a frictionless circular track on which a dipole \boldsymbol{p} rides, constrained to always point tangent to the circle. Show that the electric force on the dipole is (in the forward direction of the...

Homework Statement A dipole is centered at the origin, and is composed of charged particles with charge +e and -e, separated by a distance 7 ✕ 10-10 m along the y axis. The +e charge is on the -y axis, and the -e charge is on the +y axis. A proton is located at <0, 3 ✕ 10-8, 0> m. What is the...

imagine a door shaped circuit in the between a south and north pole such that the long sides are perpendicular to the magnetic field created by the magnet , now in my physics book , it says that the torque that rotates the door is equal to B * Md where Md is the magnetic dipole moment which...

Homework Statement Consider an electric dipole in the attached document. At point P, the fields E+ due to q+ and E- due to q- are: E+ = kq/(r-a)2, E- = -kq/(r+a)2 Then total field at P is: E = E+ + E- = kq [ 1/(r-a)2 - 1/(r+a)2] y-hat Homework Equations See question 1. The...

Homework Statement I'm going over some EM notes and I found a derivation for the potential energy of a dipole in an E field which first found the torque on the dipole and then integrated. I had a go at a derivation that goes the other way, starting from the potential of the 2 charges. I've ran...

Homework Statement A thunder cloud can be loosely modeled by two point charges -q and q at heights h and d above the Earth's surface with d > h. Model the Earth's surface as a conducting plane at z=0. Sketch the Electric field lines (on a plane perpendicular to the earth). Indicate the...

Consider we have a \Lambda type three level system, the one upper level is denoted by 3, and the two lower levels are denoted by 1 and 2. Assuming that the transitions between 1\leftrightarrow3 and 2\leftrightarrow3 are dipole alowed, while the transition between two lower states 1 and 2 is...

Homework Statement The relationship of dipole force and distance is noted by F ∝ ##d^{-3}##. One magnet is placed on a weighing scale and set the mass is set to equilibrium. Another magnet, with its positive end pointing down, is lowered from directly above towards the positive end of the...

So I am probably understanding something wrong but would gauss's law \frac{Qinside}{\epsilon0} for a sphere surrounding an electric dipole, with a point charge just outside of the sphere. If you imagine this scenario without the outside charge, the field lines through the surface all come...

the two energy level atom, whose hamiltonian takes the form \hat{H_A}=E_g|g\rangle\langle g|+E_e|e\rangle\langle e|, where E_g as well as E_e represent the eigenvalues and |g\rangle as well as |e\rangle denote the ground state and excited state. There is an interaction between the atom...

Homework Statement Hi everybody... i have a bad problem with my brain: starting from the Vectorial form of the magnetic dipole: \vec{B}(\vec{r}) =\frac{\mu_0}{4 \pi} \frac{3 \vec{r} ( \vec{r} \cdot \vec{m}) - r^2 \vec{m}}{r^5} Homework Equations i want to derive the spherical...

i have an intuition of electric field lines, and force. All quantities yielded from an operation between two quantities should hold meaning. what meaning does the value "q x d" hold? I'm looking for intuition/ an intuitive grasp of the dipole moment.

Hi does anybody here know whether there already exists a theory that describe Mie scattering for spheres that have a constant dipole moment?

I think everybody here knows the equation that gives the potential of a point like dipole, but how does the field look like if you have e.g. a metal sphere with radius $R$ and a certain dipol moment, how does this potential look like?