Dipole Definition and 796 Threads

Hi I have a question about the electric field of a dipole located at the origin. We know that the coordinate free form for the electric field of a dipole is \vec{\mathbf{E}}=\frac{1}{4\pi \epsilon_o}\frac{1}{r^3}\left[\frac{3(\vec{p}\cdot \vec{r})\vec{r}}{r^2}-\vec{p}\right] Now let...

hi i have two questions :smile:, that i cannot solve by my own: does anybody know how to calculate the potential energy of two quadrupole moments that are separated by a distance r?( i looked for it in all my physics books, but i did not find anything at all) and: if you have two...

Electric field of a dipole, two different equations?? Hi, I've been taught in uni how to derive the electric field of a dipole to be E= k p [2cos theta r(hat) + sin theta theta(hat)]/(r^3) where k=1/(4pi e0), p=qd= dipole moment, (hat) terms are unit vectors and r is the distance...

Hi, What direction does the electron's total magnetic dipole moment point relative to it's total angular momentum vector L+S? It seems to me that it would point oppositely to J=L+S since the spin magnetic dipole moment and the orbital magnetic dipole moment are both opposite to L and S, but...

Homework Statement write down an expression for the electric potential of an electric dipole at a large distance Homework Equations V=(qa cos(theta))/(4 pi epsilon r^2) The Attempt at a Solution is 'r' the distance they are talking about or is it 'a'? either way, if i substitute in...

does anyone know why the forces point in such a direction? basically, its a dipole (y-orient) in an E-field but why do the forces on the +q and -q slant as such? thanks

Can we use Gauss's Law to calculate the field distribution around an electric dipole?

Homework Statement An electric dipole placed in a uniform electric field experiences a torque which tends to align the dipole parallel to the field. At the same time, due to two equal and unlike parallel forces Eq and -Eq acting at q and -q, the net force is zero. When the net force is zero...

Homework Statement [PLAIN]http://img846.imageshack.us/img846/1269/img029z.jpg 2. The attempt at a solution My attempt and relevant equation is only there in the picture. I know how to find the electric field of an infinite plane np, gaussian pillbox etc. im not sure what role...

Explain how an atom may have a permanent magnetic dipole moment? Many thanks...

Hello everyone, I'm a bit confused about electric dipole radiation. In my E&M book "Intro to Electrodynamics" by David Griffiths, it states that the electric field from an oscillating dipole is in theta hat direction. Mathematically I have the proof as to why in my book, but conceptually I'm...

Electric Dipole and Electric Potential.. and binomial approximation! Homework Statement An electric dipole at the origin consists of two charges +q and -q spaced distance s apart along the y-axis. a.)Find an expression for the potential V(x,y) at an arbitrary point in the xy-plane...

This is part 2 of problem 4.8 from "Physics of Atoms and Molecules - Bransden, Joachain" Homework Statement Deduce [4.106] from [4.105] Homework Equations \tilde{M}_{ba} = - \frac{m\omega_{ba}}{\hbar c} \langle \psi _b \vert z \dot{x} \vert \psi _a \rangle [4.105]...

I am participating in a reading course on nonlinear optics, which is a little difficult since I haven't had any formal education in quantum mechanics other than the standard introductory solving of Schroedinger's eqn. in 1D. Happily this course takes the semiclassical approach, in which the...

Can someone help me with the derivation of the electric field at any point around a dipole. I DO NOT want the dipole moment to be resolved into components and then the field found out. I want it in terms of charge q (+q and -q constitute the dipole), a (2a being the charge separation), theta...

Hi, I had this question in my homework: An electric dipole consists of two equal loads and signs opposite separated by one distance which equals 2a. Show how the module of the electric force resulting on a proton (load +e) placed directly on the Y=axis at a very long distance from the dipole...

Homework Statement Charges + and -q are placed at -1cm and 1cm along the y axis. If their electric potential energy is -45microJ, what is q? Homework Equations U=qV V=Es The Attempt at a Solution I got an equation for the electric potential between the two charges, but it was...

Let's say I have a point dipole (as an approximation for an atom) at the origin and it oscillates in the z axis. The (theta component of the) electric field due to this dipole in the far field will be E = \frac{d}{4\pi\epsilon_0}\frac{k^2\sin\theta}{r}\exp i\left(kr-\omega t\right) where d is...

Homework Statement Show that the field on the x-axis for the dipole (negative on the right, positive on the left separated by 2a) is given by the equation E = kq / x^3 for x >>a. Homework Equations Coulomb's Law F = kq1q2 / r^2 E = F/q = kQ / r^2 The Attempt at a Solution Since...

Hi, I have been wondering about a neutron dipole moment, though hypothetical what symmetries would it be violating, wouldn't it be Parity and Time reversal? If this were to be true, would it therefore make the statement below false and the word "inverted" would imply parity? "T is the law of...

Homework Statement Find the frequency of oscillation of an electric dipole, of dipole moment p and rotational inertia I, for small amplitudes of oscillation about its equilibrium position in a uniform electric field of magnitude E. Answer: [(pE/I)^0.5]/(2*pi) Homework Equations I...

I'm reading in my organic chemistry text about the structure of alkyl halides, as a background to why certain reactions happen (specifically radical halogenation). In it there's a table of halomethanes, that tells the bond length, bond strength, and dipole moment. It pretty much looks like...

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Homework Statement A dipole consists of two charges +q and -q, held apart by a rod of length s, as shown in the diagram. If q = 4 nC and s = 2 mm, what is the magnitude of the electric field due to the dipole at location A, a distance d = 5 cm from the dipole? The diagram shows point A...

There is a two part problem that I'm struggling with. 1) A dipole with a moment of 2.5 nC . m is oriented 33 degrees from a field with strength 3.6 MN/C. What is the magnitude of the torque on the dipole? ____ mN . m I know the equation T = qd x E sin (theta) where qd is the given dipole...

1. The problem statement, and my attempt at a solution is given in pic Please help me.

Homework Statement An electric dipole in a uniform horizontal electric field is displaced slightly from its equilibrium position, where theta is small. The separation of the charges is 2a, and each of the two particles has mass m. Assuming the dipole is released from this position, show that...

Homework Statement A molecule of water has a dipole moment of 6.1×10–30 C m. Calculate the difference in potential energy between when its dipole is parallel to an electric field of 2.0×105 V m–1 and when it is anti-parallel to the field. Homework Equations U=kq1q2/r V=U/q V=Ex...

Homework Statement Can't get to the final equality ( integral = - 4*Pi/3). Homework Equations \int_V \mathbf{E }dV = - \int_F \frac{_{\mathbf{p}.\mathbf{e_{r}}}}{r^2}\mathbf{e_{r}}r^{2}d\Omega = \mathbf{p}\frac{-4\pi }{3} The Attempt at a Solution Can't find how to get -4Pi/3...

I am trying to figure out how the TEM wave looks like and how it propagate outward. Attached is a pdf of a drawing with only the solenoid and show the winding that the current is flowing in CCW and a reference. Also I draw a loop with one resistor and show the induced current and the polarity of...

I understand that potential energy of an electric dipole is U(θ)=-pEcosθ where p is the dipole moment, E is the electric field and θ is the angle between vector p vector E. However i have some doubts about its derivation. in my readings, the work done is derived as such: dw=t*d(theta) =...

Why is the dipole moment of two electrons equal to zero? \vec{d} = \sum{q_{i}\vec{r_{i}}} The distance between them is nonzero and they both have charges. It is not obvious to me why this sums to zero.

Homework Statement A magnetic dipole m = -m0^z is situated at the origin, in an otherwise uniform magnetic eld B = B0^z. Show that there exists a spherical surface, centered at the origin, through which no magnetic eld lines pass. Find the radius of this sphere, and sketch the eld lines...

Homework Statement Point electric dipole \vec{p}=p_0 \hat{z} is a distance d above an infinite metal plane of surface normal \hat{n}=\hat{z}. What is the force on the dipole. Is the dipole attracted to, or repelled from the surface?Homework Equations V(r) = \frac{\hat{n} \cdot \hat{p}}{4 \pi...

Homework Statement I have been given the problem of finding the potential of a dipole in cylindrical coordinates. The only way that comes to my mind is to extract the dipole term from the multipole expansion of the potential of an arbitrary charge distribution in cylindrical coordinates. But I...

I'm learning the subject of electric fields from Resnick and Halliday's book, and they have an equation for the field of the dipole: E = \frac{1}{4\pi\epsilon_0}\frac{p}{x^3} \left[1+\left(\frac{d}{2x}\right)^2\right]^{-3/2} Their next step is to find out what happens when x is larger than...

Homework Statement A point dipole p is embedded at the center of a sphere of linear dielectric material (with radius R and dielectric constant \epsilon_{r} ). Find the electric potential inside and outside the sphere.Homework Equations Well I'm guessing that using the method of separation of...

Does anyone know how is the direction of motion from the CMB dipole determined? Do Earth's motion around the sun affect the direction and magnitude of the velocity as seen on observations made over many months?

Homework Statement We have 2 points charges qa and qb. Qa =2 nC and is at the origin while Qb =-10nC and is at (x0,z0)=(4,2)m. a. Find the real potential for an arbitrary x and z. b. Find the monopole/dipole moments. c. Find the potential due to these moments and compare with the...

Hi. How does the number 605km/s come from the observed CMB wavelength of 1.9mm? (http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation) Please only reply in 'English' and not a bunch of calculations because Google already provides lots of calculations. I am trying to get a...

Problem: A dipole consists of charges +q and -q separated by 0.62nm . It is in an electric field 2.6×104 C/N. What is the work required to rotate the dipole from being oriented parallel to the field to being antiparallel to the field? Equations: . 90...

Hi,can anyone tell me how to calculute magnitude and direction of the electric dipole moment of a system? If the system is a bit complicated? What kind of formula I suppose to use? \vec{p}=q\vec{d}?

Homework Statement Three metal balls with unequal radii R1 < R2 < R3 are placed at the vertices of an equilateral triangle, whose sides have length a. The balls are connected by thin metal wires. A positively charged rod is brought into contact with one of the balls and transfers an amount of...

Suppose there is an electic dipole that starts to oscillate with frequency ω at t=0, then how long does it take the electric dipole to emit a photon? We know that the radiant power of such electric dipole calculated from quantum physics is P\left( \omega \right) = \frac{{{\omega ^4}}}{{3\pi...

Homework Statement The graph shows the potential energy of an electric dipole which is in a constant electric field; only the electric force is acting on the dipole. Consider a dipole that oscillates between +/- 51 degrees. What is the dipole's kinetic energy when it is aligned with the...

Homework Statement I'm reffering to http://hyperphysics.phy-astr.gsu.edu/hbase/electric/dipole.html and the approximation r_1 - r_2 \approx = d \cos \theta. I see that it is correct if I draw it up, but I wondered if there were any "more mathematical" ways to see this? Where does these...

Electric Dipole Electric Field.. URGENT Homework Statement For the electric dipole shown in the figure, express the magnitude of the resulting electric field as a function of the perpendicular distance x from the center of the dipole axis in terms of the electric dipole moment, p. Homework...

Homework Statement Show that E = \frac {q}{4\pi\varepsilon(z-\frac{1}{2}d)^2} - \frac{q}{4\pi\varepsilon(z+\frac{1}{2}d)^2} is E = \frac {q}{4\pi\varepsilon z^2} [(1-\frac{d}{2z})^{-2} - (1+\frac{d}{2z})^{-2}] Homework Equations The Attempt at a Solution After...

We have the equations available for computing the reflected and transmitted electric fields in the case when a plane wave is incident on a dielectric surface. Now what I wish to do is compute similar reflected and transmitted components of the electric field due to an oscillating electric...

I have an electrodynamics question stemming from a recent episode of the game show "1 vs 100" in which I disagreed with the show's answer. The question is: "You touch your grandma's elbow and feel a spark. What do you have an excess build-up of, besides shame?" Answer choices were...