Dipole Definition and 796 Threads

Could anyone help me with the following problem? Ammonia molecule has a dipole moment of 1.47D. Calculate the potential generated by this molecule at a point on a dipole axis at a distance of 52.0 nm from the centre of the dipole. how large will the potential be if an ion of charge...

Homework Statement The prototypical electric dipole is made of two equal and opposite charges of magnitude q separated by a constant distance d (for example, the charges can be placed at opposite ends of a length d rod). The dipole is placed in a uniform, external electric field Er = E0 yˆ ...

Homework Statement A test charge P is separated by a distance "Z" from the midpoint of a dipole. The distance between the two particles in the dipole is d. Find an equation for the electric field between the dipole and the test charge. The Attempt at a Solution Since I did not want to...

Hi When looking at the interaction between an EM-wave/field E with an isolated atom, we know that they interact via the time-dependent dipole interaction V = dE. This can be derived by looking at an electron bound to an atom, and it is used in systems, where the atom can be rightfully...

I'm not understanding how the equation of the electric field due to an electric dipole is derived. This is how my book derives it: Say you have electric dipole composed of charges +q and -q a distance d apart, with the negative charge at the origin of the z-axis. Then, at any point z, the E...

Hi, I am sort of new to Physics forum but I am urgently in need of help. It would be very much appreciated if you could clear my confusion. Let me break them down into bullet points instead of one giant paragraph. 1.Dipole moments are vector quantities. I can just add them up like I do to...

Homework Statement I have two questions. Both involve derivations from textbooks, not end-of-the-chapter problems. The two textbooks are Quantum Mechanics by Griffiths, and A Modern Approach to Quantum Mechanics by John Townsend. My first question is about the discussion of Larmor...

[SIZE="1"]Sorry for my lack of knowledge, I'm in Grade 7 I just learned that Magnets have dipoles--like this: If those dipoles formed a circle, wouldn't it be possible to create perpetual motion?

Homework Statement I'm trying to do problem 3.28 in griffith's electrodynamics. The problem statement is, to find the dipole moment of a spherical shell with charge distribution σ = kcosθ The way I tried to do it was to use the definition of dipole moment, which griffith defines as P=...

Homework Statement A Hertzian dipole is located at the origin of spherical coordinates and is aligned with the θ=0 direction. The dipole has strength I(subscript 0)\deltal and oscillates with angular frequency \omega. The magnetic field that it produces is given by the real part of the...

Homework Statement Two equal and opposite charges form a dipole, as shown in the figure. What is the magnitude of the electric field at point P, in terms of k,q,d, and x? If point P is VERY far away, show that the result is approximately E = kqd/x^3...

The potential for an ideal electric dipole is given by V(x,y,z)= pz/(4π ε0(x+y^2+z^2)) In rectangular, spherical, and cylindrical coordinates: a) Find the electric field, E(x,y,z)= -∇V. (E is a vector, can't figure out how to denote that on my computer). b) By direct Calculation find...

Homework Statement Let the dipole \vec{m} = m\hat{k} be at the origin, and call a certain horizontal axis the y axis. a) On the z axis, what is the angle between the z axis and the magnetic field? b) On the y axis, what is the angle between the z axis and the magnetic field? c) On the cone...

I was given this equation as the lines of electric fields of a dipole(two opposite charges separated by a finite distance) e=(1/r^3)*((3cos^2(theta)-1)^2 +sin^2(2theta))^0.5 and I was asked to plot it. I guess it must be something like this: but when I try to plot it in wolframalpha.com in...

Homework Statement a perfect dipole (p) is situated a distance z above an infinite grounded plane. The dipole is at an angle theta with the perpendicular to the plane. find the torque on p. if you have griffiths text, its problem 4.6 Homework Equations E(dipole)=...

Is the current direction shown correct ?

1. when there is a current in a loop and it is placed in a magnetic field then there will be the torque on it along the direction of mxB axis.but that axis will pass through which point.will that torque act through the center of the loop only?? 2. suppose a current (I) carrying loop (of R)is...

hi experts can anyone explain waht is the dipole moment.

Homework Statement Starting from the equations for a dipole oriented along z, show that the field of a perfect dipole can be written as: E=[1/(4pi epsilon0 r^3)] [3(p.r-hat)r-hat -p] The Attempt at a Solution V(r)= (p.r-hat)/(4pi epsilon0 r^2) E=-grad V =-[3p. r-hat]/[4 pi...

Homework Statement I've attached a page from the book Elements of Electromagnetics. I was wondering how he gets from eq.8.20 to eq.8.21a. What I would have done is sub in d[FONT="Arial Black"]l=a.d∅.[FONT="Arial Black"]a∅ and integrate ∅ between 0 and 2pi. This would then give you...

Homework Statement A point charge q is situated at the origin. A dipole p is placed at r. The angle θ is defined by \hat{p}\cdot\hat{r}=cos(\theta) Calculate the vector force Fp acting on the dipole by the nonuniform E field of the point charge. Homework Equations The Attempt...

The dipole moment of a water molecule is 6.2 x 10-30 Cm. Find the potential difference VB - VA between 2 points on the axis of the molecular dipole, where points A and B are 8.2 nm and 5.1 nm respectively from the center. Both points are closer to the positive end. I used the superposition...

how potential energy of electric dipole perpendicular to electric field is zero in this situation the torque is maximum so how P.E. can be zero please help

Homework Statement A sphere of radius a carries a uniform charge density \rho_0 in one hemisphere and the opposite charge density -\rho_0 in the other hemisphere. The charged sphere produces an electric potential \Phi (r,\theta,\phi). For r>>a, the potential to leading order is of the...

Homework Statement A dipole consisting of charges +/- e 220 nm apart is placed between two very large (essentially infinite) sheets carrying equal but opposite charge densities of 125 uC/m^2. a) What is the maximum potential energy this dipole can have due to the sheets, and how should it...

Homework Statement three point charges q,q and -2q are located at (0,-a,a), (0,a,a) and (0,0,-a) respectively. what is the net dipole moment of these charge distribution.? Homework Equations moment p =qd. The Attempt at a Solution Here we have to consider only the yz plane as x...

hi, I have 2 localized states in a hydrogenic atom.. we're in dipole approimation. I have to proof that <b| [p,V] | a> = <b| grad(V) |a> or equally: <b| V grad |a> = 0 (this is the dipole approximation in acceleration form) someone can help me? you can see...

Let's say you have 2 charges of magnitude 2C except 1 is + and the other -. They're separated by 2m. dipole moment=p=qL Which q do you plug in there?

Hi, given the equation for a dipole magnetic field in spherical coordinates: \vec{B} = \frac{\mu_0 M}{4 \pi} \frac{1}{r^3} \left[ \hat{r} 2 \cos \theta + \bf{\hat{\theta}} \sin \theta \right] I need to show that the equation for a magnetic field line is r = R \sin^2 \theta where R is the...

Though this might be absurd, I would seriously like to know the average magnetic dipole of a magnet. For example, you might consider a regular magnet in a remote control car's motors, or any other suggestions too. And I have one more doubt- I know that e.m.f=-d(phi)/dt and phi=integral(B.dS)...

Homework Statement Electric dipole makes small angle with uniform electric field. Find the frequency of the oscillation using dipole moment p, moment of inertia I, and field magnitude E. Homework Equations Torque=I*(angular acceleration)=I*(theta)'' Torque=p*E*sin(theta) The...

Hi, If I have a magnetic field orientated in the x-direction, a dipole positioned on the z-axis how do I find which direction the dipole is orientated? Is it just as simple as using the right hand grip rule? In which case the dipole is orientated along the y-axis? Or is it more complicated...

Hi all, I've been having a problem with understanding some of the van der Waals forces. I understand that the polarizability of a induced-fixed dipole interation is: \begin{equation}\alpha =4\pi\epsilon r^{3} \end{equation} Which leads to the potential field (assuming two different...

Homework Statement Two point charges q1 = 2\muC and q2 = -2\muC are placed at r1 = (3,0,0) m and r2 = (0,0,4)m respectively i) What is the force of q1 (in vector form)? ii) What is the electric field at the origin? iii) What is the electric dipole moment of this arrangement (in vector...

I hope that I have chosen the correct thread and that this belongs here. I understand the concept of a dipole, where you have opposite polarities at each end of a lineal object, i.e. a magnet. My question concerns the case of a sphere, where the outer surface is one polarity and the center is...

Hi. So, you surround a ferromagnet with a solenoid. Run current through solenoid to create B field withing. 2 Questions: 1:Why do the magnetic dipole moments in the ferromagnet "align" with the magnetic field of the solenoid? Doesn't lenz's law say that the magnetic field within the...

Homework Statement Calculate the electric potential due to a tiny dipole whose dipole moment is 6.0×10^−30 C*m at a point 3.6×10^−9 m away for the following cases. a) This point is along the axis of the dipole nearer the positive charge. b) This point is 45 degrees above the axis but...

Homework Statement A dipole p is situated at thecentre of a spherical cavity of radius a in an infiite medium of relative permitivity \epsilon_r . show that the potential in the dielectric medium is the same as would be produced by a dipole p' immersed in a continuous dielectric, where...

Longo, "Detection of a Dipole in the Handedness of Spiral Galaxies with Redshifts z ~ 0.04," 2011, http://arxiv.org/abs/1104.2815 If this is right, then I guess it would be the first possible hint of a nonzero rate of rotation for the universe. He doesn't attempt to state his results in terms...

Homework Statement Having problems with this subject. Given hydrogenic carbon, with binding energies of 490 eV (1s) 857.50 eV (2p) 925.54 eV (3p) 949.36 eV (4p). Find wavelengths of all lines due to electric dipole transitions between the levels. State which you expect to be strongest...

Dear All, I have a question that is afflicting me and I would be glad if you can give me an answer. I have a dipole in vacuum put at a certain distance from the surface of a dielectric material. I know the entity of the dipole, I know the distance from the surface and I know the interaction...

Yeah it's true, I heard him talking all about it tonight. He said he came up with the theory for it a while ago and he heard of it recently then he knew he was right. Among other things, he briefly said he connected quantum mechanics and consciousness. Then to top it off he said physicists...

This is from Field and Waves Electromagnetic by Cheng page 602. THis is regarding to elemental dipoles. Given:

Homework Statement Hi, This is supposed to be simple, so I guess I miss something.. We have charge q at x1=d*cos (w*t), y=0, z=0. and charge -q at x2=-d*cos (w*t), y=0, z=0. I need to do Fourier transform to the charge density. Homework Equations The Fourier transform is ...

Hi all, I know that the electric field generated by a dipole is given by \mathbf{E}= [1-i(\omega/c) r]\frac{3 (\mathbf{p}\cdot\mathbf{r})\mathbf{r}-\mathbf{p} }{r^3}+(\omega/c)^2\frac{\mathbf{p}-(\mathbf{p}\cdot\mathbf{r})\mathbf{r}}{r} e^{i(\omega/c)r} where \mathbf{p} is the dipole's...

Homework Statement Derive equation of torque: G = p X E from equation U = -p\cdotE Homework Equations G = \int x \times \rho(x)E dV U = \int \rho(x)x \cdot \nabla\varphi dV The Attempt at a Solution I tried to figure how to represent G in a way that better express the nature...

Homework Statement i just have a few questions about the radiation pattern of a half wave dipole antenna. firstly i know the for the half wave dipole we can dervie and expression for the electric field in the zenith angle and the magnetic field in the azimutal angle by using the far field...

Homework Statement Given a sphere radius R with surface charge density \rho_s=k\;cos\theta. Find the dipole moment \;\vec p. Homework Equations \vec p=\int \vec r'\rho_s \;d a = \int_0^{2\pi}\int_0^{\pi}\vec r' k\;cos\theta\; R^2d\theta\;d\phi The Attempt at a Solution To me, \vec r' =...

This is part of derivation of electric dipole potential where: V(\vec r,t)=\frac 1 {4\pi \epsilon_0} \left [ \frac {q_0 cos [\omega(t- \frac {\eta_+} c )]}{\eta_+}- \frac {q_0 cos [\omega(t- \frac {\eta_- } c)]}{\eta_-} \right ] \vec {\eta_+} = \vec r - \vec r^+ (t_r) \;,\; \eta...

I have a Nickel cylinder, 5 micron in diameter and 10 micron in length. I know the external field \vec{B} is 80 gauss, what is the formula for the magnetic dipole moment of this cylinder in the field? Now I only have the formula for magnetic dipole of spheres, which is \mu = \frac{4}{3}\pi...