Read about dipole | 48 Discussions | Page 1

  1. K

    I Magnetic Potential Energy?

    Recently I have encountered the following expression for the potential energy of a magnetic dipole of moment ##\boldsymbol{\mu}## placed in an external magnetostatic field B: $$U=-\boldsymbol{\mu} \cdot \textbf{B}$$. However, I was told that magnetic fields are non-conservative, so we can't...
  2. Elder1994

    Find the electric dipole moment for a water molecule

    The equation that we saw in class is for a continuous charge distribution, I think that for this exercise I need to treat the system as a discrete charge distribution but I'm not sure. Also, I don't know how I can calculate the intensity of the electric field needed to move this charge.
  3. R

    Divergence of an Electric Field due to an ideal dipole

    Given $$\vec E = -\nabla \phi$$ there $$\vec d \rightarrow 0, \phi(\vec r) = \frac {\vec p \cdot \vec r} {r^3}$$ and ##\vec p## is the dipole moment defined as $$\vec p = q\vec d$$ It's quite trivial to show that ##\nabla \times \vec E = \nabla \times (-\nabla \phi) = 0##. However, I want to...
  4. M

    I What is the continuous electric dipole distribution?

    An electric dipole is a system of two opposite point charges when their separation goes to zero and their charge goes to infinity in a way that the product of the charge and the separation remains finite. Now how can we have a continuous electric dipole volume distribution from such a...
  5. G

    Electric dipoles

    What is the convention? Because the field lines leave the positive charges and enter the negative ones, do not they?
  6. P

    Calculate the magnitude and direction of the torque

    Homework Statement [/B] a) (a) Assuming the HCl molecule consists of point-like ions (H+ and Cl) separated by 1.0 * 10^-10m, find the dipole moment of the molecule. b) Calculate the magnitude and direction of the torque exerted on this dipole if the molecule is subjected to an external electric...
  7. J

    I Falling electric dipole contradicts the equivalence principle?

    Consider an electric dipole consisting of charges ##q## and ##-q##, both of mass ##m##, separated by a distance ##d##. If the dipole is given an acceleration ##a## perpendicular to its moment the total electric force on it, due to each charge acting on the other, is given approximately by...
  8. Zack K

    Magnitude of an Electric Field due to a dipole

    Homework Statement A dipole is located at the origin, and is composed of charged particles with charge +e and -e, separated by a distance 2x10-10m along the x-axis. Calculate the magnitude of the electric field due to the dipole at location ##\langle 0.2\times 10^{-8}, 0, 0\rangle##m Homework...
  9. Ivan Hu

    Electric Field due to dipole - solution check

    Homework Statement Hi guys, my exam is in four days and my tutor for the electromagnetic module is neither very active nor very competent, so I would like you guys to check my solution for this question. I am afraid I might have messed up some signs or some linear algebra. Homework Equations...
  10. B

    I Dipole problem with electric fields

    Dipole problem (which is solved through mirror imaging) has been troubling me with its solution. I understand everything except how the dipole moment's coordinates came to be, since when converted into x-y axis, its doesn't make sense. (problem 4.6) The screenshot contains the solution which...
  11. Captain Levi

    Someone help explain electric dipole situation

    Ok so she says that electric dipoles are of opposite charge but equal magnitude at 3:40. But then at 5:33 she shows 2Q with -Q, at that point the magnitude of the 2Q particle wouldn't be equal to the -Q so they wouldn't be electrical dipoles right?
  12. K

    I Charge-Dipole Derivation - Assumption That x >> a

    In this derivation: https://cpb-us-e1.wpmucdn.com/sites.northwestern.edu/dist/8/1599/files/2017/06/taylor_series-14rhgdo.pdf they assume in equation (8) that x >> a in order to use the Taylor Expansion because a/x has difficult behavior. Why does that assumption work? Meaning, why can we...
  13. V

    How do I calculate the potential created by a dipole

    Homework Statement I'm given that there is a positive charge of 1 nC at x=0.25 m and a negative charge of -1 nC at x=-0.25 m. I've calculated the potential created at different points along the x-axis by the positive charge and the negative charge using the formula, $$V=\frac{kq}{|r|},$$ where...
  14. D

    How do I draw Lewis Structure Diagrams? +1 More

    Homework Statement : 2 Questions, sorry about this if It adds confusion. 1) How do I go about drawing Lewis Structure Diagrams? I've searched the web, but all I can find, even when they say it's a "Lewis structure" diagram is lewis dot diagrams. My teacher wants it in the specific form where...
  15. L

    How to calculate the dipole moment of the spherical shell?

    Homework Statement A spherical shell of radius R has a surface charge distribution σ = k sinφ. Calculate the dipole moment of the spherical shell. Homework Equations P[/B]' = ∫r' σ(r') da' The Attempt at a Solution So I believe my dipole will be directed along the y axis, as the function...
  16. B

    I Interactions between a dipole and a point charge

    After solving a homework problem, I realized I don't know what to do when there's a dipole and a point charge but the distance from the charges in the dipole is greater than the distance from the center of the dipole to the charge. As my homework problem stated, with a little context added...
  17. I

    A Obtaining position in a dipole field

    Hi all, Consider one has a magnetic dipole, the field given by: \begin{equation} \vec{B} = \frac{\mu_0}{4\pi}\left(\frac{3(\vec{m}\cdot\vec{r})\vec{r}}{r^5}-\frac{\vec{m}}{r^3}\right) \end{equation} where we can take $$\vec{m} = m\hat{y}$$. Let us say we have the a magnet vector which is...
  18. F

    I Angular dependance of NEXAFS spectroscopy - derivation

    Hi all, this is my first time posting so I hope it's in the right place, if not I apologise. I'm trying to understand the angular dependance in NEXAFS spectroscopy for linearly polarised light. So from what I understand, the quantum mechanical description of the excitation process for a single...
  19. E

    Electric Field Intensity of a line on bisecting plane

    Homework Statement A very thin, finite, and uniformly charged line of length 10 m carries a charge of 10 µC/m. Calculate the electric field intensity in a plane bisecting the line at ρ = 5 m. Homework Equations The Attempt at a Solution Not sure why i'm not getiting this but i've been at...
  20. R

    Permanent Dipole - Permanent Dipole Interaction Derivation

    Homework Statement I am trying to derive the dipole-dipole interaction derivation, which is: U=(-p1p2/4πϵ_0) (1/z^3) ((2cosθ_1cosθ_2)− (sinθ_1sinθ_2cosζ)) Where p1 and p21 are the two dipole moments, r is the distance between two dipoles on the y axis, θ_1 and θ_2 are the angles between the...
  21. G

    B LED in dipole antenna

    Hi. In this video around 6:45, this guy builds a simple dipole antenna with an LED and capacitor in parallel in the center. The LED flickers when close to a transmitting cellphone. Since the LED only lets current pass in one direction, shouldn't this quickly lead to a charge imbalance between...
  22. Albi Mema

    Forces between the dipole and a point charge

    Homework Statement We have an electric dipole with moment P=2*[10][/-5] pointing in x direction. What is the force experieced by dipole at origin when a point charge Q=3*[10][/-4] is located at (0.014 m ,0,0) Homework Equations 1. [E][/dipole]=(1/4π[ε][/0])(2p/r3) 2. p=qs 3. F=qE 4. τ=pEsinϑ...
  23. Tazerfish

    I Phase difference between magnetic and electric field

    When solving the differential equations for an electromagnetic wave you get out that the electric and magnetic field oscillate in phase. But when considering a oscillating dipole, the electric and magnetic field at a point close to the dipole are a quater period out of phase. Can someone please...
  24. G

    I Dipole: Which field lines go to infinity?

    Hi. An electric dipole field (two opposite point charges separated by some distance) has fields lines from the positive to the negative charge, but also field lines reaching to and coming from infinity. Starting from the positive charge, is there a way to compute the opening angle of the cone...
  25. O

    Torque and work of dipole

    Homework Statement An electric dipole consists of +/- Q = 330nC separated by a distance of 1200nm. The dipole is initially oriented in the -i direction (along the negative x axis). The dipole is in a uniform external electric field of E=2500j N/C Determine the following: a) The magnitude of...
  26. G

    B Is there such thing as magnetic interference?

    Say I place a magnet on a table, and I have a metal in close proximity. Will its magnetic field change due to the presence of this metal, however minute? What if I had another magnet or the table itself is made of materials the magnet is slightly attracted to? Does this phenomenon even exist?
  27. R

    Net force in a Non-Uniform magnetic field

    When there is a magnetic dipole placed in an external non uniform magnetic field, will it experience a net force?
  28. Curieuse

    Potential Energy for dipole in Electric Field

    Homework Statement To derive Potential Energy for dipole p in Electric Field E. 2. Homework Equations Potential Energy is the work done by the external agent in turning the angle of the dipole from the U=0 position to another position against the influence of the electric field applied...
  29. Guy ML

    Question about polarization density

    Homework Statement Given a sphere with radius R, centered at (0,0,0), it's dipole density given as ##P\left(\vec{r}\right)=\alpha\left(R-r\right)\hat{z}## where r is the distance from the center of the ball. I'm required to find: Bound charge density inside the sphere, bound charge density on...
  30. S

    Dipole moment arrows confusion

    My teacher posted on his website, Lewis structures of different compounds. One of them were N3- Why isn't there a dipole moment arrow pointing from the central atom to the other Nitrogen? Does the arrow only point from neutral atom to negatively charged atom?
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