What is Dipole moment: Definition and 217 Discussions

The electric dipole moment is a measure of the separation of positive and negative electrical charges within a system, that is, a measure of the system's overall polarity. The SI units for electric dipole moment are coulomb-meter (C⋅m); however, a commonly used unit in atomic physics and chemistry is the debye (D).
Theoretically, an electric dipole is defined by the first-order term of the multipole expansion; it consists of two equal and opposite charges that are infinitesimally close together, although real dipoles have separated charge.

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  1. H

    What is a dipole moment in classical electromagnetisim?

    I am rather confused about "dipole moment" in classical electromagnetisim. Since I have no previous background in this field of physics, I find it hard to understand the Maxwell's equations and other equations that involve the concept of dipole moment. Could anyone explain this to me in plain...
  2. S

    Magnetic dipole moment of a sphere

    Homework Statement Find the magnetic dipole moment of a spherical shell of radiu R carrying a uniform surface charge sigma, set spinning at angular velocity omega. Homework Equations \vec{m} = \frac{1}{2} \int_{S} \vec{r'} \times \vec{K} (\vec{r'}) da' The Attempt at a Solution So...
  3. S

    What is the magnetic dipole moment of a rotating charged record?

    Homework Statement A phonograph record of radius R carrying a unifrom surface charge sigma is rotating at a cosntant angular velocity omega. Find its magnetic dipole momentHomework Equations m = int I \bullet da The Attempt at a Solution Need to find the current first well the sruface charge...
  4. S

    Calculating Dipole Moment for Spherical Surface of Radius R

    Griffith' E&M problem 3.28 page 151 Given a spherical surface of radius R which carries a surface charge \simga = k \cos\theta Calculate the dipole moment of this charge distribtuion well using this equation \vec{p} = \int \vec{r'} \sigma(\theta') dA' = \int Rk \cos\theta R^2...
  5. A

    Does the photon has a dipole moment?

    This might be a fantastically stupid question, but does the photon has a dipole? I'm almost certain it doesn't since a dipole is formed when two charges of opposite sign are very close to one another (at least compared to the distance an observer is from them) and unlike say the neutron which...
  6. siddharth

    Magnetic Dipole Moment of a Surface Current Loop

    For a current loop, the magnetic dipole moment is defined as i \int d\vec{a} Now, if I'm given a surface current 'K', how can I find the magnetic dipole moment? For example, if a disc of surface charge [itex] \sigma [/tex] is rotating with angular velocity [itex] \omega [/tex], what is it's...
  7. C

    Help With Dipole Moment Question

    Hi, I'm stuck on a certain question in a tutorial sheet, and would appreciate a nudge in the right direction. The problem is in one particular question to which I missed notes due to illness, and won't have time to copy up before they need handed in. The question is on dipole moments: The...
  8. T

    Magnetic dipole moment homework

    Hello, i have absolutely no clue on how to start this one: a sphere of radius R has a uniform volume charge density \rho. Determine the magnetic dipole moment of the sphere when it rotates as a rigid body with angular velocity \omega about an axis through its center. thanks for the help...
  9. Reshma

    Dipole Moment of Water: Explaining Its Ability to Solve Substances

    Certain molecules have built-in dipole moments. The dipole moment of water is unusually large: 6.1 x 10-30C.m. How does this account for the effectiveness of water as a solvent?
  10. H_man

    Magnetic Dipole Moment does not include the permeability of free space?

    Magnetic Dipole Moment does not include the permeability of free space? Hi, The formula for a magnetic field in a current loop involves the permeability of free space. But the formula for the magnetic dipole moment which seems to represent the flux through a current loop does not...
  11. S

    What is the direction of the electric dipole moment?

    Point charges -5.00 C and +5.00 C are separated by distance 3.20 m, forming an electric dipole. What is the direction of the electric dipole moment? From + to -?
  12. quasar987

    Calculating Dipole Moment of Overlapping Charged Spheres

    Question: Consider 2 spheres of radius R and uniformly charged with density \rho, one positively, the other nagatively. The two spheres are particlely overlapping each other and their center are separated by a distance d (< 2R). Calculate the dipole moment of this system. What I have done so...
  13. M

    Dipole moment of non-uniform surface charged sphere

    I'm trying to find the dipole moment of a non-uniform surface charge distribution on a sphere of radius a: The surface charge distribution is: \sigma = \sigma_{0} cos \theta where theta is the polar angle. Here is what I did: \vec{p} = \int\vec{r}\sigma dA = \int r \sigma_{0} cos...
  14. C

    What is the Dipole Moment of Helium at STP?

    Hi there, I was wondering if you could help me with a question I have (I've posted it here as opposed to the homework help forums cos I alwso want a little bit of the theory explained ). The relative permittivity of helium at STP is 1.000047. Estimate the magnitude of the dipole moment...
  15. L

    Dipole moment of an isolated atom

    why does an isolated atom not have a permanent dipole moment?
  16. B

    Can You Help Me Understand Molecular Dipole Moments?

    Molecular dipole moment? What is a Molecular Dipole moment. My book explains it but i still don't get it. And here is a problem that ask me about it. Which molecule in each pair has the greater dipole moment a. SO2 or SO3 b. ICl or IF c. SiF4 or SF4 d. H2O or H2S Give the reason for...
  17. Y

    Net charge VS dipole moment in E field by infinite line charge

    could anyone compare the behaviors of (1) an object with a net charge but no dipole moment and (2) an object with net charge but with a dipole moment when placed in the electric field produced by an INFINITE line charge? thankyou
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