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Electric dipole moment is mathematically defined as, $p = q\cdot d$, where $q$ is the magnitude of the charge and $d$ is the separation distance between the charges.

I was introduced the term "Moment" as something related to force. In that context, what exactly does the dipole moment actually signify?

Akshai Christy Jacob
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    'Moment' as a word can mean many things, so I would not get too hung up on it. Electric dipole can refer to configuration of charges, whereas electric dipole moment would normally describe the number that represents electric dipole term strength in the https://en.wikipedia.org/wiki/Multipole_expansion. If you want to go deep, multipole expansion is the starting point, in essence it is a decomposition of a function defined on a sphere surface, equally valid is that it is representation of angular distribution of density, equally valid is that it is irreducible representation of group SO(3) – Cryo Nov 11 '22 at 06:49
  • Did you see this similar question https://physics.stackexchange.com/q/429901/ – GiorgioP-DoomsdayClockIsAt-90 Nov 11 '22 at 07:19
  • Does this answer your question? Why is a dipole moment called a dipole moment? – Emilio Pisanty Mar 29 '24 at 20:02

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It's best understood by analogy of mechanical torque: ${\boldsymbol {\tau }}=\mathbf {r} \times \mathbf {F} \,\!$, which is a measure of force in angular terms,- how quickly object will start to rotate by applied force to some contact point (i.e. response to torque is an angular acceleration).

Consequently, it's relatively easy to go from electric dipole moment to a torque, - if you place some charge dipole in an external electric field, then this field will apply torque to a dipole trying to align dipole with field lines. Magnitude of this dipole "turning force", aka torque is: $$ {\boldsymbol {\tau }}=q\mathbf {d} \times \mathbf {E} $$

You can also say that torque is some sort of "mechanical moment". Hope that helps !

Agnius Vasiliauskas
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  • This explanation is a little bit vague as you did not give any contextual analogy. Also, You did not relate dipole with mechanical torque which makes it harder to understand. Can you please elaborate on these points that I have mentioned? – Ghost May 22 '23 at 16:38