Understanding the Direction of Electric Dipole Moment Vector

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SUMMARY

The direction of the electric dipole moment vector is defined from the negative charge towards the positive charge, primarily by convention to maintain consistency within physics. The discussion highlights the relationship between the polarization field P and electric dipole moments p, emphasizing the equations ∇·E = ρtotal/εo, ∇·D = ρfree, and ∇·P = -ρbound. Additionally, it clarifies that the displacement field D is expressed as D = εoE + P, which can lead to confusion regarding the total electric field. The energy of an electric dipole p in an electric field E is given by the equation -p·E.

PREREQUISITES
  • Understanding of electric dipole moments
  • Familiarity with Maxwell's equations
  • Knowledge of polarization fields in electromagnetism
  • Basic grasp of vector calculus
NEXT STEPS
  • Study the derivation and implications of Maxwell's equations
  • Learn about the concept of polarization in materials
  • Explore the mathematical formulation of electric fields and potentials
  • Investigate the physical significance of energy in electric dipoles
USEFUL FOR

Students and professionals in physics, particularly those focusing on electromagnetism, electrical engineering, and materials science, will benefit from this discussion.

thunderhadron
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Hi friends as all know that the direction of electric dipole moment vector is from negative charge towards the positive charge. I am pretty confuse that this direction is allotted to the dipole moment vector with some reason or just by convention.
 
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Mostly by convention - it is done this way to make the signs consistent with the rest of physics.
 
hi thunderhadron! :smile:

yes, it seems anomalous …

the polarisation field P is the sum of the electric dipole moments p, and:

∇·E = ρtotal/εo
∇·D = ρfree
but
∇·P = -ρbound​

because of that, we have D = eoE + P, making it looks as if D is the total electric field, instead of E :redface:

(also, it means that the energy of an electric dipole p in an electric field E is minus p·E)​
 
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