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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. ...
In physics, a dipole (from Ancient Greek δίς (dís) 'twice' and πόλος (pólos) 'axis') [1] [2] [3] is an electromagnetic phenomenon which occurs in two ways: An electric dipole deals with the separation of the positive and negative electric charges found in any electromagnetic system. A simple example of this system is a pair of charges ...
Each term in the expansion is associated with a characteristic moment and a potential having a characteristic rate of decrease with distance r from the source. Monopole moments have a 1/r rate of decrease, dipole moments have a 1/r 2 rate, quadrupole moments have a 1/r 3 rate, and so on. The higher the order, the faster the potential drops off.
Further, a torque applied to a relatively isolated magnetic dipole such as an atomic nucleus can cause it to precess (rotate about the axis of the applied field). This phenomenon is used in nuclear magnetic resonance. [citation needed] Viewing a magnetic dipole as current loop brings out the close connection between magnetic moment and angular ...
It follows that the dipole-dipole interaction goes as the inverse fourth power of the distance. Suppose m 1 and m 2 are two magnetic dipole moments that are far enough apart that they can be treated as point dipoles in calculating their interaction energy. The potential energy H of the interaction is then given by:
The remaining terms predict that the potential of a dipole source (ℓ=1) drops off as 1/r 2. The magnetic field, being a derivative of the potential, drops off as 1/r 3. Quadrupole terms drop off as 1/r 4, and higher order terms drop off increasingly rapidly with the radius. The radius of the outer core is about half of the radius of the Earth.
The electron electric dipole moment d e is an intrinsic property of an electron such that the potential energy is linearly related to the strength of the electric field: U = − d e ⋅ E . {\displaystyle U=-\mathbf {d} _{\rm {e}}\cdot \mathbf {E} .}
The electrostatic potential energy U E stored in a system of two charges is equal to the electrostatic potential energy of a charge in the electrostatic potential generated by the other. That is to say, if charge q 1 generates an electrostatic potential V 1 , which is a function of position r , then U E = q 2 V 1 ( r 2 ) . {\displaystyle U ...