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Two point charges, one with charge +q and the other one with charge −q separated by a distance d, constitute an electric dipole (a simple case of an electric multipole). For this case, the electric dipole moment has a magnitude = and is directed from the negative charge to the positive one.
The work per unit of charge is defined by moving a negligible test charge between two points, and is expressed as the difference in electric potential at those points. The work can be done, for example, by electrochemical devices ( electrochemical cells ) or different metals junctions [ clarification needed ] generating an electromotive force .
Electric field lines of two opposing charges separated by a finite distance. Magnetic field lines of a ring current of finite diameter. Field lines of a point dipole of any type, electric, magnetic, acoustic, etc. A physical dipole consists of two equal and opposite point charges: in the literal sense, two poles. Its field at large distances (i ...
Typical dipole moments for simple diatomic molecules are in the range of 0 to 11 D. Molecules with symmetry point groups or containing inversion symmetry will not have a permanent dipole moment, while highly ionic molecular species have a very large dipole moment, e.g. gas-phase potassium bromide, KBr, with a dipole moment of 10.41 D. [3] A proton and an electron 1 Å apart have a dipole ...
By definition, the change in electrostatic potential energy, U E, of a point charge q that has moved from the reference position r ref to position r in the presence of an electric field E is the negative of the work done by the electrostatic force to bring it from the reference position r ref to that position r.
Electric polarization of a given dielectric material sample is defined as the quotient of electric dipole moment (a vector quantity, expressed as coulombs*meters (C*m) in SI units) to volume (meters cubed). [1] [2] Polarization density is denoted mathematically by P; [2] in SI units, it is expressed in coulombs per square meter (C/m 2).
The electric displacement field "D" is defined as +, where is the vacuum permittivity (also called permittivity of free space), E is the electric field, and P is the (macroscopic) density of the permanent and induced electric dipole moments in the material, called the polarization density.
The electric power in watts produced by an electric current I consisting of a charge of Q coulombs every t seconds passing through an electric potential difference of V is P = work done per unit time = Q V t = I V {\displaystyle P={\text{work done per unit time}}={\frac {QV}{t}}=IV\,}