Dipole moment, electric, a quantity characterising the electrical properties of a system of charged particles. The dipole moment p of an electrically neutral system consisting of n charged particles is equal to:
p = Σn i=1 eivi,
,where ei—is the charge of the i-th particle and vi; — its radius vector. The dipole moment does not depend on the choice of the origin of coordinates and is determined by the relative positions and the magnitudes of the charges in the system. A system of two charges equal in magnitude (-e, +e) forms an electric dipole with the dipole moment p=el, where l is the distance between the charges, to which the direction from the negative charge to the positive one is assigned. The electric dipole moment determines (to a first approximation) the electric field of a neutral system at distances large compared with its size, and the action of external fields on it. When the dipole moment changes, such a system radiates electromagnetic waves (dipole radiation). In the case of an arbitrary system of charges, its electric field may be described by multipoles of various orders. On the magnetic dipole moment (see Dipole, Magnetic moment).
p = Σn i=1 eivi,
,where ei—is the charge of the i-th particle and vi; — its radius vector. The dipole moment does not depend on the choice of the origin of coordinates and is determined by the relative positions and the magnitudes of the charges in the system. A system of two charges equal in magnitude (-e, +e) forms an electric dipole with the dipole moment p=el, where l is the distance between the charges, to which the direction from the negative charge to the positive one is assigned. The electric dipole moment determines (to a first approximation) the electric field of a neutral system at distances large compared with its size, and the action of external fields on it. When the dipole moment changes, such a system radiates electromagnetic waves (dipole radiation). In the case of an arbitrary system of charges, its electric field may be described by multipoles of various orders. On the magnetic dipole moment (see Dipole, Magnetic moment).