Fr.: flottabilité magnétique
The phenomenon whereby the presence of a → magnetic field can make a portion of → compressible fluid less dense than its surroundings, so that it floats upward under the influence of gravity. This magnetic buoyancy is thought, in fact, to be the mechanism by which magnetic flux tubes rise through the Sun's → convection zone and break at the surface in the form of → sunspots. The Sun's rotation would have a major effect on the rate at which these magnetic flux tubes rise. The rotation substantially lengthen the time taken for the flux tubes to reach the surface (D. J. Acheson, 1979, Nature 277, 41).
magnetic cataclysmic binary
dorin-e gatluri-ye meqnâtisi
Fr.: binaire cataclysmique magnétique
A cataclysmic binary in which the white dwarf primary has a strong magnetic field that radically affects the accretion flow in the system. → polar
Fr.: nuage magnétique
A transient ejection in the → solar wind having an enhanced field, a large and smooth change in field direction, and a low → proton temperature compared to the ambient proton temperature (L. F. Burlaga, 1995, Interplanetary Magnetohydrodynamics, Oxford Univ. Press, 89-114).
Fr.: compas magnétique
Fr.: connectivité magnétique
Of magnetic field lines, the condition for them to be connected or the process whereby they become connected or connective.
pâyâ-ye meqnâtisi (#)
Fr.: constante magnétique
A physical constant relating mechanical and electromagnetic units of measurement. It has the value of 4π × 10-7 henry per meter. Also called the permeability of free space, or → absolute permeability.
Fr.: convection magnétique
Thermal → convection modified by the presence of magnetic fields.
Fr.: déclinaison magnétique
Fr.: diffusion magnétique
The process whereby the magnetic field tends to diffuse across the plasma and to smooth out any local inhomogeneities under the influence of a finite resistance in the plasma. For a stationary plasma the → induction equation becomes a pure → diffusion equation: ∂B/∂t = Dm∇2B, where Dm = (μ0σ0)-1 is the → magnetic diffusivity.
Fr.: diffusivité magnétique
Fr.: inclinaison magnétique
In terrestrial magnetism, the angle that a → magnetic needle makes with the horizontal plane at any specific location. The angle of magnetic dip at the → magnetic poles of Earth is 90°. Also called → inclination and → dip.
Fr.: dipole magnétique
A system that generates a → magnetic field in which the field is considered to result from two opposite poles, as in the north and south poles of a magnet, much as an → electric field originates from a positive and a negative charge in an → electric dipole. A loop carrying an electric current also acts as a magnetic dipole. Magnetic dipoles experience a torque in the presence of magnetic fields. → dipole moment; → magnetic moment.
magnetic dipole moment
gaštâvar-e doqotbe-ye meqnâtisi
Fr.: moment dipolaire magnétique
Same as → magnetic moment.
Fr.: énergie magnétique
The energy stored in a magnetic field. It is the → work that must be done to establish a magnetic field in terms of the → magnetic induction. Magnetic energy varies as the square of the magnetic induction. It can be expressed in several other ways, for example in terms of the current and of the magnetic flux, or in terms of the current density and vector potential.
meydân-e meqnâtisi (#)
Fr.: champ magnétique
A field of force that is generated by electric currents, or, equivalently, a region in which magnetic forces can be observed.
magnetic field line
xatt-e meydân-e meqnâtisi (#)
Fr.: ligne de champ magnétique
An imaginary line used for representing the strength and direction of a magnetic field. Charged particles move freely along magnetic field lines, but are inhibited by the magnetic force from moving across field lines.
magnetic field strength
zur-e meydân-e meqnâtisi
Fr.: intensité du champs magnétique
Same as → magnetic intensity.
šâr-e meqnâtisi (#)
Fr.: flux magnétique
A measure of the quantity of magnetism or magnetic field. It is the number of lines of force passing normally through a given area. Magnetic flux is a scalar quantity defined as the surface integral of the → magnetic flux density. It is usually denoted by the Greek letter Φ and its SI unit is the → weber.
magnetic flux density
cagâli-ye šâr-e meqnâtisi (#)
Fr.: densité du flux magnétique
A vector quantity measuring the strength and direction of the magnetic field. It is the → magnetic flux per unit area of a magnetic field at right angles to the magnetic force. Magnetic flux density is expressed in → teslas. Also called → magnetic induction.
Fr.: hélicité magnétique
A quantity that measures the extent to which the magnetic field lines wrap and coil around each other. It is closely related to field line topology. Magnetic helicity is defined by: HM = ∫ A . B dV, where A is the vector potential of the magnetic field and the integration is over a volume V. → helicity; → kinetic helicity