From permeable, from L. permeabilis "that can be passed through, passable," from L. permeare "to pass through," from per- "through" + meare "to pass," from PIE base *mei- "to change; to go, move."
Tarâvâyi quality noun of tarâvâ "permeable," from tarâvidan "to exude, trickle, ooze; to drop," probably from Proto-Iranian *tra-vaxš-. The first component *tra- "across, over, beyond," → trans-. The second component *vaxš-, cf. Av. uxš-/vaxš- "to sprinkle," present tense stem uxš-; cf. Skt. uks- "to sprinkle, moisten," uksati "spinkles, wets;" Gk. hygros "wet, moist, fluid;" L. uvidus "watery, humid, damp." Tarâvidan may be a back formation from *tarâvaš.
A measure of the ability of a material to transmit (or "permit") an electric field. Permittivity is defined as the ratio of the flux density produced by an electric field in a given dielectric to the flux density produced by that field in a vacuum. In → SI units, permittivity is measured in → farads per meter. The constant ε0 is known as the permittivity of free space; its value is about 8.854 x 10-12 F/m.
State or quality noun from → permit.
The sum total of the physical, mental, emotional, and social characteristics of an individual (Dictionary.com).
Fr.: vitesse de phase
The speed at which any fixed phase (individual wave) in a → wave packet travels. It is expressed as vph = ω/k, where ω is the → angular frequency and k the → wave number. See also the → group velocity.
candÃ¢-ye fiziki (#)
Fr.: quantité physique
A physical → property that can be measured and/or calculated.
Fr.: densité de Planck
The density corresponding to a → Planck mass in a cubic region of edge length given by the → Planck length: ρP = c5/(ħG2) ≅ 5.16 x 1093 g cm-3, where c is the → speed of light, ħ is the → reduced Planck's constant, and G is the → gravitational constant.
The property which enables a material to be → deformed permanently without → rupture during the application of a → force. An → elastic material becomes plastic above its → yield point. See also → elasticity, → ductility.
The state or fact of being plural or numerous.
1) Physics: The condition, in a system, of having opposite characteristics at
different points, especially positive or negative with respect to electric charge or
Fr.: époque de polarité
The time during which the Earth's magnetic field was of a single polarity; an interval of time between reversals of Earth's magnetic field.
Fr.: événement de polarité
A specific event in the history of Earth's magnetic field. Usually used in reference to a specific → polarity reversal.
v âruneš-e qotbigi, vâgardâni-ye ~
Fr.: inversion de polarité
1) A change in the → polarity of Earth's magnetic field
in which the north magnetic pole becomes the south magnetic pole and vice versa.
Also known as geomagnetic reversal or magnetic reversal. Earth's magnetic
field has reversed many times in the past and the time intervals
between these changes are known as → polarity epochs.
1) General: A → dimensionless number characterizing
a porous medium, expressed by the ratio of the volume occupied by the pores to
the total volume of the medium.
The state or fact of being possible. Something possible.
ŠÃ¢yani, from šÃ¢yan, → possible.
Fr.: densité potentielle
Of a fluid parcel at pressure P, the density that it would acquire if adiabatically brought to a reference pressure.
power spectral density
cagâli-ye binâbi-ye tavân
Fr.: densité spectrale de puissance
Same as → spectral density.
principle of identity
Fr.: principe d'identité
principle of relativistic causality
parvaz-e bonârmandi-ye bâzânigi-mand
Fr.: principe de la causalité relativiste
One consequence of the theory of → special relativity, according to which no two events separated by a distance greater than their separation in time multiplied by the → speed of light may have a → causal influence on each other. Violation of this principle leads to → paradoxes, such as that of an → effect preceding its → cause.
principle of relativity
Fr.: principe de relativité
The first postulate in Einstein's theory of → special relativity whereby all the laws of physics are the same in every → inertial reference frame. In other words, no physical measurement can distinguish one inertial reference frame from another. See also → principle of constancy.