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A. 7'
A is the first letter of the Latin and English alphabet. A may also refer to: Science and technology Quantities and units * ''a'', a measure for the attraction between particles in the Van der Waals equation * A value, ''A'' value, a measure of substituent effects on the stereochemistry of cyclohexane * absorbance (''A'') * acceleration (''a'') * activity (chemistry) (''a'') * adsorption (a) * annum (a), for year * Hectare#Are, are (a), a unit of area (equal to 100 square metres; redirects to ''hectare'') * atto- (a-), the SI prefix meaning 10−18 * Ampere (A), unit of electric current * ångström (Å) a unit of length (equal to 1 metres) * area (''A'') * attenuation coefficient (''a'') * Bohr radius (''a''0) * chemical affinity (''A'') * gain (electronics) (''A'') * Hall coefficient (''A''H) * Hamaker constant (''A'') * Helmholtz free energy (''A'') * Hyperfine coupling constant (''a'' or ''A'') * magnetic vector potential (''A'') * mass number of a nuclide (''A'') * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hall Coefficient
The Hall effect is the production of a voltage difference (the Hall voltage) across an electrical conductor that is transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. It was discovered by Edwin Hall in 1879. A Hall effect can also occur across a void or hole in a semiconductor or metal plate, when current is injected via contacts that lie on the boundary or edge of the void or hole, and the charge flows outside the void or hole, in the metal or semiconductor. This Hall effect becomes observable in a perpendicular applied magnetic field across voltage contacts that lie on the boundary of the void on either side of a line connecting the current contacts. It exhibits apparent sign reversal in comparison to the standard "ordinary Hall effect" in the simply connected specimen, and depends only on the current injected from within the void. Superposition may also be realized in the Hall effect: first imagine the standard ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unit Cell Length
In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector, for example) does not necessarily have unit size, or even a particular size at all. Rather, the primitive cell is the closest analogy to a unit vector, since it has a determined size for a given lattice and is the basic building block from which larger cells are constructed. The concept is used particularly in describing crystal structure in two and three dimensions, though it makes sense in all dimensions. A lattice can be characterized by the geometry of its unit cell, which is a section of the tiling (a parallelogram or parallelepiped) that generates the whole tiling using only translations. There are two special cases of the unit cell: the primitive cell and the conventional cell. The primitive cell is a unit cell corresponding to a single lattice point, it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
