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The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A direct distance measurement of an astronomical object is possible only for those objects that are "close enough" (within about a thousand parsecs) to Earth. The techniques ...
Typical size of a fog, mist, or cloud water droplet 10 μm Width of transistors in the Intel 4004, the world's first commercial microprocessor: 12 μm Width of acrylic fiber: 17-181 μm Width range of human hair [25] 10 −4: 100 μm: 340 μm Size of a pixel on a 17-inch monitor with a resolution of 1024×768 560 μm
List of metric units – Class of units of measurement; Metrology – Science of measurement and its application; Non-SI units mentioned in the SI – Unit accepted for use in the International System of Units; Outline of metrology and measurement – Topical index of English Wikipedia articles about metrology and measurement
A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic.Each prefix has a unique symbol that is prepended to any unit symbol.
American surveyors use a decimal-based system of measurement devised by Edmund Gunter in 1620. The base unit is Gunter's chain of 66 feet (20 m) which is subdivided into 4 rods, each of 16.5 ft or 100 links of 0.66 feet. A link is abbreviated "lk", and links "lks", in old deeds and land surveys done for the government.
Length measurement, distance measurement, or range measurement (ranging) all refer to the many ways in which length, distance, or range can be measured. The most commonly used approaches are the rulers, followed by transit-time methods and the interferometer methods based upon the speed of light .
At the close of the 19th century three different systems of units of measure existed for electrical measurements: a CGS-based system for electrostatic units, also known as the Gaussian or ESU system, a CGS-based system for electromechanical units (EMU), and an International system based on units defined by the Metre Convention [33] for ...
A molecular-weight size marker, also referred to as a protein ladder, DNA ladder, or RNA ladder, is a set of standards that are used to identify the approximate size of a molecule run on a gel during electrophoresis, using the principle that molecular weight is inversely proportional to migration rate through a gel matrix.