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meter, unit of measure

(Encyclopedia)meter, abbr. m, fundamental unit of length in the metric system. The meter was originally defined as 1/10,000,000 of the distance between the equator and either pole; however, the original survey was ...

weber, unit of magnetic flux

(Encyclopedia)weber vāˈbər, wē–, wĕbˈər [key] [for W. E. Weber], abbr. Wb, unit of magnetic flux in the mks system of weights and measures; 1 Wb is equal to 1 volt-second. The weber per square meter, calle...

candle, unit of luminous intensity

(Encyclopedia)candle, in weights and measures, unit of luminous intensity; it is defined as 1⁄60 of the intensity of a blackbody, or ideal radiator, at the temperature at which platinum solidifies (2,046K). The...

ounce, unit of measurement

(Encyclopedia)ounce: see English units of measurement. ...

foot, unit of measurement

(Encyclopedia)foot: see English units of measurement. ...

solar constant

(Encyclopedia)solar constant, the average amount of radiant energy received by the earth's atmosphere from the sun; its value is about 2 calories per min incident on each square centimeter of the upper atmosphere. ...

photometry

(Encyclopedia)photometry fōtŏmˈətrē [key], branch of physics dealing with the measurement of the intensity of a source of light, such as an electric lamp, and with the intensity of light such a source may cast...

micrometer

(Encyclopedia)micrometer mīkrŏmˈətər, mīˈkrōmēˌtər [key]. 1 Instrument used for measuring extremely small distances. Typical examples are devices used in astronomical telescopes to measure the apparent d...

ephemeris time

(Encyclopedia)ephemeris time (ET), astronomical time defined by the orbital motions of the earth, moon, and planets. The earth does not rotate with uniform speed, so the solar day is an imprecise unit of time. Ephe...

ephemeris

(Encyclopedia)ephemeris ĭfĕmˈərĭs [key] (pl., ephemerides), table listing the position of one or more celestial bodies for each day of the year. The French publication Connaissance de Temps is the oldest of th...