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measurement

(Encyclopedia)measurement, determination of the magnitude of a quantity by comparison with a standard for that quantity. Quantities frequently measured include time, length, area, volume, pressure, mass, force, and...

thermoelectricity

(Encyclopedia)thermoelectricity, direct conversion of heat into electric energy, or vice versa. The term is generally restricted to the irreversible conversion of electricity into heat described by the English phys...

barograph

(Encyclopedia)barograph, instrument used to make a continuous recording of atmospheric pressure. The pressure-sensitive element, a partially evacuated metal cylinder, is linked to a pen arm in such a way that the v...

ammonia

(Encyclopedia)ammonia, chemical compound, NH3, colorless gas that is about one half as dense as air at ordinary temperatures and pressures. It has a characteristic pungent, penetrating odor. Ammonia forms a minute ...

British thermal unit

(Encyclopedia)British thermal unit, abbr. Btu, unit for measuring heat quantity in the customary system of English units of measurement, equal to the amount of heat required to raise the temperature of one pound of...

water

(Encyclopedia)CE5 A. Water molecule (black circles represent valence-shell electrons) B. Structure of ice: Each oxygen atom (white circles) is bonded to four other oxygen atoms by hydrogen bonds, the hydrogen at...

blackbody

(Encyclopedia)blackbody, in physics, an ideal black substance that absorbs all and reflects none of the radiant energy falling on it. Lampblack, or powdered carbon, which reflects less than 2% of the radiation fall...

kelvin

(Encyclopedia)kelvin, abbr. K, official name in the International System of Units (SI) for the degree of temperature as measured on the Kelvin temperature scale. ...

pitot static system

(Encyclopedia)pitot static system pētōˈ [key], device for measuring the rate at which a fluid flows. Among the principal applications of the device are an airspeed indicator for aircraft and a distance and speed...

first aid

(Encyclopedia)first aid, immediate and temporary treatment of a victim of sudden illness or injury while awaiting the arrival of medical aid. Proper early measures may be instrumental in saving life and ensuring a ...