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Calandra's essay does not name the type of the device, although the answers provided by the student suggest the use of a portable aneroid barometer. The barometer question is an example of an incorrectly designed examination question demonstrating functional fixedness that causes a moral dilemma for the examiner.
The experiment uses a simple barometer to measure the pressure of air, filling it with mercury up until 75% of the tube. Any air bubbles in the tube must be removed by inverting several times. After that, a clean mercury is filled once again until the tube is completely full. The barometer is then placed inverted on the dish full of mercury.
Aneroid barometer. An aneroid barometer is an instrument used for measuring air pressure via a method that does not involve liquid. Invented in 1844 by French scientist Lucien Vidi, [23] the aneroid barometer uses a small, flexible metal box called an aneroid cell (capsule), which is made from an alloy of beryllium and copper. The evacuated ...
Pressure as a function of the height above the sea level. There are two equations for computing pressure as a function of height. The first equation is applicable to the atmospheric layers in which the temperature is assumed to vary with altitude at a non null lapse rate of : = [,, ()] ′, The second equation is applicable to the atmospheric layers in which the temperature is assumed not to ...
The barometer arose from the need to solve a theoretical and practical problem: a suction pump could only raise water up to a height of 10 metres (34 ft) (as recounted in Galileo's Two New Sciences). In the early 1600s, Torricelli's teacher, Galileo, argued that suction pumps were able to draw water from a well because of the "force of vacuum."
In aircraft, an aneroid altimeter or aneroid barometer measures the atmospheric pressure from a static port outside the aircraft. Air pressure decreases with an increase of altitude—approximately 100 hectopascals per 800 meters or one inch of mercury per 1000 feet or 1 hectopascals per 30 feet near sea level .
The changing height of the mercury in the barometer was recorded on a continuously moving photosensitive surface. [5] By 1847, a sophisticated temperature-compensation mechanism was also employed. Ronalds’ barograph was utilised by the UK Meteorological Office for many years to assist in weather forecasting and the machines were supplied to ...
Lucien Vidie. Lucien Vidi (1805, Nantes – April 1866, Nantes) was a French physicist. In 1844 he invented the barograph, that is, a device to monitor pressure, a recording aneroid barometer.