who can explain me the experiment about the mercury barometer that made Torricelli?

Answer 1

As Torricelli inverted a tube filled with mercury over a pool of mercury while preventing the mercury inside to spill has created a first barometer. He recognized that the atmospheric pressure prevents the mercury to completely escape the tube. So the height of the column of mercury becomes indicative of the atmospheric pressure.

This how Torricelli described this:" We have made many glass vessels ... with tubes two cubits long. These were filled with mercury, the open end was closed with the finger, and the tubes were then inverted in a vessel where there was mercury. .. We saw that an empty space was formed and that nothing happened in the vessel where this space was formed ... I claim that the force which keeps the mercury from falling is external and that the force comes from outside the tube. On the surface of the mercury which is in the bowl rests the weight of a column of fifty miles of air. Is it a surprise that into the vessel, in which the mercury has no inclination and no repugnance, not even the slightest, to being there, it should enter and should rise in a column high enough to make equilibrium with the weight of the external air which forces it up? "

Answer 2

A barometer is a broadly used climate device that measures atmospheric stress (also familiar as air stress or barometric stress) - the burden of the air contained in the ambience. There are 2 significant styles of barometers – the most broadly accessible and solid Mercury Barometers, or the more recent digital pleasant Aneroid Barometer. The classic mercury barometer is usually a tumbler tube about 3 feet extreme with one end open and the different end sealed. The tube is full of mercury. This glass tube sits the different way up in a field, referred to as the reservoir, which also incorporates mercury. The mercury aspect contained in the glass tube falls, coming up a vacuum on the suitable. the first barometer of this style became devised by technique of Evangelista Torricelli in 1643. The barometer works by technique of balancing the burden of mercury contained in the glass tube hostile to the atmospheric stress a twin of a series of scales. If the burden of mercury is less than the atmospheric stress, the mercury aspect contained in the glass tube rises. If the burden of mercury is better than the atmospheric stress, the mercury aspect falls.