Tag: physics

Aneroid barometers are those barometers that do not use liquid to tell the atmospheric pressure. They are popular because of the portability due to their small weight and size.The Aneroid barometer uses a small, flexible metal box called an aneroid cell (capsule). The evacuated capsule (or usually several capsules, stacked to add up their movements) is prevented from collapsing by a strong spring. Small changes in external air pressure cause the cell to expand or contract. This expansion and contraction drives mechanical levers such that the tiny movements of the capsule are amplified and displayed on the face of the aneroid barometer. 

The Aneroid barometer uses a small, flexible metal box called an aneroid cell (capsule). The evacuated capsule (or usually several capsules, stacked to add up their movements) is prevented from collapsing by a strong spring. Since the instrument calibrated directly to read the atmospheric pressure, small changes in external air pressure cause the cell to expand or contract. This expansion and contraction drives mechanical levers such that the tiny movements of the capsule are amplified and displayed on the face of the aneroid barometer. 

Aneroid barometers are popular for their light weight and size which increases its portability. The Aneroid barometer uses a small, flexible metal box called an aneroid cell (capsule). The evacuated capsule (or usually several capsules, stacked to add up their movements) is prevented from collapsing by a strong spring. Small changes in external air pressure cause the cell to expand or contract. This expansion and contraction drives mechanical levers such that the tiny movements of the capsule are amplified and displayed on the face of the aneroid barometer.  

The instrument used to measure the altitude is known as altimeter whereas altimetry is defined as the measurement of altitude.

The surface of mercury is shiny and opaque. Therefore it is easily seen while taking the observation. The vapor pressure of mercury is negligible. Hence the barometric height is not affected. The mercury neither sticks nor wets the glass tube.

There will be a very small increase in temperature$.$ The surface area of the combined drop will be smaller than the original combined surface area of the two drops$.$ There is a small amount of work done by the surface tension as it pulls in the excess surface$.$ 

Mercury does not evaporate under vacuum conditions, whereas water does. Hence water is not used in barometers due to this effect whereas mercury is highly preferred.

The atmospheric pressure measured by mercury barometer is the pressure equal to that at the bottom of the mercury column given by $h\rho g$.