Cohesive force of mercury is greater than adhesive force brtween mercury and glass of the walls of capillary. That is why mercury do not stick to glass. Water is not a suitable barometric liquid because: Water barometer will support It is impractical to have such a long tube. That is, if water is used in barometer tube instead of mercury, the length of the tube must be greater than A greater height will be difficult to hold in a vertical position and needs a high tower to install the barometer.
So, we cannot replace mercury by water in the barometer. One can see then that the slight increase in volume decreases the density slightly. Americium, another actinide element, is slightly denser than mercury at Begin typing your search term above and press enter to search.
Which liquid is used in aneroid barometer? How do we measure atmospheric pressure? A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. A simple barometer consists of a long glass tube closed at one end, open at the other filled with mercury and turned upside down into a container of mercury.
Why mercury is used in sphygmomanometer? Mercury is used in blood pressure measurement in blood pressure monitors or sphygmomanometers. This means that, in comparison to water, mercury will expand less as pressure changes and a column of reasonable and portable height can be used for pressure measurements.
What do you mean by pressure? Pressure is defined as the physical force exerted on an object. The force applied is perpendicular to the surface of objects per unit area. Unit of pressure is Pascals Pa. Does Mercury have a high vapor pressure? In Medical Industry Modern Manometers are used to read the exact blood pressure. The same for other industries too. Manometers has Liquid Mercury as very essential Part. It also has a low vapor pressure and works on all wide range of temperatures down to C, or F.
In terms of visibility too, mercury has definitely better than water, if it is water, it would not be clearly visible. Mercury has high density and low length is essential for pressure measuring. Its high density helps to make small manometers. If the measurand fluid is air then the pressure due to it can be ignored as the term will be very small compared to the other terms.
If the measurand fluid is a liquid or some other fluid of significantly high density then it cannot be ignored in the equation. Assuming that we have air as the measurand fluid the equation above becomes:. Since g is the acceleration due to gravity and is a constant and the fluid density is a constant, the difference in pressure is directly proportional to the difference in the heights of the columns.
With some experimental work graduations could be marked on the glass to give a direct pressure reading. Rearranging the above equation gives:. If p 2 is atmospheric pressure then the result for p 1 is an absolute pressure measurement.
If a gauge pressure measurement is sufficient then we can use the following equation:. A mercury filled U-tube manometer is used to measure the flowrate of air in a pipe. One leg of the manometer is connected to the upstream side of an orifice plate and the other leg is connected to the downstream side. The pressure on the upstream side is higher causing a difference in height of the two columns of 8mm. What is the differential pressure across the orifice plate?
What is the pressure of the air in the pipe? The density of mercury is
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