Table of Contents
Why does the width of a barometer not matter?
In a column of a fluid, it is the height of the column that is important, not the width. Mercury is used in a barometer because of its high density. Or, put another way, a perfect vacuum would be unable to pull mercury any more than 760 mm up a tube.
What happens to the mercury column in a barometer?
Atmospheric Pressure and Altitude At sea level, a mercury column will rise a distance of 760 mm. This atmospheric pressure is reported as 760 mmHg (millimeters of mercury). At higher altitudes, the atmospheric pressure is decreased and so the column of mercury will not rise as high. On the summit of Mt.
Why does the height of a barometer not depend on its shape?
Because the height of the mercury is dependent on the atmospheric pressure, changing the shape or volume of the barometer does not change the level of the mercury. Three differently shaped barometers are all filled with mercury by creating a vacuum at the top of the tube.
Does the width of a barometer matter?
When atmospheric pressure is measured by a barometer, the pressure is also referred to as the “barometric pressure”. The physical dimensions (length of tube and cross-sectional area of the tube) of the barometer itself have no effect on the height of the fluid column in the tube.
Why doesnt cross sectional area affect barometer?
This is because the height of mercury is always constant, i.e., 76cm. This reflects atmospheric pressure and does not depend upon any other factor, such as area, temperature, etc.
Why does mercury rise in a barometer?
The greater the air pressure, the higher the mercury rises. We use mercury in barometers because it’s more convenient than using water. Water is less dense (less heavy, in effect) than mercury so air pressure will lift a certain volume of water much higher up a tube than the same volume of mercury.
Why is the height of mercury in a barometer independent of the cross-sectional area of the tube?
since A is cancelled out, the height of the mercury level is independent of the cross-sectional area. If the tubing were tilted at an angle of 15∘, the vertical height of the liquid would be the same so it would still work.
How does a mercury barometer work?
A mercury barometer is a vertical tube sealed at one end with a basin of mercury the otherwhere are three forces working to establish the level of mercury in the tube: The atmospheric pressure on the mercury in the basin, which pushes down on the mercury in the basin and lifts the mercury in the tube
How does the pressure inside a mercury column depend on Mercury?
In such a case the wall of the glass tube exerts downward forces on the mercury inside the tube such that the pressure exerted on the surface of mercury outside the tube is equal to the pressure (due to the column of mercury and the tube) inside the mercury column at the same horizontal level as the mercury surface outside the tube.
How high is a column of water with 760 mm of mercury?
A column of water equivalent to 760 mm of mercury, would have a height of 10,336 m. That is the reason we estimate the underwater pressure as rising by one atmosphere for every 10 meters of depth.
Can a single tube barometer measure the height of a liquid?
Yes. The diameter of the tube does not matter, only the specific gravity (density) of the liquid determines the height. A single tube barometer is actually a modification of a U-tube manometer. The “well” of the single tube barometer is a shortened second tube designed so that most of the height change is in the smaller tube.