Table of Contents
How do you find the atmospheric pressure by using mercury barometer?
Why the height of a barometer with water in it will be about 13.6 times the height of mercury in a common barometer?
A denser/heavier liquid means shorter height of the column to balance the pressure. For example the density of water is 13.6 times smaller than that of mercury, that means we would require a 13.6 times taller column of water than that of mercury to measure same pressure difference.
What is the principle behind mercury barometer?
In the mercury barometer, atmospheric pressure balances a column of mercury, the height of which can be precisely measured.
What gas law is applied in barometer?
Boyle’s Law Torricelli’s experiment did more than just show that air has weight; it also provided a way of creating a vacuum because the space above the column of mercury at the top of a barometer is almost completely empty. (It is free of air or other gases except a negligible amount of mercury vapor.)
What happens to the mercury in a barometer when the atmospheric pressure decreases?
Atmospheric Pressure and Altitude At sea level, a mercury column will rise a distance of 760mm. This atmospheric pressure is reported as 760mmHg (millimeters of mercury). At higher altitudes, the atmospheric pressure is decreased and so the column of mercury will not rise as high.
Why mercury is used in barometer instead of water?
By the use of mercury in a barometer, the total height of the barometer gets reduced as it has a higher density. As well as the mercury has lower vapour pressure, thus its molecules never get evaporated into the evacuated portion and hence it increases the accuracy while measurement.
How do you calculate barometric pressure?
To calculate barometric pressure, look at a barometer and write down the pressure reading. Then, check back in an hour and write down the new reading. Once you have both readings, subtract the current pressure from the pressure an hour ago to determine how much the barometric pressure has risen or fallen.
How does a barometer measure height?
- Measure the height of the barometer and then stand it next to the building when the sun is about 45 degrees in the sky.
- Drop the barometer off the top of the building, measure how long it takes to hit the ground, and use this value to calculate the height of the building.
What will happen if mercury in the barometer is replaced with water?
Therefore, it rises only to a height of 76cm to balance the atmospheric pressure. Water, being 13. 6 times lighter than mercury, will rise to a 13. 6 times larger height.
What if water is used in barometer?
Detailed Solution Therefore, Mercury is denser than water by means of 13.6 times dense. So if we want to used water instead of mercury height of the barometer will be 13.6 times greater than for mercury. = 1020 cm for pressure equivalent to 75 cm of the mercury barometer.
How do you find the height of a mercury barometer?
=10×105 dyne/cm2. Q. The height of mercury column in a barometer in a Calcutta laboratory was recorded to be 75 cm. Calculate this pressure in SI and CGS units using the following data : Specific gravity of mercury = 13.6, Density of water =103kg/m3,g=9.8m/s2 at Calcutta.
What are the disadvantages of mercury barometer?
- It has a long glass tube with no protection to it.
- It requires zero adjustment before taking the reading.
- The barometer must be kept vertical to get the correct reading.
- The container in which the glass tube is inverted is open from the top.
Why do we not feel the weight of the atmosphere?
Because air is a fluid, the weight of the air is transmitted to the palm of your hand and to the back of your hand at the same time. These forces cancel so that your hand overall feels no net force.
What is mercury barometer explain with diagram?
Definition of mercury barometer noun. a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.
What is the pressure law in physics?
The pressure law states: “For a fixed mass of gas, at a constant volume, the pressure (p) is directly proportional to the absolute temperature (T).”
How do you solve gas law problems?
What happens to the height of the mercury column if the atmospheric pressure is increased?
As the atmospheric pressure increases it will force the mercury in the column to rise and thereby helping to measure the atmospheric pressure. Thus, the height of the mercury column will increase with the increase in atmospheric pressure.
When air pressure increases the liquid in a mercury barometer blank?
When the air pressure increases, it presses down more on the surface of the mercury causing it to rise. When air pressure decreases so does the height of the mercury column.
What prevents the mercury in a barometer from falling completely out of the glass tube?
The column is sustained because air pressure pushes down on the surface of the mercury in the bowl at the bottom of the barometer. At the same time, the vacuum at the top of the glass tube exerts essentially no pressure on the column of mercury.
Why does the height of mercury in a barometer decreases on going up on high mountain?
If the atmospheric pressure drops it will not be able to hold up so much mercury and so the level in the barometer tube will fall. Up a mountain the air pressure is low and so the barometer reading will go down.
What are the advantages of using mercury as a barometric liquid?
- its density is very high.
- it has low vapour pressure.
- its rate of evaporation is not very high.
- it neither wets nor sticks to glass.
- its surface is shining and opaque.
Which liquid is used in barometer?
Mercury is the liquid used in a barometer. Some of the properties that make it a suitable choice are listed below: High density: Smaller length of mercury (76 cm) can balance the atmospheric pressure.
What is the difference between a barometer and a manometer?
The barometer measures pressure relative to the prevailing atmospheric pressure. The manometer measures pressure differences. These differences can be used to calculate flowrates for a calibrated orifice or nozzle.
How do you use the barometric formula?
M = kg/mol. Note that the model calculation assumes a uniform temperature, and is therefore not a realistic model of the atmosphere. The temperature tends to decrease with height, so the model calculation will overestimate the pressure at a given height.