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A narrow glass tube, 80 cm long and opens at both ends, is half immersed in mercury, now the top of the tube is closed and is taken out of mercury. A column of mercury 20 cm long remains in the tube. Find atmospheric pressure (1) 20 cm of air column (2) 60 cm of Hg column (3) 60 cm of air column (4) 20 cm of Hg column?
Most Upvoted Answer
A narrow glass tube, 80 cm long and opens at both ends, is half immers...
The Setup

- A narrow glass tube, 80 cm long and open at both ends, is half immersed in mercury.
- The top of the tube is closed and the tube is taken out of the mercury.
- A column of mercury, 20 cm long, remains in the tube.

The Concept

To find the atmospheric pressure for different scenarios, we need to understand the relationship between the height of a liquid column and the pressure exerted by it. This relationship is given by Pascal's law, which states that the pressure at any point in a fluid is equal in all directions and is directly proportional to the height of the fluid column.

Calculating Atmospheric Pressure

1. 20 cm of air column:
- In this case, the column of mercury is 20 cm long, which means the height of the air column above it is 60 cm.
- The pressure exerted by the column of air is equal to the atmospheric pressure.
- Using Pascal's law, we can equate the pressure exerted by the air column to the pressure exerted by the column of mercury:
Pressure of air column = Pressure of mercury column
Atmospheric pressure = Pressure of mercury column
Therefore, the atmospheric pressure for a 20 cm air column is the same as the pressure exerted by a 60 cm column of mercury.

2. 60 cm of Hg column:
- In this case, the height of the mercury column is 60 cm.
- Since the top of the tube is closed, the pressure at the top of the mercury column is atmospheric pressure.
- Using Pascal's law, we can equate the pressure at the top of the mercury column to the pressure at the bottom of the mercury column:
Atmospheric pressure = Pressure of mercury column
Therefore, the atmospheric pressure for a 60 cm column of mercury is the same as the atmospheric pressure.

3. 60 cm of air column:
- In this case, the height of the air column above the mercury is 60 cm.
- The pressure exerted by the air column is equal to the atmospheric pressure.
- Using Pascal's law, we can equate the pressure exerted by the air column to the pressure exerted by the mercury column:
Pressure of air column = Pressure of mercury column + Atmospheric pressure
Atmospheric pressure = Pressure of air column - Pressure of mercury column
Therefore, the atmospheric pressure for a 60 cm air column is the pressure difference between the pressure exerted by the air column and the pressure exerted by the 20 cm column of mercury.

4. 20 cm of Hg column:
- In this case, the height of the mercury column is 20 cm.
- Since the top of the tube is closed, the pressure at the top of the mercury column is atmospheric pressure.
- Using Pascal's law, we can equate the pressure at the top of the mercury column to the pressure at the bottom of the mercury column:
Atmospheric pressure = Pressure of mercury column
Therefore, the atmospheric pressure for a 20 cm column of mercury is the same as the atmospheric pressure.

Conclusion

- The atmospheric pressure for different scenarios can be calculated by considering the height of the fluid column and applying Pascal's law.
- The atmospheric pressure for a 20 cm air column is the same as
Community Answer
A narrow glass tube, 80 cm long and opens at both ends, is half immers...
atmospheric pressure = density of mercury x acceleration due to gravity x height of column of mercury.
Atmospheric pressure can be measured in atm, torr, mm Hg, psi, Pa, etc.
according to your question,
1)a.p=13.6.10.20=78.200=61500 for first.
similarly you can do for others also.
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A narrow glass tube, 80 cm long and opens at both ends, is half immersed in mercury, now the top of the tube is closed and is taken out of mercury. A column of mercury 20 cm long remains in the tube. Find atmospheric pressure (1) 20 cm of air column (2) 60 cm of Hg column (3) 60 cm of air column (4) 20 cm of Hg column?
Question Description
A narrow glass tube, 80 cm long and opens at both ends, is half immersed in mercury, now the top of the tube is closed and is taken out of mercury. A column of mercury 20 cm long remains in the tube. Find atmospheric pressure (1) 20 cm of air column (2) 60 cm of Hg column (3) 60 cm of air column (4) 20 cm of Hg column? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about A narrow glass tube, 80 cm long and opens at both ends, is half immersed in mercury, now the top of the tube is closed and is taken out of mercury. A column of mercury 20 cm long remains in the tube. Find atmospheric pressure (1) 20 cm of air column (2) 60 cm of Hg column (3) 60 cm of air column (4) 20 cm of Hg column? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A narrow glass tube, 80 cm long and opens at both ends, is half immersed in mercury, now the top of the tube is closed and is taken out of mercury. A column of mercury 20 cm long remains in the tube. Find atmospheric pressure (1) 20 cm of air column (2) 60 cm of Hg column (3) 60 cm of air column (4) 20 cm of Hg column?.
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