Question
A manometer reads the pressure of a gas in an enclosure as shown in the figure. The liquid used in the manometers is mercury and the atmospheric pressure is 76 cm of mercury.
Give the absolute and gauge pressure of the gas in the enclosure.
Solution
Atmospheric pressure of mercury = 76 mm
The difference in the Hg column in two arms of manometer as given in the figure is 20 cm.
Therefore the gauge pressure is +20 cm of Hg.
Positive sign indicates that the pressure of gas is greater than atmospheric pressure.
So,
Absolute pressure = Atmospheric pressure + gauge pressure
= 76cm + 20cm
= 96cm of Hg.
The difference in the Hg column in two arms of manometer as given in the figure is 20 cm.
Therefore the gauge pressure is +20 cm of Hg.
Positive sign indicates that the pressure of gas is greater than atmospheric pressure.
So,
Absolute pressure = Atmospheric pressure + gauge pressure
= 76cm + 20cm
= 96cm of Hg.
