Question

A manometer reads the pressure of a gas in an enclosure as shown in the figure. The absolute and gauge pressure of the gas in cm of mercury is (Take atmospheric pressure $= 76 \,cm$ of mercury)

• A. $76, 20$
• B. $20, 76$
• C. $96, 20$
• D. $20, 96$

Answer 1

Answer: (C)

Here, atmospheric pressure $P =76 \,cm$ of mercury. In figure,
Pressure head, $h = 20\, cm$ of mercury
Absolute pressure $= P + h = 76 + 20 = 96\, cm$ of mercury
Gauge pressure $= h = 20 \,cm$ of mercury