Question

A manometer reads the pressure of a gas in an enclosure as shown in figure (a). When some of the gas is removed by a pump, the manometer reads as in (b). The liquid used in the manometer is mercury and the atomspheric pressure is 76 cm of mercury.

(i) Give the absolute and gauge pressure of the gas in the enclosure for case (a) and (b) in units of cm mercury.

(ii) How would the levels change in case (b) if 13.6 cm of water are poured into the right limb of the manometer ?

Answer 1

(ii) 13.6 cm of water = 1 cm of Hg , i.e., Hg in left limb will rise by 0.5 cm and on right limb, it will fall by 0.5 cm. Thus difference in Hg level will become 19 cm.