Q2 of 81 Page 273

The heights of mercury surfaces in the two arms of the manometer shown in figure (13-E1) are 2 cm and 8 cm. Atmospheric pressure = 101 × 10 N m-2. Find (a) the pressure of the gas in the cylinder and (b) the pressure of mercury at the bottom of the U tube.


(a)The pressure of gas is the sum of the atmospheric pressure (from the open end) and the pressure in the mercury column.

Therefore,


Here, density of mercury, , heights .


(ANS)


(b)The pressure at the bottom is given by the sum of the atmospheric pressure and the pressure in the open column.


(ANS)


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