Question

A manometer consists of a $U-$shaped tube containing a liquid. One side is connected to the apparatus and other is open to the atmosphere. The pressure inside the apparatus is then determined from the difference in heights of the liquid. The external pressure is $760torr$ and density of liquid is $10gc{m}^{-3}$. Then open side is $10.0cm$ lower than the side connected to the apparatus. The pressure in the apparatus is (approx)

• A. $605.5torr$
• B. $685.5torr$
• C. $714.5torr$
• D. $720.1torr$

Answer 1

The correct option is B $685.5torr$

The presssure exerted by 10 cm liquid = rgh

$=\left({10}^{4}kg/m^3\right)\left(9.8m/s^2\right)\left(0.1m\right)$

$=9800pa$

$=0.09674atm$

$=73.5224torr$

Therefore, pressure inside the apparatus = 760 - 73.5224

= 685.47 torr