Question

How is Liquid Pressure Measured?

Answer 1

Liquid pressure:

• Liquid pressure is defined as the increase in pressure when there is an increase in liquid depth.
• Liquid pressure can be given by the following equation as;

$\mathrm{P}=\mathrm{\rho gh}$

• Here, $\mathrm{P}=$the liquid pressure, $\mathrm{\rho }=$ the density of the liquid, $\mathrm{g}=$ the acceleration due to gravity, $\mathrm{h}=$ the depth)

Measurement of the liquid pressure :

• A manometer is used to measure the pressure of liquid relative to an external source which is generally considered to be the earth's atmosphere.

Working of the manometer:

• Here in this device, a liquid such as mercury is used for pressure measurement while the other end of the Utube is filled with the gas whose pressure is to be calculated.
• The end where the gas is filled is sealed while the other end is kept open.
• However, the atmospheric pressure, as well as the pressure of the gas, acts on the liquid.
• The air in the tube is said to be equal to the pressure of the outside air when the liquid is level in both tubes.
• It is also said to be lighter than the out air’s pressure when the liquid rises above the straight level.
• The air in the tube is said to be heavier than the pressure of the outside air when the liquid is below the straight level.

Hence, by the above mentioned way, the liquid pressure is measured using a manometer.