Question

What Causes Capillary Pressure?

Answer 1

Hint:Capillary Pressure is caused due to the intermolecular forces between the liquid and the solid surface surrounding. The pressure of cohesion and adhesion causes the fluid to work against gravity.

Formula used:
The pressure difference is expressed in terms of wetting and nonwetting phase pressures as:
\[{P_c} = {P_{nw}} - {P_W}\]
Where, \[{P_c}\] capillary pressure, \[{P_{nw}}\] pressure of the nonwetting phase and \[{P_W}\] pressure of the wetting phase.

Complete step by step solution:
Capillary action can be defined as the force made to push the liquid against the gravitational force of attraction. After a certain amount of time, the liquid falls. This fall occurs when the liquid is in surface tension.

At the interface separating two immiscible fluids (or phases), then capillary pressure is mainly caused by the interfacial tension that is normally present. In other words, we say that capillary pressure results from the interactions of forces between the fluids and the walls of the solid tube. The pressure difference is expressed in terms of wetting and nonwetting phase pressures is given as:
\[{P_c} = {P_{nw}} - {P_W}\]

Note: The word capillarity meaning is to understand in terms of hydrodynamics. It is an invisible force that always works against the force of gravity. It can push a liquid up in a tube or a pipe. This rising of liquid is the capillary action. Such liquid is also known as capillary water because the water follows the principle of capillarity.