What is Capillarity:
Capillarity is a phenomenon through which liquids have the ability to rise or fall through a capillary tube.
For its part, a capillary tube is an object, with different diameter measurements, through which liquids or fluids are conducted and, it is in these where the phenomenon of capillarity occurs.
This phenomenon depends on the surface tension of the liquid, which makes it face its resistance in order to increase its surface. Likewise, the surface tension also depends on the intermolecular force of the liquid and that precisely will allow it to rise or fall from the capillary tube.
In this sense, when a liquid rises through the capillary tube it is because the adhesive intermolecular force between the liquid and the solid object is greater than the intermolecular or cohesion force of the molecules of the liquid.
In this case, the liquid will rise until it reaches the equilibrium of the surface tension and a concave curve will form on its surface, which will ultimately determine that it is a wetting liquid.
On the contrary, if the intermolecular force of the liquid is greater than the adhesion to the capillary tube, then the liquid descends like, for example, mercury that is characterized by forming a convex surface.
Now, these curves that are formed on the surfaces of the liquids in the capillary tubes, either concave or convex, are called the meniscus.