Question

Is capillary action due to cohesive or adhesive forces, or both?

Short answer

Capillarity is due to relative strength of cohesive and adhesive forces.

Step-by-step solution

Conceptual Introduction

Fluid statics, often known as hydrostatics, is a branch of fluid mechanics that investigates the state of balance of a floating and submerged body, as well as the pressure in a fluid, or imposed by a fluid, on an immersed body.

Cohesive and adhesive forces

Cohesive forces are attractive forces between molecules of the same sort.

Because cohesive forces hold the molecules together, liquids may be held in open containers. Adhesive forces are the attractive forces that exist between molecules of various sorts. Liquid drips, for example, adhere to glass panes as a result of such pressures.

The strength of the adhesive and cohesive forces is directly linked to the contact angle. The larger is, and the more the liquid prefers to form a droplet, the stronger the cohesive force is compared to the adhesive force. The lower the value, the lower the relative strength, allowing the adhesive force to flatten the drop.

Capillary action can transport liquids over long distances horizontally, but the height to which it can elevate or suppress a liquid in a tube is limited by its weight.

This height h may be proven to be provided by

$\mathit{H}\mathbf{=}\frac{\mathbf{4}\mathbf{\gamma }\mathbf{c}\mathbf{o}\mathbf{s}\mathbf{\theta }}{\mathbf{\rho }\mathbf{g}\mathbf{r}}$

Looking at the many components in this phrase, we can see how it makes sense. The surface tension, which is the immediate source of the height, is directly proportional to it.

The Capillary action

The cohesive forces are attractive forces between molecules of the same sort.

Adhesive forces are the attractive forces that exist between molecules of various sorts.The surface of a liquid contracts to the lowest feasiblesurface area due to cohesive forces between molecules. Surface tension is the common term for these phenomena.

Capillary actionrefers to a fluid's tendency to rise or fall in a thin tube, or capillary tube, according to the relative strength of cohesive and adhesive forces.

Therefore, the capillarity is because of the relative strength of cohesive and adhesive forces.