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The mode of action of capillary, sometimes called capillarity, capillary movement or absorption, is the ability of a liquid to flow, even in a confined space without the help of, or we can even say resisting the external forces such as gravity. We can easily define the capillary and the effect which is a phenomenon where the ascension of liquids through a tube or cylinder takes place. We can say that this occurs mainly due to cohesive and adhesive forces.
The liquid which is drawn in the upward direction is due to this interaction between the phenomena.
Capillary Rise Formula
The capillary rise formula is given as
Here,
h= capillary rise
σ= surface tension
θ= contact angle
Ρ=density
g= Acceleration due to gravity
r= rise of capillary of inner radius
Capillary Action
Capillary Action is defined as a phenomenon where ascension of liquids through a tube or cylinder takes place and the main cause of capillary action is adhesive and cohesive forces.
When the tube is narrow then the rise in liquid will be high. When the surface tension and a ratio of two phenomena lies between cohesion to adhesion increases then the rise will also increase. Hence, we conclude that if the density of liquid increases, then the capillary will decrease.
The amount of water we take in is held in the capillary which also represents the force with which it rises. The material that actually surrounds the pores forms a film on them. Materials that are solids closest to water molecules have the greatest property of adhesion. The thickness of the film increases as water is added to the pore and the capillary magnitude force decreases.
The film that has formed on the outer surface of the molecules of soil can also start to flow. Capillary action causes the groundwater to move through the different soil zones. When the water evaporates from the surface of the leaves, the water from the roots is drawn up by this phenomenon.
Applications Of Capillary effect/Capillary Action
There are many applications of capillary effect some of which are given.
1. The oil in the lamp wick rises due to the capillary action of threads in the wick.
2. The effect of a towel absorbing the moisture from the body is due to the capillary action of the cotton in the towel.
3. Water is retained in a piece of sponge due to capillarity.
4. A blotting paper absorbs the ink by capillary action in the pores of the blotting paper.
5. Root-hairs of plants draw the water from soil by capillary action.
Forces in Capillary Action
Cohesion/ Cohesive Force
The force which exists between the molecules of certain liquids is called cohesion. Raindrops are also held together by the same force before they fall to earth. Surface tension is a phenomenon which is known to us but not many of us know that it is also due to the cohesion. Surface tension allows objects which are denser than liquids to float on them without support and prevent them from sinking.
Adhesion/Adhesive Force
Adhesion is the attraction between two different substances like a solid container and a liquid. This is the same force which allows water to stick to glass.
If the phenomenon of adhesion is greater than that of cohesion, the liquids will wet the surface of the solid with which it is in contact and you may also notice that the liquid curves towards the edge of the container. Liquids such as mercury have more cohesive force than adhesive force and can therefore be described as non-wetting liquids. Such liquids curve inward when they are near the rim of the container.
Capillary Action in Everyday Life
When we drop a paper towel in water we see that it climb up the towel spontaneously by ignoring the gravity.
Plants and trees will not survive without capillary action.
Nutrients that dissolved in water reach the root and start to move up.
Examples of Capillary Action
Examples of capillary effects include the action of wicking in your eyes. The capillary action is used by a tear duct in the corner of each eye to evacuate excess tears into the nasal passage.
Conclusion
Capillary effect was firstly given by Leonardo da Vinci.
A trial on capillary action in 1660 was conducted by Robert Boyle, documented a partial vacuum which had no effect on the height a liquid could achieve via wicking.
Capillary Action is defined as a phenomenon where ascension of liquids through a tube or cylinder takes place and the main cause of capillary action is adhesive and cohesive forces.
The capillary rise formula is given as
The force which exists between the molecules of certain liquids is called cohesion or cohesive force.
Adhesion or adhesive force is the attraction between two different substances like a solid container and a liquid.
The capillary action is used by a tear duct in the corner of each eye to evacuate excess tears into the nasal passage.
