The capillary effect in a liquid occurs at the boundary of two media - moisture and gas. It leads to curvature of the surface, making it concave or convex.
Capillary effect of water
When the vessel is filled with H 2 O, its surface is flat. However, bending occurs at the walls. If they are wetted, the surface becomes concave; if they are dry, it becomes curved. The attraction of H 2 O molecules to the walls of the vessel is greater than to each other. This explains the capillary effect. The force raises the 2 molecules until the moment when it is balanced by hydrostatic pressure.
Observations
In the experiments, the researchers tried to determine how the capillary effect depends on the length of the tube. In the course of observations it was revealed that it does not depend on the length of the tube, the thickness of the vessel is of importance. In narrow spaces, the distance between the walls is small. As a result of curvature, they are connected to each other. The capillary effect is also summarized. Accordingly, the level of H 2 O in a thin vessel can be higher than in a wide one.
Priming
Pores are present in any soil. They also have a capillary effect. Pores are the same vessels, only very small. In all soils, it is observed to one degree or another.
The rise of H 2 O molecules occurs despite gravity. The elevation depends on the type of soil. On clay soils, it can be up to 1.5 m, and on sandy soils - up to 30 cm. This difference is related to pore size. In sandy soils they are very large, respectively, the capillary force is small. Clay particles are smaller. This means that the pores in the soil are smaller, and the effect is stronger.
Practical points
The capillary effect in the soil must be considered when designing and laying the foundation. As mentioned above, in clay soil moisture can rise by 1.5 m. If the foundation is laid below this mark, then it will be constantly in the water. This, in turn, will negatively affect its bearing capacity. To protect the foundation from moisture, waterproofing is necessary.
Concrete
This material is used in the construction of the foundation. In concrete, as well as in soil, a capillary effect is also possible, because this material has a porous structure. Through the pores, moisture spreads inward and upward.
If the sole of the foundation rests on moist soil, the water will rise, reach the basement and go higher. This can lead to the destruction of all structures. To prevent such consequences, waterproofing is laid between the ground and the sole of the foundation, the base and the walls of the house.
Ultrasonic capillary effect
This phenomenon was discovered by academician Konovalov. The scientist performed a fairly simple experiment. He attached a vessel with water to the generator radiator, dropping a capillary tube into it. By natural laws, the force began to act on H 2 O, causing it to rise to a certain level. After turning on the ultrasonic generator, the water made a sharp jerk up. The academician repeated this experiment by adding dye to the vessel. After turning on the generator, rarefaction and nodes of standing waves were clearly visible in the tube.
findings
Academician Konovalov found that if the water in the capillary fluctuates under the influence of an ultrasonic source, then the effect of raising its level increases sharply. The height of the column sometimes becomes several tens of times larger. At the same time, the rise speed also increases.
The scientist was able to experimentally prove that the liquid is pushed not by capillary forces and radiation pressure, but by standing waves. Ultrasound constantly compresses the pillar and raises it. The process will go until the pressure arising under the influence of waves is not balanced by the liquid level.
Application
The ultrasonic effect is used in non-destructive testing methods for testing semiconductor equipment. In the old days, to control the tightness of the transistor case, the device was placed for three days in an acetone bath. The use of ultrasound can significantly reduce the time to 3-9 minutes. Konovalov’s discovery is used when impregnating the windings of electric motors with insulating compounds, while dyeing fabrics - wherever moisture penetration into pores is necessary.
Vibration effect
In the process of cutting metals, especially at high speeds, lubricating coolants are used . Due to them, a decrease in friction, a decrease in the temperature of the tool, and an increase in its wear resistance are provided. It is known that liquid can penetrate under the cutter. How does this happen if it is firmly pressed against a part at a pressure of up to 200 kg / cm², and under such conditions, should the grease, on the contrary, be forced out from under the cutter?
It was not possible to explain this phenomenon by the capillary effect. First of all, the strength and speed of raising moisture is very small. In addition, they are due to surface tension. The lifting height decreases significantly with increasing temperature, which in the cutting zone can reach 300 ° C. Konovalov was able to prove that, in addition to the capillary effect, the influence is exerted by the vibration of the machine. It occurs during the processing of the workpiece. This vibration has a higher frequency and low amplitude.
Explanation of Some Phenomena
For a sufficiently long time, scientists could not explain the flowering of the royal primrose before the earthquake. The flower it grows on about. Java. And the locals consider him a predictor of trouble. According to Konovalov, powerful shocks of the cortex are preceded by insignificant different-frequency, ultrasonic, including vibrations. They help to accelerate the movement of nutrient compounds along the elements of the plant, activate metabolic processes, which ensures flowering.
Conclusion
As you can see, the capillary effect is one of the most common natural phenomena. The stems, leaves, trunk, branches of different plants are penetrated by a huge number of channels. Through them, nutrient compounds are delivered to all organs. The capillary effect is used in various fields of human activity: from tarring of sleepers and the creation of special ceramic products impregnated with molten metals, to pickling cucumbers.