# Surface Tension and Capillary Rise

• harsh22902
In summary, surface tension is a physical property of liquids that is caused by the imbalance of forces between molecules at the surface and those in the bulk of the liquid. It is typically measured in units of force per unit length and can be measured using a tensiometer. Surface tension affects the shape of a liquid's surface, causing it to behave like a stretched elastic membrane and allowing small insects to walk on it. It also explains why liquid droplets form spherical shapes. Capillary rise is the phenomenon where a liquid is drawn upward against gravity in a narrow tube or porous material, and it is directly related to surface tension. The higher the surface tension, the greater the capillary rise will be, which is why liquids with lower surface tension,
harsh22902
According to this definition I am unable to understand why does surface tension acts tangentially to surface of contact of liquid and capillary tube. And is the force of surface tension balancing the adhesive forces which lead to capillary rise OR it is the reason behind the capillary rise?

In capillary action, there are three interfaces to consider - solid/liquid, liquid/ air and solid/air. It is the balance between the three surface tensions that determines whether the liquid level rises or falls.

## 1. What is surface tension?

Surface tension is a physical property of liquids that causes the surface of the liquid to behave like a thin, elastic membrane. It is the result of the cohesive forces between the molecules of the liquid, which causes the surface to resist being stretched or broken.

## 2. How is surface tension measured?

Surface tension is typically measured in units of force per unit length, such as newtons per meter (N/m) or dynes per centimeter (dyn/cm). It can be measured using various techniques, such as the drop weight method or the capillary rise method.

## 3. What is capillary rise?

Capillary rise is the phenomenon where a liquid rises up through a narrow tube or channel, such as a thin glass tube or the space between two closely spaced plates. This is due to the combined effects of surface tension and adhesive forces between the liquid and the walls of the tube.

## 4. How does surface tension affect capillary rise?

Surface tension plays a crucial role in capillary rise, as it is the force that pulls the liquid up through the narrow tube. The higher the surface tension of the liquid, the greater the capillary rise will be. Additionally, the shape of the liquid's meniscus at the surface also affects the height of capillary rise.

## 5. What factors can affect surface tension and capillary rise?

Surface tension and capillary rise can be affected by various factors, including the type of liquid, temperature, and the presence of impurities or surfactants. Additionally, the size and shape of the tube or channel can also affect the height of capillary rise.

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