# What is surface tension, what is the definition of surface tension

Surface tension in Hindi-Friends, do you know that when a mosquito sits on the surface of the water, it does not sink in it but starts swimming. Even small ants float on the surface of the water. Don’t you ever think that they know how to swim. All this happens because of some rules of science, friends, in today’s article we will discuss those rules.

## What is called surface tension?

Definition of Surface TensionThe free surface of a liquid is always in a state of tension and has a tendency to attain minimum area. This surface tension of a liquid is called surface tension.

•”The surface tension of a liquid is the force which acts on the plane of the surface and perpendicular to the line on a unit length of the assumed line drawn on the surface of the fluid.”

• If the length of the line. But the force F acts, then Surface tension (T) = F/I it happens.

• Its SI unit is Newton/Meter
• Dimensional Formula [MT-2] it happens.

The value of surface tension for a liquid depends on the temperature of the liquid and also on the medium which is on the other side of the surface of the liquid. The surface tension decreases on increasing the temperature and the surface tension becomes zero at the critical temperature.

## What is called cohesive force (Cohesive Force in Hindi)-

Definition of Cohesive ForceEvery substance is made up of molecules, between which the force of attraction acts. Therefore, the force of attraction between the molecules of the same substance is called cohesive force.

in solids cohesive force The value of K is very high, due to which the shape of the solids is fixed. The cohesive force in liquids is very small. That is why liquids do not have a definite shape.

The cohesive force in gases is negligible, so that Diffusion properties are found. Liquids which have high cohesive forces between their molecules do not wet the walls of the vessel. Like mercury. The surface tension is due to cohesive forces.

Definition of Adhesive ForceInteraction between molecules of different substances
The force of attraction is called cohesive force. It is due to the adhesive force that letters emerge when written with chalk on a blackboard, nickel is polished on brass vessels and water soaks glass.

When the value of the cohesive force for a liquid and a solid is greater than the value of the cohesive force of the molecules of the liquid, it causes the solid to become wet. As water sticks to the glass, because the adhesive force between the water and the glass molecules is (Surface tension in Hindi)is greater than the cohesive force.

When the value of cohesive force for a liquid and a solid is less than the value of cohesive force of the molecules of the liquid, the liquid is unable to moisten that solid. For example, mercury does not stick to glass, because the cohesive force between the molecules of mercury and the glass is less than the cohesive force between the molecules of mercury.

Molecular Range- The maximum distance (10^-9 m) at which two molecules attract each other is called molecular range.

## Effects on Surface Tension-

The following factors have an effect on the surface tension:

1. Effect of Contamination –if on the surface of the water
If there is dust, some lubricant (grease or oil), then it reduces the surface tension of water.
2. Effect of Solute – If the solute is too soluble, the surface tension of the liquid increases. If the solute is less soluble, then the surface tension decreases. For example, the surface tension of water decreases when soap or phenol is added.
3. Effect of Temperature-The value of cohesive force decreases with increase in temperature. Due to which the surface tension decreases.

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