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Surface Tension

Surface tension

It is the force of attraction(cohension) between the similar surface particles of fluid which forms films .

Reasons : various forces such as vanderwaal forces , hydrogen bonding forms web of water molecules on the surface.

Concept :
At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). The net effect is an inward force at its surface that causes the liquid to behave as if its surface were covered with a stretched elastic membrane. 

Eg. A. Ants and other spinder walk through surface of water.
   
   B. Rain drop has a  shape

Additional Information :
Its dimension is same as that of force per unit length

Water has surface tension of 72.8 milli newtons at 20 degree centigrade

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