# What is Surface Tension in Physics | Definition, Formula, Units – Surface Tension

Surface Tension:
Surface tension is the property of any liquid by virtue of which it tries to minimise its free surface area.

Surface tension of a liquid is measured as the force acting per unit length on an imaginary line drawn tangentially on the free surface of the liquid.

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## What is Surface Tension in Physics | Definition, Formula, Units – Surface Tension

Surface Tension formula:

Surface tension, S= $$\frac{\text { Force }}{\text { Length }}=\frac{F}{l}=\frac{\text { Work done }}{\text { Change in area }}$$

Where,
S is the surface tension of the liquid
F is the force per unit length
L is the length in which force act

Surface Tension units:
SI unit is Nm-1 or Jm-2
CGS unit is dyn/cm

Surface Tension Dimensional Formula:
Dimensional formula is [MT-2].

It is a scalar quantity. Surface tension is a molecular phenomenon which is due to cohesive force.

Surface tension of a liquid depends only on the nature of liquid and is independent of the surface area of film or length of the line considered.

Small liquid drops are spherical due to the property of surface tension.

### Some Phenomena Based on Surface Tension

1. Medicines used for washing wounds, as dettol, have a surface tension lower than water.

2. Hot soup is more tasteful than the cold one because the surface tension of the hot soup is less than that of the cold and so it spreads over a larger area of the tongue.

3. Insects and mosquitoes swim on the surface of water in ponds and lakes due to surface tension. If kerosene oil is sprayed on the water surface, the surface tension of water is lowered and the insects and mosquitoes sink in water and are dead.

4. If we deform a liquid drop by pushing it slightly, then due to surface tension it again becomes spherical.

5. The detergents are used for cleaning the dirty clothes. The molecule of detergent can attached with water and dirt molecules and they take away the dirt with them, when we wash the clothes with detergent.

Surface Tension:
In Physics, the tension of the surface film of a liquid because of the attraction of the surface particles by the bulk of the liquid, which tries to minimize surface area is called surface tension. When the surface of the liquid is strong enough, then surface tension is applicable. It is strong enough to hold weight.