Surface Tension and Free Surface of a Liquid

Surface tension is the property of a liquid that enables it to resist an external force. It is the force that acts per unit length on an imaginary line drawn on the surface of the liquid. The free surface of a liquid refers to the surface of the liquid that is not in contact with any other surface. The free surface of a liquid tends to contract to the smallest possible area due to the force of surface tension.

Explanation

Surface tension is caused by the cohesive forces between the molecules of the liquid. The molecules at the surface of the liquid experience a net inward force due to the cohesive forces between the molecules in the bulk of the liquid. This inward force causes the surface of the liquid to contract and form a shape that minimizes the surface area. The free surface of the liquid tends to contract to the smallest possible area because the surface tension force acts perpendicular to the surface of the liquid at every point.

Surface tension is responsible for many phenomena that we observe in our daily lives, such as the formation of droplets, capillary action, and the meniscus in a graduated cylinder. It is also responsible for the shape of water droplets on a surface, which are spherical due to the minimization of surface area.

Conclusion

In conclusion, the free surface of a liquid tends to contract to the smallest possible area due to the force of surface tension. This property of liquids is caused by the cohesive forces between the molecules of the liquid and has many practical applications in our daily lives and in various fields of science and engineering.

Because of the property of a liquid, that is cohesion, the molecules of the liquid tend to attract away from the surface of glass. Hence, this property, by which liquid molecules on the free surfatce tend to contract to the smallest possible area. Another question is, adhesion is not equal to cohesion. So the free surfatce of a liquid tend to contract to smallest possible area.