Surface tension is the property of any fluid which attempts to minimize its free surface area. The surface tension of a liquid is measured as the force per length acting on an imaginary line drawn tangentially on the liquid's free surface.
Surface tension S = Force/Length which is equal to F/l in turn equal to work done/Change in area
SI unit: Nm-1 or Jm-2 and its dimension formula for surface tension is [MT-2].
The quantity is scalar. Surface tension is a molecular phenomenon that is electrical in nature due to cohesive force, and the root cause of force.
The surface tension of a liquid depends only on the nature of the liquid and is independent of the film surface or line length
Small drops in the liquid are spherical due to the surface tension properties.
The force of attraction that acts between the molecules of different substances is called adhesive force, e.g. the force of attraction that acts between paper and ink molecules, water and glass, etc.
The force of attraction acting between the same substance molecules is called a unified force. For example, the force of attraction between water molecules, glass molecules, etc.
Both Cohesive and Adhesive Forces are Van Der Waals’ Forces.
Surface tension is a tendency of the liquid surfaces to shrink to the minimum possible surface area. The surface tension has the force dimension per unit length or the energy dimension per unit area.
Dimensional Formula of Surface Tension
The surface tension dimensional formula is given by,
M = Mass
L = Length
T = Time
Surface Tension (T) = Force × Length-1 . . . . . (1)
Since, Force = Mass × Acceleration
And, acceleration = velocity × time-1 = [L T-2]
∴ Dimensional unit of surface tension = M1 L1 T-2 . . . . (2)
Substitute equation (2) in equation (1), later we get,
Surface Tension (T) = Force × Length-1
Or, T = [M1 L1 T-2] × [L-1] = M1 T-2.
Therefore, the surface tension dimension formula is represented as M1 T-2.