Surface Tension Formula

Introduction to Surface Tension

Surface tension is the physical phenomenon that involves the surface of a liquid behaving like an extended elastic membrane. It arises due to the cohesive forces between liquid molecules. This property has the effect of the liquid behaving in such a way as to reduce its surface area, hence the spherical droplets of water.

Formula For Surface Tension 

The formula for finding surface tension is given as,

Where,

• T= surface tension(N/m)

• F = force per unit length (N)

• l=length in which force acts(m)

Surface Tension Solved Problems

Solved numerical related to surface tension are provided given below:

Problem 1: Calculate the surface tension of a given liquid whose dragging force is 5N and length in which the force acts is 2cm?

Solution:

Known values are,

F = 5N and L= 2cm

The formula for surface tension is

Problem 2: The film of a soap is stretched across a wire frame and exerts a force of 0.02 N. The length of the film is 0.05 m. Calculate the surface tension of the soap film,  knowing that this film has two surfaces.

Solution:

Formula for surface tension is:  

Use the formula for surface tension, making notations that the soap film has two surfaces:  

  

Known values are,

F = 0.02N and l= 0.05

Therefore,

Surface Tension =0.2 N/m