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.
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)
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
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