What is surface tension?
Answer
Surface tension is the property of a liquid by which its free surface behaves like a stretched elastic membrane, measured as force per unit length along the surface.
The working
Definition
Surface tension is the tendency of a liquid surface to shrink to the minimum possible area. It arises due to cohesive forces between liquid molecules.
Cause
Molecules inside the liquid are pulled equally in all directions, but surface molecules experience a net inward pull, keeping the surface taut.
Formula and unit
Surface tension (T) = force ÷ length = F ÷ L, with SI unit N/m. It can also be defined as surface energy per unit area.
Examples
It lets small insects walk on water and makes raindrops spherical, since a sphere has the least surface area for a given volume.
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