Surface tension is the force exerted on a liquid's surface film as a result of the attraction of the liquid's bulk to the particles in the surface layer, which tends to reduce surface area.
The lower surface tension of soaps and detergents allows them to spread across a wider surface area while also effectively removing debris.
It is the tangential force acting on unit surface length i.e. where is the force acting on the surface length .
In SI system, the unit of Force is Newton denoted as and the unit of length is Meter denoted as . Therefore the SI unit of surface tension is Newton per meter denoted as .
Hence, the SI unit of surface tension is Newton per meter.