| Definition: | at a point of a line on the interface of two fluids or a fluid and a solid, quantity equal to the derivative of the component F of the force, tangent to the surface and perpendicular to the line, with respect to curvilinear abscissa l, thus γ=dF/dl NOTE 1 The surface tension is equal to the work ΔW needed to expand the surface by an area ΔA, divided by ΔA, thus γ = ΔW / ΔA. NOTE 2 The coherent SI unit of surface tension is newton per metre, N/m or, equally, joule per square meter, J/m2.
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