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Engineering ToolBox > Capillarity

Capillarity or capillary action is the ability of a narrow tube to draw a liquid upwards against the force of gravity

Capillarity or capillary action is the ability of a narrow tube to draw a liquid upwards against the force of gravity.

The height of liquid in a tube due to capillarity can be expressed as

h = 2 σ cosθ / (ρ g r) (1)

where

h = height of liquid (ft, m)

σ = surface tension (lb/ft, N/m)

θ = contact angle

ρ = density of liquid (lb/ft³, kg/m³)

g = acceleration due to gravity (32.174 ft/s², 9.81 m/s²)

r = radius of tube (ft, m)

Surface Tension

Surface tension is typically measured in dynes/cm or N/m.