Let h be the capillary rise in fall in a tube of diameter ‘d’ centre surface tension force in upward direction.



P = πd σ cos Ѳ

Weight of liquid column = V. γ

= ( π/4d² x h) γ

Where γ  = specific weight of liquid

Under equilibrium, the weight of liquid column will be balanced by surface tension force 'σ '

Weight of liquid = Surface tension

π/4d² hγ = πdσcosѲ

h = 4σcosѲ / γd

For pure water in contact with clean glass and air, Ѳ = 0

h = 4σ / γd

For mercury and glass, Ѳ  = 140⁰

Capillary rise in a gap between two closed spaced parallel plates:

h = 2σcosѲ / γt              Where ‘t’ is the gap between the plates.

For more help in Expression for Capillary Rise click the button below to submit your homework assignment