Question

If the capillary rise in glass tube of 22 mm diameter is 5.6 mm when immersed vertically in water the surface tension σ is 72.3 N/mm, calculate the angle of contact.

If the same tube is immersed in mercury that has 13.6 specific gravity and its surface tension σ is 510 N/mm, calculate the capillary rise in mm if the angle of contact is 136 ^o.

Answer 1

The relation between capillary rise and surface tension is given by the equation

Where h = Capillary rise

= Surface Tension

= Density of fluid

r = Radius of capillary tube

= Angle of contact

Case 1

Given :

r = 22/2 = 11 mm = 0.011 m

h = 5.6 mm = 0.0056 m

Surface tension = 72.3 N/mm = 72300 N/m and Density of water = 1000 kg/m³

Substituting in the above equation,

Solving,  

Case 2

Given,

Density = 13.6*1000 = 13600 kg/m³

Surafce tension = 510 N/mm = 510000 N/m

Angle = 136^o

Using the formula