Angle of contact `(theta)`
For a solid and a liquid, it is defined as the angle between tangent to the liquid surface and that to the solid surface inside the liquid drawn at the point of contact. It `theta` is acute for glass-water interface and obtuse for glass-mercury.
`text(Case -1)` when `theta < 90^o` liquid curve up
The liquid surface and the liquid will have concave meniscus in the solid tube
This results when the force of cohesion between two liquid molecules is less than force of adhesion between the liquid and the solid.
`text(Example)` Glass and water.
`text(Case -2)` when `theta > 90^o` liquid curve dawn
The liquid surface gets curves down in contact with solid.
When liquid is poured in solid tube, convex meniscus is obtained.
Force of cohesion is greater than the force of adhesion
`text(Example)` Glass and Mercury
`text(Case -1)` when `theta < 90^o` liquid curve up
The liquid surface and the liquid will have concave meniscus in the solid tube
This results when the force of cohesion between two liquid molecules is less than force of adhesion between the liquid and the solid.
`text(Example)` Glass and water.
`text(Case -2)` when `theta > 90^o` liquid curve dawn
The liquid surface gets curves down in contact with solid.
When liquid is poured in solid tube, convex meniscus is obtained.
Force of cohesion is greater than the force of adhesion
`text(Example)` Glass and Mercury