If angle of contact of a drop of liquid is acute, then

Explanation:

When the adhesion force is more than the cohesion force then the fluid will wet the surface and the angle of contact between the fluid and the surface will be less than 90° (acute).

\(h = \frac{{4\sigma cos\theta }}{{wd}}\)

Graphically Capillarity can be represented as:

Case – 1:

when contact angle θ is acute i.e. θ < 90° 

In case of wetting fluid, the level in the capillary tube will rise and the phenomenon is capillary rise. For water and clean glass tube θ = 0°.

Case – 2:

when contact angle θ is obtuse i.e. θ > 90°

In case of non – wetting fluid, the level in capillary tube will fall and the phenomenon is capillary fall. For mercury glass tube θ = 128°.