ANGLE OF CONTACT

The angle between the tangent to the liquid surface and the tangent to the solid surface at the point of contact is known as angle of contact.
The angle of contact is always measured through the liquid.

- If angle of contact = 90, then
   liquid will wet the walls of the vessel.
   the level of liquid will be horizontal in the capillary

- If angle of contact < 90, then
    liquid will wet the walls of the vessel.
    liquid will rise in the capillary tube.
    level of liquid in capillary tube will be concave.

- If angle of contact > 90, then
    liquid will not wet the walls of the vessel.
    liquid will fall in the capillary tube.
    level of liquid in capillary tube will be convex.