Question

Molecular forces exist between the molecules of a liquid in a container. The molecules on the surface have unequal force leading to a tension on the surface. If this is not compensated by a force, the equilibrium of the liquid will be a difficult task. This leads to an excess pressure on the surface. The nature of the meniscus can inform us of the direction of the excess pressure. The angle of contact of the liquid decided by the forces between the molecules, air and container can make the angle of contact.
The direction of the excess pressure in the meniscus of a liquid of angle of contact `2pi//3` is
A. upward
B. downward
C. horizontal
D. cannot be determined

Answer 1

Correct Answer - A
Excess pressure is always on the concave side of the surface For angle of contact of `(2pi)/(3)`, the liquid should have a convex surface. Do the excess pressure should be in the upward direction.