For a small liquid drop, the surface tension is predominant and the effect of gravity is negligible. But in case of a large drop, the gravity becomes influential because of the weight of the liquid drop itself. Therefore, the drop is flattened and attains an equilibrium state in which the upper surface of the drop is horizontal. [Note: A drop is called a sessile drop when it is attached to its base.] #### Mathematical Expressions for the shape of a Large Sessile Drop