👉 In physics, capillary action refers to the movement of water molecules in a liquid. When a small amount of liquid is applied to a surface with high surface tension and its molecules are allowed to move through it, this phenomenon is called capillary action. In other words, when a substance forms on or near an interface between two liquids, it can exert forces that cause the substances to move past each other until they reach their final position. This effect is often referred to as capillary action or cap