Capillarity and Wetting

This lecture covers the concepts of capillarity, wetting, and surface tension. It explains the contact angle, contact angle hysteresis, and the effect of surface energy on wetting. Various equations and surface energy states are discussed, including the Young-Laplace equation and the Young's Equation. The lecture also delves into different wetting states like Cassie-Baxter and Wenzel states, as well as the conditions for air pocket formation. The impact of surface inhomogeneity and roughness on wetting behavior is explored through examples like the Lotus leaf. The session concludes with a summary of the key learnings on contact angles and surface structures.