Lecture

Surface Tension in Soap Bubbles

Graph Chat

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

Description

This lecture covers the concept of surface tension, focusing on the behavior of soap bubbles. Starting with the definition of surface tension as surface energy and force, it explores Laplace's law, wetting phenomena, and the impact of gravity. The presentation delves into the Marangoni effect and the factors creating surface tension inhomogeneities. It also discusses the competition between gravity and surface tension, capillary length, and Jurin's law. The lecture concludes with a demonstration of capillary rise and the overpressure in soap bubbles.

This video is available exclusively on Mediaspace for a restricted audience. Please log in to MediaSpace to access it if you have the necessary permissions.

Watch on Mediaspace

Official source

Related concepts (29)

Surface energy

In surface science, surface free energy (also interfacial free energy or surface energy) quantifies the disruption of intermolecular bonds that occurs when a surface is created. In solid-state physics, surfaces must be intrinsically less energetically favorable than the bulk of the material (the atoms on the surface have more energy compared with the atoms in the bulk), otherwise there would be a driving force for surfaces to be created, removing the bulk of the material (see sublimation).

Capillary action

Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube such as a straw, in porous materials such as paper and plaster, in some non-porous materials such as sand and liquefied carbon fiber, or in a biological cell.

Surface tension

Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to float on a water surface without becoming even partly submerged. At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). There are two primary mechanisms in play.

Capillary length

The capillary length or capillary constant, is a length scaling factor that relates gravity and surface tension. It is a fundamental physical property that governs the behavior of menisci, and is found when body forces (gravity) and surface forces (Laplace pressure) are in equilibrium. The pressure of a static fluid does not depend on the shape, total mass or surface area of the fluid. It is directly proportional to the fluid's specific weight – the force exerted by gravity over a specific volume, and its vertical height.

Bubble (physics)

A bubble is a globule of a gas substance in a liquid. In the opposite case, a globule of a liquid in a gas, it's called a drop. Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance. Bubbles are seen in many places in everyday life, for example: As spontaneous nucleation of supersaturated carbon dioxide in soft drinks As water vapor in boiling water As air mixed into agitated water, such as below a waterfall As sea foam As a soap bubble As given off in chemical reactions, e.

Related lectures (26)

Gas/Liquid Interface: Fundamentals

Covers the fundamentals of gas-liquid interfaces, including surface tension and capillary action.

Soil Sciences: Porosity and Water Interactions

Explores porosity in rocks, water retention, and soil-water interactions.

Capillarity and Surface Tension

Covers capillarity, capillary rise, wetting, non-wetting, and surface forces.

Capillary Action: Lucas Washburn Equation MOOC: Sorption and transport in cementitious materials

Covers forced flow along a capillary and the Lucas Washburn equation.

Surface Tension: Fundamentals and Applications