Soap Bubbles
Soap Bubbles, bubbles of air enclosed in a film of soapy water. Soap bubbles are made for recreational and scientific purposes. In science, soap bubbles are used to study the properties of films, to demonstrate simple geometric relations, and to solve mathematical problems related to optical lenses and electrical circuits.
Soap bubbles are made by blowing air into a film of soapy water. A simple bubble solution consists of soap, glycerin, and water. The glycerin makes the bubbles more durable. Commercially prepared solutions and devices for blowing bubbles, usually wire rings, are available. The ring is dipped into the soap mixture until a film forms across the ring. Air is then blown into the film to make a bubble. In scientific work, bubble solutions often contain many ingredients and blowing devices are often complex.
Soap bubbles are spherical in shape because of surface tension. The air trapped inside a bubble is under compression. As the air escapes, the bubble tends to shrink uniformly until it collapses. However, gravity drains the water from the top of the bubble. When the film becomes too thin to support the heavier lower portion, the bubble bursts.
The iridescent colors of a soap bubble are produced by the interference of light, which is the effect caused by the joining together of two waves of light. Light reflected from the outer surface of the film combines with that reflected from the inner surface. The shimmering effect is caused by the changing thickness of the film.