Lava lamp
A lava lamp is a lamp which is typically used more for decoration than illumination. It consists of two parts: the actual lamp, and a container (typically a glass bottle) containing a liquid, some wax, and a metallic coil. The container is placed on the actual lamp, which heats the metal coil (now resting at the bottom of the container).
The wax and the liquid have similar densities. However, the wax has a slightly higher density than the liquid when the wax is cool, and a slightly lower density than the liquid when the wax is warm. This is due to the fact that most substances expand when heated, but at different rates.
The container is heated at the bottom, and due to heat exchange with the atmosphere, the container is also cooled down.
Wax at the bottom heats up until the density of the wax is less than that of the liquid, at which time the wax rises to the top. At the top, the wax cools down, due to the atmosphere, and the density again drops until the wax again falls. There may be both wax rising and wax falling at the same time. The behaviour of the wax is unpredictable, due to chaotic behaviour (hence lava lamps have been used to manufacture one-time pads for cryptographic use).
The original and best known lava lamp, called the Lava Lite®, was invented in the 1960s by an Englishman named Edward Craven Walker. He named it the Astrolight and presented it at a Hamburg trade show in 1965, where it was noticed by entrepreneur Adolph Wertheimer. Wertheimer and his business partner Hy Spector bought the American rights to the product and began to produce the Lava Lite, via a corporation called Haggerty Enterprises and trading under the name Lava World International®. The lava lamp became an icon of the Age of Aquarius.
In 2002, the town of Soap Lake, Washington announced preliminary plans to construct the world's largest lava lamp (60 feet in height) as a tourist attraction. Some critics, however, believe a lava lamp this large is not feasable in terms of materials needed to make it, and energy consumed.
See also: Plasma lamp
External links
- A site with information on "lava lamps", including How to make your own "lava lamp"
- GiantLavaLamp.com—Web site promoting the Soap Lake idea