Oh wow, groovy man! It’s a blast back to the 1970s, and you want to know what makes a Lava Lamp—officially called a Lava Lite®—flow.
The physics can get complicated and mathematical, but what’s mainly at play with any Lava Lamp: buoyancy. When something has a higher density than what surrounds it, it sinks. Likewise, if something has a lower density, it rises up. Science geeks call this the Archimedes Principle.
Look at your Lava Lamp, and you will see the wax substance in the bottom of the container. Edward Craven Walker, inventor of the Lava Lamp, needed a way to vary the density of the wax. The obvious choice was heat. Heat causes materials to expand in volume, and lose density.
When you turn the lamp on, the bulb in the base slowly heats the wax, lowering its density. Eventually, the wax gets warm enough to rise in the liquid. As it reaches the top of the container, the wax slowly cools to a point where it becomes slightly denser than the liquid, sinking back down to be reabsorbed and repeat the process. That’s really all there is to it! Temperature causes the wax to rise and fall.
Well actually, there is just a bit more to it. Initially the two ingredients, the wax and the liquid, need to be almost equal in density. This is where the real chemistry of Lava Lamps exists, and manufacturers do not divulge the formulas they use to create their fascinating masterpieces. Many attempts have been made to replicate it, and there are several guides on how to build your own Lava Lamp, however none likely function as well as the real thing. If you get curious and decide to make your own, remember that you are dealing with chemicals and heat. Please be careful!
If your Lava Lamp isn’t working, there are a few factors at play. New lamps need to be warmed several times before the wax breaks in and can expand to its lightest density. Also consider ambient temperatures. Cold outside temperatures will make it hard for the lamp to warm up; a direct breeze or draft can also hinder your Lava Lamps performance.
Lava Lamps have given decades of enjoyment to enthusiasts around the world. Today there are so many variations available; from modern stylistic lamps to giant four-foot-tall monsters, Lava Lamps are guaranteed to entertain, mesmerize, and now, launch stimulating scientific conversation.
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Sources:
http://www.lavalamp.com/
http://www.grc.nasa.gov/WWW/K-12/WindTunnel/Activities/buoy_Archimedes.html
http://www.howstuffworks.com/lava-lamp.htm
