What's in a Lava Lamp and how does it work?

Question

What's in a Lava Lamp and how does it work?

Answer 1

According to Wikipedia:

"....The lamp consists of an incandescent bulb which heats the contents of a tapered glass bottle containing water and a translucent mix of wax and carbon tetrachloride (although other combinations may be used). A metallic wire coil which is hidden in the base of the lamp both furthers the necessary heat convection and suspends the falling blobs of liquid wax.

The wax is slightly denser than the water at room temperature, and slightly less dense than the water under marginally warmer conditions. This occurs because the wax expands more than the water when both are heated.

Since common wax is much less dense than water and would float at any room temperature, a heavy, nonflammable solvent is added to adjust the wax density to be slightly higher than that of water...."

In short...the bulb & coil heat the wax... causing it to float to the top. There it cools a bit and sinks back to the bottom.... where it becomes heated again and floats to the top again....and so forth.