How and why do lava lamps work?

Question

This is for my Science NCEA level, so I really need as many different reasons as possible, and not the stuff from Wikipedia, as I've alreadt got that.

Answer 1

The lamp consists of an illuminating bulb, and a glass bottle containing a transparent liquid, translucent wax, and a metallic wire coil. The glass bottle sits on top of the bulb, which heats its contents. The metallic wire coil is hidden in the base of the lamp, which the glass bottle is sitting on.

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

The light bulb heats the container at the bottom, and due to heat exchange with the atmosphere, the container eventually dissipates the introduced heat. This method of heat transfer is called convection.

Wax at the bottom heats until it melts, and eventually becomes less dense than the liquid above it. At this time, a portion of the wax rises towards the top of the container. Near the top, away from the heat source, the wax cools, contracts, and as its density increases it begins to fall through the liquid towards the bottom of the container again. The difference in temperature between the top and bottom of the globe is only a few degrees.

One mass of wax may rise as another falls. The metal coil at the bottom helps to overcome the surface tension of the individual wax droplets, causing the descending blobs to agglomerate into a single molten wax mass at the bottom of the container. The cycle of rising and falling wax droplets continues so long as the bottom of the container remains warm and the top of the container remains cool. Operating temperatures of lava lamps vary, but are normally around 60 °C (140 °F). If too low or too high a wattage bulb is used in the base, the "lava" ceases to circulate, either remaining quiescent at the bottom (too cold) or all rising to the top (too hot).

Chaotic behaviour makes the movement of the wax unpredictable—hence lava lamps can aid in the generation of one-time pads for cryptographic use.

The colour of the wax and the liquid often varies and can be found in many different combinations.

Answer 2

There is a light at the bottom.. It heats up the liquid as well as the lumps of denser liquid.. They get carried up by the flow of the liquid created by the heater lamp. They reach the top and the fluid cools and the denser lumps fall back down with enough momentum to reach the bottom and the flow back up to the top.

Answer 3

In liquid lava it contains carbon,copper and other small amounts of other elements.In chemistry copper is known for its electrical conductivity.If u want to prove me wrong u can extract copper from magnets,conduct a electric circuit and see if the light bulb lights up...

Answer 4

Simple as heat rising!

The wax substance heats and expands from the light in the base.
When it becomes more buoyant than the surrounding fluid, it rises.
Away from the light it begins to cool and falls.
It is very gelatinous and coagulative, so it makes the moving "Blobs" you see.