Lava Lamps

Hi Everybody,

I have had many questions pop up in the Science Box.  I wanted to start off with something fun. 

You all made volcanoes in class and had many questions about how volcanoes work.  Now someone has asked about a close friend of the volcano, the lava lamp.  I know that I have spent plenty of time watching the “bubbles” in a lava lamp rise and fall.  Can you tell me why that happens?  Make your predictions now!

Question 1:

In a lava lamp, is it actually lava? What do they make lava lamps out of?

No, but it does look like lava!  The stuff inside a lava lamp is a waxy mixture that is surrounded by a colored watery liquid.

Question 2:

How do they make the lava lamps different colors?

The water liquid in the lamp is what is colored.  Then when light shines through the lamp, it makes the waxy substance (lava) inside the lamp look like a similar color.

So what makes a lava lamp work? Lava lamps work because the cool wax at the bottom of the lamp is more dense than the liquid surrounding it.  When the light is turned on, the light bulb warms the wax.  When the wax is warm, it is less dense than the liquid.  Bubbles of warm wax float to the top of the lamp. 

What happens when the wax floats to the top? 

Why does the wax float back down to the bottom of the lamp?

Watch this video to see the lava lamp in action and learn more about how the lava lamp.