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Lavalamp Facts for Kids Video


                                                     Lava Lamp

The lava lamp was invented in 1948 by Edward Craven Walker. Originally, it was known as Astro Globe. It is an ornamental accessory that has two liquids of different intensities. A lava lamp contains bubbles that float and sink in a liquid. It is pretty fascinating not because it is so mesmerizing but because it provides a concrete illustration of an essential law of physics, the Archimedes Principle. Varying the densities of bubbles and in turn varying their buoyancy.

How Does It Work?

The idea behind it is simple and extremely clever. The trick is to constantly change the density of the lava. When the lava is less dense than liquid, it floats and rises to the surface. When it is denser, it sinks to the bottom. The lamp uses heat to change the volume of the lava. The best way to understand it is to take it apart.

The lava is essentially a mixture of coloring and wax. The translucent liquid is mainly water. Two liquids with almost the exact same density but the wax is slightly denser. It means for the same volumes of water and wax, the wax is slightly heavy. It also means that the wax should always be at the bottom of the lamp. At the bottom of the lamp, a bulb lights up the show and heats up the wax. Heat is the key of varying the density. A twisted metal wire transmits the heat of the bulb to the wax. The molecules of wax become agitated by taking up more and more room. As result, the wax expands. The volume of the wax increases even though its weight is exactly the same. The wax is now less dense than the water and no longer sinks.

The Archimedes Principle states that when an object like a wax bubble is immersed in water, it is pushed upward with a buoyant force equal to the weight of the water being displaced. Water is pushing on all sides of the object but the strongest push is upward because the water pressure increases as we move deeper. The larger the volume of an object, the more water it displaces. The more water it displaces, the strongest the buoyant force pushing it upward. If the object is heavier than the water it displaces, it sinks. If the object is lighter than the water it displaces, it starts to float. As the principle behind the lava lamp, cold wax is heavier than the water being displaced so it sinks. When the wax is heated, the volume increases and displaces more water and increasing buoyant force. The weight of the water displaced by the heat bubble is now greater than the weight of the bubble.



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Declan, Tobin. " Amazing Facts for Kids about Lava Lamp ." Easy Science for Kids, Jul 2020. Web. 03 Jul 2020. < >.

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Tobin, Declan. (2020). Amazing Facts for Kids about Lava Lamp. Easy Science for Kids. Retrieved from

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