How does the lava lamps bubbles form?

Answer 1

The bubbles in a lava lamp form as a result of convection current. Which is the movement of fluids caused by density differences. As the bubbles at the bottom heats up, its density decreases and therefore becomes buoyant and floats to the top. However as it gets to the top, it loses its energy because it's getting further away from the heat source at the bottom. Therefore its density increases and falls down, where it heats up and floats again. This cycle is continuous... as long as you keep the lamp switch on. or my answer is this.......

The lava effect is due to the interaction between the fluids used in the lamp. These fluids are selected on the basis of their density so one tends to barely float in the other. In addition, they are chosen based on their coefficient of expansion, so as they are heated one tends to rise or sink faster than the other. When heat from the light bulb warms the heavier liquid sitting on the bottom, it gets hotter and, due to its lower density, rises to the surface. By the time the "lava" reaches the top of the lamp, it begins to cool, becomes denser, and sinks to the bottom. As the lava sinks, it gets closer to the light bulb, heats up again, and the process is repeated over and over. Therefore, the key to successful lava lamp design is the selection of appropriate immiscible fluids. The exact composition used in lava lamps is a proprietary secret, but in general terms, one fluid is water based and the other is oil based. The aqueous phase may be water mixed with alcohol or other water-soluble solvents. The second fluid must meet a number of design criteria: it must be insoluble in water, heavier and more viscous, non-reactive and non-flammable, and reasonably priced. It must also be non poisonous, unchlorinated, not emulsifiable in water, and must have a greater coefficient of expansion than water.

While fluid selection does not change from lamp to lamp, there are design changes to be considered because lamps are available in different colors, sizes, and styles. The original Century model, which is still manufactured today, was the most popular model during the 1960s and 1970s. Its gold base is perforated with tiny holes which simulate starlight and its 52 oz (1.46 kg) globe is filled with red or white lava and yellow or blue liquid. A number of interesting variations on the Century have been manufactured in past years, although not all of them are still made today. For example, the Enchantress Planter Lava Lite lamp came equipped with plastic foliage. The Continental Lava Lite lamp which, was the only cordless, non-electric model, featured a candle to warm the lava. The Consort Lava Lite lamp, according to the company's 1970s catalog, was designed with a more masculine look "perfect for the study or den, so right for the executive suite." There was also the Mediterranean Lava Lite lamp, which was decorated with black wrought iron. In addition, Haggerty offers so-called giant lamps, which range in size up to 27 in (68.6 cm) tall.