Bubbles What are Bubbles exactly?

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In summary, bubbles are created by the interface of two fluids and have a membrane that exerts a force called "surface tension". This causes the bubble to be elongated and spherical.
  • #1

I am wondering what a bubble really is, considering a case of an air bubble in water as an example, what leads to the spherical appearance?

Why it doesn't blows up within the liquid?

thanks in advance.
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  • #2
Have you noticed that you can put a metal needle to float upon the surface of water, although if you push it a bit down, it will inexorably sink to the bottom?

In the interface of two fluids like air and water, there will be an ultra-thin layer of molecules that align themselves into a membrane.

This membrane will be able to exert a force we call "surface tension", which is the "culprit" in why the needle floats. If you add a bit of soap in the water when the needle is floating, it will begin to sink, because the soap destroys the watery membrane the needle rests upon.

As for why the air-filled bubble isn't squeezed to death, consider that as it becomes compressed, the interior pressure will INCREASE well beyond the ambient fluid pressure.

Thus, you will reach an equilibrium, in which the surface tension and ambient fluid pressure will try to collapse the bubble, whereas the interior pressure works in the opposite direction.

The sphericality of the bubble is mainly due to the tiny size of the bubble; the magnitude of the pressure doesn't vary much, either the internal pressure or the external pressure.

Thus, the pressure is equal in all directions, favouring the (almost) spherical shape.
  • #3
Bubbles aren't typically spherical unless they are very small. They aren't stationary - they rise and are therefore elongated as they travel through the water.

I'm not sure what you mean by "blows up with the liquid". Where would it go? A bubble is trapped air. If the bubble disintegrated, the air would still be there, so you'd get a lot of little bubbles instead of one big one. What holds bubbles together (and makes them join and governs their shape) is surface tension.
  • #4
Many thanks for your replies.

I apologize for my wrong sentence, I meant "blows up within the liquid"... which is quite answered by arildno...
  • #5
And whereas bubbles in liquids have one surface soap bubbles have two.Donald Glaser won a Nobel prize for inventing the bubble chamber.It is said that he was inspired by examining the bubbles in his beer.I get inspired by that sort of thing.
  • #6
Dadface said:
he was inspired by examining the bubbles in his beer.I get inspired by that sort of thing.

If that's all that it takes for a Nobel, I should have a dozen of the bloody things by now.
(Unfortunately, most of my beer-induced ideas no longer make sense when I sober up.)
  • #7
What, they didn't find their way to your alley?

What are Bubbles exactly?

Bubbles are spherical pockets of gas or air trapped in a liquid or solid material. They are formed when a liquid is agitated, creating surface tension and trapping air inside the bubble. Bubbles can also be created by heating a liquid, which causes the gas to expand and form bubbles.

How are Bubbles formed?

Bubbles are formed when a liquid is agitated, which creates surface tension and traps air inside the bubble. They can also be formed by heating a liquid, which causes the gas to expand and form bubbles.

What is the science behind Bubbles?

The science behind bubbles is related to the properties of liquids and gases. When a liquid is agitated, it creates surface tension which allows the liquid to hold the air inside the bubble. The shape of the bubble is determined by the balance between surface tension and the pressure from the gas inside. Bubbles also follow the laws of thermodynamics, with gas expanding when heated and contracting when cooled.

Why do Bubbles pop?

Bubbles pop when the surface tension can no longer support the air inside. This can happen when the bubble is exposed to air currents, touched by an object, or when the liquid starts to evaporate. The thinner the bubble wall, the easier it is for the surface tension to break and for the bubble to pop.

What are some real-life applications of Bubbles?

Bubbles have many real-life applications, including in cleaning products, food and beverage production, and medical procedures. They are also used in scientific experiments to study surface tension and the properties of liquids and gases. Bubbles are also popular for entertainment, such as in bubble shows and bubble blowing toys.

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