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Question number 1: A soap bubble is black when it bursts, why? Answer: When a soap bubble bursts, it looks black due to destructive interference. When a bubble bursts, Its thickness becomes negligible, that is, thickness ≈ 0, and The condition for destructive interference is satisfied. $$2nt = m\lambda,\tag1$$ Where $n$ is the refractive index of ...

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The circles are droplets of fat (triglycerides: triesters of glycerol and fatty acids). The two phases (water and fat) are immiscible because the water molecules are more attracted (hydrogen bonded) to each other than to the fat molecules. Absent gravity, energy would be minimized by the droplets being spherical, but gravity flattens the droplets. The ...

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The real issue is that the cup wasn't really full so that adding anything more would make it spill. You can clearly see the the level slowly growing above the top of the cup, as would be expected due to surface tension. Eventually another coin finally exceeded the limit, and a little water spilled. There is really nothing extraordinary going on here. ...

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Edit: regarding your core question: no, if you drop a coin into a glass filled 'more' than the brim-level, such that any more water will cause it to spill, water will spill out. But, instead of a coin, if you insert something that has other properties that allow it to absorb water whilst not suffering any volumetric changes and has strong cohesive force ...

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An excellent resource for a theoretical foundation in capillarity and wetting (i.e. surface tension dominated phenomena) is the book by de Gennes et al.: P.G. de Gennes, F. Brochard-Wyart and D. Quéré, Capillarity And Wetting Phenomena - Drops, Bubbles, Pearls, Waves, 2003, Springer In the first chapter it deals with the first three questions you pose. You ...

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The reason is that the gas-liquid surface area is not the only surface area that is minimized. The total energy of the system (including only surface energies) is given by: $$E=\gamma_{lg} A_{lg}+\gamma_{sg} A_{sg} + \gamma_{sl} A_{sl}$$ Formation of a meniscus as opposed to a flat surface indeed increases $A_{lg}$, but, due to volume conservation, it ...

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