schuimbellen

Schuimbellen, often simply called bubbles, are spherical films of liquid enclosing air or gas. They are a common phenomenon observed in everyday life, from washing dishes to the froth on a beverage. The formation of schuimbellen relies on a surfactant, a substance that reduces the surface tension of a liquid. Water alone has a high surface tension, making it difficult to form stable bubbles. When a surfactant like soap is added, it aligns itself at the liquid's surface, weakening the cohesive forces between water molecules.

The bubble itself is a thin film of liquid, typically water mixed with a surfactant. This film has two surfaces, an outer and inner one, and the surfactant molecules are arranged between them, with their hydrophilic (water-attracting) heads facing the water and their hydrophobic (water-repelling) tails pointing inwards. This structure creates a stable, yet delicate, membrane.

Light interacting with the thin film of a schuimbellen causes interference patterns, resulting in the iridescent colors often seen. Different colors appear due to the varying thickness of the film; certain wavelengths of light are reflected and constructively interfere, while others are destructively interfered. As the bubble thins due to evaporation or drainage of the liquid, the colors shift and eventually disappear before the bubble bursts. The bursting is caused by the instability of the thin film, which eventually ruptures.