Book 3, Question 115
Why Do Bubbles Shimmer Then Pop?
A bubble is a super thin sandwich of water and soap, with air inside. Light bounces off that thin skin and mixes into rainbow colors, until the wall gets too thin and breaks!
From the book
Page from A Million Whys Book 3
More fun facts
- A bubble is a thin film of soapy water with air inside.
- White light is made of all colors. When light bounces off both sides of a bubble's thin skin, some colors cancel out and others shine.
- The colors you see on a bubble depend on how thick its film is, so the colors swirl and change as it thins.
- Just before popping, a bubble's film can get so thin that part of it looks black.
- The same light effect makes the colors in some bird feathers, insect wings and oil puddles after rain.
- A bubble can pop even without touching anything, because the water in it slowly evaporates and the film gets weaker.
Sources: Exploratorium, Scientific American
Questions kids ask
Why does a bubble turn dark before it pops?
As the film gets extremely thin, light reflecting off its two sides cancels out, so that part looks black. That means it will pop soon.