I love #bubbles - but have you ever wondered why bubbles have such beautiful colours and why they change? The colours of a bubble depend on the thickness of the bubble film. A bubble becomes thinner and thinner as it dries out (due to evaporation), before finally popping. As the surface film of the bubble becomes increasingly thinner, you can see a change in overall colour of the #bubble. Thicker walls cancel out longer wavelengths in the red range. As the bubble film gets thinner, yellow wavelengths are cancelled out. As it gets even thinner, green light is lost. Beyond this point, even shorter wavelengths in the blue wavelength range disappear. The resulting colours are a combination of the colours that don't undergo destructive interference and their degrees of constructive interference. Blue-green colors dominate in thicker films and yellow hues in thinner films. Eventually, the film becomes too thin to create interference of visible wavelengths, as all wavelengths are cancelled out. At this point the bubble appears colorless. And then - POP! #scicomm #bubblescience #lsuscifund #scienceathome #colours