Thin-film interference pattern shown by bubble film, 1980-2000.
© Science Museum / Science & Society Picture Library
White light contains a range of different colours - wavelengths of electromagnetic radiation - that the human eye cannot distinguish. Waves can 'interfere' with one another, so that if two waves combine, they either reinforce each other (when the peaks of two waves coincide) or cancel one another out (when the peak of one wave coincides with the trough of the other). In thin bubble films, light reflected from one surface of the film interferes with light reflected from the other, resulting in a range of colourful effects known as an interference pattern, or fringe.