Interference
Interference is the superposition of two or more waves that penetrate each other. One example of this is soap bubbles: a soap bubble shimmers in a wide variety of colors. This dynamic play of colours is created by the simultaneous reflection of light from the inner surface and the outer surface of the soap bubble. Both surfaces are very close to each other, as the soap bubble skin is only a few micrometers thick. The light reflected from the inside of the soap bubble has to travel a longer distance than the light reflected from the outer layer. When the light waves reflected from the inner and outer surfaces meet, they overlap. Depending on the thickness of the soap skin, this weakens or erases some parts of the light spectrum (destructive interference), while strengthening other parts (constructive interference). There are visible color differences that are reflected by the soap bubble. This superposition of light rays caused by the reflection is called the interference effect – a principle according to which optical thin layers are also applied.
