Light Interference in Soap Bubbles and Oil Films

Soap bubbles and oil films shine with rainbow colors due to light wave interference.
Light reflects off both the top and bottom surfaces of the thin film.
The two reflected waves overlap, sometimes reinforcing and sometimes canceling each other.
Different wavelengths interfere differently, creating shifting bands of color.
The thickness of the film determines which colors appear brightest at any point.
As bubbles thin out, colors change until they vanish, signaling the bubble’s collapse.
Oil slicks on water spread into swirling rainbow patches from the same interference effect.
The patterns move and shimmer because the film thickness changes with air currents and gravity.
Thin-film interference also explains colors in butterfly wings and peacock feathers.
These everyday rainbows reveal the wave nature of light in a vivid, playful way.